Stumbling/Stalling during Idle

[Mattglas]

Up until last month my car ran perfectly, it idled at 750 and never stumbled. However, out of nowhere it started to stumble and then stall whenever it idles (hot or cold). I've thrown everything I can think of at it and nothing has worked. Does anyone have any sugestions?

Here's a list of the things I've done:

• New gaskets/o-rings on top end of engine
• Readjusted the valves
• Adjusted the timing
• Checked the spark plugs
• Checked the dwell swing
• Checked compression (115psi cold on everyone)
• Checked voltage to idle motor (11v)
• Checked idle ecu and motor by removing the plug closest to the center of the car and having the idle spike to 2200
• Checked battery voltage at idle (13.5

to 14.5)

This is what happens when the car idles:
https://drive.google.com/file/d/0B2N...w?usp=drivesdk

Don't know if its related but is this amount of smoke coming out of the oil filler normal?
https://drive.google.com/file/d/0B2N...w?usp=drivesdk

[Bitsyncmaster]

Does it just the idle problem? Does it run normal when driving?

I would do a fuel pressure check.

Sudden problems could be the fuel pump but that would also show a problem when driving.

[Mattglas]

Does it just the idle problem? Does it run normal when driving?

I would do a fuel pressure check.

Sudden problems could be the fuel pump but that would also show a problem when driving.

It runs fine while driving, doesn't misfire or hesitate at all. I replaced the fuel pump a few months ago with the updated combo one. Relating to fuel, I have 93 octane in the tank. Not sure if that makes a difference. I just recently found out that it requires 87.

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[Bitsyncmaster]

It runs fine while driving, doesn't misfire or hesitate at all. I replaced the fuel pump a few months ago with the updated combo one. Relating to fuel, I have 93 octane in the tank. Not sure if that makes a difference. I just recently found out that it requires 87.

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Now I don't think the fuel is the problem. What voltage does your car hold at idle speed?

[Mattglas]

Now I don't think the fuel is the problem. What voltage does your car hold at idle speed?

It starts at 14.5v and slowly decreases to 13.5v and then goes back up to 14.5v. I have specialtautos 120 alternator.

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[Bitsyncmaster]

Does the voltage drop to 13.5 because the RPM is dropping? Just looking for clues to help find your problem. Seems odd it starts out at 14.5 volts unless your engine RPM is higher during that time.

[DMC5180]

The engine was certified to run on Standard 87 octane. Running a higher grade only hurts your wallet, not the engine. If you had a Stage II upgrade then it would be necessary to run 91 or better due to slightly higher compression ratio.

I had a randomly twitchy oil pressure gauge for quite a long time. Replacing the sender did not fix the issue. Cleaning The PCB contacts to the gauge did fix it.

for some reason I was not able to see you first video. Just going by what Dave said.

[Elvis]

are you sure your idle system is working at all ?

looks like the ISM motor is freezed an can not react on load changes

[DaraSue]

How old is your idle speed motor? I had a newer one go bad due to flaky wiring on the inside not making a consistent connection.

[Mattglas]

How old is your idle speed motor? I had a newer one go bad due to flaky wiring on the inside not making a consistent connection.

It's the original motor that came with the car. Is there any tests I could try to see if it's the problem?

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