The Bronco (1987 5spd. 2.9L) stumbles and hesitates while driving. I haven’t had it on the road long, but it seems to have started out intermittent and now has become very regular. It starts and idles fine but it stumbles and hesitates whenever it needs any power (taking off, climbing slight grade), it runs good at high rpm. It seems like every thing between idle and wide open has problem. Plugs and wires look good. I have not checked cap and rotor yet.
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The codes are as follows:
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KOEO
31 (EVP circuit below minimum voltage)
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Memory
41 (No HEGO switch detected)
63 (TP circuit below minimum voltage)
31 (EVP circuit below minimum voltage)
29 (Insufficient input from vehicle speed sensor VSS)
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Engine Running
12 (Cannot control rpm during self-test high rpm check)
21 (Engine coolant temp out of self-test range)
42 (HEGO sensor circuit indicates system rich)
31 (EVP circuit below minimum voltage)
77 (Operator error, Dynamic Response/Cylinder Balance Tests)
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Do these low voltage codes lead to one problem or do I have multiple problems?
Are these emissions codes problems that would lead to the hesitation problems?
I have an 88 donor that does not have an EGR, can the EGR be removed on my 87 or would that cause more problems?
Other than a match can someone point me in the right direction?

 

When you have a whole bunch of codes like that the TFI module is usually on the way out. Plus, you usually have idle, bogging, and stalling problems too.

 

Is the TFI the same thing as an Ignition Control Module?
Should I just replace it or is there an easy way to test it?
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Thanks

 

It is the small box attached at the back of the distributor with wires going to it. If yours is stock, you pop off the plastic caps and the screws that hold it on are underneath. Usually a long 9/32 ? thin wall socket 1/4" drive will take off the small hold down bolts.

The tool they sell at most stores works fine to put the non-stock one on, useless to break the grip of the nuts on a stock one because of no leverage with the ****.

They can be tested, I know they have a tester at Auto Zone. But, it is fairly useless unless done on the vehicle while the vehicle is hot for one that is marginal. Few people and stores have this tester. Plus, once it is removed, you need the heat sink grease to put it back on.

There is a way to test it going by the Ford factory manual, but, it all comes down to them saying, "nothing is left, replace it" The only simple test to try is gently moving the wiring harness while the vehicle is running and see if it stumbles or stalls. Some had a bad harness/connector/loose wires and there was a TSB about it. I doubt after 22 years that would be an issue.

 

<i>The tool they sell at most stores works fine to put the non-stock one on, useless to break the grip of the nuts on a stock one because of no leverage with the ****.</i>

The tool includes a wrench boss before the ****, a 1/2" wrench fits it to aid leverage when/if needed.