help/suggestions for 88 BII engine stumble/cutout

[gdw1591]

I am working on a 1988 Bronco II with a 2.9. The engine will cutout for a second or stumble on moderate to heavy acceleration. Does not appear to do it at steady speed.
I have replaced:
fuel pump relay
fuel filter
throttle position sensor
ignition control module
cap
rotor
plugs
plug wires
pcv
valve cover filter
checked vacuum hoses and fitting
cleaned IAC
cleaned throttle body
tested fuel pressure - within specs.

I know I have a problem with the kickdown cable. The outer casing is gone for about 8 inches and with full throttle, it only moves about half of the movement on the transmission end. If the outer casing is held, then the level moves about half distance at half throttle, and full movement at full throttle. I am going to have to look at junkyard for replacement.

On scanning for codes, I get
KOEO 11 (system pass), 22 (MAP out of range) and 96 (fuel pump circuit open -battery to EEC
KOER 11 (system pass), 13 (cannot control rpm dure self-test low rpm check, 73 (insufficient TP change during dynamic response test

during a test run, I disconnected the IAC (as someone told me that this could short causing the problem) - no change
disconnect a black box (MAP???) that is mounted on a bracket on the firewall on passenger side of engine. Box has a vacuum line from intake plenum and wire connector to harness. - no change

I have not cleaned the EEC connector yet, but code 96 could be the problem.

Any ideas or suggestions? Thanks.

 

[schroader]

Have you checked the compression?

 

[gdw1591]

No, I have not checked compression. At a steady state engine is alright. Problem is when accellerating. The engine either stumbles or cuts out for a second, drops a few hundred rpms, then returns and continues to increase in rpms and speed. If it was compression, wouldn't I see this problem all the time? and no power? It acts more like the fuel or ignition cuts off and then returns. I don't know if the code 22 is from when I disconnected the MAP (not then knowing what that black box was). The code 96 would seem to make sense if the power to the fuel pump (which pump or both) cut off then returned. I am also wondering about the EEC power relay. There are three relays on passenger fender well. I have replaced the fuel pump already. When I clean one of the other relays there was a lot of dried crud, which may have been some old anti-moisture paste. Thanks for the thought.

 

[kimcrwbr1]

did you reset all the hard values when you replaced the parts disconnect the battery for 15 mins check and clean all the connectors and reset the on demand codes. then warm the engine up and retest.

 

[adsm08]

Black relay is PCM power, green is fuel, the 3rd is WOT cutout, I doubt its the PCM, other things would be not working, more codes too. I'd look at fuel.

 

[kimcrwbr1]

A spot of fresh dielectric grease when putting the connectors together can`t hurt

 

[Nathan123]

My bII would sputter and stall and rev erratically at low rpm's, I think thats what your describing. I talked to my (non dealership) mechanic and he said it was a very common problem with the 2.9. He gave me a repair kit for the problem. It is simply an aluminum plate with set screws that bolts between the IAC and intake. It comes with new gaskets and longer bolts. This was a ford part. He didn't charge because he said my BII might already have it, but it might need adjusted. Sure enough mine did have this plate. I just adjusted the two screws until the engine sounded the best. My rpm's are around 900-1000 at idle. You could verify if this fuel/air ratio thing by checking spark plugs. When I checked codes though, I still get that cannot control low idle during self test, but thats it. My truck hasn't stalled sputtered or revved erratically since, and it's been about 6 months. Sorry I don't know about part # or anything, but my mechanic said this was so common back in the day that he just bought a bunch of them for stock, and he still had one left over. Something tells me that if I would've used it it was like 25 bucks.

 

[gdw1591]

Update: The problem appears to have been the second fuel filter, which I did not know about. I had already replaced the front filter, which is the only filter the replacement part books states is for this 1988. There was another in-line filter between the in-tank pump and the high pressure pump. A lot of crud came out of the old filter. No stumble, no hesitation.
Now I need to go to junk yard to find a replacement kickdown cable.

 

[YOUNG GUNS15]

the 2.9 is sounding more and more like a piece of SH1T

 

[Clem]

Keep reading about the 2.9's.
I ran one for over 240000 miles with regular maintenance and oil changes.
They are near bullet proof. They also don't have any more issues than any other Ford V6.

Ray

 

[kimcrwbr1]

Thanks for the update on your solution to the problem alot of people just disappear before finishing the thread and letting us know what it finally was GL

 

[lethal-threat-b288]

mine does that too, and when you let it idle is misses and smokes. black smoke tho and that is unburnt fuel...

 

[Robert_1967]

Thanks for post this, Mine does the same thing, when I try to speed up, it stumbles all over it self, and seems like it cuts out some time, but if I let off the gas it smooths out, I'll check the other filter eather today or tomarrow.

I also tryed to pull codes, and I get the code that everything checks out fine, did it with the key on engine off.


Robert