Engine Missing Then Overheating

[goody90q45]

The Q has been having an overheating problem this summer on days over 100 degrees when I'm in stop and go traffic or sitting with the engine idling. It will start to miss for about 30-45 seconds and once the miss goes away the engine temp starts to rise but never makes it to the "red" zone where it cause damage to the engine.

Previous owner replaced the water pump twice and I put in a new thermostat at the beginning of last summer when I bought it. I replaced the fan clutch after the first overheat and did a chemical flush of the radiator after the second overheat and it's done it one more time. The service records don't show the radiator having been replaced but I don't have this problem unless it's over 100 degrees.

Any ideas why the engine miss followed by overheating?

[Skibane]

Off the top of my head - An overly lean mixture will cause misfiring, and also makes the engine run hotter.

Vacuum leak, maybe?

Have you scanned the ECM for any codes?

[elwesso]

Honestly I wonder if the overheating is causing the missing, and not the other way around.. Remember that when the ECU reads coolant temp above 195°F it starts pulling timing to try and cool the engine down, so perhaps this is what is causing the rough running and whatnot.... The gauge inside the cabin doesn't react as quickly as the temp sensor for the ECU. My point is, I bet the engine is overheating before the temp gauge reflects it.

I would suspect the radiator personally, and replace it with one of those nice CSF all-metal radiators..

[Q451990]

Ditto on what Wes said. You need to be able to see the actual temperature with Consult or Consult software...

Heath

[db_autotek]

It also seems very unusual for the prev to have replaced the water pump twice. Once I can totally get, but a second time seems odd. I do notice the Q's I've had generally start running poorly above 100 deg days (which is a lot of days on S Florida city streets). I deduced it was a function of timing retardation combined with the ethanol, on top of that you have CA fuel :/ A cheap and informative thing is to try a good ol radiator flush, see what comes outta there. Chunks, rust, metal, whatever.

[Infinitiguy19]

Was the fan clutch OEM? Can you hear the fan roaring when you rev the car when its warm? Do you have the engine splash shield installed? Do you have the A/C on while its overheating? (My Q's A/C doesn't work!, So maybe a dumb question).