mrnick1979

I have a friend who has a 91 22re 4x4, the truck was running great then just started skipping, almost like it is running on 3 cylinders, so I checked the compression, 120,120,120,110. I checked and adjusted the valves, checked plugs cap rotor all, ok... I then hooked up the timing light and shorted out the check connector, when I shoot the light at the pulley it shows that the timing is about -40 degrees out of time??? the engine never changes tune when I short out the check connector. HMMMM.. If I remember correctly the engine will change tune when you short out the pins .... So I decided to unplug the MAF sensor while the truck was idleing....the skip went away and truck is running smooth and the timing is at 5 degrees btdc. WTH.... I figure the MAF is bad , so I get a MAF off a good running truck of a friends to test my theory , well the truck still skips and the timing is still off, can anyone shed some light or point me in what I can check next.. I am stumped here, I have owned many 22re vehicles and fixed many but this one has me stumped... help me out guys..

mrnick1979

bump, anybody????

chrisgreene243

No codes being thrown?

mrnick1979

no codes, i have been reading and reading forums, i found out it may be the TPS, the key is that the engine should change tune when i jump out the test connector, if the computer does not see the engine idleing it will not go into timing check mode when you jump the pins out... I now have to check the TPS ....
Hope this is the problem, i will let you guys know..

SPARKS89

iTrader: (1)

The engine didn't die when you unplugged the AFM??? That's weird.

I think you're on the right trail with the TPS. Idle speed should change just by unplugging the TPS also. If it doesn't change it's a good indicator that the TPS is bad, but still check it to make sure it's within spec and there are no dead spots. You may have another issue going on also. The engine should have died when you unplugged the AFM.

oldblue

those are some low compression readings. i would try a different gauge first and do another compression test.

mrnick1979

well its been a few, but I cleaned the throttle body, it was gunked up bad, now the butterfly valve closes all the way. now when I short the jumper out the engine changed tune, timing was off a little, so I put it on 5btdc. unplugged the jumper still ran like crap. I noticed the intake pipe was cracked, so I wrapped some 50mph duct tape around it to seal it up, (temporary fix) , still runs like crap, I them checked the TPS, it checks out ok, I then checked out MAF its ok, I even got a maf off mt friends truck and it didn't help. The truck is not missing on any one cylinder, I can disconnect each plug wire and it drops out on each cylinder the same. It acts like not getting enough fuel, when I give it gas it wont rev up unless you hold WOT. I have no codes and no more ideas on what to check......... help please

combatcarl

Well it sounds like you set timing after removing the jumper. Hopefully I read that wrong, it's a little tough to read run-on or un-punctuated paragraphs for me. Sorry. Not a grammar nazi. So. If you disconnected the VAFM, (MAF as you called it), the engine should stall. So... You either didn't disco the AFM, or you have an electrical issue. The butterfly in TB should not shut fully. Read up 4crawlers writeup, or get a Haynes/Chiltons, and adjust the stop screw to spec.
http://4crawler.com/4x4/CheapTricks/TPS/index.shtml
Check everything for vac leaks again. I know, you did. But double check. Jumper FP and B+, see if you actually have pressure. (With a gauge)
Change plugs/wires/cap/rotor yet?
My TPS tested out ok, too, but readjusting it helped improve things.
Here's my adventure. https://www.yotatech.com/forums/show...916&styleid=51
Check one thing at a time. Let us know one thing at a time, what checks out or doesn't. Good luck.

SPARKS89

iTrader: (1)

Check your wiring between the AFM and ECU. If that checks out ok as your buddy if you can borrow the ECU out of their truck that's running good and swap it with yours. It sounds like something is going on there. The truck should have died when you unplugged the AFM. You tested the AFM and that checks out so I would be checking deeper into that circuit.

mrnick1979

thanks guys i was leaning towards a computer, The truck actualy idles better when i unplug the afm??? Thats what was puzzleing me from the start. I will have to het deeper into the circuit, i just bought a parts truck and when i get it home i will pull the computer out and try that. I just found out that the truck previously had a short in the wiring(for the fuel pump circuit) in the firewall and was reapired by a local electrical shop. It will be a few days before i get to mess with it again but i will keep you guys posted, thanks for the help again.

combatcarl

Well, the fuel pump circuit repair is the issue. Hence why it runs with AFM unplugged. These trucks are designed to shut down the fuel pump if the engine quits running. So if the vane in the AFM closes, the fuel pump circuit is opened. Safety thing. But that's where is look first. Probably a hack job that mixed up a wire or three. And FWIW, these ECUs really don't fail unless they get wet or otherwise damaged.

T4R War Eagle

Check egr?

My94yota

I agree theres something going on here also....Any updates on this?