Ok so I have been searching around looking for ideas and things to test to fix my problem missing problem. I have a 92 Firebird with the 3.1 in it. The problem i having is that it is missing and sometimes backfires during closed loop operation only under accel. this leads me to believe that it is not an ignition problem (but i could be wrong) I checked the cap, rotor and plugs and all seem to be ok. I know there are a number of problems that can cause this such as an O2 sensor, egr valve, and maf (not sure is it is a maf or a ait sensor) (not sure if there are any others I am missing). Well reading through different posts i was reading how you can unplug certain senors to see if the problem went away. So I tried doing this. unplugged EGR no change. unplugged O2 sensor no change. unplugged sensor in intake tube no change. when all sensors are plugged in I have no SES light on. Out if curiosity i pulled the stored codes anyways and got 13 and 23, which i believe are 13. Oxygen sensor signal stays lean during warm engine cruise and 23. Low temperature at manifold air temperature sensor OR Throttle position sensor error taken from here https://www.thirdgen.org/service-eng...ht-error-codes. I am kind of out of ideas and am hoping somebody can shed some light on my problem. Sorry for the long post but i was just trying to give all the info i can think of. Thanks for any information I can get.

 

Test continuity on the plug wires - there should be very little resistance on a plug wire. Even new wires have breaks/shorts in them - can't tell you how many I;ve bought that were bad. Also make sure they are all securely on the plugs/cap. I had one that "clicked' into place on a plug, but after the car started, the electricity would pop it off - I had to go into the boot with needle nose pliers and crimp it a tad tighter so it didn't pop off.

 

I seem to be having a similar problem ,however when i checked my fuel pressure tons of air was let out, and the car seemed to run fine. Any idea what could be causing this?

 

To camaronewbie I would think that if it was just a boot popping off then it would happen when the engine is cold or warm but my problem only occurs when the car is warm and in a closed loop system. I will go back and check the wired anyways though.

 

Well updated on parts changed and still have problem. I changed the MAP and O2 (thats a story in itself) and the problem still exists. I have ordered the ACT sensor and that will be getting changed today. I got thinking that since this problem only occurs at a certain RPM range and past half throttle is it possible that part of the ECM fuel curve has gotten messed up some how and is causing the problem? Any info anyone can provide would be helpful.

 

What about your coil packs? Check the primary and secondary resistance.

 

I will look into that later also.

 

Another thought just came to mind. I remember a few months back I had to change the O-ring seal at the base of the dizzy to the block. When I had it apart I remember cleaning what appeared to be solidified metal (basically looked like chunks of rust) from around the field wires. Is it possible that maybe the dizzy is on its way out?

 

Our cars do not have coil packs.

Could very well be a distributor issue. There is an ignition module inside the distributor under the rotor that will fail - rust build-up as well as just wearing out from the heat since it's an electronic component. Might try replacing that, about $35 I think. Make sure you use the dielectric grease that comes with the new one as instructed.

 

Mis-fire under accel directly suggests a weak spark. Weak sparks will ignite the mixture fine at idle and light throttle but as cylinder pressures increase due to load the spark energy may not be enough. ALWAYS check the ignition system before proceeding to other systems.

It's very possible your distributor is in need of replacement. You can 'rent' a spark tester at AZ or one of the other chains. Get it, use it and go from there. Test them all. A single bad wire or plug can cause all sorts of havoc, especially if it misfires and the computer tries to compensate for what it sees as a lean mixture (too much O2).

 

Ok I will replace that first and if that doesn't work I guess it will be returned a new dizzy purchased. It may not be called a coil pack but i know that they have an ignition coil which can also go bad.

I will have to try that. I have never used one of those and am not quite sure on the testing procedure. While I'm under the hood I'll looking into testing the ignition coil as well. I just need to find the procedure and the values for it.

 

Camaronewbie and especially naf are right on in suggesting that your problem is most likely ignition related. More specifically, distributor related. The "primary coil" you cleaned of rust and chunks of metal debri, is more precisely known as the pick up coil. The metal gear-like peices it sits on are the pole peice and timing core. The pick up coil is a common failure item. Almost as common as the ignition module camaronewbie referred to. If your dist was contaminated with rust, you may want to simply replace it complete with a new unit. I recommend AC Delco for the new distributor.

As far as testing ignition wires for resistance, the nominal resistance of carbon core wire is 6Kohms(6,000ohms) per foot. I have had several wires test okay for resistance yet still drop spark under load. If you are unsure when your wires were replaced, replace them.

 

Yeah I had totally forgotten about the contaminated dizzy. I think that changing that and a good tune up would help. The last time did the cap, rotor, plugs and wires was back in 07 when I got the car. I think that I may and go and put a new coil on for kicks and giggles too since the car has close to 215000 on it. I'm finding things that I end up changing are still factory parts.

 

Ok update, I was running some errands earlier and the car was running pretty good. I was almost home and the car threw me an error code. It was a 32 which is a Fault in barometric pressure sensor circuit OR Fault in exhaust gas recirculation valve diagnostic switch OR Fault in electronic vacuum regulator valve. Well I guess this gives me a direction to go in. I think that i may try resetting the ECM to clear out a couple other codes that where in there from when I was changing other sensors and see if this one comes back again.

 

32 is most often an EGR problem. This type of problem usually shows up during cruise conditions. It's remotely possible that a stuck EGR could cause a misfire on accel but you would also have a rough idle. I doubt that the code 32 and your miss are related. Nonetheless, since the code showed up, perform the EGR system test prescribed for this code. I won't try to detail the test in this post. You may find it by searching on this forum, or buy a good service manual.

 

I got looking through my pictures that I have on may phone and I came across this one that I had taken of the dizzy last time I had the cap off. I have a feeling that this may confirm the idea that its my ignition system that is causing me the problem. Sorry the quality is a little bad.

 

I'd replace that, but then again, I enjoy spending money and bolting things to my car.

No really, go ahead and price a replacement.

 

Well thats the plan for this weekend. Probably tomorrow I am going to order a new dizzy, msd coil, wires, and E3 plugs for it. After that I'll have to see how it runs.

 

I think that I have figured out the problem with the EGR. I was under the hood looking at something else earlier and I noticed that the wire going to the EGR was unhooked. Well at least that was a simple fix. Thanks for the info about the code tho.

 

I pass on the E3 plugs and just go with standard copper.

 

I agree. Experience has taught me that any engine generally runs best on the plug that it came with from the factory. On yours that's AC Delco resistor.

 

Ok so I guess I should post an update. Over the weekend I changed out the dizzy, wires, plugs and coil. Car runs better than it has in a long time. I'm guessing that the miss that I had was from the pickup coil going bad. Thanks to everyone for the info and advice on what the problem could have been.