Fans come on at same time as service engine light

**bottjeremy** · 04-13-2006, 06:36 AM

Hello all, this is my first post. I have a Z28 camaro with a few mods
-Underdrive Pulleys
-K&N Cold air induction
-TPIS Air foil
-Misc Air screens removed
-CAT was removed - Problem was happening before i removed this
-Throttle body bypass

Ever since i made a few mods my fans will kick on at same time as service light. This will happen after i start the car, and it is warming up for about a minute. When i come up to a stoplight, after it is warmed up, sometimes the service light will shut of, as well as the fans. As soon as i take off again, they will spin back up. This is not a big deal, because my engine ALWAYS runs very cool. But it seems like the engine is running very rich because of this. I thought it was the thermostat, which i was running a 180degree, so i switched it out for a 190(i think). Does anyone have any ideas. I know i am running rich, because I can smell it in the exhaust.

**bottjeremy** · 04-13-2006, 11:40 AM

One thought to be added. Could this problem be created by faulty o2 sensors? The original sensors are still in my 95 z28.

**dooley** · 04-15-2006, 06:11 AM

the fans are designed to kick on at the same time your sevice engine lights comes on for some reason. i thought it was weird when it first happened to me.

i get the SES light from time to time when im cruising slow but it goes off in like 5 minutes.

i have no clue whats causing it

**CODE4LS1** · 04-16-2006, 08:29 AM

I JUST had this problem with my car after a nitrous install. I forgot to plug back in the IAT sensor when I put the plenum back in. Everything was fine for about 40 mins, but then my SES came on and my fans came on at the same time, making my idle seem like it was rich. Plugged it back in and everything is fine

**bottjeremy** · 04-16-2006, 06:36 PM

Hey, thanks for posts guys. Just got a new 4l60e trans with 2000 stall. While i had it in, i asked the guy to replace the o2 sensor's. He ended up only changing 1 of them, the one near the trans. Since he did it, the fan and SES light only come on half the time. So i assume that when i change the other one, i'll be good. I will keep yall posted on this just in case anyone else is having problems. By the way, i did check the wire on the intake elbow, which i had removed last summer, when the problem started.... it did not correct the problem, but i can see how it could have.

**mightyquick** · 04-19-2006, 04:00 AM

Other things that can cause the rich idle, fans on...

1. Temp sensor in the drivers side head, between cylinders 1 and 3(connector left disconnected or connector broken. I have had BOTH happen, just at different times)

2. Burnt O2/PCM ground/Knock sensor wires in the wiring harness bundle that goes between the passenger side inner fender and the headers.

On my '96 Z28 (SLP Headers at the time), the burnt wires in that harness kept popping a fuse in the underhood fuse box but on my '94 (Hooker Long tubes) no fuse was popped, just SES light but no SES codes when viewed with a Scanner.

**bottjeremy** · 04-23-2006, 05:58 PM

Just smoked a stickshift twin turbo 3000gt that this guy had done some mods done to. He could not believe it, and thought i had a supercharger. Ha ha. LT1 POWER!!!!!

**z28freakout** · 04-23-2006, 11:44 PM

my 1994 z28 has decided to be a bad child. It will turn over but not start. I just installed an airfoil on the throttle body and added some neat brass fittings to the thermostat housing to bleed air. after i did this the car would not start. hmmm. I tinkered with the maf sensor connecter and the IAT connecter and a few other connecters and i got it to start one time and run for a bit. I noticed also that the fans came on and the check engine light. i ran it on the street for a couple of minutes and it died in traffic. A kind man helped me push it into the parking lot it sits now. It still will not start. it was also running rich it seemd before indid these mods. O2 sensors bad? who knows. lett me what you think.

**bottjeremy** · 04-24-2006, 04:25 AM

I would check to see if your elbow is on all the way. Sometimes i had a problem with seating it all around the intake, and it was stalling. I would also reset your computer. I had to unplug my battery for about 20 minutes or so to reset it. I was told if you disconnect the battery, and touch both the positive and negative wires together, it would reset it if you can't get anything else to work. USE AT YOUR OWN RISK!! Your brass screws for the thermostat probably are not affecting anything.

**z28freakout** · 05-03-2006, 05:26 AM

well..i took it to the shop and they said the opti was no good. so i had it replaced..;( that was way too much to spend. it drove fine for a couple of days and it died on me again. omg. unbelievable. i could get it to start but it just barely stayed lit for a very short time. some kind sirs helped me push it across the intersection to a parking lot. i called the shop and had it towed. this is insane.

**bottjeremy** · 05-04-2006, 03:51 AM

I have never heard if the opti spark problem untill i started reading these forums. I have been lucky enough not to have that problem yet. I have 102000 miles on my car now. I actually have not had to replace anything major on my car since it first rolled off the showroom floor, besides the trans. My friend has a 98 camaro that he has replaced EVERYTHING on. I can say from what ive read and heard, the 95.5 camaro has a really good track record. Mine has the obd2 connector. Sounds like it could be a good post. Least problematic years of the lt1 camaro's.