My L98 won't even try to fire unless I unplug the IAC and plug it back in. I cleaned the original one I had in it and tried two new ones. Still same thing will not try to fire unless I unplug it and plug it back in. It will fire right up but die. If I don't do that, it will just crank. What am I missing here?

 

Try this: http://www.iroczone.com/2009/10/clea...rol-iac-valve/

 

I tried that and I get the same results as I was with unplugging the IAC.

 

when cranking the engine, does the it try to start and sputter, or just crank over indefinitely? If you hold the throttle open slightly, does it start or do you get the same results? Is that the only thing recently done? My thought here is that you aren't getting enough air at idle, but that's just a guess at this point as I don't really have enough information to help beyond that yet.

 

I got it to start but I have to give it a little throttle and have to give it a little to keep it running for the first minute. Then it will idle fine. When I drive it, it runs like crap if you put a load on it till it is up to temp and then it will run decent, not great but ok. It surges and feels like it is bogging out until it is up to temp. Feels like it is not wanting to rap like it should. I have new cap, rotor, plugs, wires, IAC, fuel filter, injectors, air filter. No vacuum leaks. I've noticed that temp gauge is not really working. I checked the TPS and if I did it right, I have a dead spot. I believe at closed throttle I have .58 ohm, when I open it is goes up to about .80 and then nothing for a little bit and then I get a reading up to wot and I am around 4.5 ohms.

 

You mean volts (DC) instead of ohms, right? Try this: http://www.iroczone.com/2009/10/adju...ir-idle-speed/
I thought the link I sent before had this, but the link didn't work. And, you should be in luck to follow this 100% as they were using an L98 A/T

 

And just in case: http://www.iroczone.com/2009/10/adju...on-sensor-tps/

 

It sounds as if the minimum air position may be off. The ECM is applying steps to the IAC and it may be too much air for the fuel administered. Clean the TB, reset the minimum air position, and check the TPS. Same old directions as were posted here a decade ago.

 

Tried that and My idle is a little bit better but still have a problem. Drove around for about an hour. The car ran decent, turned it off, restarted it and it ran like crap. Had no power and wanted to bog and stumble when I hit the gas.

 

Just out of curiosity, when you replaced the cap and rotor, did you mess with the timing at all? Are all of your spark plugs wires in the right order? I had a an issue with the car bogging down due to my egr valve sticking. If you disconnect the egr valve vacuum line and plug it, you should notice an immediate difference if that's the issue. What's your fuel pressure at? Is your SES light illuminated? I'm not trying to downplay your intelligence here, I'm just asking questions to help you solve the issue since I'm running out of ideas.

 

I appreciate all the help I can get. I am stuck on this one. I have tried just about everything I can think of. I have search numerous forums.

I did not mess with the timing at all when I replaced the cap and rotor. I replaced those because my cap was worn bad and did cause some misfiring. It took care of that at the time. Plug wires are in the right order, and the plugs look like they should, slighty brown. They are not wet and not white. I don't have an EGR. I have had headers and no EGR since I bought the car about six years ago. I have no SES.

I just tried to start it after sitting for a few hours and it just wanted to crank and not fire. I did the, turn the key on for thirty seconds and wait and it fired right up. Took it for a spin and it ran ok, but I am missing a lot of power if feels like.

 

Have you replaced your ignition coil? I came upon this thread, it sounds similar to your issue. Though, he should have had an SES code if the TPS was faulty: https://www.thirdgen.org/forums/tpi/...help-hard.html
I've read people with faulty ICM's have trouble starting their cars hot, but not the other symptoms you describe. Maybe your ECM is bad and that's why you aren't getting any fault codes. That's just speculation at this point, though. If I came across this issue on my L98, I would replace the TPS and ignition coil (if you haven't already), and go from there.

 

The TPS and the Coil are the two things my fellow Camaro buddies and I leaning towards too. I am going to try a different TPS in the morning. I am going to order a new coil just because I need a better one anyways.

 

Nice. Even if that doesn't fix it, it's always nice to replace old parts on an old car. Well, I don't feel bad about it anyway. Let us know what you find out.

 

So I put in a MSD Street fire coil and that helped out a lot. It fired right up ran great for about forty five minutes. Got pulled over....it was running really good. Went to fire it up after sitting for ten minutes and it had the worst idle and would not rev at all. I feathered the throttle for a couple of minutes until it would start to rev again. Drove home with no problems. I took the ICM out to have it checked and when I pull the Cap I noticed that the reluctant gear (I think that is what it is called) on top of the pick up coil was rusted bad and some of the pick ups were cracked and broken. So I got a new msd distributor. It is made a little bit different. But the car is running better. I drove it around with just a by ear timing adjustment and it ran decent for a hour or so, started and shut of good. Then when I was about to go home it was stumbling a little bit. I rechecked the tps just now and it was a little bit out. I am going to go and try it again today. I still need to actually set the timing correctly.

Should my tps be set to .54 volts? I thought 91s are speed dynsitey, and should be at .70v, Mine seems to run good at .54. And what should my timing be set at?

 

Your timing should be set a 6* BTDC. Remember to disconnect your EST when setting the base timing, as the ECM will adjust the timing at idle. The EST connector is near the firewall on the passenger side, and is a connector with a tan/blk wire. Running that thing on "by ear timing" is a bold move, but I think that your rough idle is the cause of your timing being off. This link should help with your TPS: it says .71 VDC +/- 0.05 http://www.iroczone.com/2009/10/adju...on-sensor-tps/ My TPS voltage, according to my 1990 Camaro Shop Service Manual, should be .5V at idle up to 5V at WOT. I've included a picture of the page for you. Yes, yours is speed density as well.

When the pickup coil in my dist. went bad, the whole car shut of and wouldn't restart. I replaced a bunch of ignition parts while I was at it to attempt to isolate it and that was the last thing I changed. It was easy to identify whether or not I had it fixed in my case, as the car actually started. Hopefully you finally have it fixed.

 

I have not messed with my Camaro all winter. The other day I decided to pop the hood and tinker with it. I put the trickle charger on it and checked to see if I had fuel at the rails. With about 6v at the battery I had fuel coming out of the Schrader valve, but I noticed that a vacuum line just under my map was dry rotted and full of cracks. I replaced it with a new one. I talked to another 3rd gen guy and he said if I was pulling enough air threw the cracks that it would cause me to run extremely rich. Which would give me a lot of the same symptoms. I am going to work on it in the morning as my battery should be up to full charge now.

 

And what did you come up with???

 

I have a dead cell in my battery and it won't hold a charge. lol But with a good battery it fired right up. The idle is still jumping around a lot, but it will idle on its own. I took it for a quick trip around the block and it still seems to be underpowered. So I think the Vacuum line was keeping me from starting.

 

I still have not properly set the timing. Kinda hard to do when I couldn't even get it to start. Hopefully I can get to that this weekend.