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Poor Performance, Any Ideas ?


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Hiya guys.

OK I got me my first 1990 GT Four 2 days ago and I am really unhappy with the performance :cry:

I feel it could be a boost issue, I am hoping to get a psi boost gauge to see what shes running at, I bet it cant be much as the car doesnt put you back in your seat at all.

Could you have a look at the two following pics of my engine bay and tell me if you spot anything out of the ordinary, maybe there are some visual tell-tale signs ?

I noticed some kinda dump valve installed which is a really quiet one, I wonder if that could be faulty, leaking air, or actuator problems ?

And I theres a silver plate over the air filter, I was thinking of removing this, unless you recommend I should leave it on ?

Heres the pics



Can anyone spot any potential problems or give me any advice why car doesnt seam to be very quick at all ?

Many thanks.

Matt :)

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Looks ok-ish. I`d be tempted to check all the vacuum hoses. They`re going to be getting a bit brittle by now. Also check the intake hoses and connections. The actuator vacuum pipes will be the most likely suspect purely cos of their proximity to the turbo.

The dump valve looks like a Forge jobbie :unsure: Should be ok but try running the car without it. Don`t forget to blank of the holes. :D

I`d leave the tin thing where it is unless the filter is of the oiled variety and has been oiled recently.Looks like it`s there to stop water entering via the bonnet vent. But it`s also partially obstructing a direct cold air source. You want to be thinking of relocating the filter anyway. Where it`s at now it`s dragging in huge amounts of warm air. Not good for performance.

Go for it. :thumbsup:

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Leave the silver guard on as it will help prevent hot air reaching the filter.

First things first, fit your boost guage and check what psi/bar you are boosting to.

Secondly give the car a full service.

Thirdly reset the Ecu, just disconnect the Battery for a few moment and press the brake pedal to drain any current.

This should make everything run how it should do. If these things dont help them let us know and i'll tell you what else you should try :thumbsup:

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Cheers Leeky.

I will get a boost gauge tomorrow and report with pics what shes gettin, and also put some optimax in the car too :)

I could really do with knowing how to install the boost gauge though, I dont even know where it plumbs in, nor where I could get a power source from.

Can you tell me how I'd go about this please, pics would really help.



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No problem :) Most boost gauges need a normal 12v supply. This can be easily patched in via the power cables going to your cigarette lighter socket.

You will need to cut the small vacuum pipe coming from the turbo system and insert a t-piece into it. From this T you need to run a long pipe through the firewall into the back of the guage inside the car.

Thats basicly that :thumbsup:

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am i the only one thats noticed the TRD Oil filter??? always a good sign that it's been looked after.

but then theres a slick 50 sticker, a possible sign of trying to cover up faults.

the DV does look like a forge one and they aint that loud especially at low boost levels.

does hte engine management light flash at all ??? have you checked for error codes?

the 185 celicas are pretty slow as standard, it's only when you start to turn up the boost that you start to really fall in love with the car

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Hiya GTForbes

No mate no engine management lights flash at all.

The 'only' problem I have with the power is that there isnt much, maybe I expected a bit too much with the media hype about GT-fours ? I dunno, I will try and get a boost gauge fitted today and see, I bet its only got about 4psi lol I think when I whack this up to 12psi it will make all the difference.

I'll report me findings with pics asap.

Cheers :D

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Have a look at the wastegate and check if both of the ports are connected, if the one that points towards the engine is blocked off then the previous owner has disabled the vsv and you'll be running low boost in all gears.

Nothing to be worried about if it has, this needs to be done when fitting a boost controller, possible that the previous owner removed the controller to use on another car but forgot to re-attach the vsv line.

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