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Help: Ford Experts: 1998 Taurus BCM problem?

Gentlemen (and women),

Vehicle:

1998 Ford Taurus SE, 3.0L OHV, 130K miles. I do not know if it is Flex or non Flex fuel. I believe it has ORVR (onboard refueling vapor recovery).

The problem: The car has a high idle (1100-1500 rpms) and it up shifts badly and feels like it is slipping between all gears. The final downshift when coming to a stop is always a clunk. The engine however runs good. No codes, except for an occasional P11744.

I scanned the BCM and at KOEO it shows 18% TPS. This is true if the TSP is installed or unstalled in the car. I tested the TPS both on the car and off and it is good. The TPS connector has 5.1V supply. Operating the TSP by throttle pedal with the connector backprobed and KOEO yeilds .9V at closed throttle and

4.6V at WOT.

I also checked the wiring for grounding at the BCM connector at pins 89, 90, and 91. Also there is no shorting between pins 71 and 89.

Questions:

How can I determine that the BCM is the correct one for the car. See

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for BCM lable. It is possible that the engine wasreplaced sometime before I bought it. I bought a reman Cardone BCM for O'Reilly's (78-8250) based on the data from the BCM label on the existing unit and the Calibration label in the engine compartment. BUT, the car still showed 18% TPS at closed throttle, and the transmission REALLY shifted badly or not at all. Plus the A/C quit working. I took it back to O'Riellys and put the old BCM back in.

Any advice would be greatly appreciated.

Bill

Reply to
Bill
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Disconnect the IAC and see where it idles.

I think you are relying too much on instrumentation. Suppose that the CM sets up for cold start at KOEO... what virtual value might it supply for initial crank/start?!!!

Transmission.. who knows.. solve idle problem first.

Reply to
Backyard Mechanic

Thanks Krusty. I did check the TSP % after closed loop mode and it also was

18%.

I will try the IAC disconnect tomorrow.

Bill

Reply to
Bill

Here's the point... while it's sort of splitting hairs, I would bet that

95% of Engine Control related failures are mechanical in nature, not 'electronic'

I use as the definer, something that you can cause to change or vary by touch, or cleaning.

Wiring faults are 'mechanical' by the way.

Bill wrote:

Reply to
Backyard Mechanic

Yes, it is the IAC (or the signal voltage from the PCM). I pulled the connector, and voila, perfect idle! It also shifts much better.

Thanks for the info.

Reply to
Bill

You SHOULD NOT have a perfect idle with the IAC unplugged. It should idle low or stall. Maybe you have a vacuum leak?

Reply to
Bob

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