3.6 drivability problem

[Kevin Stewart]

Hi everyone I have a 3.6 in an 82 after it runs a minute it won’t rev spits and sputters shut it off and restart driving down the road it fires and runs well for 20 seconds and starts sputtering again. I just cleaned the isv didn’t change any suggestions would be great. It’s a plastic manifold motor. Kevin

[Kevin Stewart]

There has to be someone with an ideal

[gduke2010]

Engine wiring harness? Just an idea.

[gduke2010]

My symptoms weren’t the same as yours though.

[Kevin Stewart]

I had a bad harness it didn’t start. It’s almost like after after starting it kick in to run mode then will barely rev.

[Tippy]

Which 3.6, the 964 or 993?

[Kevin Stewart]

Originally Posted by Tippy

Which 3.6, the 964 or 993?

964 after it starts and runs a few seconds will not run right it rev

[RetroSC]

Worn tracks on the AFM can make them sputter and run really odd, but not sure about this..

[964TargaC2]

Are you using the Silver Bosch Coils? If so its time to upgrade to the 993 Coil Pack

[Kevin Stewart]

Originally Posted by 964TargaC2

Are you using the Silver Bosch Coils? If so its time to upgrade to the 993 Coil Pack

I’ll look I still think it has something to do with maybe fuel pump or something after cold start shuts off

[ischmitz]

Kevin,

I had a similar behavior on my 92 plastic-intake 964. It turned out to be one of the many vacuum ports on the intake manifold sprung a leak. I used cheap rubber grommet cups from your friendly FLAPS and they deteriorated over time. So check that you have no severe vacuum leaks on your intake.

Two other issues that have gotten me are at various times and on both the Bosch Hammer was invaluable for tracking these down while driving.

1. The connector to the AFM is hitting the back firewall sound isolation. There is a Porsche TSB out to use a zip tie to force the wiring existing the plug to the AFM making a sharp bend to not hit the firewall when the engine moves under load in a stock 964. Depending on how low the engine sits in your car there could be interference. I then get the CEL and the engine idles and runs like @#@&* because the DME goes into limp mode.

2. At times my O2 sensor connector becomes wired to where the DME drives the mixture full-rich. And this causes severe bucking during cruise to where it feels like someone killed the engine.

And then of course check all the basics starting with fuel pressure, caps, coils, make sure the belt in your distributor is still good, etc.

Cheers,
Ingo

[Kevin Stewart]

Originally Posted by ischmitz

Kevin,

I had a similar behavior on my 92 plastic-intake 964. It turned out to be one of the many vacuum ports on the intake manifold sprung a leak. I used cheap rubber grommet cups from your friendly FLAPS and they deteriorated over time. So check that you have no severe vacuum leaks on your intake.

Two other issues that have gotten me are at various times and on both the Bosch Hammer was invaluable for tracking these down while driving.

1. The connector to the AFM is hitting the back firewall sound isolation. There is a Porsche TSB out to use a zip tie to force the wiring existing the plug to the AFM making a sharp bend to not hit the firewall when the engine moves under load in a stock 964. Depending on how low the engine sits in your car there could be interference. I then get the CEL and the engine idles and runs like @#@&* because the DME goes into limp mode.

2. At times my O2 sensor connector becomes wired to where the DME drives the mixture full-rich. And this causes severe bucking during cruise to where it feels like someone killed the engine.

And then of course check all the basics starting with fuel pressure, caps, coils, make sure the belt in your distributor is still good, etc.

Cheers,
Ingo

When it starts it revs we’ll a few seconds later it won’t I took the caps off and both rotor buttons only turn together

[ischmitz]

Ok, the easiest test for checking if both ignition channels work is to unplug one ignitor while the engine is idling. Each time one of the two ignitors is unplugged the idle note changes slightly but the engine must not die.

Have you checked that you have sufficient fuel pressure and fuel delivery. I had a fuel pump going bad and this can cause what you see