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Thermo Valve

Here is a newbie question of the day. I broke the limiter switch on the thermostat housing. What is the course of action now? Can it be eliminated or do I need to try to fix it. I called the stealership and they are a week out and I need the car done today.

A little background, its a talon tsi that came into the shop for a timing belt. We have had nothing but problems 2 cylinder heads later and a new piston I am finaly getting it back together but this is the only thing holding me up.

Thank you
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What do you mean "limiter switch"? /ubbthreads/images/graemlins/dunno.gif The sensors on the thermostat housing are for the coolant temperature gauge (1 wire), coolant sensor for the ECU (2 wires), A/C cutout (2 wires), and a fan switch, if I recall.

LIMITER switch?? On the thermostat housing??? /ubbthreads/images/graemlins/confused.gif

Sorry I misspoke - its a Thermo valve, part number MD103867 for the emission control system. I did find one but it does not matter any more because the darn car won't run. I started it after priming the motor and it ran great until I tried to get some miles on it. Two blocks from the shop it started misfiring and died. Restarted it and it ran on 2 cylinders and died so it's now in the parking lot waiting for tomorrow.

Before starting the motor, we did a compression test. It was 150 in 3 cylinders and 145 in the other. We also did a leak down check to make sure the head was good and again everything just fine. Also before you ask, the new timing belt and new tensioner are both dealer parts.


Well-known member
Damn, sorry to hear it's still giving you fits. /ubbthreads/images/graemlins/frown.gif

Since the possibilities are endless at this point... checking a few of the basics may get you headed in the right direction.

Has the ecu had it's caps replaced, and how does the board look?

Checking spark would be a good idea as well. See if you can narrow down which cylinders aren't firing?

Do you have a known good cas and coil you can use for troubleshooting?

Try pm'ing Brandon (UtahGalant), he's a pretty savvy cat, and he might have some spares, or know where to borrow them.

Good luck, and hope you get it figured out!

Ok got the talon started, checked all the timing marks and everything is fine.

So here is the new problem, The car will idle perfect but if you raise the rpm over 3000 it will buck and shake the whole car and misfire. Whan you get off the gas it will misfire or die as its coming back down to idle. When you restart it it will idle fine again. Also I did a compression check that was fine as well. Where should I go next Cas or something else?


Well-known member
Have you run a meter diagnostic to get the codes? it sounds like you might either have a bad masss or maybe ecu.

Good news we found the problem. The plugs were gaped to thin and not creating enough spark. She now runs like a dream /ubbthreads/images/graemlins/grin.gif