Toyota 22RE engine puzzle

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  #1  
Old 01-25-05, 02:39 AM
paul54
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Toyota 22RE engine puzzle

I have a 1988 Toyota 4WD pickup with a 4 cyl (22REC) fuel injected engine. When it is first started (cold start-winter day), the engine will rev-up to 1500 rpm. After a couple of minutes, the idle will drop and that is where the problem starts. It begins to misfire quit badly. After the engine comes up to normal operating temperature,it staightens right out.

There seems to be three phases to cold start.
1. Initial start-up with high revs.
2. Problem phase - lowers revs, but does something else.
3. Normal operating temperature with no problems.

My guess is that some sensor is telling the computer to do something during that "second phase" of warm-up and something is going wrong.
After the engine is completely warmed-up, it goes away quickly, like somebody threw a switch.

I have done a tune-up(rotor,cap,plugs,wires), replaced the tempurature sensor for the EFI, the thermostat, checked timing, and cleaned the throttle body.

During this "second phase" of warm-up all cylinders start misfiring. I've disconnected one spark plug at a time to try to identify a single cylinder. I've disconected and connected EVERY vacuum hose and sensor connection to try to identify the source of the problem and cannot reproduce or identify the source.

I can't figure out for the life of me what would make the engine start fine, get rough, then warm-up and run fine. I've also had a timing light on during this "problem phase" to see if the timing changed - it didn't.

I've also taken out and inspected the ECU for any signs of physical damage (water stains, burnt circut board, ect) When I opened the covers to the ECU, it looked like it just came out of the factory, not even dust inside.

Any thoughts would be appreciated, Thanks
 
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  #2  
Old 01-25-05, 05:10 AM
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Join Date: Aug 2003
Location: Cape Cod
Posts: 4,320
My first thought is you are barking up the wrong tree
Picture this:
The engine and O2 sensors are still warming up when the problem starts
The computer is still is "closed loop" (using pre-programmed values, not relying on sensor info)
Let's say there is a...for sake of argument say an air or fuel restriction
The computer doesn't know that and is assuming everything is factory aok
Crappy idle
Engine, O2s, warm up, ECU goes into "open loop" (sensor info), computer sees it's rich/lean, and compenastes...bammo-switch thrown idle fine

How long before it smooths out and do you know if the O2s are heated? (HEGO)
 
  #3  
Old 01-25-05, 06:01 AM
Join Date: Jun 2002
Location: Long Island, NY
Posts: 1,531
I would look at the O2 sensor when warm to see if it's switching. Your looking for .2-.8 v swing back and forth .


I would also back probe the water temp sensor signal wire at the ecm to watch voltage change thru warm up. Should start at around 2-2.5v cold assuming 32*F or less and come down to .3-.5v warm.

Had you check for codes?
 
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