Dean_GTA

My 1988 350 TPI Trans Am, runs smoother, and doesn't stall when the EST connector is disconnected. With it connected, It idles rough, and stalls every time it is put in reverse, or drive (Auto trans) With it disconnected, it idles smoother, and I can drive the car. What does this mean?

Also, what should the stock timing be set at? What should I see with the timing light? Right now it's at 6 before, on the tab.

Damon

6* BTDC with the EST wire disconnected is the stock setting.

There's probably something making your timing jump around when you plug it in- that's the erratic behavior you're describing. If it's not false knock, then it's probably something electrical in nature. Bad ESC module, ECM, maybe the distributor/module itself has issues. Could be quite a few things. Get ready to run a bunch of diagnostic trees or throw parts at it until you nail it.

customblackbird

iTrader: (15)

it shouldnt stall with it disconnected.... stock was suppose to be 6 degrees BTDC.... but some have found it to be anywhere from 0-8. bump the BTDC to about 8-10 and u should gain alil HP as well as increased throttle response.

agree with damon... u got urself an elusive lil bugger there. easiest stuff to check would be electrical/distributer. find a friend with a good running car that is close to the same year, and swap ECMs and see if it helps. if it does u need a new ECM. make sure ur distributer is ok. now is a good time to replace everything with performance parts like a ACCEL igniton modual, new plugs, new wires and MSD blaster coil.

jv9999

iTrader: (1)

I'd start with a new pickup coil in the distributor. They fail often and can cause similar timing problems.

Dean_GTA

Thanks guy! The distributor is a rebuilt unit from Auto Zone. The coil is a MSD Blaster coil. The day I put the distributor in, the car ran fine for an hour and half. A few days after, I started the car and this happened. I was doing some troubleshooting with a buddy, and realized that the car ran without stalling with the EST wire disconnected. The timing right now is set to 6* There is something wrong with the ignition system. I was also told that with the EST wire disconnected, the car runs on the distributor, and not the ecm. Could this mean a bad ECM? I will keep you guys posted!

customblackbird

iTrader: (15)

haha if autozone rebuilt it i would say big nono. i dont trust them. they dont kno anything about cars.... well at least the ones ive been to. i just use them for stupid stuff like bulbs etc.

if it started a few days after the distributer swap id say thats ur prob. u could have messed something up got the timing all screwed up. u want to hope the ECm is not bad

ATX-Iroc

try swapping the leads from the ignition module around (under the cap). if you have them backwards est tries to retard the timing and the car runs horrible

Dean_GTA

The distributor has a lifetime warranty. The reason I got one, is the MSD distributor in the car, that was a year new, was no good! I also replaced the ECM with one from Cardone. Both are rebuilt units. Is there a way for the dealership to bench test the ECM? ESC, I was told doesn't make your car stall. With the EST wire connected, the car runs bad, and when put from park to reverse, or drive, it stalls!

customblackbird

iTrader: (15)

the distributer caps that have external coils like all 350tpi's have weather pack connectors that can only fit one way on the distrubter and coil. u would have to go out of ur way to mess that up.

the EST connector basically just bypasses the timing done by the computer. when u connect it u allow the ECM to regain control of timing. when u disconnected it did u have the car off? and when u reconnected it did u turn the car off before? also some ppl believe that u have to JUMP the ADL plugs under the driver dash sometimes in conjuction with the EST connector dissabled.

it could be something as stupid as a bad ground when u replaced the distributer. id start swapping things. find someone with another 350tpi chip ECM and swap it in and see if it helps.

did u mess with the idle etc? fuel pressure problems... vacum lines etc. u could have fried the ECM, which is what i think when u connect the EST wire thats whats causing it. easiest way would be to swap it out.

Dean_GTA

I might hit the local scrap yard to see if there's an ECM with the same number. I would have to use my prom. Could the prom be bad? I know the proms are discontinued. I will have to play around tomorrow. Checked for vacum leaks, and fuel pressure was checked. (43psi with the vacum line off)

jv9999

iTrader: (1)

I still vote for the distributor. Do check the grounds on the back of the passenger side head though.

Dean_GTA

Grounds are all good. I have the timing set at 6* with the EST wire disconnected. Turn off the car, connect it, start the car, and the timing does advance to 12*-16* But it idles not as smooth, and it stalls when I take it out of park, and put it in reverse or drive. I would have gone to the scrap yard to get another ECM to try, but we just got hit with a snow storm, so I'll have to wait.

Chriznoznae1

I have the same problem except mine doesn't always stall. I have swapped ecms, idle air control motor, new tps, new egr valve and solenoid, ignition module, distributor, coil and still I have the same problems so I was wondering was your problem the ground.

JakeJr

Don't forget to disconnect then reconnect the battery to clear the SES code that gets set when the ECM detects the engine running with the EST disconnected.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!

Chriznoznae1

I was having a similar problem and tested every sensor on my car and replaced them just to be sure but I still had the problem. Turns out that my air diverter valve solenoid was stuck open because it didn't ohm at 30-50. according to chevythunder.com a burned solenoid will cause your ecm to burn out so maybe you should check that because I never suspected such a thing on mine and it drove me nuts. Hopefully the parts get here soon and I'll report back the good news.

Chriznoznae1

Ok I replaced my Air diverter valve and plugged in my new ecm but it still didn't fix the problem. As a last ditched effort before I decide to fly off the handle and sell the car I put in an older prom that I had for the car when it used to have headers and different runners. I put the chip in and drove the car around for a few minutes while it re-learned the settings and voila the car was fixed. I read from chevy thunder that if any of your diverter solenoids or any solenoid goes bad your drivers in your computer gets fried but I never thought that my Prom would actually be bad.
Good news is that I am no longer pissed off at my car and I don't have to sell it or carb it now.

benin360

im having all these same problems, and i just cam'ed mine. im not framilure with the word PROM? what is it and what does it stand for? because Chriznoznae1 you said that you replaced it with another one and it went away? how do i get one of those?

Chriznoznae1

Well if you put a cam in your car at all you need to have a dyno tune. The prom is the chip inside your computer that tells it all the parameters to run based on your setup. So if you change injectors to a bigger size or get a more aggresive cam you need to have it customed tuned so that your car doesn't run like crap, not idle/surge. My problem was that my cars chip that was custom tuned actually went bad and caused my car to not idle/surge. What you have going on is that you just need to get a good tuner and have your new setup dialed in.

benin360

thanks for the quick reply Chriznoznae1 that makes me happy that this is all i need. i was gonna invest in a custom chip and then go get it tuned.

kenkrozel

i have the same prob the car runs great when the est is not connected as soon as i plug it in the car runs terrible everything is new except the dist