Codes 83 84 85 on Updated ECU (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

BakerFJ

Benny Bodangus
Joined
Feb 18, 2017
Threads
10
Messages
170
Location
Austin, TX
1993 80 Series

I'm experiencing an issue that has not been similarly documented anywhere online, figured it a good idea to document it.
The symptoms I'm experiencing;
On cold start (closed loop), it runs great, although has a pretty high idle some days which it has never done in my 7 years of ownership.
Once warmed up, it feels to only be at 80% power, after 2000 rpm acceleration is difficult unless I find the sweet spot in the throttle pedal about an inch off the floor.
Most of the time it will not shift into 4th gear on the highway. If it does, it never has an issue doing so until it's next drive.
When it does go into 4th, it runs crappy cruising between 2000-2500 RPMs.
On some warm startups, it will not immediately run. I have to continue cranking for an atrocious amount of time until it fires up.
Typically smells like its running rich, like satan's booty.
When warm, typically stumbles at idle unless I apply light pressure to the throttle to keep it smooth.

I have codes 42 (speed signal circuit, not relevent as its due to my speedo gauge), 83, 84, 85 (TCM communication in ESA circuits 1, 2, and 3).
Our 93's are known to have a recalled issue with the original ECU (PN 89661-60170) which is simply fixed by replacing with the updated ECU (from a late 93 or 94, PN 89661-60221).

Where this all gets funky is I own multiple ECUs for my rig which I've acquired through the years.
x1 89661-60170
x2 89661-60221
All three ECUs throw the same codes. I should try driving it on each for a while to see whether the symptoms change at all.

In most cases, the 83 84 85 codes are paired with a stumbling idle at worst, and can be temporarily remedied by pulling the EFI fuse and resetting the ECU. However, that's not the case in my situation.

It is possible I'm experiencing two issues at once, however I very recently went through the entire truck. Every wire and sensor has been checked and replaced as necessary, and then every wire was triple checked afterwards to ensure nothing else could be the issue outside of the ECU.
Only issue I know of currently is the valve steams should be replaced. Internally-wise, my leak downs are all 8-10% and compression #s are good across the board.

The only unknown factors are my new Ebay VAF (which bench tests within spec) and the quality of my fuel injectors. I did have them serviced a few years ago.

So that's where I'm at, and am looking for others' input on this before I throw a new ECU at it. Has anyone else experienced issues with the updated ECU? Could it be a TCM issue?
 
The whole thing about not full throttle being faster than full throttle is interesting. I'm wondering if you have a clogged fuel filter or fuel pump.

Cold starts are going to be best because it'll dump more fuel to compensate being cold.

I don't feel it's transmission related, but I could be wrong.
 
The whole thing about not full throttle being faster than full throttle is interesting. I'm wondering if you have a clogged fuel filter or fuel pump.

Cold starts are going to be best because it'll dump more fuel to compensate being cold.

I don't feel it's transmission related, but I could be wrong.
Everything in the fuel system was overhauled only a few months ago, other than the injectors. (WIX filter, Denso pump). I'm not going to count the filter out, as I've seen crazier things happen in my time.
I agree in that I don't think it's transmission related either. The solenoids were replaced a few years back.

I will say though, the fuel filter does make sense. I haven't visited that consideration yet
 
The TCM codes led me to think transmission issue. What’s the condition of your throttle cable? Have you checked your timing?
Throttle cable could use replacement, although it doesn't stick. It's just 30 years old.
I have adjusted my kick-down cable a few times, both by FSM and assuming slight stretch in the cable. Neither solved the issue (it's at FSM spec now).
Don't recall exactly where the timing is set but it's within reason. Probably advanced somewhere from 5 to 8 degrees.

At times it does feel like the timing is the issue, which would coincide with the 83 84 85 codes for the electronic spark advance circuit.
Been trying to get my hands on a TOYOBD1 bluetooth reader so I can monitor all my ECU inputs while driving, but they're super hard to find.
 

Users who are viewing this thread

Back
Top Bottom