I just serviced ours this weekend, for it's 37,500 milestone.. oil, filters, etc.
While I was at it, I cleaned the MAP sensor. Wow, was that thing filthy! It was as crudded up as any of the pictures on the other thread (about cleaning the MAP). I mostly used a 'safe' carb cleaner to wash off the crud, and carefully used a toothpick to help ease the stubborn stuff away without touching the probe.
Prior to cleaning it, the engine had this stumble or bucking in the 55-60 mph range when I feathered the throttle on flat or slightly downhill grades. Not all the time, but enough to be annoying. Either lifting off the throttle completely, or pressing a little harder, would stop it.
After cleaning the MAP the engine is running smooth as silk everywhere - none of that bumping, bucking, stumble (etc) is evident at all. I've driven it for two days now (on the 3rd) really looking for any sign and I can't find the slightest... so, I'm very pleased at the results for far. There are some nice, long, downhill grades on I-5 as you drive south into Vancouver (WA) - and it runs beautifully on them all. In the past, if it could be felt anywhere it was there.
My theory is that the build up introduces a delay in the response of the sensor, such that the computer either "just gets it wrong" or the delay is significant enough where it goes back and forth trying to catch up to the sensor readings and because of the delay it 'overshoots' trying to correct.
I'll be watching very closely to see if this apparent improvement is sustained.
Mark
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BlackLibertyCRD wrote:
Mine was replaced at 20,000 miles because it was dirty. I found on here as well as others that if it is cleaned at every oil change, it won't need replacing. Also helps with the performance of the engine.