Crazy Intake temps

[gez]

Hi guys,

MY R33 has been with my mechanic for the past month trying to solve a mystery of why the injectors have been hitting 100% duty cycle after 6500rpm. We tried everything including a new ecu etc etc. While my mechanic took it for a drive on a really hot day approx 33 degrees he noticed that the intake temps shown on the power fc commnader were going ballistic and hitting 90 degrees which sounds pretty destructive. From that he has sussed out why the njectors go mad. It seems the Power Fc reverts to a correction map high up the RPM range to prevent detonation. We are now stuck to why the inlet temps are going mad. Intercooler is fine, etc the only things being wrong are the rad cap being dodgy and leaking at high temps. He said that it may have something to do with it but im not sp sure.

Anyone got any ideas???? Any help appreciated.

Cheers

Gez

[R31 POWER]

What turbos,intercooler and power do you have.

[gez]

Hiya mate,

I bought the car as it is. From the looks of things it has std turbos which may have steel internals, Intercooler doesnt have any signs of a make on there but it looks like a Trust unit, it has 260 degree cams. I took it to GTART (uk meachnic) to have the car mapped and it got 467bhp at the crank @ 0.9 bar and 95RON petrol. We later tried 1.2bar boost and got 505bhp but the injectors were going mad so we aborted the 1.2bar map. We later noticed that the car didnt have a thermostat which was weird. We have now also noticed that the rad pressure cap is dodgy as it leaks every time someone lays a finger on it when its hot so it looks like its not holding pressure. It seems that the car was running high bhp back in japan as a load of bits have been taken off like the uprated rad, load of guages and turbos.

I dont really fancy running 90deg intake temp as the engine will just go pop so need to fix it as the car does drive really nice.

Any help greatly appreciated.

Cheers

Gez

[Guest INASNT]

well if your radiator cap is leaking theres your problem right there. Ofcouse the car will overheat if the radiator cap is leaking. U could be getting the opposite radiator effect where the hot air is getting sucked in through your intake from the radiator.

[gez]

If the Rad is leaking how comes the temp guage in the dash stays pretty much normal???

Cheers

Gerry

[Guest INASNT]

Originally posted by gez

If the Rad is leaking how comes the temp guage in the dash stays pretty much normal???

Cheers

Gerry

farked thermostat?

[gez]

Ok, this is where it gets more interesting, there wasnt a thermostat in the car when i got it from Japan......It aint doing the car much good coz when it gets too hot the Power FC goes into a correction made and fires the injectors at 100% in order to cool the engine down little to prevent detonation.

Gerry

[Guest INASNT]

never seen a car without a thermostat!!

what does it idle at when u do a cold start in the mornings

[2rismo]

never seen a car without a thermostat? what kind of petrol head are you? If only you knew just how many cars deliberatly remove them before going on the supercruise around natex come summernats time.....

:-)

[Guest INASNT]

Originally posted by 2rismo

never seen a car without a thermostat?  what kind of petrol head are you?  If only you knew just how many cars deliberatly remove them before going on the supercruise around natex come summernats time.....

:-)

y would u remove it?? so that the comp doesent go into safe mode when the car overheats?

[Bl4cK32]

They do this mod on two stroke bikes as well. Its "supposed" to let the coolant flow flat out all the time to increase the rate at which the engine cools down. Just makes it a bastard to get the thing up to operating temp. to start with if u ask me...

[YRL05S]

He is talking about air intake temperature.

The leaking radiator cap and lack of thermostat (not thermostat housing that i think you are thinking of INASNT) are unrelated to the high air intake temperature. The car will not overheat with a leaking radiator cap unless it runs out of water (or gets close to) hence why the guage is normal. People remove thermostats (like bl4ck32) to stop the flow restriction and keep the coolant flow at a decent speed. When removed the vehicle takes longer than normal to get to normal operating temperature.

As for the excessive air intake temperature it could be many things such as blocked or damaged intercooler or a collasped hose or blocked filter/s.

With a GTR with the front mount (of that size) the intake air temp really shouldn't rise over 60 degrees, on my car i can't remember the air intake temperature ever really getting over 40 degrees and i have had sub zero temperatures registered (i live in the mountains).

Do you run exposed pods in your bay because that could be the start of the cycle.

Also if the car is running lean (you mentioned the injectors maxing out) this increases overall operating temperature of the combustion process.

[TTT]

are you possitive that the temp probe that the power fc uses is not faulty?

maybe change that or... buy a cheap temp probe ang guage and plumb it in where the power fc one is so that you can see what temps each of them show...