z0s0

Is it possible to pull the codes manually from a 95 (obdI with the obdII style 16 pin connector) as described in the "quick paper clip test" in this article? If so, what pins would I jump? Pin2 on my connector does not even appear to be live.

http://www.aldlcable.com/

z0s0

Never mind, I think I just found the answer to this one, and that would be a NO.

GRIDERMAN87

correct sir, 93 was the last year, I made the same mistake myslef

z0s0

I picked up a fuel pressure test kit today, tested the pressure at the fuel rail...it was 41psi with key on, car off. While idling, it dropped to 35psi. I did it a 2nd time and it was 39-40 key on, 35 while idling. Since normal is considered 41-47 key on, and 3-7psi drop when you start it, I'd say that's at least close enough to disregard the fuel pump? I know it's on the low end of the scale but to have it die out like it is I would imagine it would have to be much lower than that. All this was done with a little less than 1/4 tank, I would think (but I'm not sure) that all values would be a little higher with more gas in the tank?

I'll be testing the voltage and resistance of the coil tomorrow to rule that out before yanking the opti out.

z0s0

An update on this...I was able to borrow an aldl cable and checked for codes using datamaster, no codes whatsoever. I captured a datastream by running it for a few minutes with datamaster recording. This is the first time I've ever used it so I'm really not sure about the impact of some of these values, but what stands out to me is the "Fuel Trim Cell" value is 16, and is yellow in the DM display. The Lterm fuel values were each between -6 and 7%, and were light red for the whole session according to DM, indicating rich. The Sterm values varied between rich, normal and lean (mostly normal and rich) throughout. Ignition voltage stayed at a steady 13v throughout but I did see it drop to 12.6 at one point. Also noticed that the MAP reading stayed at 31-32kpa, however when I revved it to about 3500rpm, I saw it drop to around 13. Isn't it supposed to rise when you rev, or is that only if you're in gear? All this data was captured in Park, in my driveway.

I'm going to get another capture today, and start it before I even start the car and let it go for like 10-15 minutes and see if anything else pops out.

Without any codes thrown at all, does it seem less likely this is the opti or ignition components that are causing the car to die out?

As noted previously, the fuel system pressure was checked and is within spec (40-41psi). Is it possible that a full charcoal canister could cause a rich condition?

I'm going to take the maf sensor out and see if it is fouled in any way and possibly check the coil resistance. Aside from that I'm really not sure here, if anyone has any ideas, let me know. I cannot drive the car with it stalling out like this, not on the highways I commute on.

z0s0

Also should mention, the exhaust does have somewhat of a fuel smell to it, not overpowering but it's there. Gets a little stronger when I rev it.

z0s0

I just did another longer capture, everything was pretty much the same as the other, however, I did notice that the ignition voltage was at 12.1v key on engine off, dropped to as low as 7.7 while cranking, and after starting while idling stayed at 13.0-13.1. Should also be noted that I haven't driven the car on the road since the last time it shut off on me, about a week ago. I've done a number of these logging sessions, car running sometimes for as long as a half hour in the driveway, and it hasn't done it again. I'd love to drive it and see if I can get it to happen while I'm logging but don't want to be stranded, lol.

Injuneer

Send me the DM log via e-mail. May take me a while to look at it.... lot of people waiting in front of you. Put your screen name and the words "DataMaster log" in the topic.

When you open the throttle, MAP should rise. After you rev it, and close the throttle, the MAP will drop below 30kPa until the RPM come down.

z0s0

So after doing a lot of research on this problem, I replaced my coil..just the coil, not the icm. The coil was gunked up something fierce with old dirt/oil..I have not tested it for resistance yet but I'm sure when I do it will test out ok, as I still have the problem. I changed the coil, cleaned the maf with crc maf cleaner, put everything back together, and took it for what ended up being a 40-50 mile ride. I had intended to just take it for a test drive but the combo of the car sitting for a week and how good it was running/responding (cleaning the maf, most likely) I just kept going. I even threw in a couple full throttle 0-60, 0-80 runs and no stumble, no shut off. Actually had it close to 100mph at one point and again, fine, ran like a champ. I brought it home, parked it for maybe 3-4 hours, and took it down to a store down the street for some milk and it shut off on me on the way back...lol. Gotta love it. I let it sit for 5 minutes, and it started right up. Drove maybe 10 feet and shuts off again. Let it sit for 10 minutes this time, started right up, and made it the whole way home with no problems. Tonight I'm going to check for any sparks/arcing when it's dark but as this is so intermittent, I'm not expecting that I'll see anything. Being that this is such a sudden shut off...does not shudder or anything, just instant off..probably rule out a fuel issue, right? I did check the fuel pressure and it tested out right at spec..so unless the pump is having an intermittent problem, which is possible I suppose, it's not that. From what I have read on past posts on this and other sites, it really screams opti to me...which would not be a bad thing as I have an original ac-delco spare sitting right here, old original unit but was working fine when I pulled it out of the car, and the opti that's in the car has a 4 year warranty but I believe it was a reman off ebay. Spoke to them on the phone and they will honor the warranty so if it's opti, won't cost me anything but a day or 2 and some bruises.

What a ballbuster that cleaning the maf seems to have woken it up as far as response and performance goes, I mean it screams now 0-60 compared to what it was, and I thought it was pretty quick before. She runs great, right up until she turns off like a light switch.

z0s0

Ok, so today I spent some time cleaning up the opti I took out of the car last fall when I replaced my water pump. Had no opti problems at the time but figured I'd replace it as I was in there...silly me. I cracked it open and it did have what looked like burnt oil inside it and some crud...so I completely broke it down, scrubbed the hell out of it with some orange brite, and sprayed the hell out of the sensor side of it with some maf cleaner, which should be ok as it safe for plastic and electronics. So, who thinks this opti will actually work now, place your bets! I really have nothing to lose, when I pull the opti that's in there now, out, I'm sending it back for warranty replacement, so I'll just put this one back in for now, if it doesn't work I'm in no worse shape. If it works out I'll just hold onto the one that comes back for a spare.

While trolling the entire internet for the symptoms I'm having, I found this thread, the guy had the exact same symptoms I'm having, but he never posted his resolution, so I emailed him, and you guessed it, opti:

http://www.ls1lt1.com/forum/showthre...t=36607&page=2

I also found what seems to be the most comprehensive write-up I've seen yet on diagnosing no-start in LT1's, for anyone having issues it's priceless:

http://www.mainstreamtopics.com/foru...p?showtopic=78

Really good, step-by-step write-up and it seems shoebox's site was used as a source so it shouldn't be a tail-chaser.

GRIDERMAN87

I would just go ahead with a new unit, the opti is no easy job so I wouldnt replace it with anything but a new part. As far as if it will work.....probably, but for who knows how long

z0s0

I am...the opti I just cleaned and abused is only going in temporarily (until the bad one's warranty replacement ships back, or this one fails..which ever comes first.

z0s0

Just replaced my opti with the original that I took off my car last fall. Just an FYI, spraying the hell out of an opti with maf cleaner (while apart, everything inside, optical sensor included) doesn't harm it. We'll see how far I get with this "rehabbed" opti.

Started right up so I took it for a 15 minute ride. That doesn't prove anything because the shut off problem usually only happened after it had been run for awhile and then run again but it's too late to mess with it. I'll drive it some tomorrow and post whether the problem is gone or not, if only to have a complete thread out there that shows this problem and the fix.

Getsome17

I had similar issues with my car a few years ago the car would run fine run right up to 6000 rpm hard but every now and then it would completely fall on its face dropping like you said anywhere from 100rpms to 1000rpms. Eventually it got to the point where it would die and not start again for a little while, yet it was showing no codes. So I swapped out a few parts and nothing seemed to help. What it ended up being was the ignition switch on the top of the steering column was burned up and was shorting out making the car act like I was turning the key off and back on. It might not be your problem but it is defiantly something worth checking.

z0s0

This is my last post on this, unless the car shuts off again. Put some decent miles on it since I finished putting my old (delco) opti back in. Amazingly, the car has a lot more pep in the form of response..instant response, just didn't notice it before. I've found myself a few times "jumping" from stop lights, lol. Hard to tell though if that's a result of the good opti, maf being cleaned or the fuel filter being replaced...could be all three who knows. Just figured that I'd close this thread out with the fact that this was most definately opti related. And ac delco opti only for me from here on in.