Kotaru

Was hoping to start out my first thread on a better foot but this problem has crept up on my over the last few days and keeps changing.

The Car
1991 305 TBI w/154,000 miles
700R4

Problems
Varying Idle
Hard Start
Stalling


Description
Melted a sparkplug wire on the exhaust manifold out of the blue about a week ago. The car ran like crap until I got it home from work and replaced the set. My car before this started perfectly fine and held a good 600 rpm idle. Pulled hard and other than a noisy lifter on the passenger side was a reliable little motor.

But since I replaced the wires I never got my solid idle back. The car is impossible to start, it will cough and wheeze while cranking over unless you give it a little gas. It will then catch but not hold an idle until a short time later, so you have to give it gas for a few seconds before it will not stall out instantly.

Once its warmed up a little its idle will slowly vary from 1200+rpm to almost stalling again. The car will pull hard and not stumble, cough or misfire if you give it any gas (Why I've ruled out pump/filter); a little gas to WOT it runs perfectly. Sustained throttle (Highway driving) runs perfectly fine aswell, unless you slow down to an idle at which point it will start to stumble and then die. Sometimes it will hold a very very rough idle 200-300 rpm but will die if left long enough.

I've done the following;

1. Checked for codes- None found
2. Check EGR, removed it from the vehicle to test and tested the EGR solenoid - Diaphram holds vaccum and opens and closes during operation, EGR passage in manifold it not clogged.
3. Replaced ALL vaccum hoses and verified no leaks while doing a carb cleaner spray / running test to rule out any leaks around the throttle body - No change
4. Replaced the IAC with a good known unit and performed the IAC minimum idle / rest described on this forum - No change
5. Cleaned TBI unit - No change
6. Disconnected TPS sensor - No change
7. Replaced noisy PCV valve - No change
8. Checked over other sensors for loose or damaged items. - No change
9. Even fixed my cruise control in the middle of all of this mess - Obviously no change.

Some ideas before I just start throwing parts at it?

ex-x-fire

Check the fuel pressure.

deadtrend1

iTrader: (1)

If all you changed were plug wires, i would make sure:

-All plug wires are fully snapped on and firing order is correct
-didnt crack or break a spark plug
-didnt move the distributor (check the hold down bolt and timing)

Kotaru

Don't believe the fuel system is too fault due to the fact that the motor under its highest load (WOT from a dead stop) works perfectly fine, its getting fuel.


Double and triple checked. I can turn the car off and it will idle at 500rpm then turn it off again and it will idle at 1000.