I got the used injectors after doing the resistance check on my stock injectors and finding two to be bad. The original problem cleared up considerably, but there is still a rough idle (no misfire though). That doesn't mean that the injectors aren't clogged or something, but the resistance check turned up clean on the used ones.

 

Is the car still running the OEM distributor? I recently had a rough idle problem and even after troubleshooting and replacing alot of things (inc the ECM) its continued to happen. I swapped in another distributor as a "well I replaced everything else so lets replace this too" and it solved the problem. There wasn't any testing I did to show the distributor being bad, in fact all tests showed the distributor and its components to be good. If I had to guess I would say the internal reluctor or something to do with the magnets inside my old distributor. I dont know much about distributors, that would just be a guess.

 

Would a bad distributor do more than just hurt timing?

 

Joe350 ive been rereading the thread, i really want to help ya here and im pretty much comin up empty, would it be possible for you to fabricate or get an inj service kit, it would be nice to see an inj balance test, then run some seafoam through her and test her again. also another option would be to take them off and have them ultrasonicly cleaned.

the fact that that it still does it when the Iac is unplugged(the opposite of 90% of cases) suggests that the ECM is doing something with timing. Is the 19.5 in of vacuum stable or fluttering?

try disconnecting the tach signal wire,
also try putting a 10k ohm resistor in the aldl port

both of these should put the ECM in a different mode of operation, I'm sure exactly what I'm looking for, but let me know how the car reacts and I'll stew it over.

Also would it be possible to borrow a known good ECM and try?

also perhaps a known good ignition module?

 

The 19.5 in vacuum does flutter, about 1/4 in each direction.

 

Fluttering indicates a valvetrain issue. but also I could theorize the one clogged cat doing something similar

 

What type meter? I have some instructions for the older Fluke 8000 series. I know the 70 series are about impossible to calibrate in the field, and need more than just a trimpot adjustment. Scopemeters have to go back to Washinton for repairs.

Some of the Beckmans can be calibrated it you have a good regulated power supply with both voltage and currrent regulation.

Most of the rest are just throw-aways (or return to point of purchase for replacement).

 

I believe a ignition scope would help a lot here, would it be possible for ya to get on one of those?

 

Valve train issue meaning anything from my timing chain being worn to binding springs huh? Is there any way to narrow that down a bit without disassembling the top and front of the engine? Also, forgive my ignorance, but what does an ignition scope do?

 

an ignition scope measures the firing voltage of each cylinder. A skilled tech can look at these with the engine running and make some rather excellent daignostic decisions. Problems become almost instantly obvious, i.e. weak coil, bad igniton module intermitently dropping spark, low coil supply voltage, low compression, leaking or clogged inj, problem on only one bank of cyl, or a corresponding set of cly on a dual plane.

You can do a leak down test to determine if you have any bad valve seats or bent valvles, I will try to find you more detailed instructions for that.
Otherwise
Pull your fuel pump relay, start the eng and let it die
pull your valve cover and inspect for obvious problems then
have someone crank it while you watch the rockers move
Don't burn up your starter!(You are watching to see if one or two rocker arms are moving shorter than the rest) this would indicate bent pushrod or wiped out camlobe. If there aren't any obvious problems I wouldn't tear into the motor.
If you have a warm engine before you start this procedure you can do a valve adjustment while you're in there

If you really want to know the exact condition of your cam pull your plugs and measure each with a dial ind while turning by hand. you will be pullling the plugs with the valve adjustment anyways.

while you have those plugs out lay em on a peice of paper labeled 1-8 and send me a pic

As far as the air filter goes if it is clogged run the engine with it off while youre warming her up. any change in Idle?

as for the timing chain pop the cap off and turn the engine by hand until rotor turns, then turn the crank backwards. The amount of slack will be obvious before the rotor starts to turn backward.