mtroxel

99.5 A4Q Manaul V6. I've seen this before, and yesterday confirmed it. Outside temp was about 97F and very humid. Motor kept stumbling. It wasn't a miss, more like it just cut out (probably electical of some sort) but would come right back. Happens at all RPM's. After dinner outside air was 91F and still very humid, no stumbling.

VAG-COM shows no codes this morning.

4Driver4

Have you changed the Coolant Temp Sensor?

mtroxel

About 5 months ago. Could that produce those symptoms, even with no VAG-COM codes?

5v/cyl

Yes. Generally a bad CTS will not give a code. ould also be air intake temp. sensor or MAF. Try cleaning both.

mtroxel

I just cleaned the MAF a couple months ago. Where the F--k is the air intake sensor? Here's what Bentley shows, number 6. Is that on the back of the throttle body? Can I just unscrew it and clean it or do I have to take some stuff off just to get a finger on it?

5v/cyl

#6 is it. Plugs into the intake just as it turns down to the throttle body. One screw hold the retainer in. Nothing to remove except the engine cover.

With no codes and being intermittent we are just pulling at strings and covering the easy and cheap/free checks. Vac leak could also cause it, but would probably not cause issues at throttle and rpm's. I assume you are running premium fuel? You could also try to run a can of Sea Foam through the gas tank. Carbon buildup could cause problems as well.

If all fails then you need to wait for a code or catch it when acting up and look at everything close with VAG-COM to find a error.

mtroxel

Yep.

Yea I stumbled onto it. Doesn't look like Bentley's drawings at all. Not the outside or the inside. But it is the only thing sticking straight into that air intake elbow. See the arrow below.



This is the business end. Looks more like a MAF than Bentley's drawing. I just sprayed some brake cleaner on it.

mtroxel

So, last time it was hot I cleaned the MAF, and found that the side of the intake air temp sensor that faced fresh air was black. Sprayed some MAF cleaner on that and rubbed with a Q-tip till it was bright again. Did a TBA.

Today is the first day since then of 95F + temps. Still stumbles, so I picked up a new coolant temp sensor on the way home and did that tonight. Supposed to be hot all week so I'll know soon.

mtroxel

For those who stumble on this, I do think the coolant temp sensor fixed this. We've had some days with temps in the 95F range since I changed the cts, no stumbling.

godsdream

Great to see that sensor fixed it. I will consider it if this happens to me.