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Not over heating

I have a Tracker that does NOT overheat according to the gauge, but when it reaches operating temp in summer time it starts missing and back firing. My husband has to remove the thermostat in summer to keep it running even for short trips. In winter time with thermostat in we have no problems. It has 93000 miles on a 2 litre 4 cylinder, and the only time the check engine light comes on is if we try to top gas tank too full. If we pull battery cable to reset the light it never comes back on. Of the 3 time its been on a computer it has never told us anything that helps with problem. If when it does get hot enough to start missing the only thing we can do to get it running right is to raise hood to allow cooling more quickly. We feel like it is an electrical heating problem, because it fixes it self when hood is raised to cool off components, but no one we ask knows whats wrong.

What year Tracker?

About that temp gauge, is it really a gauge or is it one that just reads cold OK or hot?

Does anyone know if the Tracker has one or more than one thermostat?

BTW quite trying to top off the tank when you fill it up. Keep it up and you will cause a problem. Trust me, it is not cheaper to put more fuel in there, it is also a lot less convenient later on.

its a 2000 i thought i made that evident.there is only one thermostat and all the fuel does is back up in the charcoal canister and cause the light to come on. please don’t treat me like an idiot i’ve been doing mechanical work for almost 40 years. the only reason i’m checking here is because the computer won’t tell us anything.

There is a school of thought that removing the thermostat allows the coolant to flow too fast through the radiator (not allowing it to give up its heat).

In any case operating the vehicle any where in its operating range should not cause a misfire.

In short you are making a false connection between your vehicles coolant temperature and the onset of a misfire.

If you insist,try to make a technical connection between the misfire and the temp (why should this cause a misfire is the question you should ask)

Can you rule out a heat soaked ignition component? one that fails even within its designed operating parameter?

Might be a failing ignition module.

The engine computer should have picked up that much misfire from the crankshaft position sensor.
Is the engine a 2.0L 4 cylinder? The wiring diagram shows two ignition coils. Is that what your repair manual shows? The ignition coils are controlled directly by the engine computer. No ignition module.
I suspect that one, or both, of the ignition coils is breaking down when it gets hot under the hood.

This 2.0 Litre engine has DOHC and 4 coils, one per each cylinder. The temp is only a problem when it gets near the normal running temp in summer. If you pull in a drive thru and wait for a minute the temp will rise just enough to start missing and will go as far as cutting off. If I stop and open hood to let engine cool off faster it will start back in about 10 minutes. If I try before the engine is cool enough it snaps and back fires like the timing is off. We have had it on a computer 4 times with no codes to tell us anything.

I have a Tracker that does NOT overheat according to the gauge

How certain are you that the gauge is accurate? Do you know if the gauge is displaying the temperature or does it just display cold, warm & hot? Some look like they are displaying temperatures, but only display two or three modes.

You should never remove a thermostat. If it overheats in summer with the thermostat in and not when it is out, the problem is NOT the thermostat, but rather there is another problem (maybe a partly clogged radiator or fans not going on when they should) and that should be fixed first.

I would be suspect of the water pump and radiator, not the thermostat. BTW a thermostat can be tested with a pan of boiling water and a cooking thermometer.

“If I try [to restart] before the engine is cool enough, it snaps and back fires like the timing is off.” What is “snaps and backfires”? When timing is off enough, or, intake valves are sticking open, there can be backfire through the intake tract. Is that it? “Snap”?
What could knock the timing off that much? A camshaft position sensor (cps) breaking down from heat? Or?
Maybe, you can duplicate the heat on individual sensors: Run the engine until it get hot. Open the hood. Play a heat gun on each sensor (crankshaft position sensor, camshaft position sensor, etc). One of them may start to cause misfire.

I’m going to guess that the coils are breaking down from the heat, causing the misfires, and you’re pushing a volatile fuel mix into the hot cat converter.

Instead of simply resetting the computer, try checking to see if all the cylinders are firing when it’s heated up. You might even carefully use a heat gun on the individual coils while it’s operating properly to see if you can induce the problem.

Post back with the results.