After rereading you original post, I'm doubting that rpm fluctuations to that extreme are caused by the tune without something else going on. Maybe a bad throttle position switch? That is where a good log would come in handy. If you could find a GM tech willing to look at it, they could likely diagnose something pretty quick with a tech2.
RPM Fluctuations/Stalling
- Thread starter YoungGun
- Start date
YoungGun
Active Member
Reading about the TPS, it does sound like it could cause these issues. Then again everything else does too to a degree lol. Because the issue isnt really with the idle itself, its the throttle thats a bit all over the place. When it goes into surge mode it almost seems like its overcompensating in both directions like a pendulum.
There is a GM dealership a few miles away. I do want to learn and work on the car myself but at the same time I dont want to spend weeks troubleshooting a problem.
You can buy a tech2 clone for about $100
(1) [How To Install] VXDIAG - The poor man's Tech2 | DF Kit Car Forum
(1) [How To Install] VXDIAG - The poor man's Tech2 | DF Kit Car Forum
YoungGun
Active Member
Probably a future thing I will do. For now I am a little anxious to get the car steady/operational (havent even felt confident enough to drive over to get it inspected/registered) so I think I am going to take it to GM service center and have them take a look to hopefully find/fix or rule out some issues on Monday/Tuesday.
Ross
Goblin Guru
Jermey's car seemed to run fine at the autocrosses. I was behind him a lot in our autocross running order, so I would have noticed if it was surging at idle. I am able to run an HP Tuner's log, and check for OBDii codes, as that should give us a good diagnostic. I should be back from vacation in a week or so, and can help YoungGun then, if he gets a tow bar, or some way to move it.
YoungGun
Active Member
I really appreciate it. I think I saw that video of you both autocrossing. I will see what the GM people say and possibly try replacing some parts that are potentially causing the issue in the meantime.
Rttoys
Goblin Guru
Don’t be surprised when the dealer (possibly) dosen’t know anything. They like bone stock and new. This is over 10 years old and highly modified. I would try to find a performance shop that is good with exotec or even LS based vehicles.
Since it seems that it ran fine before, hopefully it’s just a sensor nutting up or a loose connection somewhere.
Since it seems that it ran fine before, hopefully it’s just a sensor nutting up or a loose connection somewhere.
Ross
Goblin Guru
Take your car to an automotive supply store (Autozone/Napa/etc) and they often will pull the OBDii codes for free.
Make a smoke machine and check for vacuum leaks?
Make a smoke machine and check for vacuum leaks?
YoungGun
Active Member
Yes, so is low coolant, ABS, air bags, etc (for obv reasons). Jermey mentioned that the low coolant has always been on. I did confirm coolant is filled and running.
So yes first step is to check the engine DTC's and start there. You can get that done at the local parts stores. Make sure you get the exact codes. At this point you are interested in the P codes (which are all you are likely to get from the free reading). You will get several that aren't important, such as evap and 2nd o2 sensor, but most of the others will matter.
YoungGun
Active Member
Okay cool, tomorrow morning I will take it to Autozone and report back with their readings, and then take it to the GM service center across the street depending on what those codes are.
YoungGun
Active Member
Well I'm hoping they can at least rule some things out like sensors, loose connections, leaks, find codes, and narrow the search a bit. If they can't find anything I'll send it to a performance shop. They are a little further away so I'll try them second. Don't want to risk stalling out every light for a 25 minute drive lol, doesn't sound super fun.
A dealer might be more willing to work on it if you can go to them and say it has a particular problem with the (throttle position switch switch for example). Probably any good shop could diagnose it with a Snap-on diagnostic tool also, it will just be a matter of getting someone willing to actually try.
Make sure you know for sure what your donor vehicle was.
Make sure you know for sure what your donor vehicle was.
YoungGun
Active Member
GM service center was zero help as expected by you guys lol. Got the codes from the Aeroforce guage, didn't realize that was a thing until today... Attached the picture of it. I also tried disconnecting the TPS sensor and seeing how that went, it went into severe limp mode and wouldn't give me enough power to even make it up the curb onto my driveway. It didn't stall... but I couldn't really drive it so it wasn't a great test. Here are the codes.
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P0098 Chevrolet - OBD Code Lookup
Intake Air Temperature Sensor 2 Circuit High Table of contents Possible Causes How To Fix Cost To Diagnose Possible Symptoms Description P0098 CHEVROLET Possible Causes Faulty Intake Air Temperature sensor Intake Air Temperature sensor harness is open or shorted Intake Air Temperature sensor...
obdcodelookup.com
P0102 Chevrolet - OBD Code Lookup
Mass or Volume Air Flow Circuit Low Input Table of contents Possible Causes How To Fix Tech Notes Cost To Diagnose When is the code detected Possible Symptoms Description P0102 CHEVROLET Possible Causes Faulty mass air flow sensor Intake air leaks Dirty mass air flow sensor Dirty mass air filter...
obdcodelookup.com
P0107 Chevrolet - OBD Code Lookup
Manifold Absolute Pressure/Barometric Pressure Circuit Low Input Table of contents Possible Causes How To Fix Cost To Diagnose When is the code detected Possible Symptoms Description P0107 CHEVROLET Possible Causes Faulty Manifold Absolute Pressure sensor Manifold Absolute Pressure harness is...
obdcodelookup.com
P0122 Chevrolet - OBD Code Lookup
Throttle Position Sensor 1 Circuit Low Voltage Table of contents Possible Causes How To Fix Cost To Diagnose When is the code detected Possible Symptoms Description P0122 CHEVROLET Possible Causes Faulty throttle position sensor Throttle position sensor harness is open or shorted Throttle...
obdcodelookup.com
P0132 Chevrolet - OBD Code Lookup
HO2S Circuit High Voltage Bank 1 Sensor 1 Table of contents Possible Causes How To Fix Tech Notes Cost To Diagnose When is the code detected Possible Symptoms Description P0132 CHEVROLET Possible Causes Faulty Front Heated Oxygen Sensor Bank 1 Front Heated Oxygen Sensor Bank 1 harness is open or...
obdcodelookup.com
P0134 Chevrolet - OBD Code Lookup
HO2S Circuit Insufficient Activity Bank 1 Sensor 1 Table of contents Possible Causes How To Fix Tech Notes Cost To Diagnose When is the code detected Possible Symptoms Description P0134 CHEVROLET Possible Causes Faulty Front Heated Oxygen Sensor Bank 1 Front Heated Oxygen Sensor Bank 1 harness...
obdcodelookup.com
P0223 Chevrolet - OBD Code Lookup
Throttle Position Sensor 2 Circuit High Voltage Table of contents Possible Causes How To Fix Cost To Diagnose When is the code detected Possible Symptoms Description P0223 CHEVROLET Possible Causes Faulty Throttle Body Assembly Throttle Body Assembly harness is open or shorted Throttle Body...
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P2511 Chevrolet - OBD Code Lookup
ECM/PCM Power Relay Sense Circuit Intermittent Table of contents Possible Causes How To Fix Cost To Diagnose Possible Symptoms Description P2511 CHEVROLET Possible Causes Faulty ECM/PCM Power Relay ECM/PCM Power Relay harness is open or shorted ECM/PCM Power Relay circuit poor electrical...
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YoungGun
Active Member
Kk I will do that tomorrow. Wasn't sure if that would perma clear issues. One of the mechanics did check it over for a few seconds and said he thought it might be the TPS. He didn't see any connections loose. Then again he only took a few minutes of his time. It will be interesting to see what codes come back.