As some of you know, I replaced the solenoid and filter, but still had two slight judders when warming up. Since then I have cleaned the MAF, MAP and IMRC valve, which resolved the juddering and the car drove like a dream.
Since I first cleaned the MAF and MAP after a little while the judder came back, I've re done the cleaning of the MAF with little effect and then the MAP, which seemed to resolve the issue again for a little while, I suspect some of the reprieve was due to resetting the ECU.
I have noticed that the judder, although not bad seems to come hot or cold, but is more prevalent when the air is damp.
Since cleaning the MAF and MAP and getting the car to run like a dream I knew that it was because of one of them, although I had cleaned them all at once so couldn't isolate it. However more recently I have had a niggling suspicion that the MAP sensor is at fault. I have now done some further reading and done some tests and now suspect the MAP sensor.
From what I have read the MAP (Manifold Absolute Pressure) sensor is there to adjust for the barometric pressure conditions etc, it seems that depending on where the sensor is placed has an effect on it's reliability. For example the MAP sensor on the Facelift is mounted directly onto the IMRC valve, which makes it more susceptible to heat damage than a sensor placed on a bracket and connected via a vacuum hose
See this link which I found good in explaining things a little more
http://www.youfixcars.com/map-sensor.html
Also found this site good for a general view on most sensors on a modern engine
http://www.aa1car.com/library/1999/cm69910.htm
Today I decided to have a day off work, so thought I would do a couple of simple tests
Firstly I unplugged the MAF sensor and started the engine, it stalled straight away, so a good sign that the MAF was working
Secondly I unplugged the MAP sensor directly, the car started, Ok it also put it in safe mode i.e limiting the engine to 2K, took the car out for a drive, to warm up etc. Not one single judder, once warmed up went back home and waited for about half an hour. The reason I did this is one of the symptoms that I have been experiencing is the car quite often runs like a dream first thing for the whole journey, but as soon as you have switched off and then need to go somewhere else, the judder is there, especially in first gear.
Went out in the car again and still no judder so looking promising, came back and left the car a while longer and then reconnected the MAP sensor, this time started the car and switched off approximately 5 times, but the mil light stayed on, but later cleared itself whilst driving. The car once again did the judders, not particularly violent judders like you get with the IMRC solenoid issue.
Now for the bad news, so far I have only found one place that sells the original Bosch MAP sensor 0 281 002 680, other than the obvious of the dealer or Lings at £200+. The place I have found is selling new original Bosch at around £65, unfortunately however Bosch have told them there are none available until March. I have also spoken to the company about a possible discount, which they are willing to do and I am awaiting further details. I have run it by Fahad and when I get some details from the dealer I will be putting them up on the dealers section. They also do an after market MAP sensor made by Facet for around £45. Incidentally they sell the original Bosch MAF Sensor currently for less than £100.
I would prefer to get the Bosch, but it is whether I can wait until March, so not sure whether to give the Facet a go.
