3.4 idle question...

[fallingat120mph]

So, my 86 3.2 was supposed to idle around 800. Newer years went to 880. With my 3.4 I am curious about my idle.

It was quite high early on and I tried to bring it down to 800-880 levels but it seemed too low.

Just wondering of the mechanics and if "bumping things up a bit (3.4/cams/twin plugging)" should my idle be different than fresh out of the factory.


Erik

[PeteKz]

If you changed the cam to a more aggressive one, then you probably need to set the idle a little higher to get it to idle smoothly, and to start off from a stop without causing the engine to stumble or stall. I would raise it a little and see how well that works, then a little more or less to get it where you want.

And if you twin-plugged it, you will need to reset your timing lower. Check with Steve Wong for an appropriate chip with revised timing curve.

[911MANN]

Erik: You ultimately went with an EFI setup, right? I think Pete's response is correct, and I think you (or someone) can customize your fuel supply and ignition timing program to idle where (or close to where) you want, provided you have enough supply of idle air. Hopefully, one of the EFI experts will chime in.

[fallingat120mph]

Originally Posted by PeteKz

If you changed the cam to a more aggressive one, then you probably need to set the idle a little higher to get it to idle smoothly, and to start off from a stop without causing the engine to stumble or stall. I would raise it a little and see how well that works, then a little more or less to get it where you want.

And if you twin-plugged it, you will need to reset your timing lower. Check with Steve Wong for an appropriate chip with revised timing curve.

Originally Posted by 911MANN

Erik: You ultimately went with an EFI setup, right? I think Pete's response is correct, and I think you (or someone) can customize your fuel supply and ignition timing program to idle where (or close to where) you want, provided you have enough supply of idle air. Hopefully, one of the EFI experts will chime in.

Thanks gents...

I will probably be taking it back to the shop as I feel it needs dialed in a bit. I am no MAF expert, nor twin plug guru...quick learner with engineering common sense but know my limits.

I had 20 years of 800rpm at idle and feel anything over 850-880 sounds odd. But it does run/sound better around 900-950/1000.

Big issue that towed it back home from out of state was a bad CHT sensor and after I replaced that it ran well.

Called Steve W and put an O2 sensor back on also.

Was just curious about the idle and feel 3.4 conversions are kind of a no man's land finding info other than specifics of physical items.

I will report back with outcomes, etc.


Erik

[Jeff Alton]

Not sure what cams you have, sounds like still running Motronic, single throttle intake.

Assuming a 964 or 993RS/SS type cam, we want them idling up near 1000rpm to be smooth. Say 900-1000rpm.

Cheers

[fallingat120mph]

Originally Posted by Jeff Alton

Not sure what cams you have, sounds like still running Motronic, single throttle intake.

Assuming a 964 or 993RS/SS type cam, we want them idling up near 1000rpm to be smooth. Say 900-1000rpm.

Cheers

Thanks...just online reading all I can.

993SS here and 900-1000 seems to work pretty well. Set base idle today to that and just a matter of the new feel of "new" engine and new idle.

I will keep close to 1000 and see how that works this week.


Thank you everyone...

Erik