86 3.2 chugging at 2000 rpm

[audi]

I recently had this motor rebuilt by a reputable shop, I drove it home last fall and noticed it would chug around 2000-2400 RPM, but dismissed it as old gas as they'd had the car awhile. I put it right into storage for the winter.

Now it's spring in NH so I'm trying to get the car out again...I've since drained the tank and added fresh fuel, still chugs at that RPM.

My transmission ground strap was rough, just replaced, no difference.

Pulled all the plugs yesterday, most looked fine but #3 cyl plug was carbonized and smelled of gas. Quick compression check and yes there's compression in the cylinder, the plug wire tested around 3000 ohms, put in a fresh plug and was hoping it was just a loose plug wire, but no...shill chugs and after a few minutes of running, this is what my new plug looked like:



Injectors were done a couple years ago, plug wires are Magnacores that are about 8 years old.

Any thoughts on what's up with cylinder #3?

Thanks in advance,
Audi

[Porsche 935]

Black sooty, rich.

[Arne2]

If that's the only one that's black, you probably have a bad injector in that cylinder.

[audi]

Originally Posted by Arne2

If that's the only one that's black, you probably have a bad injector in that cylinder.

That's what I was thinking, except I had them all serviced 2 years ago and they have maybe 150 miles on them since...the car did sit for a year and a half at the rebuilder's, would gas be bad enough after that amount of time to plug them up?

[mikedsilva]

As someone said to me once... everything usually works really well, right up to the point that it fails; I'm hoping that perhaps you just have a dud injector. It is easy enough to swap the suspect injector to a different cylinder and see if the sooty plug follows it around...

Cannot hurt to also make sure all connectors and sensors are 100% plugged in.

[ed317]

I had a similar experience......it was a bad injector

[Flat Six]

Could be bad injector, or injector harness. Swap #3 injector w/another cylinder & re-check.
Also might double-check distributor cap.

HTH

[audi]

Swapped injectors out, ran it for a few, the sooty plug follows the injector...

Going to pull them all and get them serviced again to be on the safe side, and hopefully the car will be running sweet again!

Thanks for the help guys, I'll post back once it's all back together.

[DanielDudley]

I run a bottle of Techron through my toy cars every spring. You would be amazed at what it will cure. I have also followed the YouTube videos of people cleaning and back flushing injectors at home. It is pretty easy to eyeball the spray pattern as you clean them.

Techron before the Spring oil change has cleared up many a stumble. Word.

[proporsche]

what are those spark plugs...???..is it not suppose to be WR7DC??

Ivan

[audi]

Originally Posted by DanielDudley

I have also followed the YouTube videos of people cleaning and back flushing injectors at home. It is pretty easy to eyeball the spray pattern as you clean them.

Thanks for the heads up, hadn't thought to search that on youtube! I'll try the Techron as well.

Now I know what I'm doing tomorrow morning haha

[famoroso]

You might consider Sal Carceller's modern fuel injector setup for the 3.2 (it comes with matching ECU tune / chip).

[scarceller]

Keep in mind that the brake booster vacuum line is attached right at the top of intake runner #3. I have seen failed booster allowing brake fluid down the vacuum line.

With car at idle and fully warm, step on the brake with it parked and in neutral, does stepping on the brake effect idle quality and/or speed? If so you may have a bad booster.

Other than this, as others mentioned you may have a bad injector.

You should install a decent WideBandO2 gauge in the car, you can then use the AFR data to test the injectors by unplugging them one at a time and looking at how it effects AFRs.

As mentioned I have a kit that replaces these injectors with much better modern day 4 hole Bosch injectors. And you get a performance chip that's designed for the injectors.

But I suggest always proving what the issue is first, before you go changing parts.

[audi]

So I tried running carb cleaner through a few injectors, including the presumed bad one, and upon closer inspection I think injector #3 is junk.



Upper is good, lower is #3 (with the pushed in needle). Not sure if it's possible to repair, but I couldn't get anything unstuck with carb cleaner.

Thanks for the replies so far, guys. Possibly interested in the upgrade kit, I'll give you a PM separately Sal.