Amfab

OK, I cant fix this, and before I take it to the mechanic on monday I want to hit you guys up for any further suggestions. Ill give you all the details

About 12 or so days ago Im driving in the Pacific Palisades and my car starts this stalling-when-I-come-to-a-stop thing.
Sometimes the idle will drop to almost nothing then rev to 1500 or so then down to 0. It will go up and down, up and down, a few times then die. Or sometimes it kinda stabilizes, but too low, like around 500RPM. Kinda rough.

About three days before this I had put the cap on the oil filler kinda cockeyed, and after driving a couple miles I saw a ton of smoke. I looked in the engine compartment and there was oil everywhere after it had run down the oil fill tube from the loose cap.
I got some orange degreaser, sprayed it all around in there and rinsed it off. everything seemed OK, for a couple days, then the idle problem started

About the same time as the idle problem started I started getting a CEL light: P0137 131 151 and 157 were the faults. Id clear them and they come back.
Those are "O2 circuit low voltage" codes according to where I looked them up. I used to get O2 related codes now and then, but VERY rarely.

I cleaned the ISV, it didnt help
I replaced the DME relay, it cleared up the idle problem but only for a day. Sometimes its fine, sometimes the idle problem comes and goes now

I keep getting the CEL

I have now replaced the air filter
Cleaned the ISV a second time
Pulled out and cleaned the MFS with MFS cleaner.
I also took a cursory look around for vacuum problems

It idles great when it is stable. but intermittently it does the up/down-up/down-die thing. Today it did it every where I went.
Is all this related?
Any suggestions?

TIA

JM993

Sounds like an Idle Control Valve issue - you might need to replace it.

Shahrams

Andrew, please let me know what you have found out on Monday. I am facing the same issue with my 96 993.
I replaced the O2 sensor, MAF and DME, checked all the lines and made sure there is no vacuum or air leak anywhere.
I also cleaned the ISV, still the same problem. I donno if I should replace the ISV.

Garth S

Underneath the oil filler is a black removable cover that "protects" two of the four O2 sensor harness connectors: I suspect that you have a snoot full of oil and or water in these connectors. If so, so much for 'protection' ...

Either way, I'd start by wrestling that cover out, exposing the connectors, and give them a good spray with WD-40: this is miscible with both oil and water, and while it is a lousy lubricant, it is a great cleaner.
One of lifes great secrets is how to open these rectangular connectors for the O2 sensors .... pull the square end outwards, as if it is a drawer ...

All this is an internet guess; however, as oil, orange degreaser, and water all invaded the vicinity recently - and the codes are sensor voltages, one could surmise that the DME is getting bad data.

AOW162435

Dust in your ISV...


Andreas

Amfab

Will do
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Thanks Garth, Ill try one more thing before the Mechainic. Its running ok most of the day today
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Its really good to be able to count on some things in life.

Thanks Andreas for being there

Canyon56

Andrew, who will you take the car to? Just curious.

(I've used a place on the Westside that another RLer referred me to and they are really smart with trouble shooting.)

Amfab

Mark Schuster at Performance Plus in Canoga Park. I have been using them for the last 13-14 years or so since Automotive Pit Stop in Sherman Oaks switched hands in the mid 90s when Walter Dieter and Victor retired

Stealth 993

If you clear the codes & they come right back, that kind of tells me there is a problem causing the code. You might have a O2 sensor issue. Or look up what else will cause it to throw that specific code.

NP993

I don't understand why you're trying to fix everything but the problem that keeps throwing codes.

Amfab

I am going to order some new O2 sensors. Part of my question is; are the codes and the idle problem related?

NP993

I would say that if the idle problem and the CEL light problem materialized at "about the same time" it's worth investigating. Keep us posted. Does a low voltage code mean that the o2 sensor is bad, or could it be something other than the sensor itself?

Amfab

Good question. I assumed that meant it was bad...

Can anyone answer that one?

Garth S

Allow me to clarify myself ... ... go back to my post: I suspect that the O2 sensor connectors are contaminated from the oil/clean-up deal: Because of that, they are sending garbage indo to the DME ... so clean them up first before flipping new sensors into play.

It is unlikely that two sensors died simultaneously .... but quite likely that two connectors could get simultaneously soaked ...

e3photo

Thought I would give this thread a bump,and a little closure. Hopefully the OP will post how he resolved his issue.
I had a similar issue where I got 131,151,137,and 157 It turns out that I had an exposed wire leading to an O2 sensor that was touching metal. It also turns out that an issue with one sensor will flag all 4. I coated the wire with liquid tape,and this solved my problem. Two drive cycles later,and all flags were set.

Hope this helps someone down the road.


Emerald