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Discussion Starter #1
I believe I have a problem with my setup. The car runs great, but if you accelerate steadily you can feel a noticable difference when the engines reaches 3500-4000 rpm. You can also hear a difference in the sound of the car when it reaches 3500-4000 rpm as well. The car also just doesn't feel like it's producing the amount of power at low rpm's that it should. I hope this post has made sence.......

1982 Supra 5M-GE
Ravin Muffler, MSD 6 & Blaster 2 coil, Taylor wires (blue),Open air element filter (Rabidchimp)
 

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My 84 Supra was the same way. It didn't really open up til it hit 3000 - 3500 RPM. The power difference was almost as notable as if it were a turbo spooling up.

84 Supra P-Type 5M-GE (No mods)
 

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Discussion Starter #3
Zombiepup said:
My 84 Supra was the same way. It didn't really open up til it hit 3000 - 3500 RPM. The power difference was almost as notable as if it were a turbo spooling up.

84 Supra P-Type 5M-GE (No mods)

Was? what did you do to fix it?
 

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I think it's just the way our engines are
Mine used to pull mostly even throughout the powerband when it was stock. But once I got an exhaust I could feel this hitch in the power. I didn't really notice this too much till I got the headers though. Like if I step on the gas and hold it steadily once the rpm's hit about 3100 it feels like it kicks and starts pulling hard.
 

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Discussion Starter #5
Supraa_luva said:
I think it's just the way our engines are
Mine used to pull mostly even throughout the powerband when it was stock. But once I got an exhaust I could feel this hitch in the power. I didn't really notice this too much till I got the headers though. Like if I step on the gas and hold it steadily once the rpm's hit about 3100 it feels like it kicks and starts pulling hard.

Hmmm. so the modifications that we are doing help the top end, more than the bottom end? Interesting, need to get his car on an dyno...
 

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Mine feels the same way. When I had it completely stock, it was about the same accel under 3500 and over 3500, just a slight increase in power. Once I put on an intake, 2.5" exhaust, and new plugs/wires/cap/rotor the difference is VERY distinct. Now it hits 3500 and pulls hard, and sounds much louder/powerful than before.
 

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Did you reset the ECU after doing the mods.? The ECU mapping needs to be reset to factory spec. after you do the mods. so that it can adapt properly to the changes that you've made to the engine.
 

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All the mk 2s Ive had have driven pretty much this way - the power really comes on after 3500. If you dont like the way this feels, put some wider tires on and always drop it around 3000. How do you reset an ECU anyway?
 

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in order to reset the ECU, i think you unhook the battery, could be wrong though
 

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The "STOP" fuse inside the black box located by the battery. Pull that fuse and then reinsert after a minute or so. No need to disconnect the battery.
 

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my car does the same thing, low power till 3000, but i think it is just the engine. As far as i know new celicas are the same way, they have no guts inm low rpm ranges, maybe its toyota's design, i'm not sure. I have a header and 2.5" exhaust with wires and cone filter, the bottom end has no power, but once it gets up to 3000 or so it takes off a lot faster, i normally shift about 4000 getting on the highway and it keeps revs up there and gets me going really quick.
 

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Discussion Starter #14
Dave A. said:
Did you reset the ECU after doing the mods.? The ECU mapping needs to be reset to factory spec. after you do the mods. so that it can adapt properly to the changes that you've made to the engine.
No I didn't do that... hmmm so after reading all the posts, is it the brake fuse or the stop fuse? Did anyone do this and see a difference?
 

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Just disconnect the battery Its easier. I disconnect whenever I work on my stereo so I reset mine every couple of weeks. Wide Open Throttle is at approx. 4000rpm. The surge is probably the flapper fully opening and the injectors going into wide open loop. I have the AFM mod, no Cat, a bottle muffler w/ fesonated tip and a depaneled airbox with stock filter and I get the same surge.

-Wil
 

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Discussion Starter #16
dohc82 said:
Just disconnect the battery Its easier. I disconnect whenever I work on my stereo so I reset mine every couple of weeks. Wide Open Throttle is at approx. 4000rpm. The surge is probably the flapper fully opening and the injectors going into wide open loop. I have the AFM mod, no Cat, a bottle muffler w/ fesonated tip and a depaneled airbox with stock filter and I get the same surge.

-Wil
OK I'll try that.... BTW I dont' have to have the throttle wide open to get 4000rpm out of the car. I have a feeling it does however have something to do with the fuel/air mixture. I might have to play with the AFM mod, I guess this will be my new project.. Figuring out why the surge. There must be something that the car is doing around 3500-4000 that causes the power jump. :?
 

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Dave's right, it's the STOP fuse, as per the tsrm, my bad...
I prefer to pull the stop fuse so I don't have to reprogram that piece of shit Kenwood Z828 I own every time I need to reset the computer. Nothing like seeing all that stupid crap on the radio's display (like a swimming dolphin or a slot machine, or even an F-1 car-LAME!!!) every time you lose memory power.

One word to Kenwood's R&D team (and other brands too, you know who you are!), just because you CAN, doesn't mean you SHOULD!!!
 

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Flyin' Hawaiian said:
...One word to Kenwood's R&D team (and other brands too, you know who you are!), just because you CAN, doesn't mean you SHOULD!!!
hahaha so true!
 

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Discussion Starter #19
Dave A. said:
Did you reset the ECU after doing the mods.? The ECU mapping needs to be reset to factory spec. after you do the mods. so that it can adapt properly to the changes that you've made to the engine.
Thought I'de let you know, I recently reset the ECU it did help, there is a noticable difference in the low end now.. But I still feel the upper end running better.

I'm starting to form the opinion (based on another thread) that the lack of power in the low end, may be due to the lack of low end torque. These cars all seem to be running 2.5 exhaust. I'm curious what size the exhaust manifold is. Also what diameter the headers are that are available. I did an experiment years ago on 67 Plymouth 383. Granted these are different engines but the physics should be about the same. Everyone thought I was nuts to go with a relatively small header, most on that engine use a large header to get the upper power. But I used a 1 5/8 header going into a 2.5 exhaust. I gained enough torque to pull a house, amazing gas mileage (went from 21 to 23 average to 25 to 27 average) (Yes this is the old gas guzzler that originally started at 8mpg) Anyway not to drag this on, I think the problem with these cars (Supras) is the exhaust setup. Maybe we are running too big in the exhaust, which would give us a great top end, but lack in the lower end. If we downsize the exhaust a bit but keep it free flowing, would we not gain low end. I don't know about anyone else, but my majority of driving is done below 3000 rpms not above. This is something I need to study more on, as I think this might solve the low end power problem.........
 

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I think the problem is in the exaust also. when I got my car it was complety stock exept for a Hks superdragger muffler. Now I have bored out the motor 30over, put on a paceseter header, hallow cat, 2 1/4" midpipe, the superdrager, and a cone filter. the car was much faster before the rebuild. I am not real savy with motors but I have some nowledge. of whats what. I had a ton of low end power bfore the rebuild and I am looking to get that back. Somebody told me if that I advance the intake cam it would give me more low end, what about shrinking the exaust down to 1 7/8" or so? Any advise would be greatly appreciated.
 
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