idles, but won't rev

4bangr

4bangr

New member
210k miles and this is the first time she left me stranded....
'97 3.4
initially, it would try to start and then die, sort of classic MAF unplugged behavior. Then it would start and idle, but opening the throttle only made it stumble but it won't rev at all, even at WOT, it just idles.
- no CEL codes
- with my code reader, i can see the TPS sensing and reporting correct %open.

- I took the MAF out and tried to test it, lots of contradictory information on the web, one basic test, between pins 1&2 shows open; which suggests a failed unit.

I'm thinking it's the MAF sensor, but i'm surprised it didn't throw a code.

any other thoughts?
 
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Could be your FPR. Mine gave out in basically the same way. Started fine, but shut off immediately after. Would stay alive when steady throttle was applied, but too much throttle and it would stall out as well.
It actually started spitting fuel in the air intake baffle.

If you want to try a new MAF, give this a shot:
https://www.amazon.com/gp/product/B006WHKKGY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
It's not OEM, but it works just fine and is like a 5th the cost, so if it doesn't help, you're not out much money.
I bought one when I was having fuel pressure issues, and now it's my spare, as my original turned out to be fine.
 
AntleredRuin said:
Could be your FPR. Mine gave out in basically the same way. Started fine, but shut off immediately after. Would stay alive when steady throttle was applied, but too much throttle and it would stall out as well.
It actually started spitting fuel in the air intake baffle.



Where is the FPR located?
Click to expand...
 
23721f.jpg


Follow the red line on this hose to the back of the fuel rail. it will be under the intake plenum. It SHOULD take vacuum from the Air Intake Baffle/Silencer (where the red line starts) but when it fails it could start just dumping fuel into the baffle through that hose and not holding pressure.

That's not to say that if it's not dumping fuel that it's NOT bad, however. Just a way that it COULD fail.

FYI, I had a CEL once when I stalled it, but then it went away by itself. Always had codes (I forget what they were, but said MAF, FPR, or Fuel Pump) though.
 
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Probably rare, but my buddy's subaru had this same condition, and it ended up being a clogged catalytic converter.
Hope its one of the other easier fixes though.
 
Oh, I'd MUCH rather replace the cat than the FPR again. You have to remove the whole air intake setup, and the whole fuel rail. But first you have to fight with the %$#^(%$ wiring harness. Should probably remove all the injectors too so you don't do like I did and break one off in the manifold. Then you have to remove the valve covers because they block the intake manifold and THEN remove the intake manifold to fetch the bit out.
Then you gotta get the fuel rail situated in your lap and get a crescent wrench on one end to hold it in place as you apply superman strength to the BRASS bolt holding the FPR on that Toyota thought was a good idea. Without stripping it.


I did it myself and I'm not a pro, so naturally I took a while longer (and broke a part), but I'd estimate that a shop would probable charge 3 or 4 hours (at $100/hr, or course) to replace the FPR AT LEAST. It's a little *****. That PLUS parts cost.

The cat can just be sawzalled off and replaced by clamping a new OEM on, can't it? Welding is the 'proper' way to go, but not strictly necessary.


Out of ALL the good things that Toyota/Hino did with the 3.4, the FPR is NOT one of them. From my research, though, it sounds like I'm one of the few on this forum who ever had theirs go bad. I guess a REAL lifetime part is allowed to be a PITA.
 
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well, i ordered a cheap junk yard MAF off ebay and it fixed it. ($30)

anyone using a non-toyota MAF? probably cheaper just to keep buying used ones off ebay.

it sure runs better now too, the SC really likes it.
 
well perfect!
I have a non-OEM for my backup that works great. I think it cost $13 on Amazon.
As mentioned before, I bought it when I was having my FPR issues, but realized I did not need it.
I actually drove with it for a week after the final FPR solution, and it worked just fine. The life expectancy is only 2 years or so, but at a 5th the price of OEM new, as long as the efficiency is the same, who cares?

Glad you figured it out!
 
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