Hi I am posting this on behalf of a mate who is waiting for a username to be authorised on ClubPolo. In the mean time I thought it couldn't harm to see if we can work out something on here. It's a hefty post....not bad for his first stab! -------------------------------------------------------------------------------------- Right so I recently got a 98 1.4l 16v Polo, Engine: AFH (first car actually) and virtually from the off Ive been having problems. What follows is quite a lengthy account of my experience to date but hopefully it may lend some clues as to what the underlying problem could be? Firstly it began cutting out and hunting for revs, the usual and apparently not uncommon thing where it cuts out when dipping the clutch on the approach to traffic lights and hunting for revs when idling at standstill. I found the 2 threads about cleaning the throttle body and replacing the temperature sender and decided to do both. I am a complete newbie and have no experience with this kind of thing until now so I enlisted the help of a mate of mine before attempting it. It was a couple of weeks before we had a chance to do it & just before then the problems just stopped completely one day!? I had been driving too and from work everyday, a short blast up the motorway, so we figured that had cleared out the throttle and engine and got itself working again. We gave the engine a look over anyway, checked the throttle body to check for fouling and it was virtually pristine. Had a look through the history and found that it had been replaced completely not long back (more on that later). Also checked the plugs which looked fine. I had picked up a temp sender from GSF but decided not to change it at that point as it was running ok.. if it aint broke... A short while later I noticed that it seemed to be losing a bit of power and the acceleration wasnt quite as good, quite a subtle change at first. When I got the car the seller mentioned that just before he came to sell it the cat had gone and there was a noticeable rattle coming from it. I didnt think much to this at the time but knew I would have to be done it at some point. When it started losing power I thought that as the cat had gone the bit of the broken monolith could possibly be rattling round inside causing more bits to break and clog up the exhaust causing the loss of power? At any rate it needed doing so got one from GSF and took it to a garage to get it put on. Over the course of the week the performance had gradually been getting worse and I noticed that it was getting thirsty. Then on the way to the garage the idle become really rough/lumpy and it was struggling to pull off from standstill and kind of stuttering/juddering really badly all through 1st, 2nd & 3rd until it got going. The garage changed the cat but told me that it was still had a problem. The idle was still quite rough and it was running really rich, you could smell petrol coming out the back. They recommended a full service and that I put an additive through it to clean the injectors. The next morning I took it in to get it checked out. I explained that I knew it didnt need a full service as we had already checked the oil, air filter, plugs etc.. and all was fine and asked if they could do anything else to pin down the problem. They ran a diagnostic check which came back with nothing. They put the injector cleaning additive through it and changed the plugs. They thought it might be the coil pack so they picked one up ready to put in but when they went to do it they found that the one in there looked new so left it. It was then running a bit better and idling ok, they ran an emission check and it was still putting out a lot of unburnt hydrocarbons. They tested the lambda sensor and said that the readings were all over the place. They also mentioned that it was quite erratic, one minute itll idle fine and the emissions are ok the next it would get a bit rough and start chucking out petrol again. They suggested that it could be a faulty lambda sensor and that I should get that done next, they could do it for 100 supply and fit but it might not solve the problem. At this point I was starting to worry about my finances so I decided to take it home and not drive it until I had a better idea of what to do next, mainly because Im wary that I could ruin another cat if I keep driving it while its putting petrol out the exhaust. I gave it a couple more short drives, noticed that when starting from stone cold it started easily and was running ok, it was only after 4-5mins when it began to warm up that it started getting rough again, so must be temperature related. Then decided to change the temp sender and the lambda sensor, got a bosch universal sensor, changed them both and reset the ECU. When we first started it up it seemed to still be a bit lumpy for like a minute but then sorted itself out. After that it seemed fine & ran well for a couple of weeks. Then I noticed that it seemed to be taking a long time to get up to temperature. It would vary from 10mins to up to 30mins on the motorway, and occasionally it would get up to 90 and then just drop off again back to nothing while driving. I and found a thread or two on here that pointed towards a faulty thermostat and/or housing. I got a replacement thermostat and housing, drained the coolant and replaced both, didnt find any leaks around the housing before changing it. The old thermostat was stuck with the pin sticking out and next day it was getting up to 90 straight away (quickly actually, only a few minutes) and it was staying at 90 dead in the middle. However, then the rough/lumpy idle returned with a vengeance! This time it would idle at 1000 then drop to around 500 & flick between the two sounding really chuggy in the process and just barely not stalling. Again it was ok when cold but as it warmed up the idle got rough, occasional drops in power and a worrying judder. Have been trying to think what we could have done when changing the thermostat to mess things up. While we drained the coolant when we opened the housing a bit did come out and leaked over the cable splice for the new lambda sensor. I took that off, opened it up and thoroughly dried it out just in case but it looked ok. We also had a look in the throttle body and found a big bit of crud inside ( looked like someone had gobbed in there), which must have come from the breathing tube. We cleaned it all up with some carb cleaner, reset ECU and started it again with the lambda plugged in. The rough idle was still there. Unplugged the lambda tried it again, ran ok for maybe 30 secs then rough idle returned. It sounded like maybe it wasnt firing on all cylinders so we disconnected the leads one by one and started it up each time. I think there was a noticeable change in the noise but it did started each time and ran on 3. We reset ECU again, plugged it all back in and took it for a drive. Then things got really bad.... The stuttering/judder returned badly, it seemed like it was flicking from running on 4, then down to 3, then even down to 2 then back to 3 cylinders with brief flashes of it running on all 4. After at bit it started to smell like it was getting really hot (although the gauge still said 90) and seemed like it was on the cusp of dying completely, had to keep on the accelerator to stop in stalling. We stopped to let it cool for a bit then set off to get it home, ran better for a few minutes then back to rubbish. Same story again today. Really not sure what the problem is now. It seems to still be temperature related and must be affecting the fuel mix that is getting sent causing it to run rich, and maybe getting choked up on petrol? The history shows that it went to a VW garage twice in 2009. The reports state that it went in with high idling problems. 1st time round they found that the injector seals were leaking, replaced them, checked cambelt timing, checked ignition timing, carried out basic settings and adaption on the throttle body, did an emissions and road test and it then seemed to run ok. The next report is for 1 month later, this time: rechecked work from previous visit, found lambda readings out of spec, replaced lambda, replaced throttle body, but problem still persists... and then nothing!? So it seems like the VW garage just gave up!?! So maybe the underlying problem may have been ongoing for some time now. Virtually everything that is usually responsible has been replaced (sometimes more than once!) and yet the problems go on. I was thinking that maybe the ECU was knackered as I have read that the ECUs for this engine(Code: 030 906 030D) are known to be faulty, but could a faulty ECU cause all of the above. The problem seems to be intermittent as it seemed to run well before we did the thermostat (although the changing of the thermostat could be incidental, suspect the problems would have probably returned anyway). This leads us to think that it could be a problem with the wiring somewhere? Maybe a short circuit? Apologies for the lengthy post but I starting to get a bit desperate and there must be a solution. Looking on the net it seems that Im not alone in my suffering, lots of 16v Polos with similar problems? To add to that, in the albeit brief periods when its been working well Ive become quite attached to my Polo and Im determined to keep the little b*stard:-) Anyone have any suggestions or advice on what I can do next? Any advice on how to go about testing the wiring would be a great help, or is there anything else people think it could be? Any help hugely appreciated!!!
I have looked on ETKA, I can't see an air flow meter in there - It has a "thrust sensor" I will look at that when we get the inlet mani off to clean and inspect for cracks.
Tonight we finished up with a motor that sounded very good. The idle settles quickly with no hunting and the engine pulls well. Time will tell... Anyway here's what we did; Removed; Airbox, throttle body, fuel rail, inlet mani, oil seperator, distributor cover and vac hoses(4). Replaced all vac hoses, cleaned out oil seperator with petrol, blanked off EGR, cleaned out inlet mani - in particular the thrust/MAP sensor with carb cleaner, cleaned throttle body and then put it back together smearing grease on the gasket surfaces. These engines breath quite heavily and that forces quite a bit of draft up the breather, the oil seperator was pretty gunked up so probably will get that way again soon, we intent to run a flush of cheapo oil through it with atf in to clean it up then put decent oil in up the right level - it looked a little over filled. The EGR valve was likely not responding to the vac from the throttle body and still open at idle. It is likely to still past on emission with it blanked anyway - so will stay that way providing there are no further problems. It also had moisture in the dizzy - not the cap. We have cleaned and dried the counter contact and will keep an eye on it - could be seal gone.
