S.S.D.D. (repost)

[Gremlin85]

Still have that same hunting idle issue even after I replaced the bad O2 Sensor.

Is it possible that if my Oil/Air Seperator O-rings are not seated correctly that it can mess up the internal engine vacuum and cause my hunting idle???

[WizPorsche944]

How about an Idle Stabilizer.

[Gremlin85]

thats replaced.

Heres a list of everthing replaced or I have done:

IAC
TPS
DME Temp Sensor
Throttle Body Reseal
Cleaned Throttle body and intake
New Vacuum lines
plugs, wires cap and rotor
O2 Sensor
Oil/Air seperator o-rings
all gaskets and seals
injector seals and caps

used 4 cans of carb clean and brake clean to find vacuum leaks.... ZERO found

Adjusted idle by bridging pins B & C with no results
used seafoam

car idles fine whe first started but about 10 seconds later it hunts for an idle.

Even if the engine is hot, i shut it off, wait 1 minute then restart and it idles fine for a few seconds and then acts up.

According to my AF Meter it idles fine when rich.

with plug B & C connected it runs rich and idles fine.
With O2 Sensor UNPLUGGED it idles fine (probably running rich too)

There is unmetered air somewhere I know it, but I can't find anything for the life of me. Its been weeks of searching with no end in sight.

I'm ready to give up.

[Gremlin85]

Anyone got any ideas on what I should check that I haven't???

If the "hats" on the fuel injectors are not seated correctly, could this block the stream of fuel and in turn cause my idle problem???

I'm really at my wits end and have done literally a hundred checks and end up back where I started.

-John

[many944s]

Are you using the factory air-box, or do you have an aftermarket cone intake? I use a K&N cone on an adapter I built and it idles fine... A buddy here in town has an aftermarket unit he bought on Ebay that also adapts to a K&N cone, but his car will "hunt" for idle with it installed. If he puts the factory air-box back on it idles fine?!?

Just an idea...
-Nick

[Gremlin85]

Stock box. No holes drilled or anything like that. It does have a K&N Drop in but thats been there even before I bought it.

I do remember though when I was checking things I gave the throttle a quick open by hand to bring the revs up quick and it back fired through the intake... scared the S*** out of me. What was that all about?

[many944s]

Of course a backfire is a give away to a timing issue... Have you tried swapping out the DME? Does it have an aftermarket chip?

[Gremlin85]

No aftermarket chip.

I was thinking timing before, but was not sure because I heard that a backfire through the intake could also mean excess fuel in the engine and it can detonate easily. I quickly opened the throttle by hand and thought I gave it that chance to do that.

I have yet to find a DME I can borrow and test in place of mine.

I don't have $200+ to spend on a hunch.

[Porsche-O-Phile]

Did you check the output voltage from the temperature sensor at the DME? Could be a cracked wire. 20-year-old wiring tends to get brittle.

[blown 944]

Actually, a backfire is not always timing.

I have experienced a lean off idle backfire with a vacuum leak (big one while setting up the s/c).

I can do it again if I try

have you checked to see if the TPS is adjusted correctly, you just have to have engine off and listen for a small "click" when you crack the throttle. If it is mis adjusted it will be using the AFM signal which may be sending a very rich mixture for idle this can also cause an intake pop .

[Blondie]

Holy smokes..

This couldnt be any closer to my problem!

I've gone through the exact same diagnostic list, Gremlin. I've been suspecting the injector hats myself, as I recently did those. My car is running stupid rich and hunting hardcore as well. Sorry I cant be of any help my friend..but maybe togather we can figure this one out?

[Razorback1980]

I am leaning toward the same deduction as blown944. You need to check the tps at the DME not at the tps itself. Of course you could also ohm the wires, but a broken wire or poor connection at the tps or dme would cause the same problem even if the tps switch itself is working correctly. Also ohm out all your grounds.

[Gremlin85]

Thanks for all your input everyone.

To answere some of the questions:

The TPS DOES click just I move it off idle. The slightest movement (about 1 degree) and it click.

I did not check the TPS at the DME. I'm stupid for not trying that. I will do that at my earliest convienence.

Blondie, i hope I can figure this out so we can fix this problem. It seems to be a common problem with the 944 but everyone else seems to get it by replacing simple parts.

Why does mine have to be so complicated?!?

Electronics were never my strong point at UTI...

Again. thanks for your input it is much appreciated!

[SoCal Driver]

Maybe the brake booster has a leak.

[Gremlin85]

Originally posted by SoCal Driver
Maybe the brake booster has a leak.

I checked all around the brake booster. I sprayed water, carb clean and brake clean and no sign of a leak. The paint has come off of the brake booster from the brake clean ....

But is it possible it could be internal? But that would also mean poor braking and my brakes are fine.



-John

[SoCal Driver]

Next time it's surging take the large hose off of the booster and plug the end. Should be taken off of the plastic fitting that is at or sticks into the booster and not the booster diaphragm itself. Could be that plastic fitting.

[Slam]

Aux air valve stuck open.

[Gremlin85]

Originally posted by Slam
Aux air valve stuck open.

I think the Aux Air Valve is only on pre 85.5 944's. They replaced it with the Idle Control Valve, or Idle Stabilizer Valve. It sits under the intake.

I've replaced that already.

I'm going to re-seal my injectors because I did a little more research on the kits available.

Looks like the caps I got from Bosh are the bigger yellow ones. The tip of the injector (or the business end) sits real far bahind the opening of the 'cap'. I ordered some that were highly recommended off of Rennbay.

SoCal,
I'll check the brake booster as well.

Watch it be the stupidest thing too...

[Blondie]

So theres two different injector kits? I got the one with the yellow hats as well...

Hmmmmmmm so the plot thickens...

Where did you order this other injector kit from?

[Gremlin85]

Originally posted by Blondie
So theres two different injector kits? I got the one with the yellow hats as well...

Hmmmmmmm so the plot thickens...

Where did you order this other injector kit from?

Not two kits per-say.... but there are different types of 'caps' and how they go on is the important factor. The ones from Rennbay are almost exactly the same as the orange ones that were on there... or so I'm told.

I actually got my other Injector Kits from ********.com ::HIDES::