Bizarre Starting Issue - 22RE

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Hey guys,

I'm the proud owner of a 1988 4Runner with the 22RE 4-banger. Recently it has been acting up on me (obviously not getting enough attention). I've followed the troubleshooting rabbit trail about as far as it will go so I am looking for advice.

The truck starts and runs perfectly fine when cold. Once hot, the engine will crank over but not start. After it cools for an hour or so, it will restart easily. This issue is very consistent.

When it refuses to hot-start, I can spray a small amount of starting fluid into the throttle body and then it will start and run without issue.

Here are a few things I've ruled out:
- Ignition is good, spark is hot blue even when cranking hot.
- Fuel pressure is good (40psi) [only checked when cold, need to confirm when hot]
- I have swapped/borrowed multiple electronic components and none of them have changed the issue, including: engine coolant sensor, air flow meter, circuit opening relay, ECU, coil & igniter.

It appears that the injectors simply are not firing when the engine is cranking when hot. I just got a stethoscope and will try to better understand what the injectors are doing.

One other oddity is that the engine does crank over slowly. Battery is brand new and reads high voltage. Grounds are good. Starter is brand new. Starter cable has good contact between both battery and starter terminal. Could this be a failing ignition switch?

Any further ideas would be helpful.
 
I have a good memory for useless things. Long ago I had a 89 Pickup with 22re same issue. It related back to the cold start injector working when the engine was warm already essentially floody it. Maybe faulty coolant temp sensor. Good luck
 
Thanks for the idea. One thing I tried was putting 12V across the cold start injector while hot-cranking. This actually helped it start, so the issue feels more like a lack of fuel than a surplus.

But this does confirm that I need to look more closely into what the cold start injector is doing as well.
 
or pressure regulator. or if that engine has the rubber pulsation damper, that thing could be cracking and losing fuel pressure as well.

might try experimenting by keying on/off a few times to build pressure, then crank.

love the 22RE....
 
Thanks, already getting some great ideas from you guys. Will keep you updated as I troubleshoot more today.
 
Fuel pressure is good when the engine is hot or cold.

I can hear the injectors clearly with a stethoscope. When the engine is cranking, hot or cold, they do not fire. Once it starts, they rattle away like they should.

My theory is that the cold start injector helps it get going when cold. Once hot it doesn't kick on so the engine has no fuel at all.
 
I had the exact same problem with a 1982 Celica with a 22R. The problem in my case was a bad ignition pickup in the distributor. You can test it by getting it hot so it fails, then spray the pick up under the rotor with a NON FLAMMABLE liquid with a low boiling point to quickly cool the part then try it. Back then I used Freon, but now you will have to find something similar, like CO2, and make sure you spray it with liquid, the gas won't cool much.
 
Thanks Todd. I had ruled out the dizzy because I was getting spark. I suppose it could also affect the signal to the ECU regarding the injectors.
 
Originally Posted By: another Todd
I had the exact same problem with a 1982 Celica with a 22R. The problem in my case was a bad ignition pickup in the distributor. You can test it by getting it hot so it fails, then spray the pick up under the rotor with a NON FLAMMABLE liquid with a low boiling point to quickly cool the part then try it. Back then I used Freon, but now you will have to find something similar, like CO2, and make sure you spray it with liquid, the gas won't cool much.


My off topic reply for the day:

You can use those canned air dusters. Just spray them inverted and you'll get a really nice frosty stream.
 
Update:

Fuel pressure is perfect.
Spark is good.
Injectors get a signal (verified with noid light) but do not fire when engine is cranking. It has nothing to do with hot/cold.

If the injector solenoid resistor is bypassed (thereby eliminating ~3 ohms from the circuit), the injectors fire perfectly.

Since the resistor readings are in spec, my gut tells me now that it is the ECU. The leads that go to the ECU get a solid 12V where it needs it and have very good grounds also where it needs it.
 
i would look to the coolant temp sensor first.
ecm bases its startup strategy by it.
would you believe that more than half of the ecm's sent to me for repair have nothing wrong with them?
 
Turned out to be bad grounding. Main wire was not connected well, some other ground wires were missing. This caused the FI circuit to see an extra 2 ohms of resistance which it could not cope with.
 
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