To start...my baby is a 92' manual coupe.

So i pulled my vette out of the garage for the first time in a month (i know...i've been busy)...and it starts up fine but i immediately notice that my digitial thermo is reading 142, which i know can't be right because its only 91 degrees out...

So I drive it down to my buddy's house so we can wash her, and in doing so the check engine light comes on. I started to notice that the ditgital thermostat was jumping all over the place, anywhere from 142 - LOW, quite sparaticaly.

When driving back home (i knew i needed to get her home at this point), I stop at my girlfriends place because it was on the way. At first, the car wouldn't start, but in the end I got her going and she got home fine.

Anyone have any idea what could be wrong with my girl? I do have a lower thermostat on there then stock which im going to switch back out for stock tomorrow. Any help would be apprciated because I need my vette to be running so I can take her back to school.

 

Did you wash the engine?

 

('95 LT1 6spd) My car is doing the exact same thing right now -- the code it is throwing is "coolant temp too low" -- When I did my long tube headers I smashed off my analog sensor (perhaps unrelated to this -- it ran many hours this way just fine), but after doing a power foam treatment (and running the car with the maf and intake duct disconnected) I now have that code and maf malfunction code (I've done this several times and not gotten that before) -- (and my coolant too reads 142) -- Otherwise the car runs better than ever... but as you say-- it cold starts just fine, but when it is hot it has to crank a bit... I will be looking into this within the next couple hours actually and I will let you know if I find anything out... -- I have been running it this way a few days and it seems fine to drive until you figure it out -- it should always start based on what I am experiencing.

EDIT: In my case I was wondering if the headers burnt something off that somehow got too close... The way you say yours bounces around (my doesn't) makes it sound like you have an intermittent connection... I was told that the digitial read-out was connected to the WP -- so I will be checking there to see if I somehow disrupting a connection there when I removed the intake ducting... Again, I'll let you know if I find something -- I am going out to change the oil now as well...

NOTE: I also have a lower T-stat (160*) -- I don't know enough about these newer computerized cars to rule it out, but that hadn't come to mind until you mentioned it... still strange that this is the first time I have seen this on the forum and just when I have the problem as well....

 

http://forums.corvetteforum.com/show...ht=142+coolant -- fjm59Vettes's post says that he moves the wires around on that sensor until the temp read properly and that fixed everything.... Hopefully that works for me -- it would make sense as some movement in that area is all I could have done....

 

Well I've got that problem fixed now -- the plug was disconnected from the water pump. Whatever used to click it in place appears to be long gone. Mine is holding on very loosely and I would expect that it could even fall off during normal driving conditions... -- In my case I bumped it off when I removed the maf plug that is coupled to the water pump/coolant temp plug. On my 95 it is accessible without removing anything else. Hopefully your fix is just as easy. Good luck

 

The thermostat has nothing to do with what the digital temp guage says. The lower the degree thermostat the longer the warm up time. Once the thermostat opens, it will not control the engine temp. You are getting a errornus reading on the digital guage that is being sent from a faulty senor, wiring, or connection. What did the analog temp guage say when the digital temp guage read 142*?

Pull the code and see what you have..

http://www.c4guru.com/articles/CCMCodePull.pdf

 

Philly, pull the code--and that will give you a starting place for trouble shooting.

 

I am fairly certain the code he is getting is the one I mentioned in my first post... In which case mine acted exactly as he has described and I figure his plug is either disconnected or he has a wiring problem to the coolant sensor on the water pump. The analog coolant sensor is completely separate from the digital sensor and even disconnected has zero impact on anything else.

EDIT: According to the chart from RRTs link I must have been getting code 15 -- I run Datamaster to check my codes so I don't tend to remember the #s.

 

Thanks guys...ill pull the codes right now and see what i get

 

So i pulled the codes and got H15 (low coolant temp) on the ECM codes (just like you thought REGT...)

I thought i'd try unplugging and replugging back in the conector on the water pump. I then started the car back up and it was working fine. Who knows if this will last but it atleast gives me a much better idea of what was wrong.

Thanks so much for the help guys.

 

I'd replace it (or the connector if that's what's broken and a new one comes with the replacement - usually about 9 bucks, though you'll need some coolant). Coolant Temp Sensor is used to calculate fuel delivery - the cooler the signal, the wider or longer the pulse width. Ground is also shared on this circuit with the Manifold Air Temp Sensor and TPS, though if you're not getting those codes, only the ECT is out. With it broken or open, ECM senses minus 38 degrees, sets a code, and it runs on backup.

 

So Iwas right. Because is still happening to me and nobody confirmed I could have been right about checking the sensor.

I was thinking it was opti - but im not so sure now because everytime that sensor is loose my car runs like ****.