HELP needed for dyno tuning problem....

[driven to build]

Here is the story,

I have a new JLP longblock and a Whipple running 75# injectors and fuel rails, TR6's gapped at 30, stock coils, E-fan, dual 255's, JDM fuel system upgrade, ect...

I went for a dyno tune and the tune went good with the first combination 8# lower and 3.375 upper. About 575rwhp and 595tq with 15deg and 11.8 or so AF with a max of 5200rpm's. We saw about 17.5#'s of boost. We added in race fuel and changed to a 2.7 upper with the 8# lower and the truck shuts off at 3000rpm's like you turned the key off mid pull. At first I thought something happend to the motor because when we went to refire it backfired and I didn't want to take a chance on hurting the new motor. So I removed the Whipple checked plugs checked compression (130-140) and borescoped the cylinders. All was good so I put it all back together. We went to the dyno and same thing happend with the 2.7 upper the second time so we put the 3.375 upper back and all is fine.

Durring both pulls when the truck shuts off it is around 3000rpm and fuel pressure, maf counts, and AF all look perfect just like the 3.375 pulley tune. When it shuts off it's only at about 335rwhp and 500+tq. It dies just like someone shut the key off that is the confusing part since it's only with the small pulley.

The second time it shut off it threw a p1114 code AIT2 voltage to low but when we cleared it and went to the 3.375 upper it did not return and the pull made the same power as it did the first time we had the 3.375 pulley on.

Please shoot me some ideas I'm stumped.

Dan

 

[fuzzie]

Have you checked all your sensor plugs....Crank, Cam ect....

 

[Fade 2 Black]

Sounds like the IAT2 sensor is messed up and giving false readings to the PCM and in return it's pulling so much timing that it's going into "safe" mode or something maybe. Try a new one or remove yours and log the temp at ambient and it should read the same as the IAT pretty much. Did you log the IAT2 (downstream air temps) or spark to see what it's doing?

What maf do you have? If the inj. parameters, cyl. displacement and maf curve wasn't done properly you could be maxing out the PCM. 01+ PCM's can't read any higher than 63.9# air/minute and must be adjusted.

 

[driven to build]

Sounds like the IAT2 sensor is messed up and giving false readings to the PCM and in return it's pulling so much timing that it's going into "safe" mode or something maybe. Try a new one or remove yours and log the temp at ambient and it should read the same as the IAT pretty much. Did you log the IAT2 (downstream air temps) or spark to see what it's doing?

What maf do you have? If the inj. parameters, cyl. displacement and maf curve wasn't done properly you could be maxing out the PCM. 01+ PCM's can't read any higher than 63.9# air/minute and must be adjusted.

The spark is not being pulled we datalogged that in fact it is only around 8 at that point in the run. IAT2 temps are 138*

I have a BA2800 we swapped that out because when he called SCT they suggested a bad MAF, that was not it. It is an '04 PCM but what you say with maxing out the air/minute might be interesting he did have to create all new tables based on some parameters that SCT gave him for the 75# injectors.

I decided to pull the Whipple again and change the injectors to 60#'ers and see what comes of it I started doing it earlier and will finish tomorrow.

Thanks and keep any ideas coming.

Dan

 

[STL Lightning]

If the CHT sensor malfunctions or reads too hot, the pcm can pull fuel and basically shut the truck down. Doesn't make sense to me that it could be the problem, but keep it in the back of your head.

Do you have a fuel pressure gauge hooked up?

-Mark

 

[driven to build]

Yep I have a fuel pressure gauge and it reads about 58 before she shuts down. The real confusing part is with the 3.375 pulley I runs like a dream, no problems and with the 2.7 pulley it shuts down at 3000rpm every time.

 

[white01]

Thats some crazy stuff there Driven. I hope you get if worked out. I've had that happen at the track when my truck was on the bottle. It would shut down half way down the track. It ended up being the chip I was using.


Rich

 

[STL Lightning]

Yep I have a fuel pressure gauge and it reads about 58 before she shuts down. The real confusing part is with the 3.375 pulley I runs like a dream, no problems and with the 2.7 pulley it shuts down at 3000rpm every time.

Do you have a different tune for the 2.7? Could it be a corrupt file or something? Maybe try using the 3.375 tune, but only pull it to 4000rpm just to see if you get beyond that 3000rpm point.

-Mark

 

[driven to build]

Thats some crazy stuff there Driven. I hope you get if worked out. I've had that happen at the track when my truck was on the bottle. It would shut down half way down the track. It ended up being the chip I was using.


Rich

I'm using a Xcal II, but this is driving me insane.

Buy the way how are you doing on your install?

 

[driven to build]

Do you have a different tune for the 2.7? Could it be a corrupt file or something? Maybe try using the 3.375 tune, but only pull it to 4000rpm just to see if you get beyond that 3000rpm point.

-Mark

We had to make some adjustments the the fuel for the 2.7 it was going a little lean so we did not make much of a pull before we made changes. I would be afraid to run to 4000 with the 3.375 tune.

The tuner did try to remake the file incase it was a corruption issue.