My bronco has been acting similar. Have you been having issues with it not wanting to shift as well?

 

The trans code U is the important thing. You are supposed to have the 4R70W which is what any help needs to be based on, not an E4OD as subford pointed out earlier too.

Am I reading this right that some where before you got this that the ECU has been changed?

Anybody?

 

Occasionally it won't shift up as it should. I have been back and forth in my head whether it is a transmission issue related to heat and high mileage or a power train EEC issue / vacuum leak / sender / sensor / vac motor / IAC / EGR / TPS / MAF sensor / OXY / TFI / changed the distributor / plugs / wires and wire positions / cleaned TB and upper intake / Seafoamed it / Seafoam in oil and gas.

I have done the following with mixed results:

1. Throw it into neutral and revving the engine up past 4K three times in a row has "fixed" it. Not so much now. Oddly, when I rev it like this there is no miss or stumble.

2. During cool weather, I had the transmission flushed and fluid changed at a Local Lucas Oil franchise which seemed to resolve all issues for about 300 miles. It started again and a bottle of Lucas Transmission additive seemed to fix it. I thought the original fluid they put in it was thin as **** and came to find out that the owner of the operation was buying and using cheap ATF from a local oil company verses using actual Lucas products . Thickening the tranny fluid had a major, if not short term, fix.

A thought had crossed my mind that because of high mileage / wear / thin fluid etc I was getting a fluid boil in the transmission and have gathered the parts to add a large, fine particulate filter exposed to air flow in the tranny fluid return line from the radiator in an effort to filter and also dump BTU's in the fluid. I just haven't had the time to install that add on gear.

Today the ECM is going to a local electronics shop to change out all electrolytic capacitors and test diodes.

 

No, never changed the ECU, it's the original. I bought this truck with only 16K on it and have it at 180K now.

 

Quick question, hope someone is on FTE today. Should the multi pin plug for the ECC have a liberal application of dielectric silicone grease applied to the pin area ?

 

I put it on the socket pins but yes you should.

 

Not liberal. I take my small tube of dielectric grease, slide it over each pin, and make sure there is a thin coat on the pin, but not a gob of it. Make sure the connector is seated square before you crank it down.

 

The learning curve seemed strange with the dielectric capacitors replaced. First off the CEL started flashing like it was spelling out codes and nothing was done to prompt it doing so.

I hooked up the code reader and did the KOEO and KOER and only got the brake, steering and cruise control faults because I didn't do them. I then re-did the KOEO to erase anything in long term memory and the CEL flashing stopped.

I drove it about 20 miles with a mix of stable cruising at interstate speeds and in town stop and go driving and I also shut it off and restarted it about a dozen times scattered throughout the drive.

My heat soaked roughness is almost gone and my only question/concern is a high idle that comes and goes but it idles around 1500 rpm about 90% of the time while driving now. Trying to kick it down doesn't seem to help.

One thing a tad strange is if I am approaching a red light and throw it into neutral and coast to a stop, the RPM seems to drop at the same rate that I am slowing down ??? Right about when I come to a full stop it's idling about 700 rpm.

I'm gonna pull the IAC and the EGR valves off and make sure that the previous funky EEC parameters haven't carboned or gunked anything up.

Any thoughts or creative solutions are welcomed.

 

The idle control is influenced somewhat by road speed in order to prevents stalls, etc..

 

So if I am understanding correctly, the 4R70W does have a speed sensor and being that is about the only thing I haven't changed out, gonna give that a shot ?

 

You could, I suppose it could be worth a shot.

Keep in mind that the CEL should never flash if the truck is not in self-test mode. I'd verify the wiring integrity around the self test connector and PCM connector.

 

It did this strange flash series only after pulling, changing the capacitors, and reinstalling the EEC. It is doing nothing strange at this time at all after hooking up the code reader and running through the test sequences.

 

The saga continues:

Last week I drained all tranny fluid, dropped the pan and changed the filter. I put 8 quarts of MERCON back in plus a bottle of Lucas Transmission additive and a quart of 75/90 synthetic gear oil.

As of 50 miles later and close to 100 degree daytime temps, all negatives such as bucking, shuttering and high idle after the truck is heat soaked, seems to be gone. No CEL, no CEL flashing upon startup.

This original drivetrain is now shifting and driving as if new and that's with it just rolling past 180K last month.

 

Good news! Hope she keeps rockin for ya

 

Dontcha love necro-posting ??

Long story short, I had the electrolytic capacitors changed out in the ecm/pcm with no improvement.

I found the the A,B,or C computer would work through an experienced Advance Auto manager and that rebuild solve my problems except needing to replace the O2 sensor because it had been subjected to 100's of miles of ultra rich running.

It runs like new now with light gray tailpipes vs the charcoal black they had displayed before.

The only issue right now is when the truck is warm and shut off for a short while, it will stumble and backfire until back up to full temp.

Because of the extended period of extreme rich running I am thinking the EGR or Idle valve is the culprit.

I can't stop trying on this POS !!! I am so close to having it running better than new!

Just this issue then on to body and interior projects.

TIA