Randomly sutters - actually shut down today (1993) 65mph

[toyotaspeed90]

I did a search, there are some people who have posted similar "issues" happening with little or no follow up. Mostly 100 series off road..... I didn't see anything 80 series related (granted only went through 3 pages of search results).

Every now and again the 80 has a very mild "stutter" while driving. I've dismissed it in the past as a bump in the road (it's that mild). Today on my way to work on the freeway, it stuttered, looked down, the tach dipped down, up, then to 0.... all dash lights were on.

Threw it in neutral, pulled over to the side (still rolling), turned the key - fired up as if no problem, and finished the drive to work.

NO CEL.

I know it's 1 of 2 things.... fuel delivery (pump failure/lean, or even crack in AFM hose - though I would guess that would throw a code) or electrical. I'm guessing #2.

I also know that someone else has had their hands on the wiring for the ignition switch (for an aftermarket alarm at some point, but they used taps, and they're all gone at this point).

I will follow up with any photos, tests, and findings. Being that I've had the vehicle 10 months now and this is the first time it's happened enough to stall out - I'm guessing it may take a while to actually figure out the problem.

Just for background: New cap, rotor, plugs, wires - did a compression test with good results, new (used) AFM, good AFM hose checked (though unsure today), nothing in the oil/coolant (that's visible), new coil, EGR mechanically bypassed (it's a 93, had the factory sensor bypass in place), new battery terminals (though I didn't love them, they could also be culprit).

I'm thinking more along the lines of loose connection at a COR or EFI fuse/relay....

 

[Tools R Us]

Fusible link condition,,, is the harness tied away from the EGR pipe?

 

[toyotaspeed90]

I had another issue - and totally at random the rig wouldn't start - turn the key and it acted like it lost all power. Tested the battery and it was nearly 100%.

I believe I found the most likely culprit. I will get photos when done.

I've run into some of Toyotas less than stellar positive wiring in the past (first Gen MR2s commonly have alternator wiring issues, which branches off into multiple wires all over the place) and it appears the 1993 Cruiser doesn't make all that much sense either.

On the underside of the driver side / engine bay fuse and relay box there is a power wire that is tied to the an alternator main wire, and that power wire branches off to 2 high current fuses (the 50/60A fuses). Then there's a positive wire (much larger gauge) that runs from the battery to the same fuse panel, and has a 10 mm bolt that connects it. There is a "bridge" and on the underside there is a positive that runs to the ecu power wire.

Now mind you - there are 2 main wires from the alternator, one directly from the battery and then the one (smaller gauge) that is run into the body and has the multiple connections made off of it.

All of those 3 white power wires had noticeable signs of being run hot - they were discolored a pinkish/beige in many spots.

New battery terminals...
Several "new" connectors from a spare MR2 harness I had...
Some wiring...
Heat shrink tubing, some connectors, and electrical tape...

I "re- engineered" a portion of the positive wiring. I cut out the ties directly from the alternator, ran a new cable from the battery to the box (no, didn't use fusible links as everything in the box is fused)... got rid of the bolt and put in a stud. I then built a new cable that ties to the same stud in the relay box, and runs to the 2 high current fuses and the efi fuse.

I also have on order an external insulates positive stud that I will mount high and away from the battery to connect accessories to.

I've run into issues in the past where 1 possible bad or corroded wire seeps the corrosion into the many branches of power wire, making a pretty big mess.

 

[toyotaspeed90]

For reference:
The power wire 'bolt' in the relay box (from factory runs to the battery)

(If you look really closely there is corrosion creeping through both the 50 and 60A fuses from the left, which is the power feed side).

You can see how there are random multiple branches...

The solution -

I will get some more photos when all done a bit better for the 'rest'.

If anyone had a spare cover for that relay box for cheap and could ship it, I'd be in the market...

 

[MyCrush]

How did this finally turn out for you? Problem solved?

I'm having the same issues that you describe...sometimes even from a cold start.

BTTT

 

[bigCatdiesel]

I've been working through a similar problem. The engine will kill randomly but I can fire it right back up. The tach gage would go crazy too. Sometimes I could pop it into neutral and coast and rev the engine to recover. A couple of additional suggestions from my experience....
check and clean all the grounds to the engine
check wire harness where it bends next to the egr pipe (I found all OK but re-wrapped it anyway).
check wire harness where the it bends and connects to the ECM under the passenger side dash (there is a metal frame it can rub with).
check injector harness connector wires (I had 2 connectors where the wires were exposed probably making contact to ground).
It finally threw a code, PO340, cam position sensor. I replaced it with new and no improvement. Then replaced Crank Position Sensor and made the repairs to the injector connectors. So far so good (driving it to work for 5 days).