Overheating?

**Red4Mula** · 07-28-2007, 01:06 PM

Well, seems like the prob is back again but this time its worse, cause of the insane temp out here in TX... At first when I bought the car the car would overheat when sitting at a redlight, so I changed the relay and bam problem solved.... Now a few months later it's doing the same thing but only this time, when it starts to overheat, the SES light comes on and while driving the car seems like its backfiring every 7 secs, like I dont know how to explain it but, it's like when givin it some gas on the road, it misses.. I cant explain it to well, but if it helps I can try to get a video of it... I'm gonna get a new relay for now, since my fans wont kick on and see what happens... But my temp sending unit is obviously bad as the temp will go to about 210 then 1 sec later drop below 160... would that have anything to do with the fans not kicking on?

**2001NBMZ28** · 07-28-2007, 01:18 PM

Maybe you can find an answer at http://shbox.com/1/4th_gen_tech2.html#cooling

**Red4Mula** · 07-28-2007, 01:30 PM

Originally Posted by 2001NBMZ28

Maybe you can find an answer at http://shbox.com/1/4th_gen_tech2.html#cooling

Sweet man ty for the link

**danziger** · 07-29-2007, 12:42 AM

Sounds to me like you pushed a head-gasket and water is getting into one of the cylinders causing the "miss". Does your coolant level drop? If not, then I would agree that it is something electrical, or that you have air-pockets in your cooling system...

**Red4Mula** · 07-29-2007, 11:10 AM

Originally Posted by danziger

Sounds to me like you pushed a head-gasket and water is getting into one of the cylinders causing the "miss". Does your coolant level drop? If not, then I would agree that it is something electrical, or that you have air-pockets in your cooling system...

Nah, I check the coolant lvl everyday, and it's as full as it can get... I also noticed that when it's starts doing that crap it does, the oil pressure drops below 20 psi..

**LS1_TA_2002** · 07-29-2007, 02:07 PM

Originally Posted by Red4Mula

the SES light comes on

Could you post the codes? Maybe this could help with the diagnosis. Even if the light turns off you should still be able to pull codes from memory.

**Red4Mula** · 07-29-2007, 02:09 PM

Originally Posted by LS1_TA_2002

Could you post the codes? Maybe this could help with the diagnosis. Even if the light turns off you should still be able to pull codes from memory.

Yea I took it to my dad's plenty of times when I first bought it because the light stayed on.. At first it was just because it had no cats..... Then when it started acting up like this I took it back to him and the only code that came up was low refrigerant lvl...

**sunsetorangess** · 07-29-2007, 07:43 PM

If your fans arent kicking on then i would say thats the problem, Either the relay or like you said the sending unit. If it was missing it would throw a code and im pretty sure your light would blink.
J

**Red4Mula** · 07-30-2007, 11:15 AM

Originally Posted by sunsetorangess

If your fans arent kicking on then i would say thats the problem, Either the relay or like you said the sending unit. If it was missing it would throw a code and im pretty sure your light would blink.
J

Yea whenever it starts missing, the SES light does come on but when we pull the code its the low refrigerant one.. Makes no sense, yea my fans just do not turn on whatsoever, even with the ac on..

**2001NBMZ28** · 07-30-2007, 12:35 PM

Not an LT1 guy, but did you try jumpering the pins on the DLC to see if they come on? I'd also look at the ECT sensor, and the IAT sensor if you're throwing an AC code.

**Blownone94** · 07-30-2007, 03:32 PM

When the car is running unplug the cts the fan should run if they dont a bad connection at the relay or possibly a bad fan motor might wanna check for voltage at the fans if you have power and ground you have a bad motor. easy way to check is tap the motor with a hammer sometimes you jar it loose and it'll run. as far as oil pressure goes i've noticed the hotter an engine gets the more viscuous the oil gets causing pressure to drop and they also have a problem of leaking past the diaphram and through the sending unit.the hotter the cts reads the more it influences your fuel trims to try and get car to run cooler and can cause misfires. fix the overheating first before worrying about the misfire.

**Red4Mula** · 07-30-2007, 04:25 PM

Originally Posted by Blownone94

When the car is running unplug the cts the fan should run if they dont a bad connection at the relay or possibly a bad fan motor might wanna check for voltage at the fans if you have power and ground you have a bad motor. easy way to check is tap the motor with a hammer sometimes you jar it loose and it'll run. as far as oil pressure goes i've noticed the hotter an engine gets the more viscuous the oil gets causing pressure to drop and they also have a problem of leaking past the diaphram and through the sending unit.the hotter the cts reads the more it influences your fuel trims to try and get car to run cooler and can cause misfires. fix the overheating first before worrying about the misfire.

Thnx to all the replies.. I understand what ur sayin it makes sense about the misfire... What exactly is the cts though?

**Blownone94** · 07-30-2007, 04:44 PM

coolant temperature sensor. on the lt1 i believe it is located on the water pump.

**Blownone94** · 07-30-2007, 04:48 PM

oh and by the way on some cars when you unplug it with car running it dies out but fans should still kick in

**Red4Mula** · 07-30-2007, 04:59 PM

Originally Posted by Blownone94

coolant temperature sensor. on the lt1 i believe it is located on the water pump.

Oh duhh i should have known that lol..... I know theres on on the block that goes to the gauge, and the other one is on the water pump, i think that one controls when the fans kick on..