Hello,

Weird sequence of events here that has resulted in my Buick throwing P0640,P0650 and P0670 Quad Driver codes. Gotta love the OBD 1.5 cars.

Last week the driver'* side front power window motor stopped working. Simple fix, verified everything worked, put panel back on and went inside for the night. Came out the next morning to go to work and the engine would crank, crank, crank but wouldn't catch at all. I disconnected the battery for 5 minutes or so, reconnected and it would crank/start just fine but immediately threw a check engine light and RPMs are up at 2K or so at idle. I have tried disconnecting the battery and starting the car over and over and sometimes the RPMs will run away on me and I have to shut it down. The engine runs smooth though, not missing or anything just really high rpms. I was driving this car every day and its never done this. I WANT to think it'* too much of a coincidence that I got in the door, and now it'* acting weird.

Here is what I have done so far:

1. Removed door panel again and disconnected everything - no change

2. Checked all functionality, mirrors, lights, horn, etc. trying to find something that is not working all of a sudden - everything is fine

3. Test light on all fuses - nothing is blown

4. Listened in engine bay for vac leaks and sprayed around intake manifold, tb, etc. - cant hear vac leak and no change in idle response

5. Remove intake tube and looked in TB - very clean as I replaced lower intake manifold last year.

6. Ohmed out injectors - all 13.5-14.5 ohms

7. Replaced IAC with new one I had sitting around - no change

8. Replaced ICM with spare I had sitting around - no change

9. Hooked up my scanner and watched sensors:

TPS - showing 0% and .52V @ idle which I verified via backprobe
IAC - counts = 110 (didn't seem unreasonable)
MAF - 11(cant remember units)
ECT - temp was correct
Timing - 17BTDC when at 2KRPM
VSS - Showing 0MPH

Really not sure where to go from here. When I bought the car ~2 years ago the PCM had been replaced a year before that by previous owner. I have a reman PCM on the way and should be here Thursday. For the car to go from running just fine to throwing 3 of the 4 QUAD Driver codes makes me think short or bad PCM.

Thanks in advance for any help.

Drew

Yeah, weird one.

Off the top of my head, I'd pull the IAC out (while still connected) and see if it does anything when you turn the ignition on.

Ok, I'll check it out when I get home.

Can anyone tell me what each of the four quad drivers control?

thanks,

Drew

No power windows/door locks etc and no running engine = bad ground buss under dash inside left hand kick/door pillar.

Power windows, locks, etc. all work. When the window motor failed, I confirmed it was the motor, replaced and all works fine. I'll check that ground buss though.

thanks,

Drew

MAF is 11...???......Since 1 lb/min = 7.55 gm/sec I'll assume you are reading grams. That is still to high for idle. Check this PID for accuracy. I also will assume your scan data was taken while engine was warm and idling. It would be very helpful to know what the fuel trims are doing.
As for your quad drivers...are there any other codes? Can you clear them and do they come back?
Is the car running OK right now?

BTW ....I have the factory information for this car if you need any diagrams or flow charts.

Hi Carfixer007,

That MAF reading (failure sure the unit was grams) was with car running but it'* idling is 2k or so RPM. I cant get the engine to come down in RPM unless I physically choke the intake with my hand/board/etc.

The only codes I have are those 3 quad drivers. If I clear them, they come right back.

Here is an odd thing I encountered last night: if I disconnect the battery to clear codes and reconnect the car will start up, do its super high idle thing and then throw code after a few seconds of running. But if I clear the codes using the scanner, the car will just crank and not start. It'* only once I disconnect the battery and reconnect that the car will even start.

thanks,

Drew

Hooked up scanner and did a quick 15 second recording to see where measurements were at. RPM immediately shot up to 2200 or so rpm and was steadily rising.

Data from scanner:

Battery = 13.7V
MIL = ON

Throttle (%) = 0
TPS Sensor (V) = .49
IDLE REQ RPM = 850
IAC Position = 0
MAF (gr/*) = 18
VehSpeed (MPH) = 0

INJ PWE (mS) = 4.5 to 5.5
ST Fuel Trim = 128
LT Fuel Trim = 128
LT Fuel Trim CL = 5

EVAP Duty % = 0
EVAP Solenoid = OFF

Coolant (F) = 133
Trans Temp (F) = 83
IAT (F) = 80

EGR REQ % = 0
EGR VLVPOS % = 0
EGR VLVPOS (V) = 0.6

KS Counter = 16
Exhaust O2 = Lean
Fuel Cutoff = NO
Loop Status = OPEN
O2s (mV) = 49

Knock Retard = 0 degrees
SPARK Advance = from 16 to 17 as log ran

TCC Applied = NO
TCC BK SW = OFF
TCC DUTY CYC (%) = 0
TCC SLIP RPM = 255
TCC Solenoid = OFF

thanks,

Drew

That MAF reading is not outrageous since the engine was at 2K,

What brand scanner do you have?

Your IAC is at zero. Is the pintle closed? If so, will your engine stall if you block the intake?
The TCC shows slip and applied shows 'NO'. That'* odd.
We may need to scan it with a different tool.