96 Z28 CBR900RR

I just bought a 96 LT1 Camaro a couple of weeks ago and already have a problem. I'm wondering if anyone has come across this issue. A few days ago it started having a slight hesitation, and started to start hard. Before this it would fire right up, now I have to spin the motor over for quite awhile to get it to fire, once it does fire it stumbles for a few seconds before finally getting to idle. When the problem started I replaced my plugs and checked my wires, plugs looked pretty good, wires are good also. The problem has escalated greatly yesterday and today. Now it will idle for about 5 minutes and then I loose all spark. If I try and give it gas or drive it around the block I can definatly feel it missing or hesitating. If I try giving it more gas it starts jerking like crazy like it wants to go but is loosing spark or fuel. I've found when it's cold, as in sitting for a couple of hours I check for spark from the coil and has a very good spark. I then can plug the coil wire back in and fire it up and run it at idle for a few minutes before it eventually misses, sputters and dies. After that test the coil for spark and none is there, or very intermittant spark. Just today I replaced the coil and spark control module and the same problem is ocurring. The only other thing I can think of that could cut spark off all together is the computer but am not looking forward to having to replace that. Anyone know of any sensor or anything that would cut off spark from the coil, or maybe a loose wire that would cause to loose all spark going to the coil?

ibanez6rg

Check your grounds, could maybe a fuel pump problem.

96 Z28 CBR900RR

Would a fuel pump problem cut spark though? I was wondering that, if the computer senses no fuel will it do that? I wouldn't think it would but I guess I've heard stranger things before. I'll check my fuel pressure and post my findings. I know the fuel pump is running though, when I turn the key on I can hear it run for a few seconds. I hope I get this thing running soon.

ibanez6rg

I just said fuel pump because you said slight hesitation, hard starting.

jdizzell

Your opti is going.

96 Z28 CBR900RR

Would the opti cut spark from the coil though as well? Since it seems to be cutting all spark once it warms up, the only things I was thinking would do that are the coil, spark control module and computer, would the opti do that as well?

jdizzell

Yes. Check for spark at the coil. If it has spark then your opti is just not giving your plugs the spark.

96 Z28 CBR900RR

Yes, that's what I'm doing. The spark is actually getting cut off from the coil so I'm almost thinking it has to be the computer doing it. I've just never heard of that before and would hate to go buy a new computer and find out it's something else. I don't know what else it could be though to cut spark off all together, with a new coil and control module. It seems the only thing left is the computer.

96 Z28 CBR900RR

Well, I rented an OBDII reader to see if any codes shot up. Had 9 codes logged in the computer. I wasn't sure how many were old though so I cleared them, then started it up again. It ran fine for awhile but then started again. I read the codes after that and only have 1. Code p412, this code is for the secondary air injection solenoid control circuit. Could this somehow affect spark control?

96 Z28 CBR900RR

OK, I've been playing around with resetting my computer and trying to get the damn thing started again. Got it to run for a little bit again and got code P0372 now, Timing Reference High Res Signal A Too Few Pulses. This code isn't even covered in my Haynes manual. Searched on google, found this also, P0372 - IC 24X Reference Circuit Missing Pulses. Looks like I'm missing pulses? Anyone know what this means? Also a strange thing, code P0412 hasn't come back since i cleared my codes again. I'm thinking my main problem is tied to this P0372 code though. Any ideas?

96 Z28 CBR900RR

Well, I broke down and called the local GM dealer in town here and asked about code P0372 that I'm got in my computer and they say it's the crank position sensor. I called every place in town and no place has one. I had to order one, won' t be in until wednesday. Here's another strange thing, it doesn't show the crank position sensor at all in my Haynes manual. I don't even know where this thing is on the car. Anyone know that?

96 Z28 CBR900RR

I found it at this site, the sixth picture down shows front engine covers from various years of LT1's, I hope i can get at it w/o having to pull my crank pulley, will be easy then. http://www.9c1.com/technical/LT1_rebuild/ar99928.htm

96 Z28 CBR900RR

Well, I put on the new crank sensor, didn't fix it. I was not happy, I did notice a bit of moisture in the old sensor though so thought I'd better check the rest of my connectors. I even pulled my computer out and checked those connectors, all looked good. Then using a flashlight I started looking for more connections buried deeper. I found behind the water pump what must be my camshaft position sensor, it was unplugged. This was my entire problem, plugged the camshaft position sensor in, been running like a champ ever since. I'll bet if that sensor was going out it would cause the same problems. When getting warm would cut spark out. Well, anyway I hope this post helps someone else out there diagnose their problems. I'm just glad to have a running car again. Thanks to all that tried helping.

Rams97LT1

Can you tell me where the camshaft position sensor is? I"m having similar problems with the car. Called the dealership here and the guy had no idea what he was talking about...Thanks.