4kq running cold- SOLVED (long)

Roa, Greg Greg.Roa at Cinergy.COM
Fri Jan 3 07:37:54 EST 2003

You know, I almost missed this, as I was scanning the archives after getting back from vacation.  My 4kq does exactly the same thing.  I can run on the highway on a cold day, and never get past the first mark on the temp gauge (the one outside of the red area).  Of course, the thing that always puzzled me was that I had a new thermostat, and the car seemed to reach regular operating temp very quickly when I got off of the highway.

I wouldn't doubt that this affects the fuel mileage of our 4kq's in the winter as well.  If the CIS sensor is reading that the engine still needs to warm up the entire time I'm driving to work, I'd guess the mixture is a bit off the whole time.

Might explain a little of the very marked difference in fuel economy I see when the weather gets cold (outside of the change to winter fuels at the pumps).

Thanks for the info Peter.  I'm going to make a "windshield" for my sensors this weekend.

Greg Roa
Cincinnati, OH
86' 4kcsq
93' 90 CS
83' 944

>From: Lines Peter <Peterl at Warn.com>
>To: "'quattro at audifans.com'" <quattro at audifans.com>
>Subject: 4kq running cold- SOLVED (long)
>Date: Mon, 30 Dec 2002 10:31:02 -0800
>About a year ago, I posted that my 4kq seemed to be running too cold in cold
>weather.  The symptoms were that the water temp gauge would drop to the
>first mark on the highway, but then rise to the middle of the range when
>stopped and idling.  The rad. cooling fan would also cycle normally if
>idling for a long period.
>I first suspected a stuck open thermostat so I replaced it.  No improvement.
>It is an 87C thermostat.
>I then checked the accuracy of my dashboard water temp gauge by inserting a
>borrowed thermocouple into the upper coolant hose connection at the engine.
>After 5-10 minutes of idling, the fan cycles on and off as the thermocouple
>reads 95-93C and the gauge is steady at the third mark (right above the
>center of the gauge).  So I'm thinking no problem with the gauge, the water
>must really be getting too cold on the highway.
>At some point during the past year I replaced the radiator due to a small
>leak, although this didn't change any of the temp. behavior and I think it's
>I then proceeded to make a cover to block air flow for about 3/4 of the
>radiator.  A short test drive showed that this did not raise the highway
>temperature one bit.  Darn.
>On a recent trip to Whistler, BC (the skiing was great, BTW) I noticed that
>even while the water temp gauge was reading very low, the oil temp was
>normal (as it always has been) and I get plenty of interior heat.  Both
>conditions that seem to indicate that the water temp is OK and something is
>wrong with my gauge.
>I also noticed how dirty my engine would get when driving on wet winter
>roads.  All the crap kicked up by other cars would completely coat the
>engine.  I began to realize that air flow through the grill is directed
>straight onto engine (not first through the radiator as on most non-5 cyl
>cars).  Is my engine getting air-cooled while on the highway?  Not likely.
>But what about the sender for the water temp gauge?  It's just sort of
>hanging our there in the breeze.  Could it be getting cooled off by the air
>flowing over it?  On my next fuel stop, I pop the hood and stuff a rag
>around the sender to block the direct airflow.  Bingo!  The gauge is now
>rock-steady at the 3rd mark whether I'm driving 80mph or stopped in traffic.
>Long story short, there is absolutely nothing wrong with the cooling system
>on my car, never has been.  It just took me a while to figure out why the
>gauge has been reading low...
>Now I'm wondering about the affect of the lower temp sender on the CIS
>computer.  I probably want to block the airflow to this one as well.
>Peter Lines

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