FastFlyer

Nomis: 1993 SC400 (stated in my first post earlier in this thread.) I did spray into the holes on the pillar (see below.)

rbert: I did spray into the holes on the black pillar. I sprayed all accessable inside surfaces of the VAF, without removing the electronics. I'm not sure if switching VAF's between vehicles will be a valid indicator unless they are the same year - the electronics may be different enough to preclude any comparison. If the VAF's are from the same year vehicle, AND CLEAN, then yea, I'd say you have a different problem - except that disconnecting it lets it run so much better. It's seems possible that your friend's VAF is also contaminated and his electronics (ECU, etc.) may be compensating for the dirt correctly. If you clean your VAF carefully it can't hurt and might help.

UpInTheLex: hairdryer - Great Idea! I do not have the BFI, or at least not as advertised. I modded the snorkle into the air filter box by cutting out the bottom of it and removing the plastic divder in the middle of it, which made a significant difference in acceleration.

Preventing dirty VAF's seem to be a very good reason to stick with the best air filters, even if they do restrict more than a free flowing filter.

I drive it 95 miles/day and am still used to opening the throttle to the point where the hestation is and...






IT DOESN'T HESITATE! Smooth as glassssss!

Piece

rbert

My friends is the same year (95) 60 serial numbers apart and same P/N vaf. I also swapped his computer, no change.

UpInTheLex

iTrader: (5)

Hey Rbert, you ever try removing 3rd cat from your exhuast, this helped me out. also i can't remember but did you clean your injectors recently?

Also did you try 02 sensors and what effect did it have?

Nomis

So rbert, you still have the same problem - right? And Fastflyer - your problem is solved. But rbert - you tried the fix listed by Fastflyer and it didn't work on your car, right? I just want to make sure I'm on the same page. Thanks.

akforte

hi rbert did u fine the hesitation problem ? i still have the same problem, i am selling my car 92 sc 400

cal9126

any updates or fixes for the hesitation problems on the sc?????

john_sc400

I'm diappointed this thread just ended with no solution posted.

What happened? Is it fixed now? What was it?

I just bought a 95 SC400 with 95k miles. it was hesitating and surging very badly at all speeds. I could feel it when cruising on the freeway. It stumbled a lot from a dead start. I added a bottle of Techron to it and within a half mile it smoothed right out. I'm guessing it was water in the tank and lines. I've added a bottle to every tank for the past three tanks.
FWIW, CostCo has 4-packs of Techron for $9. One bottle was over $5 at Pep Boys.

BUT, I still get an intermittent hesitation from a dead stop. It feels more like it surges forward and then stumbles. Rare, but irritating. I'm going to try some of the fixes found in this thread.

Nomis

[QUOTE=john_sc400]I'm diappointed this thread just ended with no solution posted.

QUOTE]

Because no definative solution has been discovered - if you find one, by all means enlighten us all.

So far we know what does not solve it:
- Trans flush using Toyota TypeIV fluid
- New torque converter
- Engine and trans mounts
- Cleaning the throttle body
- Cleaning the MAF

I've personally done the flush, new engine and trans mounts, and cleaned the throttle body and MAF - and while it seems to have helped, it has not alleviated the problem completely.

UpInTheLex

iTrader: (5)

I'm starting to believe that the hesitation is caused by the knock sensor. I think it must malfunction and pull(retard) the timing like crazy for a split second. Anyone have anything to add to this? Any experience... I'm going from a hunch. My car never misses, pings, or the like, but it can be awful sluggish, say on 87 octane, or before a tune up. It will surge or be down on power and then all the sudden power will come on. Knock Sensor is my new guess. What do you all think?

john_sc400

Could be. And if the timing was set with too much advance, it would trigger the knock sensor which would retard it,

I'm also wondering in my case, since it's intermittent, if something is sticking like an EGR or if there is a PCV on this car.

Just bought it and have no tech info on it yet.

Nomis

Some have stated that the EGR was the culprit - but I don't think anything definative came out of those discussions either.

SCV8

My would always run porly like that on 87 octane, that's why I have run 90+ ever since.

cal9126

someon had a post about this to saying that when he brought the car in to get this problem fixed the guy told him that he needed to replace the egr system,but i dont think he spent the 80 or so dollars to replace it......what does the egr do.....i know it means exhaust gas recirculation.....but how does it work...

john_sc400

Be sure that BOTH O-rings are in place and provide a good seal when reinstalling your VAF!

CantSeeMe

*I have edited this post slightly*
Hey im just curious, is it throwing any codes? I have been having all these symptoms being discussed in this thread.
This may or may not be part of the problem. But i am throwing code #63. (Solonoid Valve #2).
According to the FSM, its 1 of 3 things the solonoid valve , the harness , or the ECU.
Has anyone else with these problems pulled the codes yet?