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when when i was going at about 109 in my mkII 5mge and had the rpms at 5500 the check engine light would come on then i would slow down and in about 1 min it would turn off, this dosent happen every time i do this but i happened about 3 times in the same situation. is this a sign of some thing happening in my engine
 

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Dont get me started man.

This has been happeneing to me forever. Replaced the O2 sensor. same issue. My engine code is 21 which indicates the O2 circuit.

I am thinking that the engine is running lean for some reason. I blew my new HG at 20K because of detonation and it may have to do with this. I intend to put my car on a WB dyno as soon as I get it back together to see if it is actually running lean. I will also be running a A/F gauge for what little good it will do.

The first thing you need to do is find out what your engine codes are and what they mean. Hopefully you can just replace the O2 sensor and be good to go.
Good luck...
 

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It did it on mine right before I blew my engine :? check ur oil...thats why my engine blew :cry:
 

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If you have an 85 or 86 short the check connector and take it for another spin and see what the check engine code is exactly. More than likely its an 02 sensor, but it could be a lot of things.
 

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just to twrow mine into the pool here, it happend to me after traveling at 190kms for about 30 seconds, while trying to impress someone (and it did)... pulled over when I saw the light and after a while it went out. havent really pushed the car that hard since.
 

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I hav an 83 an it does the samething... It mostly does it up hills or if a open her up. I would give her gas an it would at as though i let off, like no response at all an if i gas lightly she would respond again... Not sure whats going on.
 

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I hav an 83 an it does the samething... It mostly does it up hills or if a open her up. I would give her gas an it would at as though i let off, like no response at all an if i gas lightly she would respond again... Not sure whats going on.
 

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I have an 83 and I have the same issue. At highway speeds when I get on it. My check engine light turns on for about 5 seconds and then will turn off. I have no clue what the problem is.
 

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I have the problem with my 86. I did change the of sensor. Stan, I am new to diagnosing older vehicles like this but can you please explain or add a link explaining shorting a connector to diagnose this. I think mine may be running lean but I'd rather find out the problem without blindly spending more money to buy parts to diagnose it.

I want to turbo mine and I think it would be better to fix this problem now rather than possibly blowing the engine later.
 

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I have an 83 and I have the same issue. At highway speeds when I get on it. My check engine light turns on for about 5 seconds and then will turn off. I have no clue what the problem is.
I have the problem with my 86. I did change the of sensor. Stan, I am new to diagnosing older vehicles like this but can you please explain or add a link explaining shorting a connector to diagnose this. I think mine may be running lean but I'd rather find out the problem without blindly spending more money to buy parts to diagnose it.

I want to turbo mine and I think it would be better to fix this problem now rather than possibly blowing the engine later.

I'm pretty sure this is common if you have modified the air intake - even if you just add a cone filter. Mine does this too see this great site - lot's of info here - excerpt below: http://www3.sympatico.ca/dean.anderson4/

Air Flow Meter

This is a mod to improve throttle response slightly. Be warned, this may also decrease your gas mileage slightly.
If you have already replaced the stock intake and exhaust systems with improved versions to allow the engine to breathe easier, you may have noticed an annoying "Check Engine" light coming on at the bottom of the dash under some circumstances. This usually happens when you are cruising at a constant speed on the highway and then press the gas pedal slightly to accelerate. The "Check Engine" light may come on for a few seconds and then go out. If you check the error codes stored by the ECU (Electronic Control Unit, or engine computer), you will likely find an Oxygen sensor code. This indicates that the engine is running slightly lean when you first press the gas after cruising at constant speed. Adjusting the Air Flow Meter (AFM) should eliminate this annoying little problem.

For an excellent write-up describing how to adjust the AFM, go to Wes Hetrick's page. He has an easy to follow procedure with pictures.
 

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shides20
what connector shorting other than the timing adjustment are you talking about. iirc timing check connector shorting removes engine load variation.

NEVER, NEVER, NEVER assume that a new part that replaces a suspected failed part is actually working correctly. Always take measurements or inspection as specified.

AFM has a range over which it's designed to operate. If you improve wih a breathing mod then you've changed the operating range. If you tighten the AFM spring you can match the AFM to the new range.

Look at tech articles written by toy at www.autoshop.com for a much better understanding of the engine design.
 

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I gotcha. I will be adjusting the afm to see if that works better. The catalytic converter was really stopped up and solved just a bit of the engine light coming on. It still comes on from time to time at high rpms.
 

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Use a can of inexpensive fuel system cleaner (or dri-gas which is also a good cleaner) in your fuel. A bad spray pattern can cause extra unburnt fuel indicating lean condition just before wot. iirc ecu ignores 0x sensor signal during wot. Anyway, fuel cleaner can't hurt, is inexpensive, and should give a small increase in mileage. Ckean every 3 to 4K miles.
 

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