[Hugh]

My question doesn't relate to chevelles, but I own a '70 SS 396. My question relates to an '88 Grand Am quad 4 engine. I am in college and I don't have a lot of money, so I have been doing many fixes on this car myself. I have an ignition problem that I don't know what angle to hit it from. When the car warms up (about 15 minutes of driving or more) it will start missing and backfiring and finally it will die out. Then I will have to let it cool down and it will start again and drive with no problem until it gets warm. I have checked the entire fuel system and the injectors, as well as the O2 sensor. The engine only has 30K on it, but the ignition has 130K. I have replaced the plastic coil housing (similar to distributor cap) and I just replaced the wiring harness that connects the two coils. I ohmed the coils and they are the same and at standards. What is going on? The car runs fine and doesn't miss until it warms up. Is it a problem with the coils or the ignition module??? Some of you guys work in shops and might have some good advice for me on how to test the coils or modules. Thanks, Hugh.

 

[Turbo396]

Hugh,

The first things I would check would be the ignition module and the MAP sensor. I had the similar problem with a F*&@ I used to drive and after having the engine gone through, I figured I would just change out the MAP sensor. Guess what, that was my whole problem. I hope this helps.

Johnny

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[Peerce]

I had a similar problem with an 89 Calais that had the Quad 4 engine, except it didn't get to the point of quitting. My problem was the coil packs. Are you sure that the fuel pump isn't quitting?

 

[Hugh]

The MAP sensor sounds like it might be the problem! I called a local shop that specializes in automotive electronic systems, and they said that the situation I described could not be the result of the ignition module and that it was unlikely, although possible, that it would be the coils. They would not tell me what they thought it would be, they want my money! I hate people like that! I am a college student and I am paying my own way through school and I am trying to hold on to my favorite muscle car and this guy won't help me out!

Anyway, I don't think that it is the fuel pump, because I had it checked and also I dont' think that the pump would work better when I put the pedal to the floor, like it does. Also, does a car backfire when it isn't getting fuel?

 

[chev64]

Hugh, Does the engine have a crank sensor? It might be the culprit and worth checking out.

 

[1bad67]

Not a mechanic by trade but I would think the miss and heat is a lean condition. Intake manifold vacuum leak? Idle high or abnormal? Is the motor getting hot? If motor is cool and it just dies it sounds like the Ignition modual.Even though its a newer car the plugs can tell you if it is lean or rich when the problem occurs. Then you know if its fuel or ignition. Changing parts can end up costing more than having a qualified tech tell you what the problem is. Being the motor was replaced look for the obvious first.

[This message has been edited by 1bad67 (edited 04-16-99).]

 

[BillK]

Hugh,
From what I the piles of bad coil packs I have seen at some of my customer's shops, I would bet on that, BUT, with the parts being as expensive as they are now days, I think it would be well worth it to pay a good shop for an hours labor to put the car on a scope and find out exactly what is breaking down. You can throw away a BUNCH of money by throwing parts at it and it still may not be fixed. By the way, if it is the coil packs, I have heard not to waste your money on anything other than GM parts in this case.
And Hugh, I hope you do not take this the wrong way, but the guys at the shop you called have bills to pay also, and they can not pay them by answering questions for free !
Hope this helps.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

 

[Gene McGill]

Did they still have the ability to get the trouble codes out of the "Check Engine" light in 88? If they did, I would start by checking out the codes.

 

[Hugh]

I know that just replacing parts can cost a lot of money, but so can shops who don't fix the problem and end up replacing stuff that doesn't need replacing. I just hate paying shops $46/hr and an extra $200 in parts that didn't need to be replaced and then I am still stuck with the same problem. I have had this happen to me 3 times in this last year and I can't afford it anymore. I like the shops in the small towns where the people are honest, but they just can't handle most of this computerized stuff anymore, and I am finding out that even the dealerships can't trouble shoot these cars if a code doesn't show up on their diagnostic. Does anyone else feel unsafe with taking their non-warranteed car to just any shop?

That is all besides the point, I am actually trying to learn from all these problems that I am having and I like fixing it myself. I agree with most of you technicians, that I do need to take it to a qualified and experienced professional to find the problem. I just need to find someone that I trust and feel comfortable dealing with. Someone else told me that it might be the crank sensor too, so now I have 3 or more possibilities! I am just going to take it in I think. I will give the shop all of this information to help them pin-point the problem and maybe I could make it out of there with only a $46 inspection fee and the cost of parts and labor. Thanks everyone for the helpful hints! I learn more about these cars everyday! Isn't the old stuff so much easier? I think so, and that is why I love my 70 SS!

 

[ocs408]

Good point Gene. Most GM cars didn't go to the OBD system(which requires a scantool to read codes) until late '91 early '92. This car being an '88 could be checked by running the codes by shorting the ALDL connector.