EEC trouble

[plinker]

I picked up an '86 Bronco 2 and have been trying to figure out what the reason is for it not running right. It wants to miss some, stall out sometimes and run rough at idle.

I have another EEC that I put in out of an '87 ranger and it runs much better with it. According to the KOER test, it has an issue with the EGR I'll need to look into according to my codes. other wise no issues it does want to idle at 1500 rpm for about a minute then goes down to 900-1000 rpm.

I also have EEC's for an '89 & 91 Rangers (spares for my '89 ranger). I tried them and the Bronco would run ok, but it'd idle at around 1500 rpm, no abnormal codes that I remember.

Is the original EEC that came in the truck faulty?

It also will not do a KOEO test with any of the EEC's I have. All it does is runs the (mid rail I'm pretty sure) fuel pump continuously . I dont know why it wont shut off when trying to run the codes. You hit the test button and the fuel pump starts to test it like it should, but does not shut off unless the reader is stopped or turned off.

The pump dosent sound that healthy so that may be the issue.

I did put new plug wires cap & rotor, o2 sensor, gas filter, new oil & filter in the truck I need to find the spark plugs I have though. I also swaped the fuel pressure regulator and MAP sensor with good used ones to try and figure this out.
EDIT: I also put a different coil in it. I had to splice the wire plug-in back into the truck harness as the original coil was somewhat jerryrigged together with the truck wire harness. There was also a problem with the coil according to my code reader but I dont remember it off hand.

Thoughts?

 

[Psychopete]

Try pulling codes with out the reader. If mid rail pump is running, it's a safe bet that the intank is running, too- They are not controlled separately.

 

[freedom5]

If the engine is cold the two wire engine temperature sensor will initially control the idle ( usually at high idle) speed then the IAC will take over. Also if the positive idle stop is adjusted too high it will cuase the engine to idle at a higher speed and to surge on start ups after the engine is already warmed up. There is a proceedure for setting the positive idle stop and you will have to disconnect the negative battery cable for at least 5 minutes after making the adjustment for the computer to reset the codes.

Hope this helps.

freedom5

 

[kimcrwbr1]

Are the computers you are using for the same tranny as you have in your truck. Did you try resetting the original computer before you took it out by disconnecting the battery for 1/2 an hour. Have you tried just putting the original back in and pulling the codes again after erasing the memory. You need the correct computer for the codes to mean much of anything 900 rpm seems a little high to me have you messed with the throttle body butterfly stop setting. A vacuum leak could be a possibility also take a length of vacuum tubing and put one end up to your ear and search around all the gaskets and fittings with the other end. change any hard or cracked or loose fitting vacuum lines. Put in a new PCV and hose just for giggles they are cheap and can create all kind of wierd symptoms. GL

 

[plinker]

Try pulling codes with out the reader. If mid rail pump is running, it's a safe bet that the intank is running, too- They are not controlled separately.

Why would the pumps be running though? Would there be something shorted out or disconnected?


The screw with the spring on it on the throttle body was backed out to where it was not making contact with the butterfly plate stop.

Pcv valve is new, will check the hose.

The truck originally had an A4LD but apparently the previous owner swaped out for a FM145 and used the engine from the donor vehicle as well.

I have no idea if the EEC is for the auto tranny or if he used the donor vehicle's EEC. I doubt it given how the wiring harness for the transmission looks.

I was under the impression just disconnecting the battery would not clear all the codes meaning you had to use a reader to erase them? I've had the EEC that came with the truck disconnected for several days (havent had a chance to mess with it) so I'll try it again soon as I get the chance.


One thing I remembernow that the PO said, he thought the cat was plugged, so he took it off and welded the flange to straight pipes.
Would not having a cat be some of the problem?


The way things are looking this is going to be a parts truck.

 

[Psychopete]

Yes, disconnecting the battery will clear the stored memory codes. You can also disconnect the jumper that puts it into test mode when the stored memory codes are output to clear them IIRC.

Will run fine with no cat.

The reason I said to try with out the reader is because there's a fuel pump test on the diagnostic connector that will run the pumps constantly when grounded. Ignore that for now if it's still doing it with both computers and see if you can't pull trouble codes again. It's possible the PO might have done some "wiring" there, somewhere in the fuel pump circuit to cause them to run constantly with the key on.

 

[plinker]

Had some time to putz with it last week (finally had some time to post too) I swaped the throttle body off a parts engine I've got, the TPS was different so I used the one off the B2, did not seem to make a difference in any way as far as I could tell.

I got to poking around and I think the throttle cable may be screwed up on the end for the pedal. I will need to look in to it as well

As soon as I get a chance I'll try doing the codes without the reader and look into the wiring & fuel pump(s).