1986 911 3.2 not running on all cylinders

[pistolpete]

1986 911 3.2 does not seem to be running on all cylinders.
I am going to check the fuel pressure tomorrow. I changed the dme with no change, What else should I check? Thank You

[john walker's workshop]

Pull the plug wires one at a time and see which cylinder isn't working. Pull that plug and see what it looks like. See if there's spark at the plug connector, Check the distributor cap for carbon tracks. Check compression in that hole. Tap lightly on that injector to try to get it going. The usual procedures.

[Fab64]

Two years ago, I was experiencing an intermittent miss with my '84 3.2 (53k miles). After checking all sensors and connections, I finally pulled the injectors out, and ran them up to R.C. Fuel Injectors in Torrance, CA for cleaning (turn-around time was 1 day). For $29/ea (total $174), they cleaned my injectors, and produced a before/after report of flow for each one (attached). I have not had a problem since re-installing them. Although, it's possible that simply cleaning and re-installing the connections at the injectors could have had something to do with it. Good luck.

[pistolpete]

I have done that on another car I have . These were done recently, also new fuel tank

[Nick Triesch]

Wait!! I had this same problem! Tightening down all the intake runners. I think to 18 foot pounds. Some are hard to get to but you can get them. Over time they do become loose and cause an air leak in a cylinder . Will cause a cylinder to not fire.

[pgeorgeson]

Another way to check if any of the cylinders are not firing is to run it for a while then get an infrared thermometer and shoot temps of the header at each cylinder. If one of the cylinders isn’t running or isn’t running properly, the temp will be noticeably lower than the ones that are. That won’t give you a solution, but it will at least tell you which cylinder you’re having a problem on.

[john walker's workshop]

Carreras also suck in an intake gasket occasionally, which kils
the idle on that hole due to way too much air.

[vedennn]

I recently ran into the same issue on my 86. Like pgeorgeson mentioned we took temps of the header and cylinder 4 seemed to be the culprit. Upon further review the gasket was in pretty rough shape. We had the injectors cleaned at RC Fuel injection as well.

[pistolpete]

I cleaned all the FI connections and the main plug and it appears to have clamed down