Der Rennwagen

Resurrecting an old post... Did you find out what the cause of the hesitation was? I'm experiencing the *same* exact symptoms. WOT, provides more fuel and clears up. It's like a slight hesitation and lean condition on partial throttle at 2800-3800 rpms *only* under load like up a hill. No hesitation at this RPM on a flat road. Other than this, the engine runs fine. Sounds like spark plugs to me?

Thoughts or fixes?

Thompson
1985 944.1
Club Sport targa
M404 [aka M030], M220

tomrc

My cure was cleaning and reseating the fuel injector connectors. I had two that were loose, I used dielectric grease after cleaning the connectors. Worked great.

Charlie944

Wow that is from the past, I had to recall what my car was doing at that point because I was recalling two seperate fixes. It turned out to be the O2 sensor for me. I unplugged it up near the firewall, and the hesitation went away. Also the spark plugs looked better too, more tan looking. Just to test I plugged the O2 sensor connector back together and the problems would surface again. More info here at F.R. Wilks DME site: http://frwilk.com/944dme/
I have been running with the O2 sensor disconnected since that time and I now have a tad over 206,000miles on the car. I hope this helps you, at least it is easy to see if infact the O2 sensor is your problem or not.
Take care and let us know.

jmporsche944

My car is having a pretty similar hesitation. Wheres the easiest place to unplug the o2 sensor?

krahmlow

Very interesting. I just tried this and it worked for my car, too, but I'd like to know why. I've been trying to fix this idle/hesitation problem for 2 years now. One of the first things I did, back when I got the car, was drop $150 and REPLACE the 02 sensor, so I'm pretty sure it's not the sensor that's bad. I'm curious, did you happen to check your vacuum level? Mine is at 14 in Hg at idle (with intake gasket, hoses, and separator seals replaced), which I think is a little low. If, as I've been told, it's supposed to be up around 20 in Hg, the low vacuum could be causing a fuel pressure/mixture problem that the 02 sensor is making worse somehow.

By the way, the 02 sensor plug should be right behind the fuel rail. At least, that's where it is on the "S."

Der Rennwagen

I recently swapped in a new oxygen sensor. Taking out the old one became a chore. Some knucklehead PO mechanic cross threaded and torqued it in good. I managed to extract it (it came out sans threads AND without the metal cap around the ceramic portion!!) but, had to drop the whole exhaust to chase the threads out before installing a new one. My early '85 is a CA build car so I needed the heated version.

Long story short, the slight hesitation was there before switching in a new oxygen sensor. I must have been running in open loop the whole time with the old sensor in there (as it clearly wasn't working) and after installing the new one, you can tell immediately when it warms up (about two minutes) and goes into closed loop adjusting up and down to obtain the 14.7 air fuel mixture.

I'm going to try dielectric grease on the injector plugs - test drive, and then try unplugging the oxygen sensor - test drive. Thanks for the tip in the injectors.

Thompson
1985 944.1
Club Sport targa
M404 [aka M030], M220

Charlie944

I also had bad spark plug wires in an instance prior to the O2 senor incident. The jacketing on the wires was all brittle and cracked (light show when in the dark) I ended up replacing the wires with the Magnecor's I have now. Let us know if the dielectric grease on the FI clips ends your hesitation.

bott63

Curious if you were ever able to find the cause of the problem!
I have an almost identical problem in my '85 Carrera 3.2
I've replaced many items, swapped parts from other good working cars to no avail...