how fast does your 4age feel? - Toyota Nation Forum : Toyota Car and Truck Forums

big_daddy234 · 06-01-2010, 01:11 AM

Hey guys , so i just finished rebuling the 4age out of my 89 GTS, i had the valves redone/new pistons, rings , bearings etc etc..... it feels slow, slower then it should. Maybe im expecting too much, i dont know. How does yours feel? does it explode with life in the top end? mine seems to struggel in the top end especially from 6000-7000 rpms, it just seems to drag on and doesent pull very hard....is this just how these engines are with stock specs? or should i be blaming a dieing fuelpump or something of that nature?

Thanks in advance for any insight.

SuperRA · 06-01-2010, 02:49 AM

I think mines feels the best at about 5500-7500. I have a smallport though.

big_daddy234 · 06-01-2010, 02:51 AM

really? yeah mines a largeport and just feels flat from 5500-7500

big_daddy234 · 06-01-2010, 02:51 AM

its not the timing

rdyzz · 06-01-2010, 07:13 AM

i have a smallport in mine. it feels good from 1500 to about 5,000rpm. it can get to redline decent but i wouln't consider it living on the top end. feels more like a midrange engine to me. this is a completely stock engine btw. i know my black top seemed to rev effortlessly to 8,500rpm. this engine can get to redline but it doesnt feel like its doing it as freely as i'd like, meaning its slower at reving then i'd like. then again it is completely stock. lol better check the timing.

your expecting to much. you didn't do anything that would make it breath better or rev faster, lighter flywheel, lighter pulley cam pulleys. more agressive cams, higher compression pistons or coumputer tuning. if anything your 4age is possibally making under 110whp if that.

RED91SR5 · 06-01-2010, 09:31 AM

Perhaps your TVIS is not functioning properly?

big_daddy234 · 06-01-2010, 12:00 PM

Quote:

Originally Posted by RED91SR5

Perhaps your TVIS is not functioning properly?

Thats a possiblity, how should i check it? thanks.

RED91SR5 · 06-01-2010, 12:29 PM

Quote:

Originally Posted by big_daddy234

Thats a possiblity, how should i check it? thanks.

Someone can chime in and correct me on this if I'm wrong but from what I've read, 88-89 4AGE TVIS plates were always open until the computer activates the vacuum valve and closes them, (i.e. butterfly plates open all the time unless vacuum to the valve), due to the spring holding them open. So the computer activated the vacuum valve to close them between idle and 4400RPM. After 4400RPM the computer shut off the vacuum valve and the spring opened the butterflys up.

So if this is the case it is possible the signal from the computer to the vacuum valve is not there or there is a damaged wire.

More likely, one of the vacuum lines is damaged etc to the TVIS setup or the TVIS butterfly plates are stuck open and the vacuum can't close them.

The only REAL way to check this would be to take the intake off and put vacuum to the setup and see if it moves freely etc. and check for voltage at the vacuum valve at idle and that the vacuum valve is opening etc.

big_daddy234 · 06-01-2010, 12:37 PM

when the tvis plate was out of the motor on the bench the butterflys were closed

RED91SR5 · 06-01-2010, 08:11 PM

Quote:

Originally Posted by big_daddy234

when the tvis plate was out of the motor on the bench the butterflys were closed

Hmmm did you test the operation of the valves by hand applying vacuum? Anyway, below is just one of the things I've read on how the 4AGE TVIS works. You can decide for yourself. You might have a vacuum leak in this area.

From: http://www.turbomr2.com/MR2/Reference/TVIS/TVIS.htm

The 3S-GTE, 4A-GZE, and 4A-GE engines use a VSV with a normally-closed valve. This VSV passes vacuum to the actuator when energized. When the engine is operating at low speed, the VSV is energized, allowing vacuum to apply the actuator and hold the air control valves closed. When the ECU parameters are met to open the air control valves, the ECU de-energizes the VSV to block the vacuum signal to the actuator and bleed trapped vacuum from the actuator diaphragm.

Evo_lucian · 06-03-2010, 08:24 AM

Interesting read even if i don't own a bigport

SuperRA · 06-03-2010, 03:29 PM

Ok, after observing, I'm changing my answer. I think it feels the best from 4-6k RPM.

Donald · 06-03-2010, 07:42 PM

If your TVIS is open at low speeds, you will have no bottom end pull, and if it stays closed at high speeds, it will feel breathless.
When operating properly, you should feel a power surge at about 4500-5000 RPM, on up to about 7000 (I think).

If you don't feel that surge at 4500 RPM, the TVIS is probably not opening, which would lead me to suspect the VSV that open it, or the wiring for the VSV.

If it feels like a dog an low RPMs, the TVIS diaphram might be shot, or a leaking /loose vacuum line.

toyotaspeed90 · 06-08-2010, 04:17 PM

if you have an aftermarket air filter element/intake you should audibly hear the t-vis change in 2nd & higher gears.

if the tb's were closed on the bench there's a problem there..... they should be open on the bench.

brandonN · 06-13-2010, 01:16 PM

I dunno what the problem with your car might be all i know is i have the exact same car 89 gt-s and it pulls like crazy had no problems bootin down the road or highway.