88 all trac falls on its face under acceleration

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88 all trac falls on its face under acceleration

Postby lt2fire » Tue Sep 04, 2018 5:24 pm

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.
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Re: 88 all trac falls on its face under acceleration

Postby dbucks2k » Tue Sep 04, 2018 6:53 pm

Are you at a higher altitude?
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Re: 88 all trac falls on its face under acceleration

Postby dbucks2k » Tue Sep 04, 2018 7:05 pm

Also does it run fine after the engine warms up?
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Re: 88 all trac falls on its face under acceleration

Postby lt2fire » Tue Sep 04, 2018 10:07 pm

no runs the same cold or warm... pretty much at sea level
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Re: 88 all trac falls on its face under acceleration

Postby dbucks2k » Tue Sep 04, 2018 10:23 pm

Hmm. Don't know then. I had a similar problem but it was only when cold and I'm at high altitude. This fixed it for me, but don't know if it'll help in your situation.

https://www.mr2oc.com/61-3sgte-turbo/28 ... ics/287627
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Re: 88 all trac falls on its face under acceleration

Postby underscore » Tue Sep 04, 2018 11:54 pm

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.
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Re: 88 all trac falls on its face under acceleration

Postby FC Zach » Wed Sep 05, 2018 5:46 am

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.
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Re: 88 all trac falls on its face under acceleration

Postby dbucks2k » Wed Sep 05, 2018 9:21 pm

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.
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Re: 88 all trac falls on its face under acceleration

Postby lt2fire » Wed Sep 05, 2018 9:54 pm

dbucks2k wrote: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.
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Re: 88 all trac falls on its face under acceleration

Postby dbucks2k » Wed Sep 05, 2018 10:37 pm

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.
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Re: 88 all trac falls on its face under acceleration

Postby lt2fire » Fri Sep 07, 2018 3:29 pm

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.
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Re: 88 all trac falls on its face under acceleration

Postby lt2fire » Fri Sep 07, 2018 6:57 pm

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
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Re: 88 all trac falls on its face under acceleration

Postby dbucks2k » Fri Sep 07, 2018 8:44 pm

That's possible. The boost sensor is tied into the ECU, TPS, AFM, and boost gauge.
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Re: 88 all trac falls on its face under acceleration

Postby lt2fire » Sat Sep 08, 2018 10:04 pm

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????
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Re: 88 all trac falls on its face under acceleration

Postby FC Zach » Sun Sep 09, 2018 11:07 am

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