Kingblazer84

So my buddy and I have swapped a 6L lq9 from a 2005 escalade we r using a psi conversions harness and computer all brand new, here's the info

Trucks starts farts and won't idle up. Runs great if foot is on the pedal, now the funny thing is it acts like the tb is choking it because if we disconnect his brake booster vac line the engine runs perfect but with it plugged in it won't idle.

No vac leaks

Swapped known good tac module , throttle body. No difference now as for codes no codes except it threw a p0101 maf code but when cleared it hasn't come back.. We are at a loss here and don't have the proper scan tool to check pids and other values properly anybody got ideas? I'm thinking PCM might be the issue even though vats were supposedly removed.


Here's a quick vid of the issue

http://s70.photobucket.com/user/low6...a5f33.mp4.html

-have the neutral safety grounded
-cant be fuel pressure, as it revs up without hesitation
-brake signal wires not hooked up- only need for converter lock-up, using turbo 400, so dont need
its all related to the fact that the throttle body closes after startup. throttle plate moves when pressing on gas pedal. I am using the right pedal and TAC.
-unplugging or using a different MAF makes no difference
-swapping throttle body makes no difference

Heres a vid of the tb on startup acuating and then us throttling it trying to get it to run

http://s70.photobucket.com/user/low6...b1d8e.mp4.html

-different intake
-different MAF
-different throttlebody
-different TAC
-different gas pedal
-tested fuel pressure to be at 54psi
-regapped spark plugs to .040

Here is a live data shot of it not running (as it wont idle!)
stft b1 0.0
ltft b1 25.0
stft b2 %0
ltft b2 %25.0
MAP 29.2
RPM 0
IAT 54
MAF .0
TPS %17.6 (but drops to seven)

o2s b1 s1 v .445
stft b1 s1 %0
o2s b1 s2 .445
stft b1 s2 %99.2
o2s b2 s1 %0
o2s b2 s2 v .445
stft b2 s2 %99.2

When I turn the key on- TPS goes to 17%, then during the start cycle it drops down to 2-3% with sometimes going to 1.6% and trying to idle under 300rpm, but wont kick it up to keep it idling where it should be

Alright, mountain man and myself worked on the beast for 5 hrs today with no luck, tested pedal app, tac module wiring between pedal and module, and main harness to tac for all 5v ref signals and ref low (grounds) all have tested good but the 1 wire that is yellow with a black chaser that is supposedly a ref low ground shows that it is not grounded..?

Tested also wiring between blue PCM connector ( as per psi conversions ) to tac module all have continuity and all have proper grounds. Now I took some video which you will see in the post further down of all the fuel trims during a enforced idle with a washer that we placed under the pedal. Now when the truck starts up on the enforced idle it goes from 8% idle to 13% till it warms up to 196C deg. Then it bogs down and richens the hell out of the mixtures when the electric fan kicks on. Also the engine seems to idle surge as well we have checked intake for leaks, checked injectors and swapped another set of them in as well with no change, watched fuel pressure no issue there as well.

When the fan is unplugged during the bog down it seems to help bring the idle back but still seems to be very rich via fuel trims, disconnecting the maf to go into speed density closed loop brings the fuel trims back to normal but will not allow the engine to fire back up when shut off we notice with the scan tool that the tps reads at 1.3% when it should be 7-8% min.

http://s70.photobucket.com/user/low6...68489.mp4.html

http://s70.photobucket.com/user/low6...537fb.mp4.html

http://s70.photobucket.com/user/low6...c4df3.mp4.html

confirmed MAP readings,

my reading is 28.9 inhg
yours is 96 kpa
96kpa =28.348788010inhg
i live a around 1300 ft above sea level so this reading seems fine

aknovaman

iTrader: (7)

Air in fuel rail needing purged? Odd as if it has a vacuum leak kit will generally idle high. Do you have 60psi fuel pressure at the fuel rail? Injectors may be sticking if it has been sitting more than 6 months. One or two may be firing enough to get it to sputter like it does I video.

2kblackgtp

iTrader: (12)

I vote change the maf. I've had two seperate instances of a bad maf not throwing a code and still running like crap with the maf unplugged. Once I changed the maf, problem went away.

Kingblazer84

Brand new fuel pump assembly lots of fuel runs like a champ if u just touch the throttle I'm gonna try another maf tomorrow

i r teh noobz

iTrader: (4)

If it runs off idle, its not VATS. Since it idles fine with a forced vacuum leak, my guess is either the TB isn't opening enough or the MAF is reading wrong and flooding it at idle.

BP Automotive

iTrader: (3)

You will want to make sure of several things with the MAF. First thing would be to make sure the PCM is flashed with the proper MAF calibration tables. If you are using a used MAF you may want to get a new one. We always recommend getting a new MAF because if this very issue.

Then you can check the pinout at the MAF connector. GM color codes are as follows- bear with me as this is from memory.

A- Black- Red/Green 57
B- Tan- Red/Green 25
C- Black/White Tracer- Ground
D- Pink- Ignition Power
E- Yellow- Signal- Red/Green 31

Bill

Kingblazer84

Disconnecting maf doesn't do anything, swapped known good maf still same issue from what I can see the dbw throttle plate closes fully before start up then opens slightly to get the initial start but then closes off and chokes the engine..

i r teh noobz

iTrader: (4)

Do you have the correct PCM? Perhaps you got sent a PCM for a DBC setup?

Has this setup ever idled? Have you tried riding the throttle to keep it running for a few minutes before allowing it to idle? My swap car stalls intermittently for about 5 minutes after the battery is unhooked. After it has time to adjust itself, it runs like a champ.

Kingblazer84

Never has idled since swap was done only has done what was stated previous we r going to contact Jon at psi and see what he thinks I have a strong feeling it's the pcm

BP Automotive

iTrader: (3)

You will also want to check your MAP Sensor and Circuit. From what you have described it sounds as if the PCM is picking up too much airflow and closing off the throttle body to control the idle air flow.

72chevelle6.0

iTrader: (22)

Sound the PCM does not have the iac driver. We had this issue once what it the PCM out of?

BigEd_72455

iTrader: (7)

The reason it runs fine when you unhook the vacuum port is because it is NOW getting air to go with the fuel. Your throttle body is either off somehow or the programming needs to be checked, or the PCM is the wrong pcm for your harness/engine. This is why I love DBC.

Brain storm here, do you have the DBW throttle pedal hooked up to the harness? If not, the PCM may not be getting a reading it should be getting and is stalling the motor.

Just brain storming.

Kingblazer84

Highly thinking the PCM is missing programming somewhere in the tb section and yes the throttle body is plugged in...

mountainman

OK, so its my truck we are talking about here..
I have been out tracing wires and grounds
everything seems fine

-have the neutral safety grounded
-cant be fuel pressure, as it revs up without hesitation
-brake signal wires not hooked up- only need for converter lock-up, using turbo 400, so dont need
its all related to the fact that the throttle body closes after startup. throttle plate moves when pressing on gas pedal. I am using the right pedal and TAC.
-unplugging or using a different MAF makes no difference
-swapping throttle body makes no difference

THIS IS GETTING FRUSTRATING!

BigEd_72455

iTrader: (7)

Who did the tune to the engine computer? Talk to them again if you did not do it yourself.

If you used something like HP tuners, check on the part of the forums here about the problem and see if anyone here can help with it.

Kingblazer84

Jon at PSI Conversions did the vat removal but i dont believe he did a tune just the basic removal of emissions stuff and vats.

BigEd_72455

iTrader: (7)

I would throw it on a trailer and haul it to him providing it is a reasonable distance. Surely he can see more with the software as to what all is going on that you can sitting there staring at it and swapping parts taking a chance on tearing something up on accident.

That would be what I would do if it were me. Even if it is a 2 hour drive, its better for him to peek inside with a connector and laptop that you bash your brains out trying to get it lined out.

mountainman

Its a 43 hour drive from here, so probably not go that route! lol

BigEd_72455

iTrader: (7)

I said REASONABLE!!!!

Hell, ship it UPS!! It will get there in about 3 weeks..

mountainman

HAHAHA!
four weeks, border will have to make sure its not a bomb!