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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 34442
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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1996 ford f150: 4th..1500 rpm..throttle body..throttle position sensor

Customer Question

i have a 1996 ford f150 with a 302 and when you stop at a red light it will idel all the way up to 4 rpm and while you driving you go to down shift say from 4th at 1500 rpm to 3rd and it goes up to around 4 rpm. ive already put a used throttle body. a new throttle position sensor and a new idel motor. and still not fixed
Submitted: 6 years ago.
Category: Ford
Expert:  Ron replied 6 years ago.
Chat Conversation Started
Ron :

Hello and Welcome to Justanswer, My name is XXXXX XXXXX I am here to try and assist your with your question.

Customer:

thanks

Customer:

im steven

Customer:

do you have any idea what may be wrong

Customer:

hello

Ron :

With all that you have replaced and the idle is still flaring, I would suspect you PCM (computer) has lost its ability to control Idle speed thru the IAC. Try unplugging the IAC and then drive it, it should idle a little slow , if so suspect the PCM is bad.

Customer:

unplug the idle motor

Ron :

Yes that would be the IAC (idle air control) valve on the throttle body.

Customer:

what is the pcm (computer) and were is it located

Customer:

?

Ron :

The PCM is the engine control modual and on your 1996 its located in the drivers side firewall in between the brake booster and the inner fender.

Customer:

how expensive is that?

Ron :

You can usually buy a reman for about $200.00

Customer:

is it possibe to be the evr valve or the Coolant Temperature Sensor? thats what a frinend suggest but im not sure

Ron :

It not very likely .

Customer:

ok well im gonna go unplug the idel motor and run down the road a min. and i wll be back and let you no more. thanks alot

Ron :

ok, let me know

Customer:

ok it idele parked at about 800rpm and changing gears a 300rpm it would drop down to around a 1000rpm so i think that is it can yyou give me more info on the pcm location and what it looks like. thanks agaim

Ron :

Here is the diagram for loaction.

DOWNLOAD HERE

Ron :

Here is removal INSTRUCTION

Customer:

will it hurt to drive it wit the iac unplugged

Ron :

No it sure will not but it may stall on you from time to time.

Customer:

im still cant place the pcm in the diagram is it like a fuse box with a lot of wires going in the firewall

Ron :

Look at the second picture, all you are going to see under the hood is the connector and the cover. It right next to the brake booster.

Ron :

Let me send you a better file.

Customer:

the second picture is blank

Customer:

ok

Ron :

Give me just a sec.

Customer:

ok

Ron :

DOWNLOAD HERE

Customer:

hey

Customer:

i found it

Customer:

1 more question

Ron :

sure

Ron :

what is the question?

Customer:

do you no what years f150 will interchange say i get one from the junkyard

Ron :

You will need to stick with the same year , make and model as well as the same engine and transmission.

Customer:

so if i found a 1993 with the 302 it wouldnt work

Ron :

No, not likely you need the same year as your 1996

Customer:

do you think it could be anything else'

Ron :

The Wrecking yard may be able to cross it over with there interchang manual but I dont think you can go back that far.

The PCM controls the IAC . The TP sensor can cause this but if the new one is working correctely then no not likely.

Customer:

ok

Ron :

let me know how it goes.

Customer:

ok thanks

Ron :

If you have found my answers helpful, please be sure to hit the accept button so I can get credit for my work.

Customer:

ok thanks sure will and ill let you no how it goes with the computer

Customer:

thanks again

Ron :

Your very welcome. Thank you as well.

Customer:

im looking at computers what the diffrence between pcm and ecm

Ron :

There is no difference, the PCM is a an ECM. Ford calls them PCM and aftermarket calls them ECM. Same thing.

Ron and 3 other Ford Specialists are ready to help you
Customer: replied 6 years ago.

are they any way of checking the pcm computer. i find one at the junkyard and want to make sure it is good

Expert:  Ron replied 6 years ago.
There realyy is no test other than installing it and seeing how it works.
Customer: replied 6 years ago.
ok when the truck is parked in neutral what should the idel speed be in (RPM).
Expert:  Ron replied 6 years ago.

It should be about 750 to 850 .

Customer: replied 6 years ago.

will it hurt to plug the computer up and try it befor installing it into the firewall housing.

Expert:  Ron replied 6 years ago.
No it will not hurt it.
Customer: replied 6 years ago.

if u buy a used or new computer will i have to have it programed or anything

 

Expert:  Ron replied 6 years ago.
No as long as its the correct PCM, it is plug and play.
Customer: replied 6 years ago.

my computer # XXXXX now will the one i buy have to have this same number.

Expert:  Ron replied 6 years ago.
Yes it need the same part number to be correct.
Customer: replied 6 years ago.
ok going in the morning to try and find one. hopefully this will fix it and i can leave you alone. thanks
Expert:  Ron replied 6 years ago.
Not a problem, your not bothering me at all. Glad to be of help .
Customer: replied 6 years ago.
i found a computer in a 1996 f150 just like mine but the engine is 351 and the transmission is automatic but all the numbers match except the last two. I put the computer in my truck it dosent idel high no more seems liket that was the problem i was wondering if the last 2 numbers didnt match up will that cause any problems. thanks
Expert:  Ron replied 6 years ago.
No it should be a good match as long as it is running correctely.
Customer: replied 6 years ago.

thanks for all your help you nailed the problem on the spot. truck runs fine now. thanks alot

Expert:  Ron replied 6 years ago.
Great JOB!!! Thank you very much as well. Glad to be of some help.