Evo Throttle Body On GSR

[vonapets]

Hey Guys,

I put a Evo throttle body on my GSR intake manifold. I port matched it. When i put it on with matching evo plumbing the cars idle sits at 3000 rpm and if i rev it at all the revs raise to say 4000 and then very slowly drop back to 3000. The oil pressure also fluctuates. The GSR throttle body has vacuum lines coming from it a the P and A locations on the top whereas the Evo one only has the P one present. I clearly have a vacuum leak. Where do i put the line from the A location? Also how do i check if the ISC is broken? My vacuum pressure is 14-16psi and before it was stable at 20.
I have replaced all the gaskets. I also cleaned the entire throttle body.

Anyone done this or have any idea on how to fix this?

Cheers,
Dimitry

 

[4piknup]

Is the throttle shut completely?
Disconnect and block the ports. Any different?
And the kicker...
Test the faiv. Look in the front of the tb and there is 2 ports at the bottom. Block them both with a bit of masking tape. Pop the pipe back on and start engine. (you won't suck tape in as there is little air flow through tb as long as throttle is shut.)
A normal engine will not start with those ports blocked.
I think the left port is isc and right port is faiv. If the engine will not start block one then the other and retest.
This will isolate the fault. I think maybe the faiv is stuffed, I don't think they are fixable. It is like a thermostat. As it heats up, the valve shuts blocking the air and lowering revs...
To test isc, once you get the idle lower, just unplug it and see if idle is different.

 

[clone]

I think the left port is isc and right port is faiv. If the engine will not start block one then the other and retest.
This will isolate the fault. I think maybe the faiv is stuffed, I don't think they are fixable. It is like a thermostat. As it heats up, the valve shuts blocking the air and lowering revs...
To test isc, once you get the idle lower, just unplug it and see if idle is different.

correct mate. also make sure your ISC you are using is the correct one. There are 2 typres of solenoids, sealed by gel and bolted. the bolted ones you can obviously open up. as for the plunger end there are 2 different types also. GSR has a longer plunger then EVO. is your using a evo in a gsr she idles high, if you use a gsr in an evo she idles low.

if your using an evo tb and gsr isc no idea why she idling that high i think i agree with jack saying you probably a leak/block

 

[4piknup]

I lightly draw file the mating surfaces to check they are flat, and use a touch of silicone on the gaskets

 

[vonapets]

Hey Guys,

Thanks for the advice. I will do the tests in the next couple of days. It was doing my head in and i took the throttle body off and checked the gasket. put it back on and tightened it firmer than before. I then did the same on the inlet manifold (tightening) and it seems to have fixed the rough idle however the car is whistling as if air is escaping the manifold somewhere. After tightening the manifold the whistle changed pitch and is less noticeable and as i said the idle is better. The car doesn't feel like it is about to stall all the time. With this said i imagine that i should take the manifold off again and use some silicone to make a better seal on the head/inlet.
Another fantastic thing is that the idle screw which i closed off while playing with the idle has started perishing. It has lost the philips and flat head top as it quite literally started coming apart!

Cheers for the responses.
Dimitry

 

[khubner1]

leaky tb manifold gasket. pull it off and get some gasket sealer on there or a new gasket. if you get real rough as guts a peiece of single ply cardboard cut to shape works. if you have to wait on a proper gasket

 

[4piknup]

nothing wrong with a bit of old weetbix box.

 

[vonapets]

Hey guys,

I used new genuine mitsubishi gaskets. I'll bathe them in silicone. Haha.
After my tightening expedition, when I first turn the car on the idle is good at 1500 rpm. (that's what it's always been). After going for a short drive the idle gets higher and stays at 2500 rpm. I let the car cool down for a little while, come back and idles fine at 1500 again! It's the weirdest thing.

 

[4piknup]

Hey guys,

I used new genuine mitsubishi gaskets. I'll bathe them in silicone. Haha.
After my tightening expedition, when I first turn the car on the idle is good at 1500 rpm. (that's what it's always been). After going for a short drive the idle gets higher and stays at 2500 rpm. I let the car cool down for a little while, come back and idles fine at 1500 again! It's the weirdest thing.

Maybe dodgy faiv as well?
Just pop the intake hose off the tb and mask the port that feeds the faiv, (masking tape again)
Put hose back on and start engine. Any different? Remove masking tape...
Retry test when engine warm.
I suspect a sticky faiv??

 

[vonapets]

I did the test. If i block either the faiv or the isc the car still runs. If i block both the car will not start. I ran the car and with the hose off i can feel vacuum through both holes. Similarly if i block one it still runs. If i block both while its running it stalls.

 

[4piknup]

When your car is hot and idling too high, does blocking the fiav bring it back to normal?

 

[vonapets]

When the car is hot and i plug the two holes it won't start if I keep them closed, if I plug them while the car is running it stalls. The revs don't drop and allow the car to run.

 

[4piknup]

so the 2 ports, one is for faiv, the other is isc...i think the isc is the firewall side and the faiv is the engine side.
just plug the one hole on the faiv side. (i am working from memory here, so i might have it wrong)

what i am trying too test is if the faiv is (maybe) not shutting fully when your car is hot, but (maybe) when the heat soak gets to it, it shuts properly.

so, get the car hot and doing its silly fast idle thing, then block only the port that feeds the faiv. leave the one near the isc open. (or try blocking one then the other)



i think it is the faiv, because the car stops when you block both ports. if it was leaking air somewhere else, blocking the ports would only lower the engine speed, not stall it

 

[4piknup]

I did the test. If i block either the faiv or the isc the car still runs. If i block both the car will not start. I ran the car and with the hose off i can feel vacuum through both holes. Similarly if i block one it still runs. If i block both while its running it stalls.

was this done when motor was doing its fast idling strange thing? because you need to replicate the problem, then test for the fault..

 

[clone]

Question, has anyone seen around an after market 4g93t intake mainifold?. I can source an s90 throttle body but this will only fit a evo mainfold , im just wondering if there are manifolds out there that fit upto a 4g93t head but can adapt the s90 or evo throttle bodies. I also dont want to butcher 1 but if it has to come to that i will

 

[Missile]

The s90 is standard fitment e.g. it will directly bolt to the 4g93t manifold. Although you may not be able to port the 93t intake manifold to 70mm?

FTZone have an aftermarket intake manifold for the 93t - http://www.ftzoneracing.com/store/index.php?act=viewProd&productId=581
There will be other places in Malaysia that will also have aftermarket/custom intake manifolds

 

[Gianni]

nothing wrong with a bit of old weetbix box.

I used nutrigrain box on my intake mani as all that protein made it stronger but it does work well. Had a 230kw 180 running like that fine.