Topic: 22re EFI trouble

[hilux911]

Hi guys, apologize for the long post, but wanted to give the full history in hopes someone can point me in right direction. Tried some other forums, but nobody has been able to help.
I’m the original owner of an 88 4x4 with stock 22re. Truck has been very well maintained and bulletproof it’s entire life, now having 321,000 on the clock.  Initial problem was a periodic condition where I was required to push the pedal down a little to start (otherwise it would catch quick and immediately stall). A few months later, it developed a hesitation/bog in gears 1 and 2 until the rpms come up. It got to the point where it became almost un-drivable. Didn’t do it cold, but after a warm restart. Easy throttle allows me to baby it along, but any time throttle is cracked it hesitated. All the EFI components are original expect tps and o2 sensors which were replaced at 230,000.

What I’d checked:
Checked and cleared ECU codes, nothing being thrown.
AFM checked per FSM, and found two values out of spec, replaced with a tested and “known good” unit from private party. No change in problem.
TPS tested and re-adjusted, same issue. Unplugged it when running, no change (still hesitated)
Fuel pressure checked, 45 psi when running. Tank is new and clean.
Thoroughly checked for vacuum leaks, nothing identified
EGR checked/cleaned. Working properly.
Water and air temp sensors checked and were within spec per FSM. O2 sensor good.
 

Truck happened to be due for “major service” (140,000 on timing chain), so before I went too deep troubleshooting, I figured I'd bite the bullet and address the stuff that it needed (anyway):
Timing chain and guides
Head cleaned/inspected. Valves sealing good. Compression check before teardown was 185 psi all cyls. Leakdown also good all cyls.
Plugs, wires, rotor, cap, fuel filer
Injectors rebuilt and checked for proper spray pattern.

I then had a mechanically sound (and very clean) motor that still hesitated in the first few gears.
Ended up hooking up my wideband air/fuel ratio meter and welding a bung adjacent to my o2 sensor to see what was going on.  After about 15 minutes, I noticed it gradually getting rich. I pulled a vacuum on the pressure regulator and saw fuel in the line. Fuel pressure was one of the first things I tested, but with key on power(45 psi) and running, but not for long enough period of time. Evidently, the diaphram had tiny leak that took quite a while to fill with fuel, which I thought led to the over-rich condition.

Thought I had it solved, but still having drivability issues.  I’d re-connected  my wideband to have a constant A/F reading in the cabin along with a fuel pressure gauge.  Two conditions/symptoms exist right now.  Here’s what I see:
1.   Within first mile or two after cold start-up, it runs extremely rich (a/f ratio 10 or less).  Removing top half of intake revealed fuel puddling cyl #4 worst, progressively better as you work towards #1. So when driving, this raw fuel must be ‘flooding’ the engine after start-up, but once it burns off, it’s fine.
2.   Once that passes, it will run right at 14.5-15 a/f ratio. Seems OK when cruising, but will not richen when you put your foot in it. Fuel pressure changes like it should w/ vac signal. About 5 psi diff between idle and cruising speeds. This had been steady since I replaced regulator.  Acceleration is flat, and it’s pointing to a fuel delivery (enrichment) issue.
Backed out the fuel rail with all injectors attached (except cold start). Pressurized the rail (40 psi) on gauge, and checked everything statically to see if anything leaked. Not a drop of fuel leaked from any of the injectors.  The pressure did drop overnight from 40 down to about 10, but nothing came out of the injectors. Triggered all the injectors with 9v battery to check operation . They all sprayed nice, and cycled as they should (these were rebuilt by Marren Fuel Injection a few months ago).
Cold start injector was individually tested same way, works as it should. I’m currently running the truck with it eliminated just in case by installing a block off plate on the intake and dead-heading the banjo fuel fitting.
The good news is it’s now throwing a code 22 (water temp sensor).  Orig one tested good (functionally throughout full temp range in hot water bath, replacing it with another had no effect on performance.
Electrically:
Checked and re-cleaned all 4 grounds again.  Removed ecu, cleaned mounting brackets and grounds.
I’ve tested the wiring and components (EFM, TPS, temp sensors, etc) again via the FSM. All devices ohmed out per manual.  All voltage tests at the ECM were also checked per the FSM, nothing out of range.
I had nothing else to test, so I sourced another ECU which is year specific for the 88 and that made no difference.  Still throwing code 22.
Recall from initial post that everything ‘maintenance-related’ has been done.  Running low on options to try, and frustration is growing. This vehicle has been my (trouble-free) baby for nearly 30 years and I don’t want to give up on it now!!  Calling on all the 22RE experts!!

[Lewis Hein]

Hey hilux911,

Welcome to the forum. There's plenty of people here who know more than you ever wanted to hear about keeping old Toyotas alive.

I'm not good at long distance diagnoses, but... it really sounds like the injectors are bad. I know you tested them, but maybe they only malfunction when they get hot? Like up to engine temperature? Or the fuel pressure regulator may still be causing problems... try a new one?

I know these sorts of problems can be frustrating. I encourage you to persevere... Well treated Toyotas with 185PSI on all 4 cylinders don't come along every day. If you get frustrated and quit, you always have the option to sell the vehicle to me at a nice deep discount...

[hilux911 [OP]]

Thanks for the reply.  Initially I really thought it was injectors, but I had a well known rebuilder also functionally test them.  I even swapped them to see if the puddling in the intake runners would move with the injector. That didn't change which also helped me rule out injectors.
To me, the ECU is telling me what it doesn't like. The code 22 suggests the ECU is getting an incomplete water temp signal, or none at all.  If it's not the sensor, the wiring to and from the sensor.  The EFI harness is the last thing I'm considering, and read that sometimes the factory crimped joints in the harness get corroded and have to be resoldered. The ground wire for the H2O sensor branches out and I re-crimped and soldered them. I even ran a redundant ground to the ECU. Still didn't make a difference.
I'm thinking the incomplete water temp signal is telling the ECU to run "middle of the road", and keeps me hovering at 14.7 AFR because it doesn't know if the engine is hot or cold. This would explain why the acceleration is flat.

I think it's electrical, and short of cleaning every single ground again (ECU to body, EFI harness grounds, head to body ground, battery ground, etc...) the only other thing I haven't swapped is the EFI harness which would rule out wiring.

Hopefully someone out there has seen this before and can point me in right direction!

[Lewis Hein]

Just curious... If it's a 1 wire temp sender, does it have a good ground?. I know it's threaded into the engine block, but maybe the threads are dirty... What happens if you hook up a resistor of the appropriate specs to tell the ECU that the engine is warm?

Of course, if it's a two-wire sensor, that all goes out the window. Sorry I don't remember off the top of my head which it is. Does a check with a multimeter indicate a short in the wiring to the WT sensor? If no short, what happens if you bypass those wires entirely?

Keep on muddling foreward. At the worst, you can replace the whole thing one part at a time and then you'll have a brand new truck for the next 30 years.

[hilux911 [OP]]

It's a two wire sender. The ground (E2 in my schematic) returns through the harness and had a at least one junction that I re-crimped and soldered.  Should point out that the areas of the harness that I unraveled looked brand new. copper wire and connectors show no corrosion or discoloration.  used ohmeter and have not detected any open or shorting the wiring. Tried a separate ground back to the ecu, no effect. The idea of trying a resistor to tell it it's at operating temp is interesting.  Will have to look at manual and identify what values it needs.

[Pappy]

A known issue on these trucks is the injector wire harness. There are several splices that get corroded and break. Solution is to pull the harness, peel back the tape, and check the crimps.

[gnob]

What does the regular o2 say alongside the WB?
Do they jive?
I

[RN37DD]

Hows the ignition timing? Check it with a timing light? If it's wrong, or not advancing, it well run flat too. A lot of times ignition problems well act just like a fuel problem.

[drayday55]

I rebuilt my engine and reloomed the engine harness.  I had a similar problem where I thought I screwed up the splice/ ground to the injectors.  I verified they were fine and still had the problem.  Turns out my cam timing was off by 1 tooth. Same problem you were having.   I dont know how many times I took appart the timing chain and I was overly confident that I had it correct.    The point is... Triple check the basics. The efi system on these trucks are so basic not much can go wrong.