2004 B5.5 1.9TDi Estate - Odd Problem Possibly Caused By Mass Air ...

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#1 · Aug 10, 2020 Hi Sorry for the longish post . . . This is my first Post, that seems a bit of an odd problem, possibly linked to MAF = Mass Air "Flow" Sensor I've had this old girl 2004 Passat Estate B5.5 (manual) since it was 4 years old. It has only let me down twice - once in its first year, and the last time was November 2019. I had driven 40 miles, with absolutely no problems, I stopped for 5 minutes to pick something up. I got back in the car, and was back on the A road. I hadn't gone more than 200 yards when the dashboard lit up like a Christmas tree and I lost all power BUT I was still moving at about 1 mile an hour - there was no response from the accelerator pedal. Foot hard to the floor - made no difference to engine - that seemed to be set at just one level. I kept going for around a mile because there was nowhere to pull off. The AA towed it back home. That evening I tried to find out what was wrong, I thought I'd found the answer as others had similar problems, a faulty Mass Air Flow Sensor (MAF) - but since then I'm not sure, because others say a bad MAF is rough engine idling. Anyway the car sat there until a few weeks ago, as it wasn't possible to deal with it over winter. I did jump start it 3 times over the winter - each time it started first time, but the accelerator pedal still seemed that it wasn't connected. I'd leave it ticking over for a couple of hours. Then a few weeks back I tried to jump start again, but the battery was knackered, so I brought a new battery and once again it started straight away BUT THIS TIME I HAD A FULL FUNCTIONING ACCELERATOR PEDAL AGAIN. Which is great - but here's the thing, I've driven locally just a few miles and everything is working okay, I've got full power BUT I can't trust it because what happened in November - it could leave me stranded again. I need to find out what caused the problem in the first place. Based on hopefully an answer, I will either replace the MAP sensor/or clean it with the specialist spray. Just a thought - is it possible a lump of muck could have stuck to the fine sensor wire on the MAP? And over winter fallen off? Or am I completely wrong and I should be looking elsewhere? Any help or advice would be really appreciated. Before knowing that "the car would sort of seem okay", I brought one of these scanners that are absolutely new to me (I haven't got a clue) - best I've achieved so far is to find out where to plug the thing in. Although if the car is working okay - the scanner wouldn't tell me what's wrong, would it? This is the scanner I brought from Amazon; AUTOPHIX OBD2 Reader, OM126P Universal OBD2 Scanner Car Diagnostic Scanner OBDII/EOBD Many thanks in advance. Stephen See less See more Sort by Oldest first Oldest first Newest first Most reactions #2 · Aug 10, 2020 Welcome to this forum! Two thoughts come to my mind based on my experiences with my Passat over the past 18 years: 1. Try unplugging the MAF connector to see if that changes or affects how the engine starts, runs and behaves. Doing this will throw some engine codes. Cleaning or replacing the MAF may be warranted, and is probably a good idea. 2. Check the air inlet duct to make sure it is not cracked and that the clamps are tight. Any air leaks here will mess up the MAF readings and cause very bad engine performance. Also check all your vacuum hoses and PCV breather hoses for cracks - these get very brittle with age and often fail. Replace as needed with silicon vacuum hose. How's your timing belt? When was it last replaced? #3 · Aug 10, 2020 (Edited) I'm guessing that's the PD TDI? Check your camshaft. Often when that goes, it'll throw a MAF code, since it doesn't flow the air correctly. Also EGR problems could cause the same code. The b5.5 Passat TDI is pretty uncommon to have a mass air flow sensor go out on. Either that, or you could have a fault in the electrical wiring to the MAF sensor, such as in the reference voltage wiring, which could be possible with what you said about the accelerator stopping. The MAF being unplugged on the tdi won't necessarily cause the engine to run rough. Another thing, you should get a vag-com interface, not a generic scan tool. You'll be able to maybe pull some codes with the generic, but not all of them. Sent from my S60 using Tapatalk #4 · Aug 10, 2020 I don't know much about the TDI but for most cars unplugging the MAF sensor is how you test it. I also don't know much about the MAP sensor, I live right next to a cheap pull and pay junkyard so I would just stop by and swap them to see if there was a difference. Normal OBDII scanners only read error codes and erase error codes if your engine light is on. If you can find somewhere with a VAG-COM they can read the MAP & MAF sensor readings and tell you if they are off. It almost sounds like an alternator problem how it died and you had to replace the battery. #5 · Aug 12, 2020 My thanks to MAF post Thanks so much to all for helping out; thscott - BlueBunnyRabbit - Code247 I'll post if I have any success. Code247 - I have been using one particular mobile mechanic within a year of getting this B5.5 - he lives 90 minutes away - he's got a VAG-COM But of all the times to happen, he can't get out to me, as his dad's got Cancer and he's looking after him. I'll try all the suggestions, including trying to find a garage that has a VAG-COM Thanks again. Stephen #6 · Aug 12, 2020

thscott - I've just gone through the replies again; How's your timing belt? When was it last replaced? Can't remember the mileage - but a new one was fitted (by the mobile mechanic) just before it hit the mileage limit. A good few years ago, maybe six. Ta. This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread. Insert Quotes Post Reply

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