Engine probs - whatta ya think?

[k&l]

Okay - new to this forum but then I really have not had any problems with my vette up to now. I have 96 CE coupe, auto, with Z-51. It had been my daily driver for about 3 years with no real problems, about a year ago I got a POS Honda to drive to work so the vette only gets occasion use - about 3K in the last year or so. About a month ago while driving to work, as I got off the interstate and came to a stop, the engine just died, flashed the batt light and service soon, it restarted fine- got to work. Later that day, while driving along, it surged a couple of times, say from 1400 to 2500 rpm. Next time I drove it no problems, no lights.

Yesterday as I started it up and let it idle for about 5 minutes, rock steady idle - no issues. I live about 6 miles in country from the nearest major road and generally 'let it breath alittle' on the way out, however at a steady 55mph, it started to surge and miss repeately then the engine quit. I pulled over and it would not start until it set for about 10-15 minutes. When it did start it would surge from idle of 800 or so to about 2500. I could go about a mile at 1500RPM before it started missing again. After 3X of this to get back home, I nailed it to get as far as possible and it ran okay (maybe a little weak) at higher rpm say 2500-3000.

The only other thing that was odd, when trying to get it started, if it didnt fire up, with the key in the on position, the injectors would be clicking, slow then faster then stop, also the air/vacuum pump up the nose would come on and off repeatedly. It was surely pumping extra gas into intake. It is showing the service soon light (duh!)

Sorry to be so long winded, but I hate to tow it to a shop if it is something I can fix. I havent had a chance really look it over yet, but my thinking is that a sensor that was going bad, died. Maybe the crank position sensor or the tps. Help ! TIA

 

[compyelc4]

Need codes.

 

[bradfordsvettes]

sounds like the pcm is getting resdy to roll a 7 sounds like a duck and walks like a duck so probaly a duck my money on the pcm Steve

 

[vader86]

Smells like an Optispark.

 

[poorboys831]

thats just what my opti did before it went south

 

[cntrhub]

The car is "sitting" for awhile. Did you charge the battery about every two weeks or so? Pull the battery and let someone "load test" it. I'd chase the simple stuff first. Theory goes, a battery will lose 1% charge a day. So if the car was sitting (w/out being charged) for a month = 31% down from a fully charged battery.

"Yesterday as I started it up and let it idle for about 5 minutes, rock steady idle - no issues." That tells me your charging system is working fine. If it wasn't, you'd be running straight off the battery. At idle, the alternator is pushing out a higher volt reading. Usually 14.2 Volts at idle. That also tells me that the components that need consistant voltage, are receiving erratic high and low surges. At idle, the voltage is steady, and all components are receiving what they need. You don't hear all that injector/vacuum pump noise did you?

My guess would be a bad battery.

 

[k&l]

Well I did kill the battery trying to get it running, so I replaced it but no better yet. Faced with hauling it to the nearest dealer and paying diagnostic charges, I broke down a bought a code scanner. There were four codes in memory.
1) p0100 - MAF or VAF Circuit Malfunction
2) p0102 - MAF or VAF Circuit Low Input
3) p0372 -Timing Reference High Res Signal A Too Few Pulses
4) p1371 - DI Low Resolution Circuit

I cleared the codes and finally got it restarted, only to cut off about 2 mins later, threw the P1371, cleared it, got the P1371 again.

Sounding like the distributor to me, anybody else have these codes.

Thanks for all you guys help, this forum's great!

TIA

 

[compyelc4]

#3 and #4 are opti pulse related.

I'm bettin' your opti too. What does the bottom of your water pump look like?

 

[SPANISHVETTS]

The second Opti on the 93 went the same way. I killed the first one when I was forced to drive down a flooded street. Be sure to change the water pump when you put in the new Opti.