Issue with IAC/TPS in swap
Thread Starter
Launching!
Joined: Feb 2003
Posts: 205
Likes: 0
From: 08003
Issue with IAC/TPS in swap Car is an LQ4 with LSA top end running an 0411 pcm from a 2002 Tahoe and dbc throttle body.
Issues: Car won't seem to run right, runs very rich, wants to stall.
I'm able to see the PCM command various values for the "Idle Air Control Desired Position" but the "Idle Air Control Position" is stuck at 310.
I'm also looking at the "Throttle Position SAE" and it doesn't matter what I do but it only shows 0%. In addition the Throttle Position Sensor voltage shows 0.
With key on I hooked my multimeter to all 3 wires for the TPS and I'm not getting anything at all on any of the 3 wires.
Did the same test with the IAC and was seeing ~10-11v at I think 3 of the wires.
Harness is from PSI conversions and brand new.
Issues: Car won't seem to run right, runs very rich, wants to stall.
I'm able to see the PCM command various values for the "Idle Air Control Desired Position" but the "Idle Air Control Position" is stuck at 310.
I'm also looking at the "Throttle Position SAE" and it doesn't matter what I do but it only shows 0%. In addition the Throttle Position Sensor voltage shows 0.
With key on I hooked my multimeter to all 3 wires for the TPS and I'm not getting anything at all on any of the 3 wires.
Did the same test with the IAC and was seeing ~10-11v at I think 3 of the wires.
Harness is from PSI conversions and brand new.
Thread Starter
Launching!
Joined: Feb 2003
Posts: 205
Likes: 0
From: 08003
I'm willing to but have no idea what to check. I sort of assumed my new harness would be setup ok and it looks fine. What should I be checking?
It should be dbc. It's out of what I was told is a dbc Tahoe.
It should be dbc. It's out of what I was told is a dbc Tahoe.
Last edited by Blue89Bird; Sep 7, 2017 at 06:55 AM.
Staging Lane
Joined: Oct 2014
Posts: 92
Likes: 3
As a minimum I would recheck the grounds from the pcm to the engine block .With the key on engine off your scanner should pick up throttle position movement both voltage and % .Did you do the throttle position learn ? Disconnect IACV and TPs turn key on for 10 seconds then key off and replug IACV and TPS (don't leave scanner plugged in )
Thread Starter
Launching!
Joined: Feb 2003
Posts: 205
Likes: 0
From: 08003
so turns out the tune was set to Platform: GMT800 which corresponded to ETC on or DBW. Basically it was set to a DBW tune.
I switched the ETC to 0 or off and rewrote it, but still having same issues. Talked to PSI who made the harness who told me I need to use a different OS. However that would require more HPTuners credits which I'd like to avoid.
Tuner said he'd look at it tonight, but wanted to get some other opinions and maybe this belongs in the tuning forum at this point (so if an admin wants to move it, please go ahead)
Should switching the ETC to off and reflashing make it work or is there more involved in this?
I switched the ETC to 0 or off and rewrote it, but still having same issues. Talked to PSI who made the harness who told me I need to use a different OS. However that would require more HPTuners credits which I'd like to avoid.
Tuner said he'd look at it tonight, but wanted to get some other opinions and maybe this belongs in the tuning forum at this point (so if an admin wants to move it, please go ahead)
Should switching the ETC to off and reflashing make it work or is there more involved in this?
You need to spend the credits and get the correct OS. If the tune is now setup for DBW, that is why you are not seeing voltages for IAC and TPS. Both of those "sensors" are not in a DBW throttle body as they are in a DBC TB, per se'. There is a form of them in there, but the strategy is completely different between the two operating systems.
T,
T,
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