Marty916

I just got my '87 Carrera out of the shop after a service (valve adjust, fluids, air filter, fuel filter, timing) and the idle is a bit rough. Compression checks out ok. It's been this way since I got it and was told that the 3.2L traditionally tends to idle roughly. I've replaced the plugs, wires, rotor cap, etc., but this symptom persists. Heads were rebulit about 40k miles ago and it made no difference in the idle situation. Is it really just inherent in the model? Could the DME relay possibly be a potential cause of this? Any other possible suspects? Thanks in advance!

Peter Zimmermann

Marty: Without the ability to actually sit in your car it's tough to make a judgment, but if the roughness has always been there it's probably "normal." I've found that the typical 3.2 car will not idle as smoothly as a CIS car, especially pre-Lambda models. You can never expect a 3.2 to go hmmmmmmmmmmmmm at idle, that just won't happen. However, there are different levels of roughness from 3.2 car to 3.2 car, and it sounds like your car has remained unchanged through many valve adjustments, plug changes and other work, so it probably is what it is. And no, I can't imaging a DME relay changing/improving the condition.

ron mcatee

I have an 88 Carrera and it was doing the same thing. After changing everything I felt was contributing to the problem, I finally looked at the injectors. They had about 105,000 miles on them and when I had them checked, two were spraying properly, two had very erratic spray patterns, and two were almost clogged and were only dripping. Once cleaned, it runs great. I would check in your area for a fuel injection shop that does Porsche injectors. The shop here in San Antonio charged me $120 for cleaning, checking, new seals, etc. I checked on new seal kits from several suppliers such as Pelican, Performance, Zim's etc., and the kits alone were around $9 each ($60 total). I thought my costs were relatively inexpensive compared to new injectors which could cost $150 each or more. Note: If you do remove the injectors be carefull when moving the fuel lines if they've been on there a while. After I had reassembled all the rails and hoses, I found both the crimps on the lines to the fuel rails were leaking. I had to tear it all down again and fix that problem. You might consider doing it all while it's apart and be done with it. All this is assuming the injectors are dirty. You also need to ensure the CO is set correctly prior to checking out other stuff. Mine was off a little and helped, but the injector job did the trick.

Marty916

Thanks so much for the input guys. The injectors are something I have never explored so that will be put on the list. The DME possibilty was just a shot in the dark. I do that quite often but so far have been lucky with no major fires or explosions resulting from my efforts.....However I did get my head trapped under an old VW Scirroco I was working on when it fell off the stands during the Loma Prieta quake back in '89.

Mike Murphy

My engine ran a lot smoother after I ran a tankload of BG44K through with a heavy right foot.

speednme

I agree with Spider911. The injectors might be the culprit. Funny thing though I was just having the same conversation with someone on the phone this morning...spooky..

Peter Zimmermann

It's amazing how a person's experiences change a way of thinking. I would never have thought about injectors for this symptom, because 99% of my customers used Chevron gasoline, and most did periodic Techron treatments. Those cars didn't have injector problems, and CIS fuel distributor problems were rare also. We serviced multiple 911s every day, and I can count using my fingers how many injectors we had to clean/replace a year. Amazing...

ron mcatee

Pete, I did everything trying to find the problem. I agree that 3.2's are touchy in the idle area, but mine was literally shaking the car. The last item on my list was the injectors and it was the problem on my 88 Carrera. I bought it with 70,000 mi on it in 1999 and it now has 124,000. I have documentation from day 1 (folder is about 4" thick) and recently met the original owner. I guess 54,000 in 8 years is about normal.

Peter Zimmermann

Believe me, I don't doubt you, or your fix!!! For me, it's mind-boggling that this type of thing even occurs because, seriously, we just didn't see it. Another factor I have to learn to consider is the age of the cars - Marc took over Red Line in 1999, your car was still relatively young at that point, but now is 20+ years old! Boy, how things and times change...

jakeflyer

"because 99% of my customers used Chevron gasoline, and most did periodic Techron treatments"

What a difference a day makes 24 little hours, er uh a fuel makes. Do most drivers know--no. A few cents more a few dollars less in repair.

However, on the 911S, I pulled the injectors when I had the engine out and and used carb cleaner cans to blow the injectors out. 2 good, 2 fair, 2 not too good. Reverse blow and forwrd blow with the little plastic tube and safety glasses. Clamp finger and thumb around the tube at the injector to hold pressure, can on the ground for stability. The rubber o rings were fairly cheap.

60,000 to 100,000 miles of bad fuel by the other owners may create problems that good fuel may not solve.

spence88mph

Check if your O2 sensor is ok by simply unplugging it (it's on the left hard side of the engine bay, follow the lead up from the cat and you'll find the plug) then starting the car, it runs fine without it, this was the cause of my poor idle.