Casper

My '87 944S shuts down when I let off the gas. It starts up fine afterwards though.

I'm thinking it my be the idle control valve, but not sure.

Any thoughts or where the Idle control valve is located?

Thanks in advance.

It'll be nice when I finally get that manuals on cd downloaded.

Tim

Bri Bro

It is located under the intake. You have to remove the fuel rail and the intake to get at it. There are a set of simple tests to determine if it is working correctly. I would advise you test it first, replacing it might not fix this problem and it would save you a couple hours of work.

Brett944Cab

Try the DME relay - one of your cheapest fixes. I have an S2, but I was having a similar problem, and this was one of the first ideas people gave me. $17 at paragon, and a simple plug-in in the fuse box.

Casper

I'll check out the DME relay. What plug? And what does it plug up.

Skip

Explain your situation in detail.

Could be the DME relay failure (and it's good to have a new or spare one). If it's chugging and dying after letting off the gas, then the TPS (throttle position sensor) or ISV (idle stabilizer valve) could be to blame. How does it normally idle? Should be ~900RPM and smooth/steady. Could simply be poor gas or clogged injectors (maybe run some Techron through a full tank).

The DME relay (Fuel Pump Relay) is located in the fuse and relay block in the upper left corner of the engine compartment (opposite the battery). The relay and fuse purpose and location is printed on the cover.

Again, more info on the circumstances of failure and repeatability will help greatly.

Good Luck!

Robert Lavigne

I had a similar problem. Fuel would cut off without warning. We first thought it was the DME relay, nope. We then started thinking outside the box and thought that it might be the alarm relay kicking in and shutting off the fuel - nope. Turned out my DME computer needed some resodering in some key spots. When the car would fail, kicking the panel on the passenger side protecting the computer would jolt it back to life. Overall, it took about 2 months of driving and troubleshooting to finally get things figured out due to the total inconsistency of the problem.

Dano_944

I'd check the DME relay first, then the main cable that goes into the DME Unit under the pass. footboard. When my DME failed, I noticed a bunch of crud in the cable and DME receiver. A good cleaning out produced lots of insulation and sand in the cable and receiver. Those floorboard-mounted DME's get lots of crud around them.

Then, if that ain't it, check the idle air bypass (under the intake manifold) and the fuel system for possible weakness/clogging/failure. BTW....How's the fuel pump and fuel filter?

Casper

New fuel filter, good fuel pump.

Here is exactly what it is doing.

It idles at around 900rpm. When I let off the gas to depress the brakes and clutch to stop, the rpm drops really suddenly after 1000rpm's. Sometimes to the point where the attention light comes on, but it comes back to 900rpm's afterwards. Sometimes it shuts off all together.

It does the same thing on the freeway when I have to be off the gas for a long time like when I have to slow down for a wall of brake lights.

It seems to help if I let the rpm drops to about 1200rpm's tap the gas and on the brake again. In that case it just drops to about 500rpm's and idles back at around 900rpm's.

I'm leaning towards the Idle Control Valve. But I won't be able to work on it til this weekend.

Let me know if you all agree or give me other suggestions.

The info so far have been very helpful and gave me a lot of food for thought.

Thanks again

Tim

Skip

"No" on the DME relay - but still nice to have a spare handy.

Sounds like a sticky ISV - you can try to clean it, but may have to replace it.

While you're tearing into things, might as well do a sanity check and fine-tune on the TPS. Here's some notes to help you with that:

<a href="http://www.tech-session.com/Paragon/Tech/944_tps.htm" target="_blank">TPS troubleshooting</a>

Good Luck!