Last night I had the computer checked as the 'check engine' light popped on last week.<p>From the printout, the IDLE SPEED CONTROL THROTTLE POSITION sensor was wigging out. What causes this?<br>Evidently if you fire the engine up with you foot on the throttle, it thinks that position is ZERO and any position less than point reads a negative values... and a light pops on. (The NewBeetles are vrey prone to this.)<br>The fix is to shut the car off, turn the key to the to the "ACC" position for about 10 seconds and let the computer reset.<p>My tech, Greg, said he had several cars come in for 'check engine' lights... the reason?? The cars have 20/50 weight and the cold snap caused the oil to be a little too thick. I don't know the specifics, but the cure is to run a lighter oil in the cooler months.<br>The shop uses 20/50, I bring in my own synthetic 20/50...<p>btw- disregard the top error on the printout.<ul><li><a href="http://home.earthlink.net/~palmerj/">My poor ol' un-updated web site.</a></li></ul>

The ecu watches crankshaft acceleration for misfire detection as required by OBDII specs. I was told if the oil is too thick the ecu can sometimes misread this drop in crank acceleration as a small misfire when it's really the oil "dragging it down".<p>Sounds far fetched... I guess the DTC would confirm this though.<br>

Jay, I'm surprised to see only one of those errors on the printout!<p>Anyway, the oil note is interesting. This just confirms what I was thinking about when I switched to Mobil 1 15w-50 synthetic at my first oil change. During a cold snap last year (yes, it occasionally gets chilly here in Dallas), I noticed that the engine was much slower to crank and turn over. I attributed this to the cold, thick oil, and if that was true not much oil was getting to the cams and turbo very quickly. I had my first service a week or so later and had them put in the Mobil 1. It immediately felt like I was running a lighter weight oil (even though it was 15w-50) and during the next cold snap that occurred the engine cranked and started as though it was the middle of summer. Just one benfit of many over conventional oil...

Maybe I can muddle this a little more-<br>The 5 valve heads have weak valve springs and somehow this causes the valves to move a little slower into the seats. This causes the computer to retard the timing.<p>Anywhoo, the result is a light and probably fouled plugs.

I live in Dallas as well and will be using Mobil 1 with my first service next month. Now I know what weight oil to use.<p>Gene<br>98.5 2.8