94 850 Turbo Sedan - Runs Rough Until It's Restarted

[budoboy]

I bought a 1994 850 Turbo Sedan recently that has a lot of things wrong with it. I bought it knowing that it has several oil leaks and probably needs the PCV system replaced as well as a bunch of other things. The car is a hodge podge of parts. For instance, I think the front fenders, hood, bumper and bumper cover are all from a cross country. I have been battling with an electrical problem (parasitic drain) that some people on this wonderful forum are helping me with.

All that to say that what I am about to explain could be caused by any number of things. This car has a lot that needs fixing and has a lot of customization (or evidence of customization) that could be contributing to the issue.

On to my question: I have noticed the following behavior when driving the car. When I first start the car and drive it, there is a very pronounced vibration through the car(engine vibration). The car feels sluggish, like a low boost car. It will build boost, but slowly. It struggles to accelerate. There is a much more pronounced exhaust note that sounds like it coming from the turbo/exhaust manifold area. I drive the car for 15-20 minutes and the car reaches operating temperature but it still drives like a dog.

THEN

While the car is at normal operating temperature, I stop the car, turn it off, and immediately turn it back on again and the sluggishness is completely gone and the car feels totally different, like going from a stock 850 Turbo to one with an ECU upgrade. It's fast and responsive. Accelerates and shifts quickly.

So my question is, what the heck is going on?

I saw a thread about a similar experience that some people say could be caused by a bad thermostat, coolant temp sensor, or both. Some people say an O2 sensor or clogged catalytic convertor. They say it could be running rich because it thinks it's not up to temp and when the car is turned off and back on, it sends the correct temp and the computer dials back the fuel. I haven't seen any obvious indication of the car running rich (no extra gas smell or black smoke coming out of exhaust). With the louder than usual exhaust sound at the turbo/exhaust manifold, I wonder if the turbo, waste gate, or boost pressure regulator is acting up.

Anybody have any other ideas? Any feedback would be greatly appreciated.

Regards,

Bryan

[Chuck W]

Have you checked for any trouble codes? Does the CEL actually work in the car?

[scot850]

Try replacing the electrical portion of the ignition switch. I had one car that had a mirad of weird issues including rough running and a restart usually fixed it. A worn ignition switch was the issue. Can't guarantee it in your case. Before doing this have you tried just switching the car off and restarting straight away? Other issue would be the ECT/coolant temperature sensor or its wiring and connector at the back of the power steering pump.

Neil.

[budoboy]

Have you checked for any trouble codes? Does the CEL actually work in the car?

That's actually a good question. The CEL is not lit but I don't know if I really is operational. I'll need to check for codes.

Regards.

[BlackBart]

I was going to say massive vacuum leaks, turbo / intercooler line split or loose connections, PCV, etc. But the re-starting and running fine is odd. The coolant sensor idea is good. Cheap to change.

Is it related to temp and expansion somehow?


Do you know the manual button under the hood procedure for checking codes?

[Chuck W]

That's actually a good question. The CEL is not lit but I don't know if I really is operational. I'll need to check for codes.

Regards.

Just see if it lights up when you turn the key to the RUN position. If it's not on, then the bulb is out (or removed).

Don't throw parts at it until you check CEL function and then check for codes.

[budoboy]

Thanks for all the feedback and advice.

In reply to Neil's post, I did try the "turn off and back on again to clear the problem" technique while the engine was still cold and it didn't seem to help. Once the coolant got to a temperature where the heater blower fan turned on, I tried turning the car off and on again and it was better. So it definitely seems like it's related to temperature in some way.

I checked the CEL and it is indeed not working (blown or pulled, I don't know which).

I read the codes for all of the A block and B1 and I ran out of time before I could do the rest of the B block. I got the following codes:

A2 - 325 Memory Failure (probably because I have disconnected the battery several times to troubleshoot the electrical drain).
A3 - 312 (I can't find any reference to what that would be, but the ABS light was not illuminated until I cleared the A3 codes.
B1 -
122-Outside temperature sensor open circuit or shorted to 12 volts
124-Driver’s side interior temperature sensor open circuit or shorted to 12 volts
126-Passenger’s side interior temperature sensor open circuit or shorted to 12 volts
132-Driver’s side air duct temperature sensor open circuit or shorted to 12 volts
134-Passenger’s side air duct temperature sensor open circuit or shorted to 12 volts
151-Signal from fan speed sensor missing or too high
211-Driver’s side damper motor position sensor open circuit or shorted to 12 volts
221-Passenger’s side damper motor position sensor open circuit or shorted to 12 volts
231-Ventilation damper motor position sensor open circuit or shorted to 12 volts
232-Ventilation damper motor position sensor shorted to earth
233-Floor/defrost damper motor position sensor open circuit or shorted to 12 volts
235-Recirculation damper motor position sensor open circuit or shorted to 12 volts
311-Driver’s side damper motor shorted to earth or shorted to 12 volts
312-Passenger’s side damper motor shorted to earth or shorted to 12 volts
313-Ventilation damper motor shorted to earth or shorted to 12 volts
314-Floor/defrost damper motor shorted to earth or shorted to 12 volts
315-Recirculation damper motor shorted to earth or shorted to 12 volts
322-Passenger’s side damper motor active too long
325-Recirculation damper motor active too long
411-Blower fan seized or drawing excessive current
412-Driver’s side interior temperature sensor inlet fan shorted to earth
414-Driver’s side interior temperature sensor inlet fan seized
415-Passenger’s side interior temperature sensor inlet fan shorted to earth
417-Passenger’s side interior temperature inlet fan seized

As you can see, I hit the mother load with B1. Now it looks like my parasitic battery drain issue could be a bunch of of things.

I cleared all the codes I have read so far, since I don't know if some of them had been "fixed" and just never cleared. Again, it was strange to me that resetting the A3 terminal made the ABS light turn on. I started the car after the code reset, but I didn't have time to take it for a drive to see if there was any difference in the driving experience after clearing the codes. I will try to read the rest of the B block tomorrow.

Regards.

[Chuck W]

All of those B1 codes are for the ECC (Electronic Climate Control), which would have no bearing on your drivability issue.

Some of those (like the interior sensor fans being blocked/seized) are easy to clear up.


My cars have all been OBDII, so I think the codes are a little different. You're probably going to need to drive it for a bit to see what codes pop up, since you had the battery disconnected before checking.

Does your cold running issue go away if you restart the car while it's still cold/cool?

[budoboy]

Does your cold running issue go away if you restart the car while it's still cold/cool?

No, it does not happen if I immediately restart the car while it's cold. It seems to happen most consistently when the engine is fully warmed up.

I didn't yet get a chance to finish reading the codes for the B block or do any more troubleshooting of the car.

[Chuck W]

I would drive it for a bit and recheck codes.