89shane350

iTrader: (1)

Hi Y'all

so basically it starts to stall out in gear, BUT ONLY RANDOMLY. I've searched and ended up replacing just about everything from suggestions from similar problems and some extra things that i felt were time to replace anyway.

Here is an example of it, last night i drove 2 towns over, about 30 mins one way, and drove all over this town and eventually head home no probs what so ever. I turn into my subdivision and the car starts cutting out for like half seconds at a time, like power loss, slows down almost stalling, then kicks back up to normal power, then it starts doing it faster back and forth, feels like its stalling out. i turn into my drive way and it died... i restart, it idles fine put into gear and it dies instantly every time i tried. but in park it purrs like a kitten??

is it possibly the tranny or tc?? the tranny has been slipping for awhile but still drivable, the car is 100% stock from the air filters to the muffler.

timing set at 6, set minimum air, tps in spec and no trouble codes.

Here are some things i recently replaced, mostly all ac delco.

distributor(came with new pick up coil and ignition module), cap, rotor, plugs, wires, ignition coil, fuel pump, air filters, muffler, fuel filter, fuel injectors, vats disable via custom chip(only mod on the chip), the wire harness from the coil to distributor, intake runner gaskets, cleaned inside the plenum, cleaned inside the runners, cleaned the throttle body, set the tv cable, ecm less than 5 years old, correct prom, jasper engine less than 10k miles, checked all fuses, checked inline fuses, checked grounds, just about every sensor is new except the maf and o2, cat is good, replaced all vacuum hoses, ecm has been reset a million times, and has all the proper heat shields.



89 350 tpi and the temp was at 200 degrees

So you can imagine my frustration...

Any help is appreciated, I'm at my wits end here folks, this once daily driver is about to be driven off a cliff!(if it would make it there )

so if anyone has had this problem or worked on cars with similar please advise.

sorry for the long post

-Shane

2600-watt-rs

damn seems like everything i was going to say you have already replaced.. Maybe the chip? My brother inlaw had a chip on his truck and would only act up when it wanted to. I dont know man.. GL though

89shane350

iTrader: (1)

lol, thx, i know fml! i also bypassed the neutral safety switch just to clear my mind about it...
sadly I'm getting a good deal on a 5 speed civic for reliable transportation until this clunker/lemon/money pit shapes up

erik69&85

iTrader: (1)

OK, not sure if I have the answer but since you have thrown the kitchen sink at this problem.....

My 85 Z28 had a similar problem that had me and the old guys at the Chevy dealer stumped. Does it only happen when the car gets nice and warm (hot)? That tends to be an electrical circuit problem. After several test drives by Chevy mechanics we had narrowed it down to the tach filter. Don't know if they still had one in your car but in my car it was a small gray cylinder mounted to the firewall right behind the distributer. It smooths out the pulse signal from the distributer to one constant signal.

No one ever talks about that tach filter on this website..... But when i disconnected the tach, I never got that problem. Turns out that when it gets hot (and its failing), it can't take the load and shorts the ignition system leading to the engine dying or starting to die. For me, it would start to die, come back, start to die, etc. At total random times (when it was hot). The problem is, you can't buy that part anymore.... got to find a NOS one or pull one from a parts car. I got lucky and a friend had a NOS one never used.

If your car doesn't have a tach filter, I would still look for a failing electrical circuit,, usually around the ignition and definity inside the engine bay. When they get warm, they get all weird. (The old Chevy mechanic took my car out 3 times before it finally happened to him and he could try to figure it out.)

Good luck, I know the feeling....

89shane350

iTrader: (1)

interesting eric, i'm gonna go look right now!
also i replaced the 3 relays on the firewall(pump relay, burn off, and the other one) 3 different times i forgot to add lol

89shane350

iTrader: (1)

it seems they quit putting then on camaros in like 87, but kept them on corvettes till 89, any other suggestions?
could a torque converter or tranny cause this?

camarorsssss

iTrader: (2)

Just a thought, but the ignition control module you have in the distributor that you replaced, is it a gm icm or some other company? If it isnt gm, i would replace it with a gm one. Dont know if thats your problem but it wont hurt anything.

supertrade

Had a mechanic once tell me that the first fuel injected models on these cars had ECM that basically sucked. Said he had one where just banging on the passengers side dash made it wig out. I can say that when I first bought my 1990 formula, it has alot of weird problems and cost me alot in replacement parts to no avail. Finally, I replaced the ECM and 90% of them were solved.

red rock

iTrader: (2)

Have you checked all ground connections. The ECM needs a good ground.

ex-x-fire

Unplugged the tcc on the trans & drive it. Its a 4 terminal plug. It won't hurt the trans if you drive it for a day or two, then see if it acts up. It might be the switch on the brake pedal. If its the tcc staying engauged, it should feel like stoping a car w/ a manual trans while in gear.

89shane350

iTrader: (1)

the ignition module was replaced w an ac delco and it did the same thing, then that one was replaced with the new distributor unit, still does it.
and i was going to unplug the transmission plug you recommended, except i went to move the car today and when i started it, it died about 5 secs later when i shut the heater off.(it was on and fan on high from the last time i drove it.) and now it just cranks and won't turn over!

89shane350

iTrader: (1)

also the grounds seem good and the ecm isn't to old, i hope thats not it.

backgammon7

You did have a good amount of gas in the car right? Mine would do that when I ran it below 1/4 a tank.

I know its a simple thing, but it could easily be over looked.

89shane350

iTrader: (1)

full tank :+)

oldschool226

I HAD an 04 ford van that acted up once in awhile similar to yours and 4 trips to the dealer in limp mode later they found the power control module (new style ecm) had gotten wet. I would bet you need an ecm.

89shane350

iTrader: (1)

interesting, should i buy a ALDL USB cable or just take it to a shop?

89shane350

iTrader: (1)

im gonna replace the ac/delco ignition mod under warranty sense its out of the car anyway just to see if the new mod burnt up already. might take a few days, amazon third party seller.

89shane350

iTrader: (1)

i ordered a new ecm today with over night shipping, with a coupon code i got it for 38$ from advance after core! i did this because i tryed to check for a code and after i jumped the pc port the light stayed solid and did not blink 12. if this doesn't work im getting a new prom. and the crap place i got the delco ignition mod from wont honor the 1 year warrenty, screw "stock lifts llc" a amazon vender

89shane350

iTrader: (1)

ok new ecm, nothing, i sprayed starter fluid in it and it started and revved up in the 7k range by its self i shut it off as fast as i could, but it took me by surprise... at first i thought maybe i sprayed in to much, but i looked at the linkage and the cruise control cable was pulling the throttle back for some reason, so i just unhooked it car starts now but runs like crap, like if you had a spark plug wire plugged in the wrong cap spot... i hope the engine wasn't damaged when it revved up, i have a aldl cable and tunerpro, but im not sure what im looking for, i did a short datalog and asked the diy prom guys, but i'm about to scrap this pos car and be out thousands and cut my losses, i wouldn't give this to my worst enemy! this evil car seriously caused me to start smoking again out of frustration.

so any suggestions on why it runs so darn rough? could the engine rev mess up the timing or anything like that? im all ears.(eyes? lol)

red rock

iTrader: (2)

Smoking sucks, but so does a bad problem. I'm sure you have checked for vacuum leaks, but one of the bad leaks I had was from my runners. The bottom bolt underneath the plenum works it's way out. Also check the throttle body butterfly shaft for slop. Vacuum leaks can cause a whole host of rough running problems. By the way I smoke too, It's more expensive than my car. lol Some times the most obvious is the most overlooked. I see you have "reset the ecm" a few times. Has it ever given any codes?

oldschool226

Sorry the ecm didn't work. Will it start and stay running without the starter fluid? You can check for a gasket leak by spraying it with starter fluid it will rev up if its leaking.

89shane350

iTrader: (1)

yea starts and runs now w/o the fluid, but it runs real rough, so maybe the ecm did fix it. i'm scared i effed the car up with the over rev, fml.

and red rock i replaced the runner and tb gaskets not to long ago when i put in the new fuel injectors, i have a vacuum tester i'll try just to dbl check, if smoking cost more than ur car then u dont have a pof lemon money pit like mine lol.
so if i get the nerve to work on it today ill chk vacuum, timing, or maybe just take it to a shop to check the valve train. idk anymore!

red rock

iTrader: (2)

I hear ya, mine had issues when i got it, but i worked them out with some basics. Again, have you ever gotten any codes to point you in some direction? I would think with the trouble your having it would throw some kind of a code. Anyway don't give up, you'll be an expert when you find the problem. Just a note: there have been some post on here with people getting the runner gaskets on backwards if they aren't careful. I'm not knocking your mechanical skills, It can happen to anyone.

oldschool226

I would rev it up for few seconds to about 2500. Shut it off while reved up. Pull the plugs if they are wet you have an electrical issue if they are dry you have a fuel issue wich could be a vac leak or you'll see a bad cylinder could be a simple as a wire. With no codes on the original issue intermitted poor running I would have the coil checked it would'nt throw a code and could fail when it warmed up.

89shane350

iTrader: (1)

yea i hear yah, i got it back from a shop once with them on backwards, ive changed the fuel injectors so many times over the years i got it down whelp i official gave up, i start my new job next friday and aint risking it or blowing any more of my cash money on tools and such, i think it was the ecm. and i think the cruise con. broke something or came loose in the engine when it over revved, im dropping it off a a reputable shop tomorrow. ill let yall know what they find and if its going to a junk yard or not >:-(

red rock

iTrader: (2)

Good luck, I hope it isn't too serious, wouldn't want to hear of another one going to the bone yard.

z28romance

Did you check the IAC during any of this? i didn't see you mention it. A dirty/defective IAC can cause a lot of these problems.

Blue1990camaro

iTrader: (1)

my 91 rs did that but oposite when it was cold, and only randomly, it drove around fine for 6 hours STRAIGHT then all of suddon nothing kept stalling and bucking then was fine again, we wer stumped for about a week till we pulled the plugs, 3 plugs had cracks in the ceramic part and wer shorting to the block....

Fritomaster

Hope they find out.... Curious what it is.

TTOP350

iTrader: (8)

sounds like a bad maf to me..

89shane350

iTrader: (1)

yes iac is new and set, in first post i mention setting minimum air.
interesting thought on the spark plugs.
WELL i just got the ****sucker this morning from the shop, it was early and i picked it up, the shop charged me a fee for looking at it and they said its all good and no problems after test drive and no internal damage from revving, so i had someone drop the money off on friday and i went to get it today before they opened, well wouldnt you know when i pull away from the shop it died right then and there... ok, maybe a fluke, its been sitting awhile... so i head through town and it feels weak as in not much hp. it starts almost stalling and bucking... grrr! does this till im half way home then takes a crap... dies and won't start, stranded for the 7834795795 time! middle of ****ing nowhere.. omg that sh*t show shop are so lucky they didnt have an answer machine, i was so GD furious! should call out of work to kick this guys ***, get a refund, and have them pay the tow bill... his words echo though my head waiting on a tow "Ain't nothing wrong with it" as i drew closer to a breakdown. not sure what to do besides light a truckin match on this pos. im done for awhile again... can't even look at it right now or even think strait...

red rock

iTrader: (2)

Sorry to hear that, I wish I was closer to help. You not only have a problem car, but a **** poor mechanic. I would defiantly be having words with them, they obviously didn't test drive it very long. The mechanic for the guy i bought my car from, basically said the same thing. He said there's so much that's been done in the way of mods, that's the way it's going to be. That's one of the reasons i got the car so reasonable. The PO got sick of it. The throttle body was the biggest culprit on my car, it leaked a lot of air. A good mechanic is hard to find i guess.

89shane350

iTrader: (1)

MYSTERY SOLVED !!!!!!!!!!!!!!!!!!!!!!!

IT COST ME $102 but whatevas! ok **DRUMROLL***



scroll down!



















































The A12 computer ground was loose(On the harness that connects to the rear of the computer.) and intermittently ungrounded the computer and cause the car to "Buck" as it was on and off loose, die when it was to loose, and not start when it didn't connect enough.

Thanks to everyone and if you have a similar problem check the grounds, the ground wires, and most of all the GROUND TERMINAL(S) ON THE PLASTIC WIRE HARNESS CONNECTOR THAT PLUGS INTO THE THE BACK OF THE COMPUTER!

All in all worth the $100 diagnostic by a Master GM wire technician and a $2 terminal ! lol

-Shane

red rock

iTrader: (2)

I thought you checked all the grounds? Anyway, a learning experience. Glad they found it.

89shane350

iTrader: (1)

i did! lol i check the wire, the ground at the other end, and it seemed fine to me at the harness, it didn't seem loose to me. Now back to my rattle hunt... i forgot how much of a rattle trap it was from driving newer cars for last couple of months