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Discussion Starter #1
Well my T-Bird is proving particularly difficult. Have replaced the spark plugs and wires with motorcraft. No change. Even replaced the alternator, bearings going bad after 13 years, not bad. But no change. Pulled the MAF sensor connector and tested no change. Checked compression, less than 2% variance at 205psi. Seem to have plenty of compression. Vacuum is 19.5 in/Hg Fuel pressure 40psi at key on, otherwise 30 when running.

Any ideas on other items I should check?

So my current ideas are

Buy the AutoTap Express DIY software ( $ 200.00) http://www.autotap.com

Buy a computer at the junk yard (ECU) and try it. ( $ 75.00) part number has to match.

See if my daughters car computer matches mine and switch.

Take to Ford, at this point it runs so bad I will probably have to have it towed in.

Any thoughts suggestions?

The car is a bone stock 97 with a rebuilt 4.6L engine. The engine was rebuilt a year ago and has operated perfectly up until this point.
 

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Discussion Starter #4
no codes are present. It's my dads car. I will ask him to try running with no MAF and get back to you.
 

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did you try running it without the MAF?
This sounds a lot like what my car is doing (and I had a 96 about 10 years ago that developed the same problem)

I tried running mine without the MAF as well...it ran horrible but in a different way...what is unplugging the maf supposed to change or proove anyway?
 

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When you unplug the MAF, the PCM reverts to a static table that attempts to guess the air coming in based on RPM and throttle position. If everything else with the engine is fine, the engine will run smoothly off of this table, and this can be used to prove that the MAF is what is causing the engine to run rough.

Do keep in mind that the table was created for the stock engine. Changes will affect airflow and the table will be off, so a tune can be used to create a new "Load with failed MAF" table.
 

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Discussion Starter #8
The MAF being unplugged did not help. The engine is stock so the tune should be good.
 

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I know you said you changed plugs and wires, what about coil packs?? BAd one or one going bad shorting out something like that perhaps??
 

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How many miles on the car? stock everything?

Do a leak down test? Hows the coolant? Is it consuming coolant at any rate? (cracked crossover or head gaskets going). a leak down test, and a couple squirts of oil in the cylinder would tell you if it is top end or low end if there is a compression leak.

Other than that... look into your o2 sensors.
 

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he hasn't mentioned if its during warm up or first start.... but I image that if he is saying that it runs rough enough to not make it to the dealer then its running that bad after going into closed loop.

so i guess the question begs does it run decent when started from a cold start?
 

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If it's not a vacuum leak, I would check the coil packs if they're still the originals. If you're geographically near your dad, it would be pretty easy to swap them out with the ones in your car to test.
 

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Maybe injectors? Or an injector drowning out the cylinder causing a bad miss?
 
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