Help 7.3 missing, no codes, did buzz and contribution tests

[Probuilder]

I have the FU chip and burner in a early 99 7.3 F 250- With DAC2 PCM.
I installed the chip and everything worked great for about 2 months.
I decided to reprogram different tunes on the chip, and change the order of them. When I reinstalled the chip everything seemed ok but I didn't try the 1200 rpm Hi Idle tune, until I was jumping hooking up my 18' car trailer, tune used to get he truck warmed up a little faster.
Once I switched the chip back to Heavy tow, the truck started missing on idle and all the way up through the rpms. EGT's were about 400 degrees higher than normal, running 1200 degrees running down the road @ 60mph on flat ground.
When I reprogrammed the 6 pos chip I didn't put the stock tune on it. I shut the truck off and reprogrammed the chip again, and just removed the one program and reburnt the stock program on the chip.
Now I have tried to remove the chip, while in stock setting, and then check for codes, I come up with nothing, no codes at all.
So I took the truck to a ford garage, after completely removing the chip from the PCM, they can't come up with any codes that are stored either and no pending codes.

Ford garage did a contribution test, #3 and #8 are only contributing 80% but the buzz test is perfect.
They told me that it was because of the chip tuning??????? That something was loaded wrong????? Is Ford right? I know the PCM is a DAC2 and we are installing DAC3 tunes to the chip????????

What do I need to do to get this truck back to stock, and running right?
I need to use this truck to pull my 34' and 16K goose neck construction trailer Tomorrow.

[907DAVE]

Do you have the "new" gray CPS?

Many people are experiencing issues with this CPS causing 3&8 CCT codes.

[F-127]

There isn't a problem with DAC3 tunes for DAC2 PCM.

Has it ever acted up without the chip?
Once it started missing, did it continue to miss until the chip was removed and run fine immediately afterwords?
Were all the files from the same family when you reburned the chip, ex. All VOAA7P6 tunes, and not a VOAA7P6 and something else?

My first gut reaction when reading the title of your thread was valve cover gasket(the connection though it). It could have happened to fail at the moment you flipped the switch. The connections on the valve cover gasket can be tempermental, running on all 8, miss for a while, then work perfectly again. There are two plugins, one for each bank, going into each valve cover. Maybe try putting some slight pressure on the plugin to see if either develops a miss, or if it acts up on you, try again to see if it clears up. I've done two valve cover gaskets in the past few weeks.

I see Dave posted about the CPS while I was typing this which is another good possibilty.

[Power Hungry]

Troy,

The files you're using have been on the server for some time with about a dozen people running it without issue, so I'd say we're pretty good with eliminating that as a problem. This leaves either a physical chip problem (most likely PCM connection), or something else wrong with the vehicle.

The chip connection is easy enough to verify. Just pull the chip (keep keys in your POCKET!), brush the contacts with little Scotch Brite, and reinsert. In many cases, that clears up any drivability problems.

Outside of that, there could be a variety of mechanical/electrical issues that could be causing you some trouble. Some popular ones are:

CPS
UVC Harness (This one is good for poor drivability along with high EGTs)
Injector O-Rings, copper washers, or cups leaking (Also high EGTs... happened to me recently!)
IPR (May cause drivability issues , but generally not higher EGTs)

One simple trick to isolate injector related issues is to remove the UVC connector on each side (1 at a time, of course) and see if there's a noticeable change in engine drivability. Usually this is related to very extreme cases where the engine is missing badly and has no power. If the engine is running smoothly at idle, then this is probably not the case and is usually something much less serious, although it might be a bit more difficult to track down.

If you can get us any more feedback on how the truck idles, runs at low speed, if it's missing and how severe, or any scan tool information at all, that would be helpful.

Give me a shout if you have questions and we'll see if we can get your truck figured out.

Take care.

[Probuilder]

Ok, Sorry should have given you more info.

Things that I have already tried:
1: changed out the CPS, no change after swapping that out.
2: changed the UVC's on both sides, still no change.
3:Unhooked the IPC- no change/ but has a small amount of oil inside the plug in.
4: Unhooked the MAT- no change
5: unhooked the IAT- no change
6: When I pulled the chip out it runs the same as with the chip in and on stock setting.
I have to turn the chip up to at least Daily Driver to get any power out of the truck.
7: unplugged one side at a time (UVC's) major change in the way the truck runs.
8: The truck has a Gray CPS in it now but I just swapped that out with a new Black one- still no change.

Now for more info on the way the truck runs:
It feels like it is missing on 1 or 2 cylinders only, No major knocking on one side or the other, of the motor. The motor will shake when idling, and all the way up through the rpm range. Loss of power through the whole rpm range, but seems to get a lot better when at 2200 and above, but might just be the power band of the motor.
No the truck has never acted up without the chip, until now.

9: Ok, when I pull the chip out of the truck, no matter what tune it is turned to, does that return the truck back to stock?
10: Or does the PCM still have the tune programmed into it?
11: This truck has never had an update done to it, the PCM, could that be a problem?
12: how do I check the IPR? Can I just unplug it, like the IPC and it go to Default?
I don't have a scanner that will read the truck codes, that is why I took it to Ford Garage. All I have for a scan tool is a Actron CP9180. It will come up with a lot of codes, but can't do the contribution tests or buzz test.
Ford garage came up with no codes present, except the one that tells them it had a tuner in it, so they told me.
13: How much do I have to spend on an AutoEnginuity software to diagnos these problems with the 7.3 motor/ truck. I already have a laptop computer.

Thanks for all the help, Troy You can call me at 319-432-4648

[Corey Cohron RIP]

Troy, Bill is out of town today through Sunday. He does have his laptop with him, though, so I'll let him know that you answered his post from yesterday, and we'll see what we can do. :)

[Corey Cohron RIP]

Ok, Sorry should have given you more info.

Things that I have already tried:
1: changed out the CPS, no change after swapping that out.
- Didn't think that was it, either.

2: changed the UVC's on both sides, still no change.
- That was a good effort. Was my first suspicion.

3:Unhooked the IPC- no change/ but has a small amount of oil inside the plug in.
- Oil is usually a sign of possible failing ICP, but only scan tool will be able to confirm.

4: Unhooked the MAT- no change
- MAT only has slight effect on injection timing. Nothing significant.

5: unhooked the IAT- no change
- Same with IAT.

6: When I pulled the chip out it runs the same as with the chip in and on stock setting. I have to turn the chip up to at least Daily Driver to get any power out of the truck.
- With chip removed, the PCM is completely stock.

7: unplugged one side at a time (UVC's) major change in the way the truck runs.
- Confirms that at least both banks are working. Now the question is, are all the injectors working?

8: The truck has a Gray CPS in it now but I just swapped that out with a new Black one- still no change.
- Again, didn't think this was going to be the problem, but didn't hurt to try.

Now for more info on the way the truck runs:

It feels like it is missing on 1 or 2 cylinders only, No major knocking on one side or the other, of the motor. The motor will shake when idling, and all the way up through the rpm range. Loss of power through the whole rpm range, but seems to get a lot better when at 2200 and above, but might just be the power band of the motor.

No the truck has never acted up without the chip, until now.
- It sounds like isolated cylinder miss. When running the Buzz Test, did you hear any cylinders that sounded different? Meaning... did any injectors sound "dull" or "softer" than others? When I had an injector issue with our truck, I was able to isolate which injector was the issue by doing a buzz test and listening for an injector that didn't sound the same as the rest.

9: Ok, when I pull the chip out of the truck, no matter what tune it is turned to, does that return the truck back to stock?
- Yes. See above.

10: Or does the PCM still have the tune programmed into it?
- No. See above above.:D

11: This truck has never had an update done to it, the PCM, could that be a problem?
- Highly doubtful. PCM calibrations don't just "go bad".

12: how do I check the IPR? Can I just unplug it, like the IPC and it go to Default?
- If you disconnect the IPR, the truck will not run. The IPR is a pressure regulator, and with it disconnected there will not be any pressure to the injectors. The only way to check the functionality is with a scan tool, and even then you may not be able to accurately diagnose an IPR problem versus an injector issue or other High Pressure Oil problem.

I don't have a scanner that will read the truck codes, that is why I took it to Ford Garage. All I have for a scan tool is a Actron CP9180. It will come up with a lot of codes, but can't do the contribution tests or buzz test.

Ford garage came up with no codes present, except the one that tells them it had a tuner in it, so they told me.
- Ford equipment doesn't tell them you have "tuner" on it. That's garbage. As for codes, driveability issues rarely set codes and you'll really need to be able to log PIDS such as ICP, IPR %, PWM, EOT, and maybe a few others in order to come to a conclusion as to which direction to look.

13: How much do I have to spend on an AutoEnginuity software to diagnos these problems with the 7.3 motor/ truck. I already have a laptop computer.
- Corey can help you with pricing on A/E.

Thanks for all the help, Troy You can call me at 319-432-4648
- I'm tied up at the moment but will be happy to give you a shout this afternoon when I'm back on the road.


Troy,

Please see replies above. I'll give you a shout this afternoon.

Take care.

[Probuilder]

No the truck has never acted up without the chip, until now.
- It sounds like isolated cylinder miss. When running the Buzz Test, did you hear any cylinders that sounded different? Meaning... did any injectors sound "dull" or "softer" than others? When I had an injector issue with our truck, I was able to isolate which injector was the issue by doing a buzz test and listening for an injector that didn't sound the same as the rest.

The buzz test sounds equal on all cylinders, but the contribution test showed that the #3 & #8 cylinder showed about 80%???????? Not sure what that means, but that is what the Ford Stealers said. But, I am not sure as I didn't hear it myself, and the Dealer may just be trying to sell me a new truck.


Ford garage came up with no codes present, except the one that tells them it had a tuner in it, so they told me.
- Ford equipment doesn't tell them you have "tuner" on it. That's garbage. As for codes, driveability issues rarely set codes and you'll really need to be able to log PIDS such as ICP, IPR %, PWM, EOT, and maybe a few others in order to come to a conclusion as to which direction to look.
Will the AE Software scanner do these tests?

13: How much do I have to spend on an AutoEnginuity software to diagnos these problems with the 7.3 motor/ truck. I already have a laptop computer.
- Corey can help you with pricing on A/E.
That would be great, I found the Ford kit on Sinister Diesel for $379.95 is that a good deal.

Thanks for all the help, Troy You can call me at 319-432-4648
- I'm tied up at the moment but will be happy to give you a shout this afternoon when I'm back on the road.
A phone call would be greatly appreciated. Even though it sounds like it isn't a problem with your chip or program. Your customer service is above and beyond what I expected!!!!!

[Corey Cohron RIP]

SP03 - Total Ford Bundle - is $359.96 + shipping. :) (Service ticket has been updated)

[Probuilder]

Groovy Chick,
What service ticket?

[Corey Cohron RIP]

The one started via Online Support.

[Probuilder]

Bill,
you wanted me to start an online support ticket for this problem, but I can't seem to log in to the support system. I don't know what my user ID and password are.

[88Racing]

Bill,
you wanted me to start an online support ticket for this problem, but I can't seem to log in to the support system. I don't know what my user ID and password are.
Your info from the forum doesn't carry over you have to register for it.
So click on registration and start a user account.

Closed the other thread.

[Probuilder]

I got the online support account setup, and listed.

Corey, Bill said that you could help with the AE scan tool order. I need to get that ordered so I can get that info to Bill, to figure out what is going wrong with this truck.
If I order the SP03 (Ford Bundle) will that also work on any ford from '96 up including cars?

[Probuilder]

Corey,
When I clicked on the link to purchase an AE SP03 it tells me that the link is broken??????
How do I purchase this?

[cleatus12r]

The link is fixed!!

[Probuilder]

The link still isn't working.
This is what I get when I click on the link.

[Corey Cohron RIP]

All fixed... your order should ship tomorrow. :happy-dancing:

[Probuilder]

Got the AE scantool today. Here r thr results.
P1280
P0237
P0113
p1119
P0475
P1211
P0541

On the buzz test the last 2 buzzes were dull in sound and not as fast as the others.

On contribution test, got these codes.
P0269
P0284
P0541
P0640

It sounds like the back 2 injectors are bad, correct?
But, codes come up as #3 and #8 aren't contributing as much?
So what do I do from here?
Do I need to do more tests?
Thanks

[cleatus12r]

Got the AE scantool today. Here r thr results.
P1280 ICP circuit out of range low (short to ground either in the sensor in the wiring harness....or no injection pressure after long crank times)
P0237 MAP sensor circuit problem.
P0113 Intake air temp sensor or circuit open.
p1119 Again, an intake air temp sensor or circuit open.
P0475 Exhaust Backpressure Valve malfunction (could be bad sensor or plugged pressure tube).
P1211 Not an issue. Normal for a chipped 7.3L
P0541 Intake air heater malfunction. Not an issue.

On the buzz test the last 2 buzzes were dull in sound and not as fast as the others.

On contribution test, got these codes.
P0269 #3 contribution
P0284 #8 contribution
P0541 Intake Air heater (no problem)
P0640 Intake air heater (no problem)

It sounds like the back 2 injectors are bad, correct?
But, codes come up as #3 and #8 aren't contributing as much?
So what do I do from here?
Do I need to do more tests?
Thanks


If you have a gray-colored camshaft position sensor, then #3 and #8 usually fail the CCT. It's just the nature of the beast.
Don't sweat the P1211 as it's normal for a chipped 7.3L to set this code after a hard run in a "hot" tune.
Also, the P0541 isn't important as it just shows up because of an intake air heater delete or disconnect. It IS a problem if you still have the heater and wiring intact.

[Probuilder]

It is a grey cps in it right now. Should I swap it out to see if that fixes the problem?
Or will it not make a difference when actually running?
Should I check the pressures on the ipr, ipc oil pressure, etc?

[907DAVE]

I would swap the CPS with a black or dark purple one, clear all codes and re-test.

The CPS will have no effect on the Buzz Test, but will effect the Contribution Test.

This is not going to cure you misfire issue, instead make things a little more cut and dry. It will eliminate the phantom 3&8 misfire that the gray CPS is know for.

But I am going to put my money on that #8 injector being bad.

Good Luck

[Probuilder]

Dave,
Did the CPS swap and retested.
Still got these codes:
KOER:
P0476 Exhaust Pressure Control Valve Range/ Performance
P0541 Intake Air Heater- Not used.
P0640 Intake Air Heater- Not used.

KOEO:
P0475 Exhaust Pressure Control Valve
P0640 Intake Air Heater- Not used.

On the buzz test the last 2 buzzes were dull in sound and not as fast as the others, just like before.

I don't have the FU Chip in the truck at all. I took it out to perform all tests.
Any help would be appreciated.
How do I test the ICP, IPR sensors? I know that you have info on here on how to perform all these tests, but I can't find it.

[SICKS-O]

i see that you posted you already did the UVC harnesses, did you replace just the injector/glow plug harnesses or did you do a valve cover gasket as well? a scan tool will only get you so far on a 7.3, but can point you in a direction, from there things are going to get more hands on. since cyl 7 and cyl 8 dont have a strong buzz that narrows things down a bit.

there are a few possibilities, wiring harness chafing, UVCH or valve cover gasket connector problem or injector failure.

i would first check for chafing of the engine wiring harness, particularly in the area above the drivers side valve cover where the junction block is. if there are any chafes repair them and retest. if the problem is still there unplug the engine harness from each valve cover gasket and test the resistance between the connectors and the appropriate pins at the junction block, the continuity should be good. if not that problem will need to be addressed. the next step is to check each valve cover gasket pin for each injector circuit (other than a dvm you may need a special tool that plugs into the valve cover gasket that is available, never tried doing it without it) the resistance should within a certain margin. (i cant remember the specific amounts off the top of my head). if the resistance is within spec there could still be an injector failure but possibly an issue with the engine harness between the valve cover gaskets and idm or the idm could just be no good.
if the resistance at the outside connection of the valve cover gasket is not within spec (specifically cyl 7 and 8) then you will need to pull the valve covers and unplug the UVCHs. test the resistance at each pin from both sides of the valve cover gasket connector to eliminate that as a possibility, obviously there should be no open circuits and should have good continuity. from there you want to test resistance at the UVCH connector itself to get another reading for each injectors coil resistance and see if it matches the reading you originally got from the outside. if it the resistance is now within spec there then is an issue that was over looked with the valve cover gasket itself or the engine harness. if the resistance is still not in spec you could go as far as testing the continuity of the uvch but more than likely the injector(s) have failed and need to be replaced.

if you get all the way to the injectors them self and the resistance and continuity tests have checked out good it is possible there is still an injector failure but since there isnt any hard evidence yet i would swap cyl 7 and 8 injectors with 2 other cylinders (using new o-rings and washers of course) then retest and see if the problem followed the injectors that were originally in 7 and/or 8. if the problem didnt follow those 2 injectors and stayed at 7 and/or 8 then things get more interesting. at that point the IDM is starting to look suspect but post back your evidence before i get into that lol.

good luck.

[Probuilder]

UVCH and gaskets were changed out.
Wiring harness between the IDM and valve cover gaskets has been changed out and tested, just did that last night. (Since I had an extra one laying around)

I will get a o-ring kit and swap out the injectors to let you know on that.

Thanks for the help

[SICKS-O]

no problem, did the best i could for 3am lol. since you have OKed the wiring before spending any money or getting your hands to dirty i would test the resistance of the injector coils with a digital volt meter, i dont think you will be able to do it easily without the tool they sell that plugs into the valve cover gasket, it has color coded pigtails for dvm leads. you may be able to make your own test harness if you have any spare harnesses laying around.
i think the easiest thing to do would be to uncouple the junction block that is on top of the drivers side valve cover and test the injector coil resistance from the pins on that block, of course you will need to know which pins are for the injector circuits. when i get another break at work i will grab our 7.3 service manual and post the acceptable resistance range for the injector coils. following this procedure will save you time and trouble. if the resistance of any of the injectors doesnt check out then you will know you will need to replace them, if the resistance is good there is still a chance that an internal part of the fuel injector(s) has failed and i will try to help you diagnose further.

-Joe

[Tempsho]

Lots of good information in this thread for troublshooting a 7.3L that's missing! Good luck with your problem and let us know what fixes it.

[Probuilder]

Does anyone have a link to a wiring diagram for the junction block above the drivers side valve cover? I am looking for one that will tell me which wires run to the injectors, to test them.

Sicks-0, First thank you for all your help.
Why am I getting a P0475 and P0476 code in the computer? What is this pressure valve? Now I am not getting the boost that I used to either, and the truck is consistently getting worse, as far as running and power.
KOER:
P0476 Exhaust Pressure Control Valve Range/ Performance
KOEO:
P0475 Exhaust Pressure Control Valve
Just a thought, but if my EBPV sticks when I am warming the truck up, it will smoke and have no power. Could this be a problem, and defueling the truck? Or would that not have an effect on the buzz test? (Probably not but just a 4 am thought that ran through my head when I quit working on it last night)

Again thank you all for your help.

[907DAVE]

I can shoot you some diagrams if you like, just need your e-mail address.

[Probuilder]

Dave,
Probuilder72@gmail.com
Thank you

[907DAVE]

You got mail.:)

[Probuilder]

I cleared all codes, reran the tests, KOER and KOEO. This was all done after checking the resistance on all injectors. They all come out the same and with in specs.

These are the new codes that I get with the AE Scanner on my laptop.
P0475
P1280 ICP too low.

Now on the idle I am running a Injection pressure of 481.96 psi and at 2200 rpm it is at 1153.2 psi. Do these numbers sound right?

The truck is the same as before, so no change.

[907DAVE]

Just for giggles try running it with the ICP disconnected......or have you done this already?

[907DAVE]

And just so we are all on the same page here - the truck is missing at idle and under load, correct?

Would you guess it is a steady miss, or more of a random misfire?

There are no more CCT faults?

No actual CEL when running?

[Probuilder]

And just so we are all on the same page here - the truck is missing at idle and under load, correct? correct

Would you guess it is a steady miss, or more of a random misfire? Steady

There are no more CCT faults? none

No actual CEL when running? no light

I will try the CCT with the ICP unplugged when I get back home.

But why is the P0475 code in there?

[907DAVE]

The P0475 indicates an Exhaust Backpressure (EBP) Control performance concern. Monitor the exhaust backpressure reading Key On Engine Off (KOEO) and at idle. This value should be equivalent to atmospheric pressure. A typical reading at sea level would be 14.6-14.8 PSI.

Monitor for an increase under load to see if increases, not to exceed approximately 35 PSI. If no increase is noted, check/replace the sensor and exhaust supply tube for carbon restrictions and recheck for proper operation.

This will not cause your misfire.

If you are feeling really ambitious you can pull both valve covers off and disconnect the injectors, one by one, with the engine running. You are looking for the one that doesn't change the way the engine runs, or has the least effect on it.

Kinda a crude way to do it, but gets the job done.

[Probuilder]

number 8 has almost no change to the engine. But the rest cause the motor to slow down and miss worse. So does that mean that the #8 injector is bad?
Also this truck has 342K on it. Would u just replace q injector or should I change all 8?
Can these injectors be changed out with a set from a 97 motor? I have a spare set of those laying around. So it would be a cheap fix for me. This truck is an early 99, build date of 5/98.

[907DAVE]

Yip, #8 injector bad.:woot:

As long as the injector "codes" are the same they are interchangeable.

[SICKS-O]

are 7 and 8 still giving a weak buzz? i would also do a compression test on cyl 8.

[SICKS-O]

number 8 has almost no change to the engine. But the rest cause the motor to slow down and miss worse. So does that mean that the #8 injector is bad?
Also this truck has 342K on it. Would u just replace q injector or should I change all 8?
Can these injectors be changed out with a set from a 97 motor? I have a spare set of those laying around. So it would be a cheap fix for me. This truck is an early 99, build date of 5/98.


do cyl 7 & cyl 8 still give a weak buzz?

the engine not running much different with #8 unplugged is a good clue, but doesnt tell us if the injector is at fault. i would suggest a compression test on that cylinder before going further.

i wouldnt replace anything until you have found the cause of your problem. if you do need an injector or 2 i would only replace whats failed. 8 new injectors are BIG money.

the simple answer is no. those are single shot injectors, unless theyre from a cali model. either way doesnt matter because the flow rating is different, 97-older 7.3 = 90cc injector, 99 = 120cc injector, 99.5+ 130cc injector.

you will need an AB model injector or a long lead injector for cyl 8 (if ford offers one).

[Probuilder]

Ok so you are saying that it maybe the compression and not the injector? Even though the buzz is very dull in sound, on the buzz test?
I will try to find someone that has a compression tester for these trucks.
I have just about had it with this truck, I am looking for a 7.3L that is newer so that I get more info from the scanner, than I do with the E99 systems.

[88Racing]

Is this resolved?

[cleatus12r]

I had left a bit of a resolution on the service ticket that Troy started, but have yet to hear back about it. If you can leave this thread open for a bit, I'd like to hear back from him myself.

[Probuilder]

Cody,
I have replaced the #7 and #8 injectors, but to no avail, I still have the problem. It don't seem to be as prominent, but still has the miss. I am in the process of going back through every check that everyone suggested prior to replacing the injectors. Does anyone know what this motor should have for compression, and what is acceptable?
I am about ready to buy a bow tie, if I cant figure this out. :matt-roloff:

[Power Hungry]

We need to get you down here for a weekend and see what's going on with your truck.

[Probuilder]

you are a long way away from me. Otherwise I would get it to you, to figure out.
I am looking at a different truck, that way I don't have these problems.

[cleatus12r]

Troy,

You need AT LEAST 340 PSI while the engine is luke warm. A HEALTHY engine will usually be in the 370-400+ PSI range. Anything lower will usually cause a miss until the engine warms up or the boost comes up a little bit.

Low compression will usually be accompanied by white smoke from the exhaust that burns your eyeballs if you stick your face in it.

[SICKS-O]

did you do a buzz test with the new injectors in 7 & 8?

[Probuilder]

SICKS-O did you do a buzz test with the new injectors in 7 & 8?
Yes all good.

Here is what I have done since last post.
Did the buzz test, everything sounds good on all 8 cylinders. Contribution test is good on all 8 also.
I am lost as to what is going on here.
Now the truck doesn't have the miss, but also has very low power even with the FU chip on 100 hp setting. It feels like the chip isn't even in the truck. my boost used to go to 26-28 psi now it only goes to 15 psi max, blows black smoke really bad. Even smokes on the idle, it is also black, sitting in garage for 3 to 5 minutes, when warm and idling, will burn your eyes really bad.
Oh MPG is down to average of 8.

I took the new injectors out of 7 and 8, put old ones back in, truck still has no miss, but the rest is still the same- no power, smokes on idle when warm, smokes driving it, with the FU chip in.

Take chip out and everything runs perfectly. No smoke, no miss, nothing, and has power, contribution test good, buzz test good, boost up to 26psi, 16 mpg average. I am LOST

Any ideas now? Ready to trade truck off, but can't with it running like this.

Could there be thick oil trapped in a injector boss that causes the solenoid to buzz correctly but injector not work right??????

[Probuilder]

I have also thought that it was the chip connection. So I have pulled the chip out and reinstalled it, after checking the connections, still no different.

[Probuilder]

injection pressure is @ 730 psi, when cold, then drops to 602 when warm.
Now injector buzz test when engine cold:
1,2,3,5,6 all buzz good.
4,7,8 buzz slow.
When engine warmed up:
All buzz perfect, with new injectors in 7 and 8.

Could this be an oil problem in the rails?
Compression on all 8 cylinders is good: Cold - between 375 psi and 389psi
Warm: 378 psi and 387 psi.

When cold engine misses, when warm miss goes away. With or with out the FU Chip, now.

I think the motor is possessed :rolleyes:

[907DAVE]

Do you have a good way to check fuel pressure?

I would be curious to see what the pressure actually is in the head.

You can pull the 1/8" plug from the rear of the driver side head, and screw in a gauge to monitor this.

Its possible that the check valve/ screen/ vibra-lok fitting at the end of the fuel line that feeds the head is restricted.

[Probuilder]

Do you have a good way to check fuel pressure?

I would be curious to see what the pressure actually is in the head.

You can pull the 1/8" plug from the rear of the driver side head, and screw in a gauge to monitor this.

Its possible that the check valve/ screen/ vibra-lok fitting at the end of the fuel line that feeds the head is restricted.

I am running AE Scanner - Ford ProLine Pack. Can't I check it with that system? At least at the Fuel Filter I know I have 79 to 81 psi, that is what the return spring is set to.
How high does the gauge need to read, if I put it on the back of the head?

[907DAVE]

If you are running 80 psi fuel pressure (which seems high), then the fuel pressure at the rear of the head should be very close to that.

Also be sure to check the pressure under a load (driving) at both locations.

[Freedomisntfree]

wow... im dying to know what ur problem is.. seems like youve done everything but swap out PCM with a different one. if you can get your hands on one, throw it on, if no changes throw it back on ebay and get your money back .. i just sold mine for $200 after my auto to manual swap. if you have allready ruled this out and i missed it on this thread plz disregard ... good luck

[Probuilder]

I am running between 79 - 80 psi at the fuel filter return.
At the back of the heads I am running 76psi no load and 69 psi under full load.

[907DAVE]

Why is the pressure so high?

Might try dropping it back down to 60.

[Probuilder]

We installed a different fuel pressure spring in the return. This was done over 2 years ago, to smooth out the idle, and cold weather starts. It also brought the fuel economy up just a touch. It is still with in Specs from International and ford.

[Probuilder]

We have taken all mods off, returned the truck back to stock. The truck will run great until we install the FU Chip, then everything goes back to the bad running motor.

Just like this post:

Here is what I have done since last post.
Did the buzz test, everything sounds good on all 8 cylinders. Contribution test is good on all 8 also.
I am lost as to what is going on here.
Now the truck doesn't have the miss, but also has very low power even with the FU chip on 100 hp setting. It feels like the chip isn't even in the truck. my boost used to go to 26-28 psi now it only goes to 15 psi max, blows black smoke really bad. Even smokes on the idle, it is also black, sitting in garage for 3 to 5 minutes, when warm and idling, will burn your eyes really bad.
Oh MPG is down to average of 8.

I took the new injectors out of 7 and 8, put old ones back in, truck still has no miss, but the rest is still the same- no power, smokes on idle when warm, smokes driving it, with the FU chip in.

Take chip out and everything runs perfectly. No smoke, no miss, nothing, and has power, contribution test good, buzz test good, boost up to 26psi, 16 mpg average. I am LOST

Any ideas now? Ready to trade truck off, but can't with it running like this.

Could there be thick oil trapped in a injector boss that causes the solenoid to buzz correctly but injector not work right??????

[907DAVE]

Guess I missed that post......

Would have to be a calibration issue then.

[Probuilder]

Well, IT is FIXED finally. :happy-dancing:
There was a bad calibration in the chip. I think it was from when we updated the chip burning program for the FU Chip. I wiped all programing off the computer, reinstalled and re-burnt the chip. Now everything is back to normal. Who would have figured that it was a cheap fix.
Thank you everyone for all your help in this matter, it has been a long drawn out test.

[Probuilder]

Not sure but someone may want to put this in a sticky somewhere on this forum. There is a lot of good testing info from everyone in this thread.

[907DAVE]

Well, IT is FIXED finally. :happy-dancing:
There was a bad calibration in the chip. I think it was from when we updated the chip burning program for the FU Chip. I wiped all programing off the computer, reinstalled and re-burnt the chip. Now everything is back to normal. Who would have figured that it was a cheap fix.
Thank you everyone for all your help in this matter, it has been a long drawn out test.

WOW!!!:doh:

Glad its working for ya!

[88Racing]

Moved from emergency....
A thread this old will be closed otherwise....