Part throttle stumbling

[1158]

ECU Serial# 24383
Smanager version 2.2.7.0 (Just updated to 2.2.8.0 but this happened during 2.2.7.0)
I believe it is a P28 ECU

1998 Integra GSR

Here is the setup:
Benson sleeved block
Benson balanced and micropolished crank
CP pistons and rings (9.25:1 compression, 83mm bore, 87mm stroke)
Pauter rods
ACL bearings
OEM (TypeR) oil pump
Blueprinted assembly
ATI Damper
ARP Head Studs
SuperTech SS Valves
SuperTech dual springs/Ti retainers
3 angle valve job
Skunk2 Tuner stage 1 cams
TR3030R Turbo/.63 A/R
Garret Intercooler core: 24” x 6.3” x 3”
Al charge piping: 2” hot / 2.5” cold
Full Race AC Manifold
Tial MV-R 44mm wastegate
3 inch Vband DP with closed loop dump
3 inch Thermal Turbo Exhaust
QTP E-cutout
Manifold/DP/turbine housing coated by Swain Tech
Skunk2 Pro Series Intake Manifold
Stock TB bored to 64mm
Tial 50mm BOV
Injector Dynamics 1000cc injectors
Walbro 400lph fuel pump
Walbro FPR
BKR7ES-11 gap set to 0.026
NGK wires
Hondata 4 Bar map sensor
PLX M300 Wideband

Edited for new datalog times -> I have been chasing this issue for a long time. At part throttle the car will occasionally stumble/hesitate/stutter whatever you want to call it. I finally got a really good datalog of the problem. In the included datalog the issue occurs around 1:15. Prior to that, from 00:20 to 00:50 under almost the same conditions (RPM/TPS/Manifold Press/ECT/IAT/timing all very similar), the car was running fine. I slowed down to make a turn then after making the turn and getting to cruise speed is started to stumble. This happens in all gears, in this particular case it happened in 3rd gear. As I said I have been trying to sort this issue for a long time. I thought it was the tune, but the car was just retuned and I think that can be ruled out. I have replaced the engine/transmission grounds and cleaned the grounding locations. In the datalog right before it starts to stumble S trim is behaving normally, then when the car starts to stumble S trim pegs itself. I can't see any reason why this is happening but I'm not an expert either.

It seems to happen in warmer weather a lot more. Over the weekend temperatures here were warmer and it was happening a lot. Then yesterday, during the same 20 min drive to work it only did it once. It didn't happen at all on the way home. Temps over the weekend were in the 70-80 degree range and then in the low 50s yesterday.

I have not tried another S300 to date (I have inquired about trying a friends known good ECU)

[Spunkster]

You have not posted the datalog

[1158]

You have not posted the datalog

Right, I noted that. I've been trying to post the datalog for an hour. Is there a size limit on file uploads? It is almost 9mb and it will not attach. The upload progress bar stays on my screen and never finishes.

I can email it to you if the upload will not work.

[1158]

Well I still cannot get the datalog file to upload through the forum.

I used a file hosting site to store it.

Link is here: http://www.datafilehost.com/d/7f086e5b

[Spunkster]

You can make the datalog much smaller by setting a new start and endpoint and then saving the datalog, THis will allow you to upload a much smaller file that is not an hour long and hard to pinpoint the problem area.

[1158]

You can make the datalog much smaller by setting a new start and endpoint and then saving the datalog, THis will allow you to upload a much smaller file that is not an hour long and hard to pinpoint the problem area.

Ok, thanks. I didn't know about that feature. I will do that right now. As for pinpointing the problem area, that was why I specified the time it happened. Otherwise it would be looking for a needle in a haystack.

[crucian]

Does it happen when your cooling fan comes on and off? What fan do you have?

[1158]

Does it happen when your cooling fan comes on and off? What fan do you have?

13" pusher. It is not related to the fan. Fan doesn't come on at cruise speeds. Have it set to default (stays off over 30 mph).

The stumbling was tune related and I have been slowly working it out. I have it now to where it only stumbles with with either very higher/lower IAT. I have to tweak the temp compensation values.

[1158]

Well I guess the problem was not in the tune. I thought I was on top of it and then tonight trying to drive to work it was almost undriveable.

I made zero changes from when I drove it in the morning (when it ran almost flawless). Tonight I tried to take the car to work and it was just terrible. Part throttle AFR is 18-19 (again no changes from the morning) and virtually all of the cells in the estimated fuel change table in Hondata are 20% or higher.

I don't see how this could be related to CPR install (especially since the part throttle stumble was there b4 I switched to CPR) so for now I'm not thinking it is CPR. Besides I don't see how a CPR issue would cause the car to run lean. Fuel pressure datalogs are good.

I will post up the calibration and a section of the datalog in a short while.

[crucian]

Put the car in open loop and get it part throttle tuned on the street or a dyno. THE TUNE IS WAY OFF. I can see why it's stumbling just by looking at your fuel tables and datalogs. Nothing is smooth. It's all over the place. Looks like whoever tuned the car tuned the high speed table and not the low speed. If u get a good open loop tune, you wont have to use closed loop.

[1158]

Put the car in open loop and get it part throttle tuned on the street or a dyno. THE TUNE IS WAY OFF. I can see why it's stumbling just by looking at your fuel tables and datalogs. Nothing is smooth. It's all over the place. Looks like whoever tuned the car tuned the high speed table and not the low speed. If u get a good open loop tune, you wont have to use closed loop.

The part throttle tune def needs work but the issue with the full lean condition to normal and then back to full lean happened that 1 night. It was most def not tune related. The car had not done that before and it hasn't done it since despite me driving it a ton.

From the morning when it drove fine to the night when it drove like crap(last data log I uploaded) I made zero changes. I was hoping to get feedback on why that happened. Almost all cells in the fuel adjustment table were telling me to add 20-25% more fuel. Only thing I did after that was check my vac lines (but made no changes and found no issues) and unplug and check all the injector clips. I made no other changes for 2 days and that issue hasn't happened again. I have been working on the part throttle tune and the car behaves at part throttle though I know it could be better so it is very much a work in progress.

[crucian]

Like I said, quit trying to drive in closed loop and give it a good open loop tune. Make sure all ur compensations are adjusted according to ur current sensor feedbacks. ie, IAT ECT. Make sure ur dead times are on point for ur fluctuating battery voltage.

[1158]

Like I said, quit trying to drive in closed loop and give it a good open loop tune. Make sure all ur compensations are adjusted according to ur current sensor feedbacks. ie, IAT ECT. Make sure ur dead times are on point for ur fluctuating battery voltage.

Question. I'm working on the tune in open loop (right now at idle) and I'm getting close. I switch to closed loop and AFR drops to high 11 low 12. What would cause that? The wideband's display matches the values in Hondata's display in both open and closed loop.

Here are the cal files and data logs. Only change between the cal files was to switch from open loop to closed loop.