1994 Mark VIII engine/power troubles

greenehoosier

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My Mark runs great above about 2200 rpms, really screams. It will still bark the tires at 60mph. Anywhere below that RPM it is a real dog, I get a miss and a backfire. Under steady acceleration, under load, I get a miss. If I floor it above that RPM level it really lets loose. The only things I have done to it are new plugs (did not change anything) and the seafoam treatment. Any ideas? Yes, there is a CEL, but it has been on since I have owned it- before the problem. Is there a cheap code reader for these? Thanks!
 
Read the codes. How long have you had the car? I would have had the codes read on day one. Actually I wouldn't have bought it without checking the codes if the CEL was on. There's something wrong or the CEL wouldn't be on. Do that right away and then post the results.

Basically you're taking a car that has a problem somewhere and flooring it. I'm not sure that is a good idea...
 
Bad or dirty mass air flow sensor. Bad Throttle position sensor, or huge vacuum leak are the most likely culprits.
 
Take it to Advance or Auto Zone and they'll read the codes for free.

They don't do OBD 1 systems.

As for OP, OBD 1 Ford systems can have their codes extracted for whatever it costs for a paperclip. You jump the EEC-IV connector and then the CEL will flash the codes at you.
 
For my 1994, I bought the Equus 3145 code reader with the 6 foot extension cable from Amazon. Its a good little code reader it does. koeo, koer, cylinder balance test, and something else i forget. But it works plain and simple.
 
this is what my 94 did with a small crack in spark plug wire tube drove me nuts and replaced alot that i didn't need. problem is you cant see it arching and only did it with a load on the motor. if your wires are old this maybe the problem.
 
Thanks for all the replies, guys! Plug wires will be week after next- Spring Break! One of my students says he may have a code reader, if not I will pick one up. It is something simple, I am sure. It runs TOO good to be anything major.... MW Hillbilly- we are neighbors! I live in Bedford. I spent many years in Bloomington, I worked at Royal while I was a student at IU! Good to see another Hoosier on here.
 
MWHillbilly- mine is that way too, under load with low rpms. Floor it going downhill and it will SCOOT~!~ Floor it uphill and it falls on its face until you build some RPM's...
 
OK, I realized I had a code reader for my 1988 Thunderbird Turbocoupe. The manual says something about EEC-IV, so I am thinking I may have one that will work, if not I may just jump the terminals and see what codes I get from the CEL.
 

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