1991 22re stumbles hesitates shudders bucks, and still gets 27mpg

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H

HntWhtTail

10 Year 15 Year
Joined
Mar 19, 2006
Threads
96
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499
Location
Belgrade,MT
I finally got my 2wd mini back from the brother in law. I took it on a short road trip 150 miles, Intermitintly it will start bucking, under throttle, limiting speed to under 50 mph. It seems worse when going uphill or down., If i shut the truck off for just a few minutes the problem goes away. When cold I can jump in and everything is fine. the round trip to work and back 14 miles no sign of problem on one trip then randomly appears on the next. With all of this going on over two mountain passes hauling a spare box for the truck, I still got 27mpg. Bucking and all still beats the hell out of the 13 mpg in the 60..
I done the following
Replaced plugs, distributer cap, rotor, air filter, oil and filter change.
tested tps has constant increase in ohms from idle to full throttle no dead spots.
any help would be much abliged.
 
Are you positive on the math? 27MPG running rough or well, seems high. Not that you should be complaining, just curious. As for the stumbling, fuel filter been done? All vaccum lines are good, no leaks or cracks or missing ones?
 
Sure smells like a clogging fuel filter to me, but then again it could be a zillion other things. There are some things I would not suspect because of the 27 mpg (such as intermitten mas sensor malfunction) There are other things I would not suspect because you did not indicate that you were getting a check engine light (such as 02 sensor).?????????
 
I would...

start with a tune up. Then follow that up with the in-tank filter and fuel filter replacement.

Included in those procedures I would check for codes and the ignition timing.

Then if all that doesn't work. I'd inspect the timing chain and oh, what the heck, I'd replace it.

If none of that worked I'd have to beak out the ohm meter and start checking components(TPS, and Oxy sensor). Then the only place left I can think of would be the exhaust and compression.


And look on the bright side. If you tune it up and replace certain PM parts and it STILL doesn't fix your problem. You just did a lot of PM you should have already done and that you probably wouldn't have done anyway if you would have known the exact problem and just fixed it.


IMO, a properly running Toyota is money in the bank...
 
I did the fuel filter about 3 years ago, no check engine light. I have visually inspected all vac lines all present and accounted for. Timing chain sounds like fun!!! Thanks for all the ideas, I will check everything mentioned and update post as it goes along. Math is correct for the mpg. It shocked me when I did it. This truck has always done very good on gas, when driven like grandpa it use to pull 32 on my daily commute to work 87 miles round trip for 2 1/2 years. rarely went over 60mph only one small hill a good tail wind most nights.
 
I had similar rough engine going up hills and during hard acceleration with an '85 22re. I did a full tune up and checked all vacuum lines. Finally found a clog in one of the vacuum lines running from the charcoal canister, looked like a piece of filter material had come loose and gotten lodged in the vac line.
 
I did a basic check of the tps, ,
how does one check the afm?
I had the radiator flushed yesterday, because it needed it no bucking on the way home but I don't know how the radiator would affect it..
 
Clean the throttle body. I had missing problems and clean the body with B-12 carb cleaner and she runs like a champ.

Grouseman
 
On the ride home started to hesitate again, I was reading about the afm, and I thought for fun I would open the air box up, when running if I manually open the valve in the air intake, it hesitates, and almost dies is this normal??
 
So I searched and found some test numbers for the afm, so I was going to disconnect and test. I pulled the two scews out and gently pulled on the harness it came out with a couple of burnt looking terminals with some connectors attached. I think I may have found my problem pics in a few minutes...
 
sorry no pics camera is mia...reading from vs to e2 either pin is 1968, 1793 way over specs listed in another post.
 
HntWhtTail said:
So I searched and found some test numbers for the afm, so I was going to disconnect and test. I pulled the two scews out and gently pulled on the harness it came out with a couple of burnt looking terminals with some connectors attached. I think I may have found my problem pics in a few minutes...
Click to expand...



:confused:

:idea:


Hilux said:
dang man I'm sorry....

I ran accross some info that might help you out but it was before you had a problem and I don't remember how I found it.

I'll try and explain what I can remember....and hope it fits your criteria.

ok while some surfing I came across Marlin Crawlers forum, in it was a post about a piece of harness known to go bad. The guy was an ex engineer, or son in law of an engineer that worked at the facility the Toyota harnesses were made. He went on to locate the problem area... some type of erosion in the area (IIRC) that you are having problems....


I'm going hunting for it wish me luck!
Click to expand...

Hilux said:
important efi information!!!
Click to expand...
 
Relplaced afm complete with pull off from junk yard. tests fine truck still having problem....I will keep replacing parts until it stops.
 
no feeler guage, just connected mm and slowly moved throttle from none to open watching reading, increased with no big gaps or dropping off, I had a mustang once that the tps went bad and when performing the same test, it would lose continuity at about 3/4 throttle then connect again a little deeper into the gas, it behaved very similar to the toy, however the same test did not show any problems with this tps, it was the first thing I checked.
 
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