Hey guy's,
Decided to do some digging around and resolve some issues with my 2005 A4 B7 Avant 2.5 TDI 120kW BDG.
Main issue: Issue started @ roughly 1500 rpm only, under slight acceleration/idle. Accelerates great doesn't loose power starts great everytime does matter hot or cold. I discovered it when I started up the car, had it in park and slowly started accelerating up to around 1500 rpm. What happens is as soon as it got to that point started spluttering a bit kinda like chocking. As soon as I accelerated harder was fine. It was just at the 1500 mark. Same as when I drove and got to that point it any gear started hesitating. But like I said as soon as I accelerated took of fine without a problem. Up to the 1500 mark fine and above that fine, does not miss a beat very smooth.
So started digging around and at first thought it might be an injector issue. (Injectors in this car are mechanical with only one out of the 6 having a wire coming out of it.) So decided to pull the right hand side (passenger) rocker cover off and get the injectors out. As soon as I got the cover off I saw the exhaust rocker arm off wedged in the side of the engine block, with the hydrolic lifter/tappet broken above it with the bottom half of it still in the hole (see pic). Pulled it all out with a magnet and checked the exhaust cam for damage and it seemed to be fine. All other lifters and rocker arms where good and in place as they should be. So seeing as though I had to change the one decided to do them all, all lifters and all rockers. Put everything together and thought sweet. Timing marks spot on. While I had the injectors out decided to pull them apart clean them up, soak the tips over night in Carb cleaner and blew them out with air compressor.
(tried inserting pic with no luck)
Turned engine on, seemed to run a lot better was not chocking or cutting out as much as before, was a lot smoother, but still not right. There was still slight hesitation around the 1500rpm, and this time a lot of white smoke after a bit. So it seems to me there is still an issue, with burning the diesel in the cylinder itself. I'm thinking because I couldn't see the valve on the rocker arm & lifter that was slipped off/broken, there could possibly be an issue there inside the head with the valve/s. Got the diesel compression tester out to test each cylinder and make sure I am getting correct compression in every cylinder. And got the issue above with the 10 bar in each. Can't believe it. As I said the car runs and idles and starts smooth just at the 1500rpm white smoke strong diesel smell and then once it gets past it it is fine again.
I'm finding it really hard to believe all valves are bent, or that all cams are damaged. Seems very unlikely to me.
Any advice with why i'm getting 10 bar exactly in each cylinder with car starting / running smoothly? I thought it was a faulty compression gauge but after getting another known good one it was the same. Bang on 10 Bar in each cylinder.
The only reason I'm doing this is to try and resolve the un-burnt fuel issue I'm having, white smoke at 1500rpm only and strong smell of diesel along with slight hesitation when it gets to 1500rpm. but as soon as I accelerate it's fine.
Any ideas as to why I could be getting un-burnt fuel out of the exhaust? I pulled injectors and cleaned them well and tested them, they seemed to work fine. I was really expecting to find one or two valves gone but this is not the case seeing as though all cylinders compression is the same.
I found a couple of older workshop manuals for the 2.5 tdi engine and all said compression should be 27 - 33 bar with minimum 22/23 bar. It said under 19 bar engine is gone. So really confused now as to what are the chances that both sides of the engine head left and right are all gone at the same time. This is what I find very unlikely but I guess still possible. Weird thing is I'm getting exactly 10 bar on each of the 6 cylinders... seeing as though the engine starts and idles smooth apart from the issues at 1500rpm.
VCDS giving me no fault codes at all currently. I did get a fault code before:
01318 - Control Module for Injection Pump (J399)
34-00 - No Elaboration Available
But after clearing it it hasn't come back. Could this issue be in the injector pump? Really not sure where to look next and really hoping someone here has a good working knowledge of the 2.5 TDI BDG engine and can give me some input or ideas on what to check.
Sorry for the long post just trying to give a good understanding of whats going on and what I've done already.
Thank you very much and really hope someone can help, Cheers
Decided to do some digging around and resolve some issues with my 2005 A4 B7 Avant 2.5 TDI 120kW BDG.
Main issue: Issue started @ roughly 1500 rpm only, under slight acceleration/idle. Accelerates great doesn't loose power starts great everytime does matter hot or cold. I discovered it when I started up the car, had it in park and slowly started accelerating up to around 1500 rpm. What happens is as soon as it got to that point started spluttering a bit kinda like chocking. As soon as I accelerated harder was fine. It was just at the 1500 mark. Same as when I drove and got to that point it any gear started hesitating. But like I said as soon as I accelerated took of fine without a problem. Up to the 1500 mark fine and above that fine, does not miss a beat very smooth.
So started digging around and at first thought it might be an injector issue. (Injectors in this car are mechanical with only one out of the 6 having a wire coming out of it.) So decided to pull the right hand side (passenger) rocker cover off and get the injectors out. As soon as I got the cover off I saw the exhaust rocker arm off wedged in the side of the engine block, with the hydrolic lifter/tappet broken above it with the bottom half of it still in the hole (see pic). Pulled it all out with a magnet and checked the exhaust cam for damage and it seemed to be fine. All other lifters and rocker arms where good and in place as they should be. So seeing as though I had to change the one decided to do them all, all lifters and all rockers. Put everything together and thought sweet. Timing marks spot on. While I had the injectors out decided to pull them apart clean them up, soak the tips over night in Carb cleaner and blew them out with air compressor.
(tried inserting pic with no luck)
Turned engine on, seemed to run a lot better was not chocking or cutting out as much as before, was a lot smoother, but still not right. There was still slight hesitation around the 1500rpm, and this time a lot of white smoke after a bit. So it seems to me there is still an issue, with burning the diesel in the cylinder itself. I'm thinking because I couldn't see the valve on the rocker arm & lifter that was slipped off/broken, there could possibly be an issue there inside the head with the valve/s. Got the diesel compression tester out to test each cylinder and make sure I am getting correct compression in every cylinder. And got the issue above with the 10 bar in each. Can't believe it. As I said the car runs and idles and starts smooth just at the 1500rpm white smoke strong diesel smell and then once it gets past it it is fine again.
I'm finding it really hard to believe all valves are bent, or that all cams are damaged. Seems very unlikely to me.
Any advice with why i'm getting 10 bar exactly in each cylinder with car starting / running smoothly? I thought it was a faulty compression gauge but after getting another known good one it was the same. Bang on 10 Bar in each cylinder.
The only reason I'm doing this is to try and resolve the un-burnt fuel issue I'm having, white smoke at 1500rpm only and strong smell of diesel along with slight hesitation when it gets to 1500rpm. but as soon as I accelerate it's fine.
Any ideas as to why I could be getting un-burnt fuel out of the exhaust? I pulled injectors and cleaned them well and tested them, they seemed to work fine. I was really expecting to find one or two valves gone but this is not the case seeing as though all cylinders compression is the same.
I found a couple of older workshop manuals for the 2.5 tdi engine and all said compression should be 27 - 33 bar with minimum 22/23 bar. It said under 19 bar engine is gone. So really confused now as to what are the chances that both sides of the engine head left and right are all gone at the same time. This is what I find very unlikely but I guess still possible. Weird thing is I'm getting exactly 10 bar on each of the 6 cylinders... seeing as though the engine starts and idles smooth apart from the issues at 1500rpm.
VCDS giving me no fault codes at all currently. I did get a fault code before:
01318 - Control Module for Injection Pump (J399)
34-00 - No Elaboration Available
But after clearing it it hasn't come back. Could this issue be in the injector pump? Really not sure where to look next and really hoping someone here has a good working knowledge of the 2.5 TDI BDG engine and can give me some input or ideas on what to check.
Sorry for the long post just trying to give a good understanding of whats going on and what I've done already.
Thank you very much and really hope someone can help, Cheers
