1989 Toyota 4×4 truck (1 Viewer)

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Joined
Feb 1, 2023
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Location
Pasadena California
I can't get my truck to run. Engine light says Mass air flow sensor or oxygen sensor. I've now put three mass air flow sensors and a new ogxegn sensor new EGR, the engine is new and it still isn't running. Light doesn't come on when cold but will after about 2 minutes of driving it. Does anyone have any suggestions?
 
does it run or doesn't it?
if youve thrown parts at it and its throwing the same codes, you likely have wiring issues.

what EXACTLY is it doing or not doing that its supposed to be doing?

who rebuilt it? who installed it?
 
I know people tend to call an air flow meter (AFM) a mass air flow sensor (MAF) so I will assume it has an AFM based on the year. They aren't very easy to come by these days, where did you get 3 of them to try?
Anyway, I'm with Gnob on this one. Sounds like a wiring issue. It probably runs for a few minutes because it is in open loop, then it warms up and tries to rely on sensors.
 
does it run or doesn't it?
if youve thrown parts at it and its throwing the same codes, you likely have wiring issues.

what EXACTLY is it doing or not doing that its supposed to be doing?

who rebuilt it? who installed it?
Engine is strong, won't idle, showed symptoms of the mass air flow sensor being bad but there's no way after the third one. Drove the truck for 3500 miles after new engine with no problems. Could it be a partial plugged cataloyc converter?
 
is your crossover tube cracked or damaged. vacuum leaks?
melted o2 wiring is pretty common too.
Nope all of that checked out to be good. This truck still has original catalytic converter and muffler and the truck was driven for a long time on five cyclenders. Is it possible that the catalytic converter could be plugged cause it to not breathe correctly causing these issues?
 
Is this issue just recent? After engine rebuilt? check all your vacuum lines and try disconnecting the EGR vacuum source.
 
Nope all of that checked out to be good. This truck still has original catalytic converter and muffler and the truck was driven for a long time on five cyclenders. Is it possible that the catalytic converter could be plugged cause it to not breathe correctly causing these issues?
clogged exhaust is typically more apparent at higher rpm.
 
Is this issue just recent? After engine rebuilt? check all your vacuum lines and try disconnecting the EGR vacuum source.
Yes after engine rebuild. I'm at a complete loss as to what to do. Short of replacing the wiring harness and fuse relays all other components have been replaced. New EGR valve and Mass air flow sensor. 😳😳😳😢
 
Yes after engine rebuild. I'm at a complete loss as to what to do. Short of replacing the wiring harness and fuse relays all other components have been replaced. New EGR valve and Mass air flow sensor. 😳😳😳😢
Did you return this to the shop who did the work? They missed something for sure. I bet you it's something simple, check the basics like timing etc.
 
What if you just open the throttle a little bit? Have you tried manually adjusting the idle? If so, how does it run like that?

TPS adjustment is a good idea. Engine should usually be able to run in a closed loop mode even if there's problems.
 
Yeah they've looked and re-looked and had another shop also look. But now I'm broke again so it's just going to have to sit now 😳😢
This sucks, do you have a vacuum gauge and a timing light? Also a compression gauge set would be nice. Let's just start with basics first and go from there.
 

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