Running fine, hour later wouldn't start?

[derrickgott007]

Here is a weird one for you guys....

My cars a 97 Z28 LT1 with cold air intake and new plugs, wires, water pump. So my girlfriend picks me up from work yesterday and we go home. Car runs fine and we stop at her house and take a nap. I go outside an hour later and it won't start. I had to floor it to get it to start, and when it ran it ran like crap. It would backfire and pop and had to keep babying the throttle to keep it crap idling. Here is whats weird. I unplugged the MAP sensor and it didn't run. I unplugged the MAF sensor and it didn't run. (Both things my dad said to due).

So I let it sit over night and this morning it fired right up and then ran for a few minutes and then started running like crap again and then it just stopped and wouldn't restart. I also have a new fuel filter on the car.

Haven't had a chance to scan it for codes yet, but what does it sound like to ya'll?

I did notice something odd. A teeny tiny bit of antifreeze was on the front top of the passenger side valve cover.

[Fastbird]

Burned a couple of plug wires maybe? One would make it run like crap. Two+ will cause it to run HORRIBLE.

[Z28pr0jekt]

check if you are getting spark... if not coil/icm/opti

[krayzie7th]

When its driving like crap is the Check engine light flashing?

[derrickgott007]

My ses light has been disconnected by previous owner. but it seems like it starts to have a pop sound from the exhaust while idilng every few seconds before it starts to run like crap. then it gets to sounding like its off time or has a giant cam in it.....then a few mins later it dies.

[OutCast]

opti

[krayzie7th]

^^agrees hate to say it but its sounding like the opti.

[Tyler Wheat]

Sounds like an optical sensor problem. My vote goes for an opti swap to get it back on the right track.

You might check for spark while its running like that just to be sure its not a fuel issue, but I'm pretty sure all signs will point to the opti. If you know anyone with a scanner, hook it up and see what comes of that.

After you get all that fixed, you might want to get that SES light taken care of. If it was still hooked up, it might have been set off some time ago, letting you take care of the problem before it got to this point.

[derrickgott007]

Sounds like an optical sensor problem. My vote goes for an opti swap to get it back on the right track.

You might check for spark while its running like that just to be sure its not a fuel issue, but I'm pretty sure all signs will point to the opti. If you know anyone with a scanner, hook it up and see what comes of that.

After you get all that fixed, you might want to get that SES light taken care of. If it was still hooked up, it might have been set off some time ago, letting you take care of the problem before it got to this point.

I had it scanned not to long ago by my dad, a GM Tech. The only code it showed was a CPS sensor fault because the wires were broken at the connector. Also, I ran it with a miss for few months before I could get new plugs and wires. During that time I replaced the waterpump and the A/C Compressor fell off because whoever changed the block on the car didn't put the back bracket on it and the front three bolts broke off in the ALT/PS/AC bracket....That wasn't fun.

Could having run it for so long with a burned plug wire have affected the OPTI? My dad said he thought that if you ran it too long like that that it would burn out the opti or ruin the cover because of the burned plug wire.

[SmokinSuperSport]

Running it with the misfire could have been a contributing factor. The main death of the opti probably came from when you changed the waterpump. Ran into this with my friends car, the waterpump blew so we just changed it. It must have gotten some antifreeze on the opti when it blew or when we changed it because it developed a high rpm miss after and eventually went away. A few weeks later he didn't use the car a few days, went to start it and ran exactly like your describing. Changed the opti and put a new pump in again for the hell of it because it had to come off anyway. Now it runs like new. Hope that's helps some.

[SmokinSuperSport]

Oh yeah and I forgot to mention Opti failure doesn't always throw a SES light at least on the OBD1 car, not to sure if OBD2 cars are more sensitive to Opti failure though. Check your coil and ICM like the others said because they are cheaper to replace then the opti. I'd still defintely have the SES light fixed so your more aware of future issues too.