Stage II injectors and "romp" issue

[Pocket]

I just tuned a truck with Stage II injectors, and got everything set up almost perfectly.... with one exception.

The truck will "romp" one or two times right after cranking, especially if it's been sitting for a while like several hours or overnight. It won't do it every time, but it's enough to be noticed. I know it's my tuning, and it's the first time I've tuned single shots. Once the romp goes away, it idles perfectly smooth without being choppy. I made adjustments and figured out how to "successfully" make it romp worse :doh: but I haven't quite figured out exactly how to make it completely disappear.

One thing I do know is that it does have leaking injector o-rings (uses a few quarts in about 200 miles), and he's going to fix it pretty soon. However, it won't romp when he switches out his chips for a different set of tunes from another tuner, so I know the issue is on my end.

Everything else is fine. It drives great, has good power, it's quiet, EGT's are nice and cool, and there's hardly any smoke whatsoever. It runs like a raped ape, and we flogged the hell out of it while testing out the tuning. Just looking for pointers on the cranking romp, and what I'm doing wrong here. If anyone has had this issue, what did you do to fix it?

Oh, it's a PMT1 PCM also.

[907DAVE]

About once a month mine will do the same thing, and once every few months it will romp - then die.

Have you tried playing with the ICP in those areas?

Also there is a MFD desired while cranking and ICP while cranking function that was suggested could make a difference.

[Pocket]

About once a month mine will do the same thing, and once every few months it will romp - then die.

Have you tried playing with the ICP in those areas?
That I have tried. Adjusting the ICP helped to smooth out the idle more than addressing the romps. I've also adjusted the PW, which seemed to have a greater effect on the romping issue than ICP did.

Biggest problem was we ran out of time yesterday before I could really figure it out. I know the PW was initially too low at idle, and as I raised it the romping was disappearing. Probably a bit more PW at idle, and it might disappear completely. I'm sure with more time I might have gotten it, and I'm going to meet up with him next week for another session of tweaking. Mainly just wanted to get a head start on the romp issue and take suggestions from a few folks here. :thumbs up yellow:

Also there is a MFD desired while cranking and ICP while cranking function that was suggested could make a difference.
That I have not looked at. Might have to take a peek.

[907DAVE]

Just out of curiosity, what is PW @ idle?

[Pocket]

Just out of curiosity, what is PW @ idle?

It was trying to drop down to .9 ms at idle. LOL That's when the romping was the worst. Problem was I was calling for more fuel than that in the pulsewidth map, but I didn't have the ICP set right the first time either, so it was dropping the pulsewidth.

When we finished for the night, I watched it idling at about 1.3 ms.

I need an emulator. Takes too long to make changes when burning to a chip over and over again.

[907DAVE]

FWIW I have had idle stability issues with any PW below 1 ms.....right now its chilling around 1.4.

Emulators are sweet, I learned more in that first week I had it then I think I did in an entire year of messing around.

[mattr66]

Watch for ICP stability. What oil pump is on this truck? Also you might want to adjust the cranking fuel function....

[Pocket]

Well I finally met up with him again today to work more on the tuning, and this time we had more time to spend on it. Before getting with him, I went back over the tunes and adjusted the pulsewidth maps. Burned the tunes to his chip, cranked it up, and it fired perfect and settled right into a nice even idle with no romping. ICP and pulsewidth at idle all looked good, no more jumping around. I figured out my mistake on the PW map, had it dipping way too low.

He had been talking to me about problems with EGT's and boost, so I looked over his truck and found an intercooler boot had partially blown off. Fixed the boost leak and everything returned back to normal.

His truck runs great now. It's got great power, and even in the highest hp tune it's only turning out at most a very light haze at WOT, going uphill, at over 8000 ft elevation. I'm stoked at how it's running, considering this is my first truck with single shot injectors to tune. On our last test run he said his truck sounds more like a gas engine now than a clattery diesel.

At any rate, he's trying out a few different configurations of a couple of tunes to see which shift strategies he likes best. He wants to test out towing different trailers, driving both mountains and down in lower elevations, etc. Next time we meet, we'll finalize his shifting for each tune, and he'll be set.

Going to get some mileage reports from him too.

On edit: Thanks for the help too guys. I really appreciate it.

[Pocket]

Watch for ICP stability. What oil pump is on this truck? Also you might want to adjust the cranking fuel function....

Hey Matt, today after making the changes, the ICP was very stable this time. Same goes for pulsewidth. It's cranking and idling like stock now.

Oh, he's running a stock 17 degree pump too. It's keeping up nicely with the injectors, holding steady WOT at 3000 psi and just over 40% duty cycle on the highest HP tune, pulsewidth maxes out at about 3.6-3.7 ms.

After spending the day with him, I'm ready to get rid of my stock injectors and go with singles.

[Pocket]

FWIW I have had idle stability issues with any PW below 1 ms.....right now its chilling around 1.4.

That's where I've got his sitting at too now.