Crazy car driving me crazy!!!
Thread Starter
Joined: Sep 2004
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From: Michigan & Florida
Life is getting in the way, because, as you know, it's a busy time of year. Had the sensor for several days now, just no time to install it. The 2 cold start tune files aren't expected until, or shortly after, 12-9-25, so please be patient!!
Thread Starter
Joined: Sep 2004
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From: Michigan & Florida
UPDATE....Sorta. Yesterday, I called the shop where the tuner works. He was busy, so I left a message. He didn't call back yesterday, and hasn't yet this morning. I'll try him after lunch, say 1:00. If I hear anything back, Ill post it. Maybe my wife has a point, IDK. But she thinks he has pretty much decided not to work on my car anymore. That's not the guy I know. I hope she is wrong....
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Joined: Oct 2022
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From: Louisiana
Did you get the sensor installed? Also sounds like you may to find a new tuners. If I remember right he told you a few weeks ago he was going to look it over. I wouldn't mind the taking a little time but I would mind someone not sticking to there word and then not answering the phone.
He is probably losing money on your car, OR he is of making money off your car and not fixing it... he looses either way
The fact that you have NOT tried another ECT sensor yet seems to imply you really have no intrest in fixing the car, maybe because once its fixed you will have nothing to do?
The fact that you have NOT tried another ECT sensor yet seems to imply you really have no intrest in fixing the car, maybe because once its fixed you will have nothing to do?
Here is the cold start file that his tuner provided.
The only thing I noted is that the IAT says 88 deg F and the coolant sensor says 72.
True cold start they should be within a few degrees of each other.
Ron
The only thing I noted is that the IAT says 88 deg F and the coolant sensor says 72.
True cold start they should be within a few degrees of each other.
Ron
Thread Starter
Joined: Sep 2004
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From: Michigan & Florida
I'd like to thank Ron for all the help he's doing to try to help me. I'd also like to thank all the rest of you that are trying to help, as well. Today I finally felt well enough to go out and install the new GM coolant temp sensor I've had for 3 weeks. So I disconnected the old sensor in the engine, and connected the new sensor to the C5 pigtail. I then grounded the sensor with a test lead. Ambient was around 58°. Turned the key on, and noted a temp reading of 84°, which was probably correct due to me holding onto it. Car fired right up. Next, I put the sensor in the fridge. After maybe 20 minutes, I took it out to the car and hooked it up again. This time coolant said 73°. Car fired right up, again. So, I put the sensor in the freezer. 20 minutes later, sensor said coolant was at 48°. Started the car and it ran for the usual half second, then stalled. DOHHHHH!!!
More convinced than ever it's in the tune. All this BS is SO FRUSTRATING!! Car runs so well at all speeds and rpm's, and starts immediately IF coolant is 68°-70°. DAMN!!!!
More convinced than ever it's in the tune. All this BS is SO FRUSTRATING!! Car runs so well at all speeds and rpm's, and starts immediately IF coolant is 68°-70°. DAMN!!!! Thread Starter
Joined: Sep 2004
Posts: 3,212
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From: Michigan & Florida
The only thing I can say about the temp discrepancy is perhaps the time of year (July?) warmed the air rapidly, and the coolant took longer to warm. I'm going to keep an eye on what the exact coolant temp is that it wont start.....
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From: Central Cal.
If a COLD START indicates 88 IAT and coolant is 72, what was AMBIENT at that time?
If it was 88, coolant would also be that temp (88).
Basically, whichever indicated temp is way out of line from ambient points to a bad sensor,
On a cold start EVERYTHING should be at or about ambient.
If it was 88, coolant would also be that temp (88).
Basically, whichever indicated temp is way out of line from ambient points to a bad sensor,
On a cold start EVERYTHING should be at or about ambient.
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Verdad Gallardo Thread Starter
Joined: Sep 2004
Posts: 3,212
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From: Michigan & Florida
If a COLD START indicates 88 IAT and coolant is 72, what was AMBIENT at that time?
If it was 88, coolant would also be that temp (88).
Basically, whichever indicated temp is way out of line from ambient points to a bad sensor,
On a cold start EVERYTHING should be at or about ambient.
If it was 88, coolant would also be that temp (88).
Basically, whichever indicated temp is way out of line from ambient points to a bad sensor,
On a cold start EVERYTHING should be at or about ambient.
TECH Senior Member
Joined: Jun 2016
Posts: 22,295
Likes: 3,617
From: Central Cal.
Not arguing, but things warm up quicker with that much temp change, especially aluminum compared to, say, iron.
TECH Fanatic
Joined: Oct 2022
Posts: 1,779
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From: Louisiana
If a COLD START indicates 88 IAT and coolant is 72, what was AMBIENT at that time?
If it was 88, coolant would also be that temp (88).
Basically, whichever indicated temp is way out of line from ambient points to a bad sensor,
On a cold start EVERYTHING should be at or about ambient.
If it was 88, coolant would also be that temp (88).
Basically, whichever indicated temp is way out of line from ambient points to a bad sensor,
On a cold start EVERYTHING should be at or about ambient.
Thread Starter
Joined: Sep 2004
Posts: 3,212
Likes: 1,612
From: Michigan & Florida
I am afraid the answer to all of this may never be discovered. I do feel it is somewhere in the tune, but I simply don't know enough about tuning, and am dependent on the tuner/whoever does the tune. If I ever do find the answer, I will post it. It took 2 years before I finally figured out my A/C disengaging at idle problem. That was partially due to having a 25% UD balancer. Hoping I'll find out when I get back to the tuner in Michigan. Thank you all for trying to help
Last edited by grinder11; Dec 19, 2025 at 08:36 AM.
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From: Louisiana
Man you live in Florida, there is many shops out that way that tune and do performance builds. I live in Louisiana so we dont have much of anything around here. There is a few shops here but not many. For the most part you have to know someone, I came too Tampa in 2022 to work in mosaic refinery and one of the things that stuck out to me the most was how many performance cars I saw on the street and how many performance shops I saw. I was sitting in McDonald's eating and I heard a car going wot and I walked outside and there was literally a car on a dyno in a shop next door to McDonald's. Long story short man you should be able to find someone to help you out that way, if the tuner you have isnt available search around and find a new one. Im willing to bet its something simple that you guys are overlooking.
Thread Starter
Joined: Sep 2004
Posts: 3,212
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From: Michigan & Florida
He is probably losing money on your car, OR he is of making money off your car and not fixing it... he looses either way
The fact that you have NOT tried another ECT sensor yet seems to imply you really have no intrest in fixing the car, maybe because once its fixed you will have nothing to do?
The fact that you have NOT tried another ECT sensor yet seems to imply you really have no intrest in fixing the car, maybe because once its fixed you will have nothing to do?
Last edited by grinder11; Dec 19, 2025 at 09:37 AM.
Thread Starter
Joined: Sep 2004
Posts: 3,212
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From: Michigan & Florida
The tuner told me the sensor wouldnt work. He said info from all the senders was normal. Guess I should've listened. But, at least I now know it's not the ECT sensor....
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Joined: Oct 2022
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From: Louisiana
unfortunately sometimes fixes aren't the fix, at least it was a cheap fix and you now know you have a good sensor. Assuming all wiring is working as it should. Honestly you need to find a remote tuner, thats they way go go. Even more so at your age and if you have health issues, its alot easier to walk outside and plug up a laptop then chasing down someone trying to get him to look at your car.
Thread Starter
Joined: Sep 2004
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From: Michigan & Florida
Yes, I realize now for sure the sensor isn't the issue. QUESTION-Doesn't it seem that if it were a wiring/harness/sloppy pin fit in the ECT circuit, that the tuner would've seen the issue on his HPTuners? Again, he said he saw no red flags, and all was good as far as the sensors were concerned. I am thinking this has been a perfect storm situation that started with my instructions to change the cold start tune at least 4 years ago. I remember telling him to please lean out the cold start mixture, as I felt it was too rich. I should've left well enough alone, DAMN IT! DAMN IT, again!!! It was fine the way it was. Started at 10° or 110°. Of course, the problem didn't manifest itself in July, or August, due to higher ambient temps. But it did in September. Moral of this story: Be careful what you ask for!! When he changed things, he probably thought it was for 36lb injectors, which was wrong, because I have 42lb injectors. Anyway, whatever was done is blurred by history. The guy probably tunes at least 30-50 cars each year, minimum. Asking him to remember what he did in 2021 would be asking a lot.... I think, as the guys here have suggested, that now that we know the tune is way outta whack due to the tables being altered for 36lb injectors to compensate for my 42s, the entire tune should be shitcanned and start over again from the beginning. Tuner says he should be able to use the WOT, Dyno, open loop tune by scaling it over to 42s. But he is going to change everything else. Whatta PITA. Worst thing is I'll probably never be able to post exactly what the problem is, and hopefully, WAS!! I hate no solution threads!!
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Joined: Oct 2022
Posts: 1,779
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From: Louisiana
Yes, I realize now for sure the sensor isn't the issue. QUESTION-Doesn't it seem that if it were a wiring/harness/sloppy pin fit in the ECT circuit, that the tuner would've seen the issue on his HPTuners? Again, he said he saw no red flags, and all was good as far as the sensors were concerned. I am thinking this has been a perfect storm situation that started with my instructions to change the cold start tune at least 4 years ago. I remember telling him to please lean out the cold start mixture, as I felt it was too rich. I should've left well enough alone, DAMN IT! DAMN IT, again!!! It was fine the way it was. Started at 10° or 110°. Of course, the problem didn't manifest itself in July, or August, due to higher ambient temps. But it did in September. Moral of this story: Be careful what you ask for!! When he changed things, he probably thought it was for 36lb injectors, which was wrong, because I have 42lb injectors. Anyway, whatever was done is blurred by history. The guy probably tunes at least 30-50 cars each year, minimum. Asking him to remember what he did in 2021 would be asking a lot.... I think, as the guys here have suggested, that now that we know the tune is way outta whack due to the tables being altered for 36lb injectors to compensate for my 42s, the entire tune should be shitcanned and start over again from the beginning. Tuner says he should be able to use the WOT, Dyno, open loop tune by scaling it over to 42s. But he is going to change everything else. Whatta PITA. Worst thing is I'll probably never be able to post exactly what the problem is, and hopefully, WAS!! I hate no solution threads!!
Joined: Apr 2006
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From: Grand Rapids, Michigan
Just out of curiosity, who is your tuner in Michigan? You're downstate and I know of at least one tuner down there that is absolutely worthless. Not even sure he still tunes cars, so many people had bad luck with him.
Thread Starter
Joined: Sep 2004
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From: Michigan & Florida
His name is Rich. He is a very highly respected tuner, and was the tune guy at Wheel to Wheel. I'm sure it's not him. He's really good. Tuned many top cars, as well as high perf street cars. He's spending a lot of time going over my tune files thru the years on his own time. My car has done some weird things. Last summer, he had it working even when cold. Then one day the problem returned, except now it didn't start when hot!! He was totally flabbergasted. He said its like my ECM totally lost the tune he put in it, and he says that just doesn't happen. IDK......