My 86 Coupe has been running rich and pings a little at about half throttle while cruising down the road. I've tried using the best fuel possible with every additive known to man with little result. The car only has 60k on the clock but it is 23 years old so I'm thinking one or more of the sensors are bad. I've recently replaced the TPS and the MAF sensor and will be replacing the Idle Air Control sensor due to a rough idle after it warms up. It definitely runs better on cold days than hot ones too.

Starting this little beast has also been tough at times. After sitting over night, she'll start right up but, If I drive to work and let it sit for a few hours I have to crank it for a bit before it'll fire and even then it has a tough time getting up to Idle unless I put my foot in it...which I HATE doing.

There are so many switches and sensors to choose from that I don't know where to start. I need help before my wife makes me get rid of it!

 

Did you change the chip with an aftermarket one????

I would suggest that you pull codes from the computer and see if any are stored in the system. IF so, that will give you a place to start looking into the problem.

You might try the oxygen sensor, they are only about $20 at autozone for a Bosch.

 

There is a superchip in the car that my mother-in-law's husband (former owner) installed many years ago. I was also thinking about the O2 sensor but would that cause dfficult starts?

 

I don't know about difficult starts but it could be causing the rich condition. My car was running rich, so I hooked up my scanner and it indicated a bad 02 sensor because my block learn reading was way off. My suggestion is to hook a OBD 1 scanner up to your car and get a read out of whats going on with your motor. This is sometimes the fastest and best way to figure out a problem.This will also give you a reading of what your EGR valve is doing, a bad or sticking EGR valve will cause the engine to ping...WW

 

First, the PING is a indication of lean not rich. You may be running rich to begin with but then leaning out.

Okay, let me tell you about my experience before joining the Forum. I fell for the advertising hype about the Hypertech chip that promised 50 more HP by just installing their chip. I bought the chip and the 160 degree stat at the same time and installed. Easy installation.....but for the next two years I experienced the same problems that you are having. Some times the car would run great. A small hill and I would get the PING. I tried different brands of fuel, different grades 87 thru Premium, added octane boosters and I would still get the same thing on and off on a small grade and sometimes on the flats. I finally just started to play with the distributor. Make a run around the block and then change the distributor and make another run until I eliminated the PING....well most of the time.

I eventually had a custom chip burned by Tom Wong on his dyno. He did a base line using the chip (Hypertech) and discovered that the chip was advancing the distributor to over 43 degrees (he doesn't like to go above 34) and at the same time it was reducing fuel resulting in the engine running lean and giving the PING! So here I had been fighting this condition for years and it was the CHIP. Once Tom burned a new chip and have never had this problem again.

I don't know if this is the same chip that you have, but worth looking at.

John

 

O2 sensor doesn't come into play on a cold start. Maybe a leaky cold start valve (9th injector) or a fault in that circuit?

 

Hey, I have a New Superchips chip for you! $50 shipped!!! it will eliminate the lean condition.

 

The Chip that is in there is WAAAY Old. I can't even find where this thing came from. I think I still have the old one so I'll try putting it back in before spending extra money on stuff I don't need. There have been way too many shade-tree mechanics under the hood of this thing so I hope they haven't left me with a pile of junk. I'm an aircraft mechanic/ Crew Chief for the Marines so not doing things by the book really tend to get under my skin.

Thanks again and I'll keep trying.

 

Ok, there doesn't seem to be anyone in my town who has an OBD1 scanner so i went ahead and switched the super chip for the factory chip. So far on the three mile trip to work it seems to be running better but noticeably less aggressive. The shift points are earlier and much smoother and there is definitely less horse power. What kind of map do your chips have on them? I don't have any other mods other than the chip.

 

Stick to this, Leave the factory chip in. Your not racing so what diff does 1 sec mean in a quarter?

 

The chip on a 1986 does not control shift points, it only controls lock-up functions of the torque convertor which will not effect the shift.

My guess is you have leaking injectors which is causing your hard starting condition when it is warm but not when it is cold. The pinging is probably releated a failed item on the car or incorrectly set base timing, not the chip. My experience with superchip or any aftermarket chip is they have stock timing curves at all throttle positions except WOT so they should not be causing part throttle pinging. You really need to hook up a scanner and check for knock retard when you hear the pinging. You should see the knock retard on the scanner, if you do not you have an issue with the knock system.