LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Why Does My Car Do This When Its Warm?

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Old Nov 16, 2003 | 09:23 AM
  #16  
Like My Taillights?'s Avatar
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fyi from Shoebox's site: http://shbox.com/1/temp_sensor2.jpg

I think this sensor is only for the temp gauge on the dash. There is another temp sensor for the computer.
Old Nov 16, 2003 | 09:30 AM
  #17  
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guys WTF....i know this for sure its the stupid OPTI..any time you lose power trying to give trhottle its the opti spark!!!
Old Nov 16, 2003 | 10:12 AM
  #18  
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Dude...when your talkign about things like the OPTI-whic are expensive and a pain in the *** to get to..it's Better to relieve all doubts first and get ithe car offically scanned. THat way if it's a cheapo issue he can fix that..or if it actually turns out to be the opti atleast he'll have confirmation. How many times do you hear about people spending like 100's to replace items and never fix the issue..then later find out it was something cheap that went wrong like a bad EGR or something. Costly mistakes suck the most...they take away form modding money.
Old Nov 16, 2003 | 10:31 AM
  #19  
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I was going to replace the optical side of my opti (slotted wheel and sensor stuff), about $200, but when I got down there I found out that the four wire connector that sends the signal to the ecm was all mangled up, so the computer didn't know what was going on, which of course caused the wonderful virtual rev-limiter problem... Luckily, the part was returnable, so all it cost me was a hard night's work and some antifreeze.
Old Nov 16, 2003 | 12:10 PM
  #20  
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I just replaced my opti at 105K miles and now have a stumble at idle when warm. This is absolutely a closed loop problem. Yes, it could be the opti, or one of many other things. Just cause your opti has a lot of miles on it does not mean it is the problem. I am still trying to diagnose my problem, but it seams common sulprits are the IAC, temp sensor (not sure i understand how?), IAT, O2's, and heaven forbid the MAF! Just think it might be worth scanning before doing an opti swap.
Old Nov 16, 2003 | 12:45 PM
  #21  
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I had a similar miss when the car warmed up it would miss and hesitate. So I replaced the Opti, and guess what? That wasn't the problem, After checking and replacing everything electrical (Because I got a lot of spare parts) It was my #5 plug wire which were fairly new Magnecors. It isn't always the opti when you have a miss after warm-up and as others have said I would do that after checking everything else out.
Old Nov 16, 2003 | 03:00 PM
  #22  
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Just to get my two cent in.

I have had this problem going on three years now. It just started suddenly one day, driving along fine but as soon as it warmed up (8 to 10 min.) started having the same symptoms (hesitation/Loss of power). This was "3 years ago" It has not changed or gotten worse just the same thing everyday. Believe me when I tell you I have replaced everything under the hood short of the crank and pistons and nothing ever changes, doesnt get worse doesnt get better. I am at a loss, and I give up. I have just accepted the fact that this is how it is going to be.
As far as scanning it I have had it scanned multiple times and also ran a operational diagnostics scanner while driving to check all the sensors and everything looked right (doesnt mean it was though). Like I said this is just My 2 cents and my experience.
Old Nov 16, 2003 | 04:30 PM
  #23  
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yea i noticed when i first got the car it was kinda cutting out from a launch from a stand still at a street light, and has been getting worse by the week pretty much, its not a bad plug or wire, have new plugs and wires, and new coil. when the temp goes up past halfway it gets really bad backfires pretty much all the time.
Old Nov 16, 2003 | 09:26 PM
  #24  
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Cool

When my water pump was going south(kind of a slow process),it would drip onto the opti and buck and run bad,then run good,then bad.When it finnaly bit the dust,you could see coolant on the ground and everywhere around the opti.When that was replaced,car was fine,somehow opti was saved as well.When one morning months later I started the car ,and drove it down the street,it really started bucking,spitting,(thought I lost the engine),then ,thought it was the opti,so had it towed to the dealer,found out it was the intake manifold sensor(black thing on top of the intake manifold,AND THE HARNESS CLIP AND WIRES)Replaced that,ran up to redline again.(opti o.k.).I would get the car scanned like mentioned above.(do the cheap stuff first,before you start throwing things on that may or may not fix the problem.Sounds like a sensor or something .Hope this helps.(same opti for 108500mi now,still runs smooth).My02
Old Nov 16, 2003 | 09:28 PM
  #25  
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Cool

Sorry,ment MAP sensor on the engine top.
Old Nov 16, 2003 | 10:14 PM
  #26  
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hey did ur map sensor throw a code?
Old Nov 17, 2003 | 08:39 AM
  #27  
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Cool

I don't know if it threw a code ,because I had to get to work,and had no time to mess around with the unknown(for me).It had to be fixed regardless,so I had it towed,and repaired.
Old Nov 22, 2003 | 11:33 AM
  #28  
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Car

My car did the same thing. I've replaced the fuel filter, plugs, opti,pcv valve, wires. The problem is still there. The computer isn't throwing any codes. A friend an I were completely stumped, he thinks it is an emissions issue. So I took it to the shop to get it checked out. Again. They found once one of the 02 sensors heated up the problem began. Also, the ECM is bad. That explains the reason why there aren't any codes showing. I went around gunning parts and the problem wasn't fixed. Go have it checked through. Then, go from there.
Old Nov 22, 2003 | 03:48 PM
  #29  
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I would guess o2 sensor
Old Nov 27, 2003 | 03:33 AM
  #30  
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Problem

That's all I heard..OPTI OPTI OPTI OPTI. That was only part of my problem. I needed. New plugs, those were changed, no change in engine performance, still ran like crap. New fuel filter, still ran like crap. New Opti, still, ran like crap. New O2's, still ran like crap.
New ECM. Problem solved. Your problem may lead somewhere else. I should've known. Because my car ran like crap before it evem went into closed loop. Granted. I needed to replace all the parts I meantioned above.
Don't go doing guess and check like I did. The reason why I was tricked was, the ECM wasn't throwing a single code. Needless to say, it failed.



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