GT4 Problem

[as_cool_as_u]

When my GT4 gets into high Revs its feels like its pulls back and doesnt have the power that it should have...
what could this be...i use 96 petrol someone told me it could have been tuned for 91 would that be right??
any ideas guys??

[Al]

Its because of the turbocharger, im assuming its a st185 here.

The stocker ct26 turbo isnt efficient at higher revs because of the design of the exhaust housing and turbine.

[flygt4]

yeah the ct26 runs out of puff pretty quick. after 6000rpm its all juss extra heat and no more power.
what sort of revs you mean by higher?
also on a turbocharged vehicle it is better to run highr octane fuel.specially if u hav higher than factory boost.98 would be better.dont run 91.

[as_cool_as_u]

Yea it is a st185 and it runs yea runs out prety quik even round 5000 rpm, its factory az think fiter,exhuast,BOV etc will improve this problem?
We dont have 98 octane petrol in christchurch

[Al]

exhaust will help slightly, but it will still lose power, the only way to stop it losing power over 5500rpms is to get a decent turbo

al

[as_cool_as_u]

mmm k so how much for a hybrid Turbo?

[Al]

that still wont fix it, you still retain the exhaust housing, with hybrid turbo you will make more power than stock obviously, but it wont keep making power till redline

only affordable bolt on turbo avail that will still make power to and past the redline is the ct20b from st205s and gen3+ mr2s

[Twolitre]

Replace the fuel filter, distributor cap, distributor rotor, spark plugs, leads unless already done so reasonably lately, check ignition timing, check for ecu error codes then remove your catalytic converter, upgrade your exhaust to at least 2.5" and don't worry about the bov you don't need one.
Your car will go a hell of a lot better and then if you choose to you can move onto more serious modification such as IC, ECU etc

[matt dunn]

When my GT4 gets into high Revs its feels like its pulls back and doesnt have the power that it should have...
what could this be...i use 96 petrol someone told me it could have been tuned for 91 would that be right??
any ideas guys??

the gt4 that i spent a lot of time chasing this fault was mild detonation.
The knock sensor picked it up and retarded the timing.
Car was only runinng 2-3 psi above std boost and dead on std ign timimg.

The fault that they were complaing of was not constant power. Sometimes would go ok but most of the time just felt gutless.

To prove the point (as you cannot disable the knock sensor)
either try a tank of avgas and see if it improves it ( 0r try 98 if avail)
or retard the ign timing by 3-4 degrees. this will slow down overall performance but better to lose 3 degree's of advance through manual adjustment than let the computer retard it by 10.

Matt

[Mr Revhead]

how goods your boost gauge? maybe your actuator/turbo isnt holding boost? just another thought.

[Malcolm]

It'd say it is partially due to heat soaking of the stock intercooler. Does it do when cruising at speeds above 60km/h? When the intercooler heat soaks it causes the ECU to pull back timing and close the T-VSV (small bleed valve/solenoid that allows 2-3psi extra boost when open).
As mentioned, the stock ct26 is pretty inefficient, however a t04e 50 trim wheel on the standard turbo will greatly improve top end power, and will keep on giving you power until redline (trust me, I had one of these on my 185). Will set you back between $700-1200 for the upgrade and a rebuild of the turbo.
Getting rid of the standard intercooler for a front mount or WTA isn't a bad idea either

[as_cool_as_u]

Would like to try av Gas aye...the guy down the road at the petrol station said i should try sum but said its got lead in it and i might fuk the sensors and stuff....true??

[gtstarped]

[quote="Al"]that still wont fix it, you still retain the exhaust housing, with hybrid turbo you will make more power than stock obviously, but it wont keep making power till redline only affordable bolt on turbo avail that will still make power to and past the redline is the ct20b from st205s and gen3+ mr2s[/quote]

A standard CT-26 will perform fine with the right maintainence and a decent exhaust and down pipe. It does give out a little but nothing that you can't deal with. A 50 trim T04E will pull so much better all the way through though and is worth it if you can justify spending close to a grand. It still wants to keep going once it gets to redline.

If you just want a good performing daily drive with good power, do the basics as TWOLITRE mentioned and also turn the boost up to 14psi or so. The difference between a badly maintained 3S-GTE and a mildly modified one is like day and night.

[MrBob]

check for fault codes aswell. Another member here had exactly the same problem, turned out to be stuffed O2 sensor, was running in limp mode.

to greatly improve topend, gut the cat and get a 3' exhaust (no smaller), and a decent filter. Providing nothing else is wrong, these mods should remove any hesitation between 5-61/2 g. Then get a decent IC and run 14psi (about the max efficiency of stock ct26), and youll get a huge improvment in topend. In this guise the ct26 will hold boost all the way to red, no problem (from experience with a couple of 3sgtes).

If you do want to upgrade turbo, dont waste your time with ct26 or ct20b. Save the pennies and get a decent BB turbo. CT20b is overrated, considering the price people sell/buy them for..

[THE 20V]

Man I dont know what you guys have heard.

But I used to own a ST165 and it boosted hard all the way to 7,000rpm.

The CT26 is THE BEST standard turbo ever made.

Its almost the size of a T04.

I hate to say this man, but I think there's something wrong with your turbo.

[matt dunn]

Man I dont know what you guys have heard.

But I used to own a ST165 and it boosted hard all the way to 7,000rpm.

The CT26 is THE BEST standard turbo ever made.

Its almost the size of a T04.

I hate to say this man, but I think there's something wrong with your turbo.

In my opinion the ST165 is a far better car engine wise than the ST185's
I'd rather have an ST165 any day!

[Al]

The CT26 is THE BEST standard turbo ever made.

[WALT3R]

Avgas runs a higher octane level than regular petrol... we all know that, it wont improve the performance, wont clean out the engine, all it will do is burn cleaner and slightly hotter, want to waste money? go ahead. If you want smooth running and a slight power increase (as two litre has said), oil filter, petrol filers(both main and aux), ht leads, distributer cap and rotor, and get some high quality spark plugs (veridian are good, $25 a pop). The exhaust? good idea, a 75-80mm straight through is all you need if running up to 250 kilowats. just add mufflers untill you are happy with the noise, i did and it went great. If you do a filter, make sure its getting cold clean air, itl last longer and go better,i turned one of my bonnet intakes around and put a pod under it so it was sucking clean air, right were the factory filter is... gr8. these mods should be got for another 10-25 kilowats and wont break the bank. You should expect this kind of performance from a factory set up, they ristrict them for a reason. What you need to do is find the restrictions and eliminate them... exhaust is the first..... bov's only sound cool, you have an internal wastegate that dumps it inside the exhaust, more than adequate. Front mounts are great, but hugely expensive, all comes down on how much you want to spend

[flygt4]

the higher octane rating is why he would want to use avgas or 98....
wen u put too much boost thru the shitty stock intercooler as said b4...it will detonate enuf to trigger the knock sensor and retard the timing....happened in my st185 wen running anything less than 98.
and whoever said st165's the better than 185's.... on what basis.... unless u personally like the look then the 165's r pretty average..the 185's can be too. st205's kick ass tho.

[WALT3R]

FLYGT4: wen u put too much boost thru the shitty stock intercooler as said b4...it will detonate enuf to trigger the knock sensor and retard the timing.

As this chaps engine is stock, i dont think youd have any problems with this hence why no need to run avgas..... might as well put nitrogen into the tyres while hes at it haha