88 all trac falls on its face under acceleration

lt2fire

Member
FIXED!!!! It was an incorrect washer on the fuel pulsation damper.

Just got an 88 alltrac that falls on its face under acceleration.
Previous owner said that it was the cat that was clogged. I removed the cat and gutted it. I also saw that the exhaust turbine housing was cracked so I replaced that. Got it all back together and it does the same thing. When reving in neutral it will stumble slightly but will still rev. When in gear it will just bog and not do anything over a certain RPM.


I'm open to suggestions if I don't figure it out soon i'll have to sell it as i'm in a time crunch right now.

Has a new fuel pump in it.
 

underscore

Well-known member
I'd do the usual checks for an intake leak, exhaust leak, and alternator issues. When I forgot to install my alt belt once it behaved like that.
 

FC Zach

Active member
Air flow meter? Years ago I had a similar symptom where my car felt under powered and sluggish until a certain RPM and at that point (like a switch was flipped) it would run fine. Since my car had a few undiagnosed issues at that point in time, it could have been completely unrelated to the AFM but it's one of the parts I replaced that got the car running normal. . It's at least something for you to look at or even swap if you have access to another. There's a test procedure in the repair manual.

Here's one example of the test procedure but you'll need to check the book for specifications.
26312910499_8c16076995.jpg
 

dbucks2k

Member
It's also possible that it's the TVIS. If it has a vacuum leak or isn't working properly then it will stay open. Causing horrible acceleration at lower rpms.
 

lt2fire

Member
dbucks2k":3jathang said:
It's also possible that it's the TVIS. If it has a vacuum leak or isn't working properly then it will stay open. Causing horrible acceleration at lower rpms.


How would that work? I would have thought it may hinder tourque a little but would still accelerate.... mine just bucks like a pissed off horse.
 

dbucks2k

Member
It's just an idea. Because Toyota designed the fuel map to work with the TVIS. And if the TVIS stays open it causes issues with the velocity of the air going through the runners. And can mess with the air fuel ratio. But again it's just a thought.
 

lt2fire

Member
Haven't had a ton of time but I checked for vacuum leaks and couldn't find any but will look again.

I also unplugged the TPS and the car drove exactly the same... to me that may mean it is bad.
 

lt2fire

Member
I also just realized that my boost gauge is not working at all.

If the sensor is bad that could lead to not getting enough fuel when the turbo spools up right?

although it will rev in neutral.... hmm
 

dbucks2k

Member
That's possible. The boost sensor is tied into the ECU, TPS, AFM, and boost gauge.
 

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lt2fire

Member
Ok I pulled the vacuum line from the Turbo pressure sensor and put a bolt in it.

Didn't change a thing.

So I guess now I move on to the AFM????
 

FC Zach

Active member
I don't understand why you haven't already. . It's free to check (if you already own a DVOM).
 

lt2fire

Member
FC Zach":3c4vls6f said:
If you need the specs, I'll look at my manual and share them here.

Could you do that please?

For the life of me I can't find it in my Factory service manual. It tells me to go to a page that isn't there. I must have downloaded an incomplete one.
 
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