2004 Grand Prix E85 Conversion issues.

Hello all,

I have a 2004 3.8L GTP competition group that I recently changed over to E85 (kind of). Modifications are as follows; E85, 3.0 pulley, 60# Siemens injectors, 1.8 roller rockers, pacesetter headers, wizair CAI, fuel pump rewire with new AC Delco sending unit/pump. I am working off of an Overkill gas tune that I had with a 3.4" pulley.

I have been reading a lot about tuning but I think I got in over my head too quickly. I have realized tuning is a true art form!!! I have read the 60# tuning method here and some of the other sites. I tried to follow the settings and the car ran either too rich or too lean. I found that 1.20 on the Flow rate got me close on my fuel trims. I have attached my most recent scan and tune for reference. Unfortunately, I am using the stock narrowband sensor so I know that I am limited. I know I need a wideband soon but I spent way more than I planned for this conversion and money is tight so I have to work with what I have now.

My question is can anyone point me in the right direction with this tune. I have changed the Injector Flow rate and subtracted timing from the knock that was in this attached scan. I just want to get it close so no damage is done until I better understand how to tune or pay someone to help me out.

Thanks for any insight

Rick

Why not just set the injectors for what they are and tune the MAF curve to bring fuel trims back to normal. The MAF is basically what is controlling how much fuel it's given the motor based on the airflow it's seeing.

Do you know of a "how to" for this process that relates to the 3800 series III? I've seen some around that use DHP or older versions of HPT. Most of the "how to" I have seen show how using wide band for the Maf tuning.

I bought the Engine management Advanced tuning book and I am hoping to go to the Tuning schools September GM class here in Ohio if the funds permit then. I comprehend better when I learn hands on. Unfortunately I have no one around me that knows tuning. I have thought of getting a Dyno tune from ZZP or Intense and asking if they can help me understand the process better.

anyone have any input on this scan? I used the LTFT learn feature in HPT. I recorded during the relearn process just to view what was going on. It was a 26 minute scan and it seems like the LTFT never really adjusted. The STFT looks good (i think). I have the PE set to 100% during this scan. Any ideas why the LTFT is staying so negative?

Attachment 67500

If you had already been tuning the MAF curve you may have added in a bit more fuel than you needed. For a simple test you could take 2-3% back out of the MAF curve and see if the trims get closer to zero.

I have not touched the maf table. This is the first time resetting and relearning. I was going to start the tune procedure for the LTFT here.

http://www.grandprixforums.net/threa...rting-Hptuners

At the 20% injector adjustment and then the fuel trim adjustment the car does not run correctly now at wot. I think it has to do with fueling issues. I noticed that the injector duty cycle was at 121% and that should not be the case with the 60# injectors.
What I was thinking of doing was starting over with my tune. I have been told that all I have to adjust for the injectors is the KPa. So I have 60# injectors, I have seen that I should multiply the stock table by the difference. stock is 36#. So should I go 60/36=.66 so multiply the main injector file by 1.66???? does this sound correct?? attached is the scan from the issue I was having as well as the tune.

Attachment 67560Attachment 67561Attachment 67562

Injector duty cycle does not work correctly with larger injectors on 04+ cars.

Quote:

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Originally Posted by Rickisrad

At the 20% injector adjustment and then the fuel trim adjustment the car does not run correctly now at wot. I think it has to do with fueling issues. I noticed that the injector duty cycle was at 121% and that should not be the case with the 60# injectors.
What I was thinking of doing was starting over with my tune. I have been told that all I have to adjust for the injectors is the KPa. So I have 60# injectors, I have seen that I should multiply the stock table by the difference. stock is 36#. So should I go 60/36=.66 so multiply the main injector file by 1.66???? does this sound correct?? attached is the scan from the issue I was having as well as the tune.

Attachment 67560Attachment 67561Attachment 67562

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Does anyone have any input on this scan and/or tune?? I can not figure out why it is surging at high rpms.

Anyone? I am trying to tune for E85 on this car. 07 GT. When I try to look up other information the links and pages are dead.