Thought I'd condense my other post down and hopefully get some fresh ideas. This issue is it idles like a champ. But any throttle and it bogs down.

Here is the setup:

2004 LQ4 from Silverado 2500HD swapped into an old Cruiser
NV4500 swapped in place of the stock 4l80e it came with
e8248 fuel pump
Corvette regulator and filter combo(AC Delco P# GF822)
exhaust leak on passenger side
no cats
VATS programmed out as well as rear o2 sensor (JET DTS programmer)
STOCK harness with un-needed junk pulled(autotranny wires, rear o2 wires, and purge valve)... only the VSS wires were removed from the PCM plug and put back on.
headers
new hard and flex lines throughout (3/8" and 6an but also about 12" of 5/16" at tank)
VSS installed
Drive by wire system installed
everything else stock
I've got engine block grounded directly to the battery... all other stock grounds for the harness are at stock locations.


Engine sat for about 8 months before being run.

Things I've done/tested so far:

fuel pressure is at 60psi
soaked injectors in sea foam (no change)
run engine with a can of sea foam and about 7 gal of 87 oct gas (no change)
no engine codes aside from no MIL (P0650)
checked the TB butterfly to ensure it opens both with and without the engine running
replaced a E2000 fuel pump with e8248
confirmed MAF functionality by pulling MAF away from TB as well as unplugging. Both cause the engine to idle like crap.


Would the PCM not having input from the auto tranny spaz it out?

Would a plugged fuel filter cause this? Even though it is still giving the right pressure reading.

Wait its an 04? Does it have the return/FPR fuel rail? Or is it returnless? Can't remember?

I am thinking its the tune. Contact Jim Performance and ask him. You might send him the PCM.

It is returnless style. That is why I'm using the Corvette filter/pressure regulator combo ;)

I'm guessing it is a tune issue also.

It is returnless style. That is why I'm using the Corvette filter/pressure regulator combo ;)

I'm guessing it is a tune issue also.Ok just checking as one of the Jeep guys had the vette FPR and the return rail and it was fucking up bad as well!


http://www.jimsperformance.com/

Bringing this from the grave in hopes my beating my head against a wall will save someone from the same issue.

The issue is indeed a tune issue. Using a 4.8L manual tune, I was able to identify some parameter differences. I changed those values in my tune and flashed the PCM.

Fired up and throttle response is NICE.

So, there is something different in an auto tune that will cause the LQ4 to idle fine but not run off idle. I'm not sure which of the following groups listed helped the issue:
Fuel Parameters
System Parameters
Diagnostic Parameters
Idle Control Parameters

It should work until I can have the time and money for a professional "mpg" tune done.

With the above said, if anyone can point me to a stock LQ4 tune with a manual trany, it would be GREATLY appreciated.

THANK FUCKING GOD!!!!!

I knew that was it! haha!!!!


Heres a VIN with a LQ4 NV4500 1GCHK29U24E103332
Heres the truck http://cgi.ebay.com/ebaymotors/04-CHEVY-2500-H-D-4DR-1-OWNER-EXCAB-69K-4X4-6-0L-5-SPD_W0QQitemZ170392952584QQcmdZViewItemQQptZUS_Car s_Trucks?hash=item27ac361f08


I am think its the system parameters. And the fuel maps are different for the 4.8l as well. It won't make full power.

Like I said before the PCM though the trans was toast so it defaulted to limp mode :idle only".

Have the dealer flash this tune with the above VIN.