Diagnoses on Stalling Problem Please

I’m having stalling problems – usually at idle or coming off idle. It will start to stutter, then shut completely down. It’s infrequent, but extremely frustrating. It may go a couple days without a problem, then act up for several miles. Doesn’t seem to be an issue at highway speed, unless it’s “coasting.” I’m thinking throttle position sensor. A quick glance at the black spaghetti revealed no loose connections or breaks.

Since the least expensive position sensor I’ve found is $150, I thought I'd see if anybody else has had this problem.

Thanks in advance

Stacey

[gl1674]

Should not stall because of the TPS. Me thinks the MAF is a more likely culprit. With engine running try gently wiggling the connector on the MAF - see if you can cause it to stall.

After a little more digging in the archives, and also noting that I recall the dip stick poking up last week, I plan on cleaning the MAF and TPS, take my blood pressure medicine - grab a six pack and change out the PCV valve, change the fuel filter, and shake a chicken foot of the engine bay - perhaps even douse with clear mountain holy water.

We'll see what happens.

It's times like these that make me really appreciate carburetors. Can you put a pair of weber triple throats on these puppies and still pass smog? (lol).

[Mr. Pockets]

Originally posted by sgabbard
It's times like these that make me really appreciate carburetors. Can you put a pair of weber triple throats on these puppies and still pass smog? (lol).

I don't think I'll ever miss carburetors after my GL.

[oab_au]

Originally posted by sgabbard
After a little more digging in the archives, and also noting that I recall the dip stick poking up last week, I plan on cleaning the MAF and TPS, take my blood pressure medicine - grab a six pack and change out the PCV valve, change the fuel filter, and shake a chicken foot of the engine bay - perhaps even douse with clear mountain holy water.

We'll see what happens.

It's times like these that make me really appreciate carburetors. Can you put a pair of weber triple throats on these puppies and still pass smog? (lol).

Don't forget to check the breather hoses that run from the cam covers, to the air box, in front of the throttle bodies. The small passages, in the box, that they connect to can block to cause crankcase pressure. This can push the dip stick up and cause the stalling problems.

I would check these first. It may save doing the PCV valve Then you can enjoy the sixpack.

Harvey.

[want-a-fast-svx]

Originally posted by oab_au


Don't forget to check the breather hoses that run from the cam covers, to the air box, in front of the throttle bodies. The small passages, in the box, that they connect to can block to cause crankcase pressure. This can push the dip stick up and cause the stalling problems.

Harvey.

Could a crack in these two places on the box cause random stalling as well??? Im having random stalls since the five speed swap and these two areas are cracked right by the nipple on both sides

[oab_au]

Originally posted by want-a-fast-svx


Could a crack in these two places on the box cause random stalling as well??? Im having random stalls since the five speed swap and these two areas are cracked right by the nipple on both sides

Yes sure thing, all the air that the engine consumes, has to come through the MAF sensor, so that the right amount of fuel can be added. Any air leak between the MAF and the intake manifold will cause the engine to idle lean. Won't make much difference to the open throttle running.

Seal the cracks with silicon or such.

Harvey.

Well I might have the stalling resolved. I did the following this afternoon. I let it idle for about 30 minutes and took it for a 30 minute drive - no problems so far:

Replaced the PCV valve (I think was the culprit)
Removed the MAF and cleaned the element with carb cleaner
Blew out all vacume lines coming into the throttle body (no buggers).
Cleaned the throttle body with carb cleaner.
Blew out all passages in throttle body.
Blew out the valve cover breather lines (they were clear).
Cleaned the TPS.
Changed the fuel filter.
Changed the oil and filter (never hurts).
Sealed up a few minor cracks in the intake box with silicone sealer.

If it stalls again, I'll probably cuss like a sailor then cry like a little girl.

Well, yesterday I cussed like a sailor then cried like a little girl. Seems the issue has not been resolved. I can’t seem to pin down a pattern either. It died at idle while warming up – then drove fine the 20 some odd miles to work. Then, it started stumbling on the expressway home – actually died a couple times – then drove fine for another 10 miles without a symptom. Today, no problems (so far). I’m ruling out the catalytic converters, since it seems to be infrequent. I would think if it were the cats, it would get progressively bad every time, as they heated up. I found some test procedures for the MAF in the archives – I’ll give that a shot. Is that still the odds-on favorite? What’s the little valve directly under the throttle body setting on top of the engine?

Just to recap the symptoms, at idle or coast, it may stumble then die. If you catch it in time, you can pump the throttle, and it will pick back up. At highway speed with a constant RPM held, the RPM may stumble and drop about 1000, then jump back up. On occasion, it may idle fine at a stop light, then when you give it gas, it dies suddenly and painfully (usually with cars waiting behind).

I love old cars.

[poweredx2]

Your car should be flash a code if its running that bad,I have a ghost issue if I put the car in park with the cruise button pressed in it will stall yes thats strange I think the vacuum line to my cruise is worn or leaking,also please check your cats get rid of them if you can.

Thanks. How does one check the cats? I've replaced them before on my Jeep Grande Cherokee, and the muffler shop said he was surprised it still ran as clogged as they were. Is the only symptom rattling?

[svxistentialist]

There are three cats on the SVX. Rattling is not infallible. If the ceramic substrate inside is broken, this may cause rattling.

However, without it being broken into little chips, it can still be blocked enough to stop gas from passing through. If this is the case, that blocked cat would heat up a lot. With a single pipe also, you would be able to feel the fact that exhaust gas was not getting through. With the SVX however, two feed into one, so the burnt gas from the other side would still get through.

Please do not do away with the cats. Without them, unburnt cancer-causing hydrocarbons are let away to the atmosphere on the streets. These will poison old people, young people, your children, anybody's children walking the streets.

Too high a price to pay.

Joe

[svxistentialist]

Also, just thought of this; Harvey made a good point about the breather pipes.

I find with them, that because of the high temps they are subjected to, they tend to harden as they age. You may find if you pull on these pipes, they are loose and belled out a bit around the flange meant to hold them tight. Try pulling them out a half inch or so. You should find a tighter spot, and by doing close off an air leak.

And I presume you have run the diagnostic to see what codes the engine is putting out?

Best of luck with it.

Joe

[immortal_suby]

Originally posted by sgabbard grab a six pack and change out the PCV valve, change the fuel filter, and shake a chicken foot of the engine bay - perhaps even douse with clear mountain holy water.

(lol). [/B]

Originally posted by svxistentialist

Please do not do away with the cats. Without them, unburnt cancer-causing hydrocarbons are let away to the atmosphere on the streets. These will poison old people, young people, your children, anybody's children walking the streets

...and also put you on some EPA poo poo list.

I havn't run any diognostics yet, but will dig around in the archives some today at lunch - if time permits. I'm guessing it's a series of turn key on - turn key off - breath out of side of mouth - put in neutral - turn key on - rub glove box twice etc. then wait for magic morris code flashes.

I love new technology. Now, if I can just find the Ctr-Alt-Del buttons on my dash.....