Hello everyone. I am new to the Third Gen world and I have looked at your website for answers in the past and decided to finally join. Great site and a lot of great info.

I am currently having an issue with my '90 RS Convertible. It is a 305 TBI and is currently running terrible. About a month ago I had the car out and had no issue with it. The next day I drove it and then it developed a miss. I pulled the ignition cap and rotor and changed it because it was bad (no improvement). I then decided to put new spark plugs in it, because I wanted to and though MAYBE it would make some kind of improvement (long shot no improvement). I then changed the distributor....the pick up coil was very rusted and looked to be falling apart into pieces and instead of messing with changing just that, I figured I would buy a distributor and change everything (distributor ICM pick up coil etc.) I installed the new distributor correctly and then timed it by disconnecting the EST wire and setting the timing at 0 (timing mark in the wide or big V). Drove the car today and it ran great until it warmed up. Still running terrible. My next step would be the coil (I think). I did spray the ignition wires down with water and didn't get a light show, so they should be good. Any help would be greatly appreciated. Thanks Third Gen members.

 

Since the car drove great until it warmed up that's a classic sign of a bad ignition control module. To eliminate the coil and the plug wires you can measure the resistance of the plug wires with an ohmmeter and make sure they're all close in resistance, and then the ignition coil measure the primary and secondary winding resistance and check against the factory service manual (can't recall the spec off the top of the head) - do it cold then do it hot when it's misfiring and make sure the resistance didn't change...

 

Your coil has a possibility of being bad, and your timing should not be set at 0 put it to 8

 

Thanks for the info bwiencek. It sounds like I am going in the right direction. The first thing I am going to do is check the coil then bump up the timing a slight bit. If all else fails I will check the ICM. It is a new part on the distributor, but we all know how new parts are from the parts store. I use to work at an Advance Auto and we had some new Alternators, Starters, etc. go out the door that were bad. Thanks again. I will check it out and post back with my solution.

 

Thanks for your input Redchevy808. I was going to go in that direction next and hopefully fixed the issue. One thing that I don't think I mentioned was that the car is running rich. I will bump the timing up, but I thought 0 was the setting for Throttle Body engines and 8 was the setting for Tuned Port engines? I have seen in some posts that bumping the timing up from 0 was a smart thing to do, so I will give it a shot. Thanks again.

 

You didn't say you were running rich - you first need to determine if you're loading up the engine with fuel from being overly rich and causing a misfire because of the overly rich condition (and blowing out spark or not being able to light the fire) or if your misfire is due to ignition cutting out electrically...

Check the Coolant Temp sensor for proper signal to the ECU (if it's 'dead' and telling the computer it's cold it will run ok at startup but then load up once the engine warms up) Also check the injectors for leakage and check for a bad fuel pressure regulator...

Since you worked at a parts store I know you've probably seen the cheap imported modules be DOA or die immediately after install... Also - check the remanufactured distributor's pickup coil for loose/bare wires that might get shorted out as the distributor moves around/shakes and gives an intermittent timing signal

 

Zero is factory for TBI, most seem to run better just a little advanced, somewhere around 4ish. Runs bad/rich when its warmed up. Got any way to datastream? Probably an erroneous sensor reading, coolant temp sensor or air temp sensor could be the cause. I chased a similar problem thru the ignition sys at substantial cost then changed the CTS and it went away. Only sensor on the car my scan tool couldn't read.

 

Sorry about the running rich part. Still in the dark here with this car. I check my ignition coil and that is fine according to specs from the internet. I also changed my Coolant Temp Sensor and then checked it as well with an ohm meter and everything is fine there. I also bumped up the timing on the car and still no change. After changing the distributor I decided to drive it to work and that is when it ran fine when cold and bad when warm. I did get an engine light and checked it and it store codes 23, 32, 42 in it. Code 23 is for the air temp sensor or air charge temp sensor that sits in the air cleaner assembly. I check that with info from the internet and that checks out fine. Code 32 is EGR. When I rev the engine the diafram moves up and down in the EGR. Code 42 was when I disconnected the EST for timing. Since I disconnected the battery to reset the codes nothing has yet to return. Still running bad and don't know where to go from here.

 

I don't have anyway to datastream. Still in the dark here with this car. I check my ignition coil and that is fine according to specs from the internet. I also changed my Coolant Temp Sensor and then checked it as well with an ohm meter and everything is fine there. I also bumped up the timing on the car and still no change. After changing the distributor I decided to drive it to work and that is when it ran fine when cold and bad when warm. I did get an engine light and checked it and it store codes 23, 32, 42 in it. Code 23 is for the air temp sensor or air charge temp sensor that sits in the air cleaner assembly. I check that with info from the internet and that checks out fine. Code 32 is EGR. When I rev the engine the diafram moves up and down in the EGR. Code 42 was when I disconnected the EST for timing. Since I disconnected the battery to reset the codes nothing has yet to return. Still running bad and don't know where to go from here.

 

Did you check the sensors when HOT and not when cold?

Since you have no way to datalog - you can pull the connector from the PCM and test the resistance from the pins on the connector and see if the wiring and harness connections are good - that's about all you can do without a way to data-log what the computer is seeing.

 

I did check the sensors hot and cold......no difference. I also did the same with the coil and had no difference there too. Today I pull the connectors off of the Coolant Temp Sensor and the air charge temp (sensor in the air cleaner) and tested the voltage coming through the cable. I had 5 volts coming through for the CTS and I believe it was 5 volts for the air charge temp sensor with the key on. When the key was off I had nothing of course. I read a thread on the site about code 23 and they were mentioning about a ground on the passenger side of the engine in the back on the head and that is why I tested the voltage coming through the cable. I thought that if I had voltage then the grounds should be fine.....right??? I can try checking the resistance through the wires from the computer. Where is the computer located, by the way??? Other than that I am in the dark still and I may have to take it to a local guy I go to for state inspection and other things. I am thinking that I am on the right track, but I don't know what is going on with the car. I know that if I take it to someone it is going to turn out to be something so stupid. I don't think I have had this much heartache with a car yet. Its a stumper. It has been a great car and I am planning on handing it down to my currently 9 year daughter when she is 16. She loves it.

 

My Camaro is running like a champ once again. My problem turned out to be pure stupidity on my part. I dropped it off at a local garage that I go to and the mechanic checked it out and one of the spark plug wires in the back of the engine on the boot going to the spark plug (not the cap) was arcing off of the exhaust manifold. Go Figure.....always check and go back to the basics. So, end result is a new set of plug wires. Thanks for all of your info.

 

My Camaro is running like a champ once again. My problem turned out to be pure stupidity on my part. I dropped it off at a local garage that I go to and the mechanic checked it out and one of the spark plug wires in the back of the engine on the boot going to the spark plug (not the cap) was arcing off of the exhaust manifold. Go Figure.....always check and go back to the basics. So, end result is a new set of plug wires. Thanks for your input.