86_951_

Bringing it back home from a drive it started misbehaving. It doesn't want to run between 1200-2200 RPM. If it's idling and I hit the gas it hestitates a lot, and almost stalls. If it can work through and spin the engine up past 2000 or 2500 RPM then it's ok.

I opened the hood and worked the throttle. I can hear a sucking/whistling sound that seems unusual to me. But I didn't listen to it very closely when it was healthy.

I'm a first time owner (purchased it with 87K and all new hoses and belts in sept). Does this sound like something familiar?

Thanks.

hardtail15

Try replacing the spark plugs first, mine was doing the same thing, thats all ti was. But it wasnt sucking/whistling that could be normal for the 951 though.

Mamooguy

Is the airway clear? When I changed my air filter a few months ago I found crap in there you wouldn't believe (leaves, bugs, cement-like dirt, a mummified mouse).

evil 944t

Make sure the Intercooler hose connections aren't off. They pop off and create an air leak, causing the stumbling problem.

tyro

What are you showing for boost? Full boost at a normal (~3k) RPM?

Check the path from air flow meter to throttle body, there may be a rubber coupling that has come off/is loose/has a crack.

Lots of threads here describing how to pressurize the intake system to check.

Here is a link to the Arnnworx site for boost testing: http://www.arnnworx.com/boost_testing.htm

Marcquito

Sounds like a boost leak!

Check all of the hoses in the turbo system. One of them has bound to come off. Also check and see if the wastegate is stuck open (I doubt it, but check to see) Also do a boost leak test and see if anything is leaking anywhere else and fix it.

86_951_

Once it stops stumbling the boost jumps up to 1 BAR. When healthy it shows .4 Bar at idle, and then climbs up to 1 BAR at 2400 RPM or so.

This would be the first time I worked on any car, let alone a Porsche. I'm very much inclined to bring it to someone, but I'm not unwilling to try on my own. What do you think? I read through the stuff at Arnworks and it seems like I'd be getting in over my head.

tyro

Working on it isn't a big deal if you have another car to drive. I never used to do my own work - then realized it wasn't all that difficult(for me).

When you say 1 bar, you mean the gauge points straight up and not to the right (toward 2)? It should show around 1.7 at full boost, assuming your car is stock.

reno808

or they dont have a crack in them

86_951_

Yes, straight up when under power and healthy. It will climb to 1.7 at full boost. Or it did before Saturday. Once this cropped up, I drove home and put it into the garage.

I definitely have another car to drive while this one sits. I'm going to see if I can find an air leak and go from there. Like I said, all the hoses are new, so maybe somethings just loose.

tyro

You should see 1.7 bar on the stock gauge around 3000 RPM when at full throttle in a higher gear.

I'm guessing it's a mild leak, as I know mine will barely run when a hose is completely off and it certainly won't start.

Take your time and inspect all of those hoses, clamps, etc. Have a bright light handy and prepare to get a little dirty getting to know your 22 year old car!

Hans

Had this, was the throttle position switch on mine.
For test: disconnect the TPS. Just pull the connector to the black box on (or in jour case under) the throttle housing.
Try again.
Idle OK, revving up ok, then TPS dead....

86_951_

Thanks. I'll give that a shot this afternoon. If it's something with the air flow system I'm going to save it for my mechanic. I'm just not ready to do all the pressure testing myself without the right tools.

86_951_

I took it to the shop and they diagnosed it to be a faulty airflow meter. Now the question is new or used.

A new meter is going to be $700+ and will be warrantied. Or, they have a part from a shop car that will be $300+.

So, which way would you go?

kevincnc

Neither. You can get a good used one here or on ebay for probably less than $50 and put it in yourself. Post a "WTB AFM" thread and you'll find one.