1. We had some really hot muggy weather in the last few weeks and the car would stall at red lights, or pulling into parking spaces. It was not a quick stall, but more like a slow death RPM drop. If I turn the A/C off, I could sometimes keep her from stalling. Not always. The car never failed to start up immediately after stalling, and racing the engine seemed to solve the problem. This seldom happened below 90 degrees F.

2. Sometimes the car loses power for no reason. It's not a slow down, it is like the entire system has been grounded out, or like a misfire of a sparkplug. It only happens for a second, and then goes away. The car has never stalled from this event. When this happens, it is usually on acceleration, but sometimes will happen on the hiway. It is not as temperature dependent as the first problem seems to be, but it seems to occur more frequently in the hot weather.

Any takers?

As always, TIA.
--
D.P. Mulvey in Central VA. 1991 744 NA, 150K Miles

I've been dealing with something similar lately. Both problems you describe in fact DO seem related, and the common bind seems to be the ignition system.

Ignition problems are a pita to trace, but one of the common faults is that they tend to rear their heads in hot and humid weather, probably because such weather undermines an electrical field, causes shorts, and gets the parts (already really hot from flow) even hotter.

There are probably three possibilities. One is the crank sensor or wire, which on your vehicle is a MUCH cheaper replacement than earlier models (which more or less need a new distributor since its riveted in place). The second is the coil. The third is the ICU (ignition control unit) on the driver's side front fender by the battery (the parallel cable looking thing).

If you are an electrical dude check for continuity, etc. Some intermittent problems are a BITCH to trace since they rarely happen completely and never when you are equipped for a diagnosis. If you jst want to replace parts till the problem dissapears I would start with the RPM sensor and cable, then the coil, and finally the ICU though as long as the ICU is tight against the fender I wouldn't worry to much.

Of course I would FIRST check all the grounds, make sure the fuel pump runs well by jumping the sockets (see faq), and that the plugs and plug wires are new and clean and properly gapped.

good luck,
rt

Thanks for all the help. I had the problem again today and was able to better diagnose with the answers to my post. What I thought was the Fuel pressure regulator was actually the EGR Vacuum Controller. Sometimes it pays to be ignorant!! I disconnected both vacuum lines from the controller. The cream colored line that goes to the intake manifold had lots (as technical as I can get w/o instruments) of suction. The yellow line had none. When I placed the lines end to end, the car tried to stall. I took the car for a short drive w/ the vacuum lines disconnected. It ran GREAT!! As a matter of fact, it is the smoothest it has ever shifted in 13 years. I know running w/o the EGR connected will cause pollution problems, so I am going to tear into the controller this weekend to try a rebuild. Seems pretty straight forward in the FAQ. Out of curiosity, what happens to the engine when this part goes bad, and what complications arise in the event I FUBAR the rebuild, and have to drive a few days w/o the controller in place? This is the daily driver, and the 2 be daily driver which would allow the brick to become a true project car got totaled when a moron in a pickemuptruk decided to attempt defying laws of physics by trying to get his front bumper to occupy the same molecular space as my trunk!

BTW, I am going to replace the crank sensor. How difficult a job is it?
--
D.P. Mulvey in Central VA. 1991 744 NA, 150K Miles

My egr doesn't have an actual controller, so I don't know much about what you face with that. On the earlier model turbo its just hoses to the EGR canister by the battery from the throttle body.

As for the later models crank sensor, from what I've read replacement is really easy. On the earlier models the crank sensor (hall sensor) is riveted into the distributor, and buried under the dist.'s various wheels and parts (meaning repair is full disassembly, and drilling or you get a new dist.). However, the later models just have the crank sensor inserted and screwed in by the fly-wheel I believe.

You can see a picture of the crank sensor below. It costs about $35.

Best,
rt

hello. i have a 89 whith the same problem. i tryed a few things that didnt work. new air filter. new flame trap. turn off ac. that didnt work. it sounds like there is a slight blockage in the pcv system. in my car. the top larger hose that goes into the top of the kine thing has a severe bend. that when very warm gets bent more. i grabbed a zip tie and zipped the hose to the fuel injection rail. and viola. its much much better. its ghetto but its cheaper then replacing the special hose part. it works almost all the time as long as i let it sit for a moment b4 i shut her down. and it is mad cheapooolaaa. i had this problem for 5 years b4 i tried this. i was happy then..

My1994 940 Turbo was doing problem #1. I changed a bunch of stuff, fuel pump and filter, Crank sensor, fuel pump relay, etc. It looks like the fuel pressure regulator ended up being the fix. If you should change the FPR, make sure to get the fuel hose, and vacuum host that attaches to it replaced also. The old ones will be in pretty bad shape.

R Duke

2 sounds like crank sensor wire

I had both of these problems at the same time on my '91 780. Turned out to be a leav in the vacuum hose. I had that replaced and it runs very nicely. Until you can get it worked on you can prevent it from stalling at the lights by keeping the engine taching at around 1500, it will take a little more pressure on the brakes and shouldn't be done for any great tiem or distance but it will keep you going until you can get it to a shop or get the hose.