93 bronco idle surge it idles rough

[Coleaclark]

Alright guys i checked the codes at autozone and none have came up i have no idea whats wrong it has new plugs new wires IAC Cap N Rotor also a new fuel filter I have searched and search for vacuum leaks and cannot find any timing is on.. Map sensor gets 5 volts when i prb the back end it has about 1.2 i think any ways any help would be greatly appreciated

[Mikey350]

On my '94 I went through four IACs, the first three were "Standard" brand, the fourth was a BWD. Just because a part is new, doesn't mean it is good.
(Ok, now flame me for not getting a Motorcraft the first time.)

A quote from "Big Daddy" Don Garlits from the late 80s after suffering a tranny failure.
"That transmission was brand new, new parts need to be massaged, I hate new parts."
http://www.nitromater.com/nhra/6744-...ment-ever.html

[Daves 88']

Have you searched the forums here? It's the icon about 6" up, in the middle/right of the page, that reads "search" in white lettering.

[Coleaclark]

yeah hey i did see the search and i have searched maybe i wanted to post a question this is what this site is here for right?? for help..

[Daves 88']

Elaborate your problem. Does it idle rough always? Any other symptoms? Put your Bronco information in your signature so we can help you better. What size motor? Which Transmission? Any mods to it? Look at other people's signatures to get an idea.

[Coleaclark]

It idles rough all the time also when i rev the motor it has a delayed rev when it comes back down but drives good has alot of power no engine light no smoke i did buy the standard Auto zone IAC.. im just very confused

[hizootiemizark]

I would get a Motorcraft IAC if I were you. Check ROCKAUTO.COM they have good prices and quick shipping. Return the one to Azone when the new one comes in. It very well could be the problem but even if its not you'll have a much better part.

[Coleaclark]

okay last night i got the bronco running fine had all the power back today when i was on my way to get gas it ran fine for like 3 miles than i lost power again and the bad surging came back any help please would be great it.. where are all the main grounds everthing works lights radio etc

[art1124_99]

Try pulling the vacuum hose off your EGR when it is surging. you will know instantly if it works. let us know what happens

[Coleaclark]

in park at idle when i take the green vacume line off the egr it doesnt make a different plus there is not much vacuum coming from that hose

[Coleaclark]

any help would be much appropriated

[omp]

Have you check for intake leaks at the base of the manifold? A can of throttle body cleaner, as its running spray around the base of intake manifold and where it meets the head, also anywhere there is a gasket on the intake side.. say just behind the throttle bodys, sounds like U have a bad vacuum leak. Also Search for TPS voltage and adjustment here or on Google, should be around 4.5V if i remember at closed position. 93, should be SD system so its pretty basic, measures air flow, and air temperature in manifold along with coolant temp.
The Idle Air Control valve, you can remove leave it plugged in. Have someone turn the ignition on, you should see and feel it buzzing and opening up.

[lil beast]

I am also having the same problem I have read all the forum that I can I just bought a 1988 ford bronco 5.0 with and rebuilt engine ran fine when I bought it drove it on the freeway at about 65 mph for 2 hours or so when I got home put it in reverse it died since then it has a bad idle surge, once the truck warm up in park it surges from 400 to 1100 then when I put it in drive it will idle at about 1100 rpms at a stop light, then when I tap the throttle it shoots down and almost dies. I checked for vacuum leaks none found.I just changed the IAC today and didn't change a thing. Going to buy a TPS tomorrow to see if that's the problem.I also have new distributor,wires,spark plugs,filters, and I just found three grounding straps not connected can that be the problem if not any ideas???

[omp]

Main ground is front lower right side of block. Have you tried doing key on engine self test. It's obd1 but can still test itself, a paper clip or one of the cheaply ford Scanners, autozone will do it well as my local store has the older scanner.
I'd bet on tps or air leak.

Post #48

http://www.f150forum.com/f10/88-302-...-47966/index5/

Also check PVC valve if it's stuck open.

[Daves 88']

Did you give it a full tune up after buying it? New plugs, wires, oil, filters, etc... to start fresh. Then look it over real good for bad connections, bad vaccum lines, etc... Booba something, or other, did a write up for replacing all vaccum lines in a sticky on the forum somewhere.
Take off the vaccum line from the fuel pressure regulator and if you smell gas replace it. My FPR caused mine to surge after I stopped it, or at a stop sign, or slowing down in traffic. The exhaust smelled like rotten eggs too.

Bad egr flow would cause a Check engine light. I would assume a bad iac would too , but what do I know? I cleaned my old factory iac bottom( non electrical) end, and it works ok.

[Coleaclark]

alright i bought a OBD1 reader and here are the codes i have got 126, 114, 116, 636, 121, 122, 118 what the heck is going on??

[Coleaclark]

anyone give me any ideas??

[Coleaclark]

The FPR line does smell like fuel but cannot see any fuel

[Mikey350]

A bad FPR will not throw a code directly, as it is only vacuum operated, no connection to the EEC.
If the diaphragm in the FPR is leaking enough fuel to see it, you would have a very dangerous situation with a lot of raw fuel dumping directly into the intake manifold, I imagine it would indeed run rough just before it exploded.
Take Daves 88's advice and change the FPR.

Most of the codes you posted have to do with the engine being too cold to test. Warm up the engine fully, then rerun the KOEO and KOER test. Read the manual for your tester on how to clear the CM codes and clear them.

[Coleaclark]

Replaced FPR and still have the problem whats my next step