2 years in the making...Very frustrated

[jhammel85]

So I've got a problem that I just cannot find out the cause. I have code numbers now but still a bit lost...this is quite a long post, sorry.

Basically, when the truck starts up warm (most of the time) it will run fine for about 30 seconds or so, then start hunting for idle. While doing this, it runs extremely rich. Slight puffs of black smoke. All while keeping 32-38 psi on the fuel pressure gauge. For what it's worth, key on, engine off fuel pressure is within spec, 38psi. it does all of this for maybe 10 seconds at the most then it finds itself and runs fine.

The only other time it will do this is if it is idling for a very long time. Like in traffic or in a long line at the drive through. Takes at least 5-10mins of strait idling for it to act like this again.

I'm getting KOEO codes 86 and 95. Constant memory 95. Code 86, I don't really understand, since I thought the 3/4 shift solenoid is not connected to the EEC at all? Isn't it vacuum actuated? It also can mean that it corrected a lean condition but I think it's only for the 1.9 Escort engine.

95 is "Possible bad fuel pump ground or open between fuel pump and pin 8 at PCM (Fuel Pump Monitor signal) - Power / Fuel Pump Circuits"

If you click on this link below, You'll get to see the vid of what it does. Fast forward to about 26 seconds in (a little under half way) and you will see it do it's usual stumble and then find itself.

http://s17.photobucket.com/albums/b...n=view&current=video-2010-09-07-19-48-341.mp4

My next course of action is to take a look at the terminal at the EEC and check pin 8 for corrosion or something. Then get a color and follow it the best I can both visually and with a diagram.

Thanks!

 

[jhammel85]

I don't see much of a point running KOER tests when these should be fixed 1st.

For what it's worth, the truck has done this since day one. I have replaced:

- the Engine Coolant sensor (eec, not gauge)
- Oxy sensor
- dropped the EGR and went with a 88 computer
- TPS Sensor
- Fuel Pump Relay
- IAC Valve
- Air Charge Sensor
- Map Sensor
- Wires, plugs, cap, rotor (all motorcraft)
- TFI

Again, sorry for the long post.

 

[jhammel85]

Bump

 

[Mike828]

Just throwing ideas here....
Are you using the '87 throttle body?
I am with a '91 or '92 computer to get rid of EGR too. Mine is a 5 speed but sometimes when I come to a red light mine will sputter down to 5-600 rpm and sound like its gonna die but never does and catches itself and resumes it's usual high idle of about 1000 rpm.
I know I've seen posts on here by AllenD about using the large throttle body with a later non-EGR computer but I don't remember all the details.
Also TPS and IAC part#s are different for EGR and non-EGR 2.9's.

 

[jhammel85]

Thanks for chiming in!

The TB is '87 and so are the TPS AND IAC. I thought they were only different because they have different connectors?

All of this has happened way before I put the 88 EEC on so I don't think that's a problem. I'm hoping that a new Engine Wiring Harness will help. Somethings up with the fuel pump circuit..... I think..

 

[lost86broncoii]

Have you checked the wiring to the relays? Mine's been having issues similar and I just noticed some wires are almost broken in half going to/from the fuel pump relay, it took some digging around to find the damaged wires. Worth a shot checking out all the wiring for damage...

 

[Steiger Man]

Vaccum leak? Try unplugging the brake booster then plugging the line. My sons 86 was doing this. The brakes will suck, but to test out the engine running problem.

 

[Mike828]

Seen this?

http://www.therangerstation.com/forums/showthread.php?t=86605

 

[Psychopete]

If you feel that it's an issue with the ground between the fuel pump relay and the computer, you can by-pass that circuit at the diagnostic connector. There's a fuel pump test terminal that you simply take to ground. This will cause your pump to run constantly when the key is on run, taking the computer control out.

Edit: Actually, check the MAF Conversion article in the tech library under the Intakes section. It states right in the pin-out that '86-'87 does not utilize pin #8. You might check in your main harness to the computer for if a wire is present.

I think there was a change in the electronics from the EEC to the A4LD in '88, but I am not 100% sure. This is just based on what I've read. I do know there is an additional R/W wire in the NSS on the side of the trans on a 1988 A4LD in addition to the start circuit and reverse lights Edit: (5 wires on A4LD versus 4).

No reason to not run KOER at this point, I would definitely suggest doing that. Your current codes, while resolvable (I think I have the wires I could even send to you with the pins from an '88 harness), I don't think are causing your issues. Just have to chase some of these slight differences. Edit: That may make these codes not relevant, but maybe someone will chime in that's swapped an 88+ computer into an 86-87 model and seen/dealt with some of these issues. But if the wiring isn't there....

 

[jhammel85]

You know what.....I have an 87 EEC sitting around. I'll swap that in and see what kind of codes I get to get myself back to square one.

The thing you mentioned about grounding out the terminal wire - the previous owner did this to my truck at some point. I recently found that and fixed it but still the problem persists. Even after clearing codes completely (with code tester / removing EEC from power), it still ran rich.

I'll put in the 87 EEC tonight and see what happens. It will at least rule out the "using an 88 EEC" thing. It'll probably lose code 86.

For what it's worth, I also just got a new engine harness for my truck. I found a few differences. I found under my hood there are two severed fusable links that are over near the coil. one of which is a Brown wire with a yellow stripe that goes to a fusable link, then blue and grounds out. The other one is black, goes to blue and grounds. I need to check my book but I'm hoping one of these have something to do with the fuel pump signal that goes back to the pump. I doubt it...

On my truck, both of these are severed and I've known about them but knew nothing as to where they would go. Now I know where they go. I wouldn't be surprised if this is all wiring related......I cannot wait to install this new-to-me harness.

 

[jhammel85]

Little update:

Here are some of the culprits:

Here's the fusable link brown / yellow wire that's broken. Like I said, I believe it grounds out but I'm not doing that until I confirm it with a test light or identify what it's actually for.

(Not leaving it hanging like this by the way!)

It's a bit twisted but it's brown / yellow. This is after cleaning it up with soap and water. Note the right portion of the picture where it comes in...You can make out the brown / yellow much better here.

Here's the other one. Directly off the junction near the coil.

Color is blue. I believe this one grounds out? I'm going off memory again..I'll test it with a light later and try to actually ID on a diagram.

 

[jhammel85]

Have you checked the wiring to the relays? Mine's been having issues similar and I just noticed some wires are almost broken in half going to/from the fuel pump relay, it took some digging around to find the damaged wires. Worth a shot checking out all the wiring for damage...

I've gone through these where I can see them. I havent ruled it out but everything seems to be undisturbed.

Vaccum leak? Try unplugging the brake booster then plugging the line. My sons 86 was doing this. The brakes will suck, but to test out the engine running problem.

Recently, I had a complete brake booster failure and plugged the line as I drove it into the garage. Of course, I still had the same symptoms I've been having. Thanks though!

Seen this?

http://www.therangerstation.com/forums/showthread.php?t=86605

I did see this! Thanks for posting. I'm definitely using that diagram too.

 

[Psychopete]

I did see this! Thanks for posting. I'm definitely using that diagram too.

Be weary of the wiring colors !!!! I divorced out everything but the fuel pump circuit to make it more readable, but it's a very generic diagram that you'd find back in a Hayes for instance.

I am going to be busy tonight with family over, but I own both 1988 and 1987 EVTMs and will try and help out when I get a chance to. That would be the best to have in narrowing those wires down. Some of those wires look awfully familiar, but don't remember what they are off the top of my head.

 

[jhammel85]

Thanks for your help bud! I appreciate it!

The Haynes manual will one day be replaced with an EVTM and a Shop Manual for my '87. I really need to get my hands on one..

 

[jhammel85]

Well, Tomorrow night I plan to put up the "new" wiring harness in the garage and clean it up. While checking over some things on it tonight, I noticed that the Brown / Yellow wire that goes into the fusable link goes to blue on the other end and goes into a multi port connection. It looks like the one that I posted with the blue wired fusable link hanging out of it. It actually goes into that same spot so I dont know what to really think...My "new" harness is from an 87 Bronco II so everything should be the same. we'll see when I start labling.

Tomorrow night, when I hang up the harness for cleaning, I will check the colors of those wires vs the ones on my truck now.

Thanks again all...Sorry for the rambling