Sensor problem?

[invercone]

I have a 2003 1.9 TD1 with an ASV engine which was laid up for nearly two years (because the Spanish authorities have become over-enthusiastic about requiring UK vehicles to be re-registered in Spain at a cost of around 1000 euros - but that's another story). After all that time it started and ran beautifully at first, but the next day was very difficult to start, ran extremely roughly and the accelerator would not work. While I am quite happy dealing with mechanical problems I'm afraid I have little knowledge of electronics.

After searching this forum, I replaced all the vacuum pipes and the car ran fine, but since then sometimes it will play up with no accelerator and other times it will run almost perfectly. I now suspect that this is related to the ambient weather conditions (temperature, humidity?). Presumably this could be a sensor problem but can anyone please suggest which sensor I should consider replacing.
David

 

[Muttley]

I would suggest that you invest a little cash in VCDS - a suitable diagnostic cable is about £20 (I got mine from Gendan, who are authorised distributors for Ross-Tech) and the VCDS-Lite software is free to download from the Ross-Tech site. This will let you see what fault codes have been set and stored in the log.

The free version will not give you all the info about what each code means, but the Ross-Tech wiki has a list of fault codes that will help. And if you want to do anything like turning down the EGR you will need to register the software.

Sensors that may be affected by outside weather include inlet air temperature and altitude (i.e. ambient air pressure). There is no humidity sensor.

Is the problem related to cold starts i.e. first thing in the morning?

It might also be worth looking at the turbo actuator to see if any corrosion has built up during its long stay motionless.

 

[invercone]

As a follow up, and in case it is any help to others, I decided that the MAF sensor was a likely culprit. Since a replacement was under £25 on ebay I decided to take a chance and buy one. It took 5 minutes to fit and totally and instantly transformed the performance of the car - it now goes like the proverbial bomb. The only, very slight, problem is a slight puff of smoke on start up.