Air Temperature

[richard33]

Please can someone help with this problem.

I have a GTM Libra unusually fitted with an unmodified 1992 MR2 Turbo engine. As the car only weighs about 600kg the acceleration is quite vivid!

However, under hard acceleration the engine can rapidly cut/surge/cut/surge etc., which on a recent sprint put me off the track. (before anyone asks, I had already fitted a new high output fuel pump).

Trying to sort the car on a rolling road, we removed the rear body section and found that even under max throttle through to the rev limiter, this phenomenon more or less disappeared. We therefore concluded that the problem was related to under bonnet temperatures. I am now in the process of adding more fans, greater cooling ducts, exhaust wrap etc, but one thing still puzzles me.

Attached to the rear bulkhead (just above the turbo!) is a device that looks like an air temp sensor (hopefully see pic attached).

What is this ? and Where is it mounted on a standard MR2T?

Any info would be appreciated.

[Bibbs]

GTM huh? Awesome, I was a member of the club quite a few years back. I was into Mini's and looking for a nice GTM Rossa as my first car. Didn't find one :D

That sensor is mounted on the engine lid on the MR2 Turbo (would be about the turbo area - up by the pre-intercooler hard pipes). It is then linked to a chunky fan on the intercooler.

It is a VERY common mod to disconnect it. This makes the fan run all the time.

Are you sure this is the issue?

[richard33]

Thanks for that Bibbs.

I tried disconnecting the sensor - and the fan still doesn't run! I plan to hardwire the fan to a switch on the dash and also fit an auxiliary fan to blow air across the engine bay.

I am reasonably certain that the problem is related to under bonnet temps, as it was ok with the rear clip removed.

Pic of car :

[Bibbs]

Overheating (or the cooling system not being able to keep up) is a common problem (as the GT4 guys don't have the same issues), but usually the engine just cooks itself. I've not heard of stuttering etc before. The latter (gen3) engines were a bit more hardy too, with the earlier ('89 - '93) ones warping heads and blowing gaskets.

Mine was slightly tweaked, and i just left that fan on all the time. Water/Methanol injection into the hard pipes also helped with the temps. I also had bigger and more air scoops.

http://i53.photobucket.com/albums/g54/Bibb...om/PICT2503.jpg

I know the air flow come in at the sides and bottom, and then out through the top of the engine lid. Do you have enough air flow from under the car?

Nice looking GTM, I'd be tempted to swap the wing for a more curvy, modern, carbon banana one. What do you ude it for? Looks track ready!

I sold my MR2 when she started falling apart (gearbox, radiator, heater matrix, water pump, thermostat and driveshaft, all in a week - also needed the head cleaning as all the waterways were full of a tar like substance) and moved over to a Honda.

http://i53.photobucket.com/albums/g54/Bibb.../Image00336.jpg

I'm now back to the Toyota fold, with a Hilux.

http://i53.photobucket.com/albums/g54/Bibb...17062009253.jpg

[richard33]

I see you did a bit of bombing around the Nordschleife in the Honda - the Hilux may be less fun there!

I've just returned from a VLN 4-hour race there (not in the Libra!). I think we were the only Brits from a field of 178cars and it took all day Friday just to get the car through scrutineering - despite having presented the car for a full pre-scrutineering session a few weeks ago. Welding extra doorbars and replacing the seat (perfect, but 4months out of date!) and 600 euros later, we got into the race and lasted 2 hours before cracking the sump on the concrete Karousel. Not a perfect weekend!

Now to get on with hacking lumps out of the Libra - very quick (0-60 under 4 secs).

[Bibbs]

What was the Nur car? (the pic of the MR2 are also Nur).

I'm sure the Hilux would be okay .. I could take the apexes over the grass, no worries. Take all the shortcuts you can playing on the computer.

Good luck with the cooling, I assume it's a sub 1000kg car?