Bizzare issue with LT1 running like crap
Thread Starter
Teching In
Joined: May 2023
Posts: 1
Likes: 0
Bizzare issue with LT1 running like crap So. I have a 1995 z28 camaro 6sp. 90% stock got a headerback borla exaust and CAI. Nothing else big just simple skip shift eliminator etc. so, car recently starting to run very hot about just over half on the center temp mark im assuming 210-220 roughly. Which isnt horrible but for the lt1 isnt that good. Car stumbles has almost 0 power at that temp. ONLY AT THAT TEMP. Car occasionally misfired invetween shifts when cold aswell. Opti was replaced about 5-6 months ago not by me but i have a warranty it was $380 and i have recipts etc for pump/seals/gaskets/opti etc job was well done. Punp started leaking about 2 months ago. I discovered today my fans arent turning on at all and thats why its so hot. Didnt help my oil was a litte bit low and coolant couldve used a top off. But after weeks of being scared to drive my car in fear of engine failure. I decided to say **** it and try random things hoping its not my opti. Pulled my air pump fuse and ses light came on fans did too. Put it back in reset my ECU and fans stayed on and dropped to operating temp and started running absolutely flawlessly again… felt like when i first got the car. Im getting about 8-9 mpg city but cruising 80 on freeway i get 20mpg? (Before that fix and no cruise control and a cooler night) im so stumped on what the hell is going on. Why is my car running amazing after forcing my fans to turn on and turning my airpump on and off and resetting ecu? Car quite literally felt like it was going to jump off the frame before this fix it was so bad now, nothing??? I know this will come back while it retunes but what is going on??? Reading timing fine since the reset would still have an opti interference if the opti was bad. What can i do?? I dont want to spend $1300 on fixing a working opti. Sorry for the rambling on im just so lost.
So. I have a 1995 z28 camaro 6sp. 90% stock got a headerback borla exaust and CAI. Nothing else big just simple skip shift eliminator etc. so, car recently starting to run very hot about just over half on the center temp mark im assuming 210-220 roughly. Which isnt horrible but for the lt1 isnt that good. Car stumbles has almost 0 power at that temp. ONLY AT THAT TEMP. Car occasionally misfired invetween shifts when cold aswell. Opti was replaced about 5-6 months ago not by me but i have a warranty it was $380 and i have recipts etc for pump/seals/gaskets/opti etc job was well done. Punp started leaking about 2 months ago. I discovered today my fans arent turning on at all and thats why its so hot. Didnt help my oil was a litte bit low and coolant couldve used a top off. But after weeks of being scared to drive my car in fear of engine failure. I decided to say **** it and try random things hoping its not my opti. Pulled my air pump fuse and ses light came on fans did too. Put it back in reset my ECU and fans stayed on and dropped to operating temp and started running absolutely flawlessly again… felt like when i first got the car. Im getting about 8-9 mpg city but cruising 80 on freeway i get 20mpg? (Before that fix and no cruise control and a cooler night) im so stumped on what the hell is going on. Why is my car running amazing after forcing my fans to turn on and turning my airpump on and off and resetting ecu? Car quite literally felt like it was going to jump off the frame before this fix it was so bad now, nothing??? I know this will come back while it retunes but what is going on??? Reading timing fine since the reset would still have an opti interference if the opti was bad. What can i do?? I dont want to spend $1300 on fixing a working opti. Sorry for the rambling on im just so lost.
If certain sensors are unplugged, your car will stay in open loop. Likely why your mileage is so bad.
Good news is that if it runs great like this, your optispark is probably fine.
I'd wager on a vacuum leak.
On The Tree
Joined: Oct 2011
Posts: 179
Likes: 3
From: Eastern Kentucky
Ahhhh, the old LT1 cooling issue. The LT1 primary (RH) fan doesn't turn on until 225 degrees and it'll turn off at 217. The secondary fan (LH) comes on at 232 degrees and turns off at 225. You said yours runs "approx 210-220" and that isn't hot enough to trigger either fan.Both fans should come on when the A/C is on. With the age of these cars getting up there certain things may have been done in the past that aren't helping. Are you sure that the previous owner(s) didn't just stick in a 160 degree stat and possibly the wrong one? The LT1 T-stat is a very specific 180 degrees. It must be a LT1 specific 2 way full bypass t-stat. Although any Gen 1 t-stat will fit in the hole it will not work and it will overheat. I've had parts people try to give me the wrong stat because their computer was wrong. Any thermostat other than the stock will require a programming change on the ECU. The best (IMHO) way to fix the issue is to get the correct 180 degree stat and start from there. Do you have access to any tuning software 'cause that sure would help. The correct 160 degree stat is a Hypertech #1008. The 180 degree is 12555290. If we've got to start somewhere and blind let's start cheap. ;-) Good luck and keep us posted. Have a blessed rest of your day.
