Missing Power on lowend

[cbul7210]

Hi All,
I recently got a 1991 Toyota Supra 3.0 non turbo and I love the car except I have a minor annoyance with it, It seems like it only makes power when tach hits around 2500 on up and taking off from stop sign or stand still it seems very doggy, I checked the timing on it and it is running at 10 degrees where it should be according to specs, plugs look OK and engine temp is normal, Was wondering if anyone else has had this problem and how to trouble shoot it, BTW more info, Has new timing belt installed and ingition coil replaced, Plug wires look like they are in good shape (no arching), any info in this would be appricated, Thanks
Cbul7210

PS not sure what is differnce between 7m-GE and the 7mGTE, Hope I am posting in the right forum :1zhelp:

 

[Ma70.Ent]

7MGE = non turbo
7MGTE = turbo

If you have seemingly weak low-end and it starts to work a lot better at above 3800 RPM, it could be an ACIS problem. Other than that, I'm not sure.

 

[cbul7210]

Hi there, If I may ask what is an "ACIS"
and to add some more info, There is no check engine light lit up. and i had one mechanic suggest dirty injectors but thinking that one over wouldnt it affect the whole power range exp on the top end part?
Reason for this post is im trying to elimiate some of the obvious problems before deciding to take it to a shop (which I really cant afford at moment) and i do appricate all the suggestions
Cbul7210

 

[benchwarmer]

Does it idle smoothly and at the appropriate rpm? If your idle is off due to vacuum leaks or a faulty TPS you will have power loss at low rpms.

 

[CRE]

I'd start with checking the ACIS diaphragm, then the vacuum hoses, then the VSV. ACIS is an accoustic modulation system in the intake... basically just a computer controlled valve which changes the way the air flows. If it's shot you'll loose power on the low end.

If no one else covers it I'll post up some more info... I'm at work right now though

Or you could try using the advanced search function and search ACIS in the 7M-GE forum.

 

[cbul7210]

Benchwarmer,
Car idles at a grand cold and warmed at app 650-700 and it idles smooth all around.
Cbul7210

 

[Ma70.Ent]

ACIS Info can be found by searching or reading the bottom of the sticky. Here's how to fix ACIS:

http://www.supramania.com/forums/showthread.php?t=61090

 

[cbul7210]

Hi Ma70.Ent,
I found that thread in search but thank you in posting that link. I will clean all the mechanical parts and look at the vac hoses as well this weekend, Will keep ya'll updated as to weather this corrects my prob. Other than that, I really like this car exp the looks of it. Alot of potental with it :evil2:
Cbul7210

 

[gofastgeorge]

Auto, or manual ?

The reason I ask is that I know the auto ECU
has a time delay on allowing full timing & fuel for a few seconds
after releasing the brake pedal.
This was for the well being of any old farts, or total idiots
who may loose control of the car by getting on the gas to hard under the wrong road conditions.
I guess they figured someone who knew how to drive would by the 5-speed,
and people who couldn't would buy the auto.

I improved 60' times by a couple of 10ths by installing a
toggle switch on the brake signal wire going to the ECU.
When I want to launch harder, I flip the switch so that the
ECU no longer sees that the brakes are applied.
The switch needs to be thrown before staging,
or as your rolling up next to the mustang at the stop light.

The brake signal needs to be applied to the ECU for normal driving.
It is what kicks the cruise control off,
and releases the lock-up torque converter.

 

[IJ.]

Hi Ma70.Ent,
I found that thread in search but thank you in posting that link. I will clean all the mechanical parts and look at the vac hoses as well this weekend, Will keep ya'll updated as to weather this corrects my prob. Other than that, I really like this car exp the looks of it. Alot of potental with it :evil2:
Cbul7210

Very polite

You can stay!!
(welcome to SM)

 

[AJ'S 88NA]

Hi there, If I may ask what is an "ACIS"
and to add some more info, There is no check engine light lit up. and i had one mechanic suggest dirty injectors but thinking that one over wouldnt it affect the whole power range exp on the top end part?
Reason for this post is im trying to elimiate some of the obvious problems before deciding to take it to a shop (which I really cant afford at moment) and i do appricate all the suggestions
Cbul7210

To pull codes you have to use a jumper wire in the same locations you use for checking the base timing, E1 and TE1. You turn the switch on and count the number of times the CEL blinks.

BTW if you didn't use the jumper wire to set the timing then it's probably off.

 

[cbul7210]

Hi gofastgeorge and aj's 88n
My supra has an auto trans (i wish it was manual as i think they are more fun) and AJ when I checked the timing I did jump the comp box as per repair manual (e1 and t1). the only thing i wasnt able to do was to set RPM's to 650 on the nose as I didnt have one of those meters but on tach it showed on warm idle right above the 500 mark so i guestimated it was at 650 or so. I figured since it had a new timing belt installed just before i got car that if it was off a tooth the timing wouldve been off by a noticable amount.
Hope this added info is a help and thanks again for helpin me on this.
Cbul7210

 

[AJ'S 88NA]

Hi gofastgeorge and aj's 88n
My supra has an auto trans (i wish it was manual as i think they are more fun) and AJ when I checked the timing I did jump the comp box as per repair manual (e1 and t1). the only thing i wasnt able to do was to set RPM's to 650 on the nose as I didnt have one of those meters but on tach it showed on warm idle right above the 500 mark so i guestimated it was at 650 or so. I figured since it had a new timing belt installed just before i got car that if it was off a tooth the timing wouldve been off by a noticable amount.
Hope this added info is a help and thanks again for helpin me on this.
Cbul7210

Stock gauges are usually not very accurate, so it's probably close as the idle is set by the ECU.

If the timing belt was not installed per the TSRM, I.E. turning the motor a couple of revolutions, and checking the marks, it could be off and affect your low end. Pull the cover and check it.

 

[Nick M]

You have a bad torque converter. The stator, which applies one way direction, is spinning both ways.

Your car probably drives normal on the freeway right? It just can't get out of its own way from a stop, and stall is close to 2500.

One other thing. Your car is heavy and has a small engine. It just won't get out of the hole as fast as you would like.

 

[Tire Shredder]

You have a bad torque converter. The stator, which applies one way direction, is spinning both ways.

Your car probably drives normal on the freeway right? It just can't get out of its own way from a stop, and stall is close to 2500.

One other thing. Your car is heavy and has a small engine. It just won't get out of the hole as fast as you would like.

:withstupi

+1 for nick