Ok guys ive been reading this forum for quite awhile trying to figure this car out. My Father in law bought this car new (1986 Trans Am 305 TPI) and recently gave it to my son. He parked this car in his garage in 1999 and didnt drive it again because he was tired of ppl bugging him wanting to buy it. The car has 88,000 miles and hasnt had anything removed or cut, everything he had done to the car was done by the dealership.I trailered the car home replaced all fluids, filters, plugs, wires and the fuel pump etc. The car actually ran quite well for about 3 weeks and then acted like the fuel pump went bad. I then ordered an AC Delco pump and a new sending unit from the dealership in town, didnt change the problem. You can start the car and idles fine no miss but you drive it on an average of 2 miles and it acts like its running outta gas. It will restart and idle (but misses) and wont rev above 3000 rpms.you can let it set for awhile and it will start and run like new for another 2 miles. OK here goes the parts list ive changed 2 AC Delco fuel pumps, Module, Pick-up-coil, coil, new mass air flow sensor and burn off relay, fuel pump relay, ECM, ECT sensor, new injector O rings, new upper plenum gaskets, injectors tested 17-18 OHM's, 42 psi at the rail, fuel regulator line is dry. So like i said im outta ideas and there are very knowledgable ppl on here so im up for ideas. Thanks

 

Long shot: Try changing the fuel filter again.

 

test injectors hot?

 

looks like the tps is the last on the list have you checked the ecm ground behind the rh cylinder head ?

http://www.gmtips.com/3rd-degree/dox/tips/ecm/prom.htm

 

The injectors never get hot and Ive changed the filter everytime i changed the pump. If the TPS was bad wouldnt it throw a code or run bad from the start? I havent checked the ground on the the head yet though, i did look under the dash when i replaced the ECM and the wiring looks brand new. Ive looked under the car and you could wax the underneath. This car never seen snow in it life until this year (when it comes) the only code it throws up is ECT detected high temp?

 

Oh sorry didnt read that question right, yes the engine was up to operating temp when i checked them.

 

A bad tps may not throw a code 21 or 22 if there is a bad spot in the potentiometer you can do a sweep on the blue feedback wire or do a ohm sweep from the center post to each side post slowly opening the throttle. If you are getting a ect high temp better the reason to check the engine ground strap and ecm ground at cylinder head and d2 of the ecm.

 

Didn't see an ECM ground strap? It's held in by a plastic cover.

 

the ecm case is not grounded

 

I would start by diagnosing the ECT code. The ecm uses the ECT to let it know what the engine temp is. This could make an engine run bad if it reporting to the ecm that the temps are high when you have a cold engine. Have you let the engine sit there and idle and get hot? Does it run ok when hot or still run the same? Cant rule out the injectors. Just because they ohm ok doesnt mean they are ok. They can act up when they start working electrical or mechanically. I would even try putting the stock ecm back in and see if that does anything. I've seen remans bad right out of the box.

 

Funny thing is the MAF code was the only code I got but replaced the Engine coolant temp sensor cause it looked pretty corroded. After I replaced the MAF is when I got the code about the ECT. I've let it idle for at 30 minutes and idles like new but it seems it only does it after I drive it a few miles. If I remember correctly the TPS has 3 wires so which ones do I place the leads on?

 

The same information again the center lead is a blue wire on the tps this is the feedback to the ecm. At idle or just koeo the voltage will be .54 and will increase as the throttle is opened to almost the 5v ref at wot.

 

Set multimeter on low volts. Connect black lead to ground, probe red lead to the blue wire of the TPS while it's still plugged in. Ignition on, engine not running of course. Make sure engine is at temp that the problem occurs. At closed throttle, voltage shouls be .54 volts. I forget the exact figure, but at WOT it should be over 4 volts, probably more like 4.5 volts. Also imporant to check here is that the transition is smooth throughout the throttle sweep.

 

Since you had a MAF code at first and replaced it, which I guess it got rid of the code. You also replaced the ECT at the same time and now you have an ECT code. Did you get the right sensor? How did you install it? Put anything on the threads of the sensor?(sealant, tape, etc) High temp code is probably the ecm recieving a max temp reading like if the connector to the ECT is unplugged or the sensor isnt grounded. If the ecm is recieving a reading from the ECT, maybe its a higher reading than it should be which could be caused by the wrong sensor or bad one. Only other thing I can think of would be resistance in the wiring coming from the ECT to the ecm.

 

First of all I wanna thank you guys for the help. Now that I think of it, I did put thread sealand on the ECT. The funny thing about this is I'm a Ford guy hahaha and my son absolutely loved this car since he was early enough to remember. I'll will check the TPS when I get home Friday.

 

I'll post pics of this car the way I found it and after I washed it off. If this car wasn't as unmolested as it is I would have done ordered a intake and carb for it.

 

You need to remove the ECT sensor and clean the sealant off the threads and also clean the sealant that would be left in the hole the sensor goes in. Install the sensor back in and that should take care of the ECT code. When you put sealant on the threads, the sensor wont get grounded enough or not at all on the engine. The sealant acts like an insulator. The sensor gets its ground through the body/threads of the sensor.

 

the ect does not use the case as a ground this is just a thermistor in a sealed case the black wire is the ground and connects to the back of the passenger side cylinder head.

 

At this point Im open for suggestions, when I get home I'm gonna check the grounds and the TPS. Acts just like low fuel pressure but after multiple AC pumps I ruled that out. I might have to take a small video, this car is killing me slowly hahaha

 

If you haven't fixed the problem yet. check vacuum leaks and I know you said you replaced the coil, but maybe you got a bad one from the shop. Happened to me once. I also ended up switched to an HEI distributor unit simple conversion and it solved my problem which was similar to what you are describing.

 

85-86 tpi is hei computer controlled distributors.

 

right didnt know that sorry my 87 diffenatly wasn't

 

is your fan running constantly? Ever considered a bad chip (prom)?

 

Fan comes on at the proper time and temp, as for the coil I can change that easy enough. Don't mean to second guess you guys but every time I've had a vacuum leak its been constant and not after running awhile and then stop after setting.

 

Alright I borrowed my Uncles Snap-On scanner and hooked it up. It said 14 Coolant temp signal low or shorted and 42 Electronic spark timing (EST) problem.

 

The code 42 is set when the est wire is disconnected to set the timing . The code 42 can also be set if there is no 5v when the engine is running on the bypass wire caused bye a bad icm. The timing will not advance when the engine is reved if there is a issue.



Like I said in earlier post check the ground side of the ect the yellow wire goes through the passenger side fender well next to the bulk head and to pin c10 of the ecm.

 

This. Sounds like injector problems to me.

EDIT: I see you tested them warm and they tested ok.

 

I know someone said change the fuel filter "again", but I couldn't see in any of your posts where you've changed it at all. Have you?

 

you test injectors with motor turned off

 

..... You need to Ohm check the injectors ... unplug the injector harness from each injector and test the two terminals on the injector ... ohm meter should read around 16 ohms ...........

 

Take the scanner and with the vehicle running, let it warm up, pull up sensor data and check what the coolant temp sensor is showing for temp. Dont over complicate it. The car is giving you the direction to look in.

 

I changed the fuel filter with every pump change, the tank is clean and the sending unit is new. I checked the OHM's with the engine at operating temp and off. They checked at 16-17. The engine was running 151 degrees according to the scanner, everything read fine at the scanners capability except the coolant temp sensor and the EST. I did check the ground on the drivers side head and it was tight with no corrosion and like everything else on this car wires looked new. When I replaced module and pickup coil I did notice the black plastic piece ( can't remember the name) that the module connects to was a little bit brittle.

 

Also the TPS was out of adjustment, I checked it and adjusted it. He drove it to work so we'll see how it runs.

 

CTS is only like $11

 

151 degrees? How long was the car running for? Do u have a 160 degree thermostat or something? I thought these cars ran at 220 degrees +

 

It's a factory thermostat, yea it was operating temp. Of course it was like 30 degrees last night. I changed the ECT sensor but put thread sealant on it so when I change it again I won't use anything. Well he just got home and its doing it again, drive it 6 miles to work said it ran fine all the way there but on the way home 8 hrs later he pulled in and acted like it was running on 4 cyl's. Man I hate this car!

 

Good news is, these are actually pretty trouble free,reliable cars. Once you get all of the sensor issues sorted out.

 

Change your CTS. That thing should be running at proper temp regardless of how cold it is outside. Get the engine warm and then let it idle. Cars run the hottest at idle. If that is a stock thermostat then it should open at 195 degrees and your fan should be coming on at around 226 degrees.

 

not sure but could it be a catylitic converter?

 

Well that was the first thing I checked, his papaw had it hollowed out in the late 80's. but I am gonna change the ECT and trce the ground wire. I just wanna say thanks again guys.

 

Basic problem: Car starts and runs fine during warmup enrichment, dies soon after from apparent fuel starvation "acts like it's running out of gas".

Checked or replaced: Fuel tank, fuel pump (and strainer sock I assume), fuel filter, fuel pressure (and regulator I also assume), injector ohm readings, MAF, ECM, ECT, EST, TPS, CTS.

The car has sat for long periods of time, I wonder if the injectors aren't partially clogged? They would still flow enough fuel during warmup enrichment for the car to start and run until it reaches normal operating temperature and all enrichments cease, at which time it would fuel starve. This wouldn't necessarily manifest under normal checks. You can do an auditory check of each injector with the engine running for proper injector cycling, but this still isn't a definitive yes or no of the problem. You can try Seafoam or another fuel system cleaner and see if it helps the problem. If the injectors are partially clogged, you can have them ultrasonically cleaned, or better yet taken apart and rebuilt (which generally results in better flow than stock).

 

Suggestion:
Disconnect the set timing connector to disabled ECM timing control.
Connect timing light, start engine, rev and hold at 2000 rpm if the timing mark is erratic when it should be rock solid, you have a problem in the distributor.
One item to check is the pick up coil in the distributor, and it's wires/connections.

 

Mine ran super rough, got codes, fixed it all.

MAF
EGR Val/Sol
ESC - electronic spark control
TPS

Replace all that - runs better but still get EGR code when cold, after hot, goes away.

Also, add a bottle of fuel injector cleaner, make sure the tank is full, make sure the gas cap is on tight or system will not pressurize. When my tank is half full, I have issues with fuel pump running dry, especially after a left turn -

Love to hear what solves this issue, keep reporting.

 

Well I'm outta town again, I've gotta few things to try when I get back. What is the stock timing with this thing and which side is the pointer ( told ya I was a Ford guy) hahahaha

 

6 degrees advanced with the est disconnected.

 

How did you fix the EST?

 

Doesn't anybody test/replace oxygen sensors any more? Before heated O²s, the sensors were a wear item. The zirconia elements are susceptible to contamination.

If you still have the MT-2500 / MODIS / Solus scanner available, monitor the O² signal from the point of cold start until the system reached closed loop. Also watch the injector PW to see how drastically it might change once the system enters closed loop.

 

Also, my '86 suffered a similar set of problems after it sat stored for a period of time (it has 49K on it). Just because the injectors are getting a firing pulse and the solenoids are intact (17Ω) doesn't mean they are operating or delivering fuel. Performing an injector power balance test would be a good indication of their performance. All you need for that is a reliable tach (not the in-dash one).

Further, even if they are delivering fuel, there is no assurance that they spray patterns are correct. Some could be streaming, fogging, or dribbling fuel instead of spraying.

And when it's all said and done, you may want to re-evaluate the idea of driving one of these in the snow. We only get about 40-60" of snow a year around here, and the one time I got caught in snow with the old TA was not a fun experience. I've had far better success driving my one-wheel-drive pickup in winter.

 

Since the car sat for 14 years, you can guarantee the whole fuel system is suspect

The old bosch injectors like to seize up for no apparent reason too, so Id look at them first. Next, check out the regulator. Not out of the question for the internal diaphragm to dry out and crack/leak after so long

If the injectors do turn out bad, Id suggest switching them to a newer set of ford pencil 19lb injectors instead of OEM replacements

 

I hear injector advice all over the place. You say 19 LB, another guy told me 32 LB .... ?? ... 26 LB -heard a few

Whats the best ?