thomcasey
(I ain't no puny human)
07/18/19 08:19 PM
New stumble on initial press of accelerator pedal (SOLVED)

Started my car the other day and found it is now stumbling on the initial press of the accelerator pedal. If I push it fast, it stumbles and leans out. If I press it slow, it is fine. I verified the TPS is reading correctly and it idles just fine. This started right after being started. I can't find a boost leak anywhere. I made a log and it can be seen HERE. I am stumped.

cupajoe
(Member +)
07/19/19 01:44 AM
Re: New stumble on initial press of accelerator pedal

sd?

thomcasey
(I ain't no puny human)
07/19/19 04:36 AM
Re: New stumble on initial press of accelerator pedal

Yes. Went to SD last year.

Dan D
(220, 221... whatever it takes)
07/20/19 08:07 AM
Re: New stumble on initial press of accelerator pedal

Did this just start happening as our weather turned hellish?

Does it go away when the car's warmed up?

Or - did you fill it up at a BP station that used to be Rickers, now Get Go with typical shit Get-Go gas?


thomcasey
(I ain't no puny human)
07/20/19 12:36 PM
Re: New stumble on initial press of accelerator pedal

Holy crap!! It started 2 weeks ago and gets worse with it being warm. It is very possible that I put gas in it at the former rickers / new getgo station on 56th on Lawrence. I never thought about it being the gas.

Dan D
(220, 221... whatever it takes)
07/20/19 12:41 PM
Re: New stumble on initial press of accelerator pedal

I haven't put any in the galant but I did in the CTS-V before I realized they had switched. It was not a happy car! Idle was wandering, knock retard was problematic, and I got horrible gas mileage that tank. (ok...11.2 vs 12.5... it's always horrible but worse than normal horrible)

If it's not that, then I'd be testing whatever IAT sensor your using for your SD setup.


thomcasey
(I ain't no puny human)
07/20/19 01:36 PM
Re: New stumble on initial press of accelerator pedal

I have a go IAT. When I log (the link to the log is on the first post) it reads 40 all the time for some reason. It is connected with the ECMTuning kit and has always read that way, but a bad gas does sound very plausible.

Dan D
(220, 221... whatever it takes)
07/20/19 07:30 PM
Re: New stumble on initial press of accelerator pedal

I think with ecmlink you can adjust setting to basically let you run with a simulated iat. You can probably play around with that and rule out the sensor if you don't otherwise have diagnostic/test equipment at your disposal to test it off the car.

Otherwise screw Get Go for taking away my favorite gas 😬


thomcasey
(I ain't no puny human)
07/21/19 07:51 PM
Re: New stumble on initial press of accelerator pedal

I verifies that I filled up with Shell the last time so gas should be good. I just ordered another sensor since it is reading 40 degrees VA the normal 70 to start. Only $12 for a fast sensor

cupajoe
(Member +)
07/21/19 08:21 PM
Re: New stumble on initial press of accelerator pedal

For the time being while you wait for a new sensor go into the MISC tab and check lock IAT, it'll lock at 77*. See if the issue goes away.

thomcasey
(I ain't no puny human)
07/22/19 08:26 AM
Re: New stumble on initial press of accelerator pedal

IAT setting does not exist on the MISC tab.


Found a setting on the ECU Inputs tab. I locked it:


Even locked, IAT shows -40 and problem persists.


diambo4life
(Member)
07/22/19 09:49 PM
Re: New stumble on initial press of accelerator pedal

Add more fuel to those cells where it's stumbling and see whether the issue lessens or gets worse.

thomcasey
(I ain't no puny human)
07/23/19 08:50 AM
Re: New stumble on initial press of accelerator pedal

I would have to change everything below 3500RPM, not really willing to do that when I know I have a sensor that is reading -39/40, which indicates a bad sensor per GM. At least when I get the sensor I will know for sure it is good and adjust from there.

thomcasey
(I ain't no puny human)
07/25/19 01:45 PM
Re: New stumble on initial press of accelerator pedal

Changed out the IAT sensor and the ECU still see's -40 for intake temp. Would a shorted wire cause this? I am using the ECMTuning plug and play kit to a 2g MAF plug (Car had a 2gMAF plug there already, so I bought the complete wiring kit from ECMTuning for that plug). I have no problem checking the connections to the plug itself, but I just can't find much information on what would cause an issue like this, where the IAT is seeing high voltage to throw it to -40.

I found this post on Tuners, but there is no resolution. -40 IAT


transparentdsm
(I have to say something dumb Member)
07/25/19 06:21 PM
Re: New stumble on initial press of accelerator pedal

Are you sure the 2g maf harness is wired in correctly? I'd check all the wiring for the maf.

thomcasey
(I ain't no puny human)
07/25/19 06:52 PM
Re: New stumble on initial press of accelerator pedal

Well, it has been working for several months, at least until a few weeks ago. Maybe one of the connections broke.

thomcasey
(I ain't no puny human)
07/26/19 09:52 AM
Re: New stumble on initial press of accelerator pedal

Ohmed out the connections and they were good. Went ahead and cut the connector and direct wired, still seeing the issue. Next to verify it is getting all the way to pin 8 or if the IAT section of the ECU is bad. I have a fresh ecu to install if needed.

thomcasey
(I ain't no puny human)
07/26/19 12:26 PM
Re: New stumble on initial press of accelerator pedal

All wiring tested good. I even swapped the ECU for a fresh repaired one from ECMTuning, still seeing the -40 in the logs. I can disconnect the sensor without the car noticing or anything. Is there a setting I can set to put the IAT @ 70/77 vs the -40?

thomcasey
(I ain't no puny human)
07/27/19 11:32 AM
Re: New stumble on initial press of accelerator pedal

I zeroed out SDTempWeighting to disable IAT with SD and still have the same issue. Here is a video showing what it does when I stab the gas. HESITATION

transparentdsm
(I have to say something dumb Member)
07/27/19 11:47 AM
Re: New stumble on initial press of accelerator pedal

so i finally had some free time to check out your log. try disabling the airflow smoothing w/ SD operation in the MISC. tab, its the one thing i can see.

edit: im not sure this is going to do anything to help or hinder you and probably wont change anything with your IAT's, but it is something i noticed.


thomcasey
(I ain't no puny human)
07/27/19 12:09 PM
Re: New stumble on initial press of accelerator pedal

Thank you. I will do that and report my findings. I have also obtained a test TB just in case something is cracked with mine post plate.

thomcasey
(I ain't no puny human)
07/27/19 04:11 PM
Re: New stumble on initial press of accelerator pedal

That didn't change anything. Plugs were covered in soot. Cleaned and gapped them. No real change. Problems are all below 3k rpm. Maybe timing? I suppose I could check Monday evening

thomcasey
(I ain't no puny human)
07/29/19 02:33 PM
Re: New stumble on initial press of accelerator pedal

I went ahead and swapped out the TB for the once from my son's motor and the problem seems to be gone. So, something on my TB is leaking bad, even though it didn't present on the Boost Leak check. I ordered a used TB from PerformancePartout and will send it out to be cleaned and rebuilt when I receive it.

iceman69510
(Turn Right Racing)
07/30/19 07:41 AM
Re: New stumble on initial press of accelerator pedal

Curious. That's good news.

thomcasey
(I ain't no puny human)
07/30/19 08:30 AM
Re: New stumble on initial press of accelerator pedal

Yes, it is very curious. There is a FAIV Bypass plate installed, with a new seal. And it was working fine for about a week before I started seeing the issues. I am thinking maybe a crack developed from the bypass installation (primarily breaking the factory FIAV screws loose) and allowed the extra air to enter the system. I am installing a new ISC in the replacement TB today and then using link to adjust the idle/BISS to be sure everything is actually good.

thomcasey
(I ain't no puny human)
07/31/19 04:48 PM
Re: New stumble on initial press of accelerator pedal

Well, I didn't wait long enough. Stumble came back. Had my son sit in the car while it was idling and I injected brake clean at the base of the injectors and found this on Injector 1!!



iceman69510
(Turn Right Racing)
08/01/19 08:11 AM
Re: New stumble on initial press of accelerator pedal

Ahh. One of those got me once too. Amazing what a difference that can make.

thomcasey
(I ain't no puny human)
08/01/19 08:47 AM
Re: New stumble on initial press of accelerator pedal

Yea, so I ordered a PTE injector specific set. So, I am not really sure what is causing the -40 reading for the IAT, but that can be bypassed and troubleshot at a later date. Not tom mention, it will be easier to work it if the car runs right first.

thomcasey
(I ain't no puny human)
08/09/19 08:26 PM
Re: New stumble on initial press of accelerator pedal

Injector seals didn't fix it. Looked closer at my logs and saw that my Baro reading was -9.8inHg with the engine off (I am at 1100ft, so it should have been zero or positive. I heard may rumors about the OmniPower MAP sensors having quality issues (mine was only 10 months old) so I replaced it with a new AEM 3.5 Bar and she is al good now.


Contact Us | Privacy statement GalantVR-4.org

Generated in 0.004 seconds in which 0.002 seconds were spent on a total of 4 queries. Turbo powered.


Hertz's Galant VR-4 Page