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90 EB bronco w/351 sometimes when you start it up the idle will
go up to 1000 rpm and stay there then when you tap the gas it
will come down like normal but then... It will start fluxuating
up and down rapidly from 500 to 1000 rpms and somtimes stall??
Then somtimes it will run fine.
I borrowed a code scanner from a buddy but It basicaly told me
to buy a new truck! (he he)
I got several diferent codes but im still not shure.
By the way the engine is very new (4000) miles but Im shure
all the sensors and ect. were reused from the old engine
Any help here would be apreciated.
Most likely suspects are IAB or TPS. If you have a condition where you get lots of codes, pull the neg batt cable to reset. Drive briefly and then pull codes. Hopefully you'll only get one or two - sometimes one problem can set off other codes so you have to go back to the beginning.
I've had the same symptoms twice on my Bronco and once on my 90 F150 and all times it turned out to be the EGR Valve. What a mechanic explained to me is that the valve sensor gets a carbon build up and will missread the valve position. This is a fairly common problem with the 88 - 95 Ford V8s.
Thanks for the pointers I will take all into consideration
I ran a few more checks after I cleared the computer and
now it tells me it's somthing in the Thermactor system
which I found out that is the air pump and it's accessorys
so I hope to find something with all this info. Thanks
solution turned out to be the TPS. This is really only a mechanical rheostadt. it wears out. If you used the old parts for your new engine, you inherited all the old "mileage" on all your old sensors. Ditch the old TPS. I'll bet your problem will be solved. I'd like to know if that does it for you!