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New stumble on initial press of accelerator pedal (SOLVED)

thomcasey

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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.
 
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cupajoe

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sd?
 

thomcasey

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Yes. Went to SD last year.
 

Dan D

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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 sh*t Get-Go gas?
 

thomcasey

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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

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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

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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

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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

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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

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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

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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.
 

thomcasey

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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

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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
 
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thomcasey

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

thomcasey

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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

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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

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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

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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.
 
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