My 87 305tpi idles really rough in the mornings (on cold starts) and sometimes it even shuts off. I have to keep the rpms up untill i can let go and it wont shut off. If driven while cold the car jerks a lot under normal acceleration. when it warms up, sometimes it will stall at a light. It has me stumped. Can it be a sensor? timing?

The major things I have changed:

spark plugs
wires
cap and rotor
injectors
fuel pump
coolant temp sensor

nothing improved

 

You need to scan it so you can see what all the sensors are telling the ECM. Otherwise you're just throwing parts at it and hoping to get lucky.

 

Just scanned it now...pulls a 42. Last night i was setting the timing so i had the est wire disconnected, and i didnt clear the codes after. now heres the strange part


if i set my timing at 6*BTDC, the idle is really smooth, now i turn it off, connect the est wire, fire it up and it only runs for 1-3 seconds. now let me get a verification...if you turn the dissy clock wise...that retards and counter clock wise advances?

Right now i have the timing set where the engine wont ping (yes i know it isnt accurate and its harmful) now when i check it with the timing light, its wayyy off the timing tab. With the est connector unplugged the harmonic blancer will point about 2" below the tab. is that too advance or too retarded?

 

HMMM, that sounds familiar. If I am understanding your question properly then the timing is at about 15-20 retarded. I don't think the engine would run like that. Are you on the correct plug wire? I know might sound like a dumb question but here is an example. On a V6 the #1 plug is at the front of the engine on the passenger side. On a V8 the #1 plug is at the front of the engine on the driver side.

Now, code 42 points to the ignition module. I don't know for sure where yours is. My '91 with a 305 is in the dizzy. Some parts stores have a means of testing these. Just be sure you get the right grease from them when you put it back in. Damage to the module will result otherwise. On my '91 Camaro with a 3.1L I had the same code and symptoms. My computer was freaking out because I had a bad injector. I replaced it and the issue went away. Test the injectors and the wiring to the injectors. The injectors should read 11-14 ohms if I remember correctly. You might also want to get a noid light to plug into the injector connectors. You should have a steady consistent pulse like you would a spark plug. Anything else would show a possible problem.

Is your check engine light on? When I had this issue I had a code 42, but no light.

 

The wires are set up right, i checked numerous times using this

The check engine light did not come on. All spark plugs are getting spark. Now the car runs fine when normal operating temperature is reached. Its only in cold weather when my idle jumps or when driving the car jerks alot. It feels like i was driving a manual and releasing the clutch too early, and this happens in all gears

 

Well i changed out both coolant sensors that go on the intake manifold...it improved alittle. it let me advance the timing a bit more and now she pulls better. Tomorrow morning ill see how she starts up under cold weather

 

Ok well it idles rough the rpms jump all over the place. 500-1500rpm. i shut it down, fired it up and ran better 750-1200rpm but not smooth

When driving while its cold the car jerks alot. I changed out the tranny fluid/filter and that did not help it out. i only noticed improved shifting

 

Well i sea foamed it and it helped in the morning, but it still jerked. A little thinking and i thought about disconnecting the cold start injector. well turns out it ran perfect, it idled "normal" around 1200rpm on the cold start and back down to 750rpm idle 600 in drive.

now the question is...is it harmful to run with the CSI unplugged?

 

It won't hurt anything other than starting, but it's odd that it made any difference. When you scanned it, was the engine temp reading right?

 

Well i scanned using the jumper on the ADSL, but the temp gauge seems accurate. I filled up with 91 octane and was able to retard the timing a little...that helped get some power and smoother idle Ill hook my timing light later and hope i can set it at 6*btdc....although i heard TPI likes 0*? opinions welcomed