z0s0

Having a strange problem with my Z28, started a few weeks ago with some "stumbles" while driving, the rpm's would suddenly drop like it missed but only a few hundred or 1000 rpm, not all the way to zero. The problem has escalated to where it now has actually shut off on me a few times while driving. The first few times it's done this, it started right back up. However, the last few times it's been hard to start after it's shut off...but it does start. I tried having it scanned for codes at Autozone but the scanner kept saying "error". It was a yellow obdII scanner. Went to a different parts store, the same thing happened...but the happened to have the same scanner so not sure what's going on there. I plan to test the fuel pressure at the rail, and test the coil per shoe's site and see what that turns up,hopefully this weekend...just wish I could get some codes to help point me in the right direction, any ideas?

z0s0

So this issue just took on new urgency...I'm at work today 30 miles from home and she won't start, just cranks and cranks. No sign of even wanting o start. All I did yesterday was replace the fuel filter, got her this morning ok but a lunchtime it did shut off on me again so it obviously wasn't the fuel filter.

RamAir95TA

The problem you had with the scanner is common with 95s. Most Autozones do not have the capability to read the OBDII-connector for OBDI.

The coil and fuel pressure tests are both good starts. Can you hear the pump prime when you turn the key to ON?

GRIDERMAN87

You may also want to check your connections on the crank positioning sensor, it can also cause some of the problems your having

RamAir95TA

OBDI cars do not have a crank position sensor.

And even if they did, the CPS is only used to detect misfires. Its feedback is not used by the PCM for fuel/spark. It can't cause any driveability problems by itself.

GRIDERMAN87

Oh must have read it wrong, thought he was using an obd2 scanner, my fault. My connection broke on mine once and it caused it die out and not start.

z0s0

Yeah, I've done some digging and have found that mine (and all '95's) is obd1 but uses the obdII connector. Long term, I'm going to get the ALDL cable and some of those free programs, to pull the codes myself and do my own tuning etc. Also going to test the fuel pressure and the coil...if those check out I'll move on to the dreaded opti. Short term, I just gotta make it home. It started about a half hour ago and quit but at least its starting again. We'll see...

Anybody know where to get one of those aldl cables cheaper than $60?

Chaos1187

Thats the cheapest Ive found them is 59.95 lol so a nickel but after tax really nothing saved lol. Less someone on here or another forum has one for sale.

GRIDERMAN87

When my opti went out it did something pretty simmilar to what yours is doin, would run fine and then just die out. then after i let it cool off it would start again, but the problem got progressively worse untill it wouldnt run for more than about 5 min before it would die out

94CamaroZ28/SSClone

My 94 Z28 did the same, turned out Mu coil and Opti went bad. So get a new Coil and Optil with Spark Plugs and Wires.

z0s0

so...it died on me before I even got out of the complex where I work. Shut right off, $125 flat-bed tow charge later I get it home, let it sit, ate dinner, went out and it started right up. I revved the hell out of it a few times, then held rpm's at 2000, then 3000 for about 10 seconds each, nothing...no stumbles, no shut-off. The same car that would stumble or die with the least bit of gas 2 hours ago is running like a champ. She turned a year old (for me) yesterday and starts pulling this crap, lol. I've got the week off coming up so although I would much rather be cruising around in it with the t-tops off, looks like I'll be tracking down the ghost in the machine. Sure wish I could pull codes right now instead of waiting a week or more for a $60 cable though. Oh well..I'll start with testing the coil and maybe doing a fuel pressure check If I can get a gauge over the weekend, I'll post the results. I'm starting to think opti...the opti was a reman I bought on ebay last september...worked great for a year, hopefully it's not the opti. I did my head gaskets in May, so my wires and plugs (stock ac delco wires, tr55 iridium plugs) are basically brand new.

z0s0

let me ask this..when I did my waterpump last september, I replaced the opti too, it was the original gm unit that was in there and seemed fine when I pulled it. OF COURSE, I pulled it apart to look inside because of all the problems I've read with these, there was a little bit of oil in it. I think I pulled the little metal disk off too but I'm not sure. I put it all back together...can they be taken apart and put back together like that? Does that metal disk have to go on a certain way? Hopefully I can just put that one back on if it turns out to be opti.

94CamaroZ28/SSClone

Once the Opti warms up, that's when you get the RPM missed and stumble. The Coil once warms up, will make the car shut off.

rclearyiii

Are you near Raleigh NC? I have a scanner that works on the 95 model. Use it on my sons frequently. If you are nearby..you are more than welcome to use it.

z0s0

No, I am in upstate NY, but thank you very much for your offer.