Stalling after higher RPMs

[smagnotta]

Anyone know the cause of a 5-speed 7M-GTE stalling after hitting higher RPMs? For example, say a half hour drive on the highway and then winding down the RPMs when approaching a stop sign or stop light?

It does not happen all the time but seems to happen the most when going from a high RPM and then reaching idle.

I have replaced some things but I am thinking coil packs maybe?

I have another problem but I thought another thread would be a good idea.

Thanks for any ideas on this issue.

 

[oneandgone]

Sounds like both problems are caused by the same thing...running too rich. What are your mods??

 

[YoNkErS87t]

do you have an aftermarket BOV?

 

[smagnotta]

Mods:

Lexus AFM
550 cc injectors
HKS SSQV BOV
racing intercooler with custom pipes
suprasport turbo elbow, 3 inch downpipe, 3 inch exhaust, tanabe cat back
1 super flow CAT
(Stock Turbo)
SAFC
HKS EVC electronic boost controller
Zeitronix Wideband O2 sensor (just the lambda and the air/fuel ratio are hooked up)

I used the wideband. I just got it and installed it. It's working and I adjusted the air/fuel ratio with my SAFC. I was running rich. Not pig rich but it needed tuning. It helped a little bit but the car still has the following problems:

(1) misses at idle
(2) backfires when decelerating
(3) stalls after high RPMs

I don't think the missing at idle is due to richness because I checked the Vf voltage and it says 2.5 and the air/fuel ratio is at 14.6 and 14.7 with the wideband.

I have replaced the spark plugs twice as these problems have been occurring for a while, the plug wires and one coil pack. Even the ground to the coil packs. These were things that needed changed but it did not affect anything.

I found that replacing the stock O2 sensor helped some with the backfire problem. It was the original one with 122,000 miles on the car and was ready to be changed.

I have the S-AFC at -20% and -23% at most of the higher RPM levels.

I am getting 23 miles per gallon and I drive it both in the city and the highway.

I replaced a lot of things on this car. Here is a partial list of parts I have not replaced or have not done:

1- TPS -Throttle position sensor
2- CPS -CAM position sensor
3- Check or reset the timing
4- ECU - the main computer
5- 2 original coil packs.

Thanks,
Sal
'87 T

 

[oneandgone]

If the bov is vented to the atmosphere rather than being recirculated that's probably the cause. I used to have the exact same problems with the same bov, and very similar mods. I'm now running the AEM and have converted to speed-density, so everything is smoothed out.

 

[lagged]

you can try tightening down your BOV a litttle more to try to help the stalling problem.

 

[smagnotta]

The thing is - the BOV is being recirculated. It isn't venting to the atmosphere. I forgot I also have the Walbro fuel pump in the list of mods.

The missing at idle and stalling after high acceleration was occurring in my car for the past 3 years. These problems were there before all my modifications if my memory is right. I even have a metal head gasket and all the work associated with that too.

The backfire under deceleration is a new problem that has shown up in the past year.

Could timing have something to do with these problems? Or a bad ECU?

 

[IJ.]

Bad/blocked stepper motor for the ICS?

 

[albertmdh]

i've been stalling alot after a hard run through 3rd gear, after i let off, it stalls, and the power steering goes out(aaaah! i live on windy roads!) and i have no mods, so im interested in what fixes this as well.

 

[DrakeMK3]

What is your vacuum reading?

 

[Anomili]

I had almost the identical sypmtoms in my 87T. Turns out that my afm had self imploded. The symptoms got worse and worse until the car ran the same regardless of whether or not the afm sensor was plugged in or not. I'd recommend checking your afm to see if the resistivity of the various circuits are what they are supposed to be.

 

[albertmdh]

how do i check the vacuum reading?

 

[DrakeMK3]

Hook up a vacuum gauge to your vacuum lines and read what the gauge says but be sure you know how it reads (in PSI or Hgmm, etc.).

 

[smagnotta]

(original author)

I have a brand new AFM from SupraSport. The electronics are the originals; I have no error codes.

My vaccum: when I first start the car -- around 16.5 PSI

When car warms up and is on for a while -- around 18.5 PSI

 

[albertmdh]

sorry for butting in on your thread, man, i seem to find i have alot of the same questions/problems as alot ofpeople.

 

[smagnotta]

No problem - I welcome it!

I just wanted people to respond to the right person that's all...(Not to mix up the answers)...

 

[smagnotta]

"Bad/blocked stepper motor for the ICS"

What is the ICS stand for please? I forget... Thanks

 

[shaeff]

"Bad/blocked stepper motor for the ICS"

What is the ICS stand for please? I forget... Thanks

i think he means ISC, - idle speed control. its on the front of the intake manifold, about 2" in diameter. has a (if i remember correctly) 6 pin plug that goes into it.

edit: here ya go- http://www.cygnusx1.net/supra/library/TSRM/fi/FI_106.html

-shaeff

 

[YoNkErS87t]

Check the Isc and your timing.

The timing would be pretty easy to check if you have a timing gun. Only takes a minute to do.

 

[IJ.]

Shaeff: Thanks I'm using a Ford ICS so often make that error !

If the stepper is dead dying or it's passages are filled with crap it will cause those symptoms described.

It can't react fast enough to catch the idle when closing the throttle.

Pretty sure the Toyota ECU does the shut the fuel off on trailing throttle thing so you give it a squirt back off the ECU shuts the fuel off the revs drop the ISC is meant to add some air to catch the idle as the fuel comes back on(sort of like pressing the gas a touch to stop it stalling)