Hello everyone, I have a 93' 940 turbo with approximately 181,000 miles on it that has recently died twice.

The story: This car has been running horribly performance wise for the past month mainly due to me neglecting to replace a couple of sensors. Yesterday I started the car, it idled for 10 minutes then I drove it down my driveway and then to the end of my street (apprx 400ft) when it died. No sputter no warning just as if someone hit a switch. I had it towed back to my house and checked the timing belt, it was intact. I checked the obvious stuff like any loose wires. I checked the fuses, switched out my ignition coil with my old spare, checked the spark plug wires but haven't actually taken the plugs out yet. I had all the ignition components replaced about 20,000 miles ago so they should still be fine. I can hear my main fuel pump whir when I put the key to start and I can hear and feel the fuel pump relay click. I also checked the radio suppression relay and its circuit board and contacts look fine (it also clicks). Amazingly some hours later the car decided to start once I put it back together. I started it 3 times after that and it ran like nothing ever happened. Next day I start it, drive to work. I go to my car after work, start it, let it run for 5 mins then put it in reverse and just after I put my foot on the pedal, it died. No sputter, nothing. I checked the relays again and tried wiggling some wires but still nothing. I had it towed back to my house. I will mention that If I repeatedly turn my key from off to start without cranking the engine there seems to be a loud clunk noise coming from where the main fuel pump is. It will make this clunk noise a couple times then it won't do it anymore. Can my pump be dying? I haven't had to time to check for voltage at any of my fuses or coil. I just want to get those "gears turning". I always hear the pump whir when the key is in start and I have replaced the fuel pump relay for good measure. I have a radio suppression relay on its way from ipd also.

--Will my fuel pump show symptoms of dying or will it just quit? I will check for voltages across my fuses and coil and check my plugs this weekend and report back. thanks for any replies or experienced guesses.

 

Has your fuel filter been changed regularly?
Also check all the vacuum hoses for wear or breaks.

 

did you check for any OBD fault codes?

you don't need a code reader for those, they have an LED thing.

Engine and OBD Diagnostic Codes

 

Turns out my crank sensor wires were grounding out. The rubber on the wires where they enter the sensor was totally disintegrated and is the source of my problem. Just threw some electrical tape on it to isolate the wires and presto she started back up. I had a feeling it wasn't a fuel problem because there was no hesitation when it died. Either way, problem solved. And just to answer your questions: I had the fuel filter replaced when I got the car 20,000 miles ago, the codes I'm getting from OBD are for faulty air temp signal, faulty coolant temp signal, and faulty injector number 2 signal.

Thanks for replying back guys.

 

the temp things will probably cause it to run too rich when its warm. and make for lousy fuel economy. or too lean when its cold and be hard starting (but its more inclined to be the first).

I'll bet these are all wiring related.

I'm really glad our 87 240 hasn't had these problems, its one of the years known for them, we're original owners, and the wiring is still fine 400K miles later, always parked outside. mild coastal northern california climate probably helps, a lot.

 

Horrible gas mileage at the moment but the coolant temp sensor is only like 20.00 bucks. I have no idea where the temp sensor is though. And as far as I know, the number 2 injector sounds like its opening and closing like it should so I don't know if that's an old code or what. I have never taken the time to clear them so I'll have to do that when I get my crank sensor in.

 

Me and my 93 940 Turbo are headed for MA in the morning.
Interested in a photo op and on site troubleshooting?

 

the engine temp sensor screws into the head, under the intake manifold .... depending on the exact engine it can be in any of several holes. I think its towards the back on my 92 745T and in the middle on our 87 244. the turbo also has a knock sensor, I think the knock sensor is near cyl #2 and the temp is near 3. oh, there's an oil pressure sensor in there too.

the coolant sensor is screwed into the radiator, along with high and low speed pressure sensors, these control the electric fan.

 

Ha, I would be but I now have to find a way to get the brake lights working on a 99' chevy lumina so it will pass inspection

I am getting horrible gas mileage. When you say its on the radiator, do you mean on the bottom left corner? I can see a row of 3 sensors when I look through the bottom part of the grille. But isn't there a coolant sensor mounted on the block itself?

And while I'm at it, what is this thing for?"> is it a sensor? It has a two wire connector attached to it and the hose coming off of the sensor just leads back behind and under my intake manifold.(its hard to see what it's actually attached to because of all the junk in the way) I took that big intake hose off to get a look at the sensor thing from inside the hose but it appears to just be hollow as if to allow air to pass through. Does this lead to my flame trap?

 

the row of three guys on the bottom of the regulator are the low speed and high speed pressure switches for the electric fan. I believe the coolant temp sensor is on the top side of the radiator.

that valve on the air pipe in your picture is the PCV return, I think. they have to let it in prior to the turbo as downstream from hte turbo its all pressurized. AFAIK, you have to replace the whole airpipe to replace that solenoid valve

 

Thank you very much for that info. I accidentally put too much force on that hose and cracked it when I was trying to move it out of the way. Are there any negative implications for doing that? I really don't know how the whole pcv system operates.

 

PCV is pretty simple. on the side of the engine block under the intake manifold, is the 'flame trap'... this catches oil spray and lets it drain back down into the engine block, its connected via that hose to the intake. Maybe you could use some sort of heat resistant tape to tape up the cracked pipe. or maybe degrease it and use ABS cement on it?

I'm really not sure why there's a solenoid valve on that, or when it turns on. the idea is that any fumes from the hot crankcase get sent into the intake to be burned in the engine.

 

Well, my car isn't going to be driving anywhere until I get that new crank sensor so I'll just order that pipe in the mean time and throw it on when I get it.

thanks for all the help