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Discussion Starter #1
Hi Everyone,

I usually only have to read the forum, and learn, and search and find my answer is already there. So firstly a really big thank you to anyone who ever posted anything useful that I have read.

But today I have a problem I cant find the answer to:

My van is a 1.9 tdi conversion - 1z, worked great, I bought it that way, so I have to admit I haven't done the work myself.
Yesterday and this morning I changed the injection pump to an 11mm unit, something I'd been wanting to do for ages, but took a while to get parts, lathe down the pulley etc.
Really pleased with my work I fired it up, set the IP timing using vag-com, altered the IQ modifier to give 3.0mg/Str. All great so far, so I took it for a test drive.

This is the problem: when I accelerate hard, not necessarily at WOT, the tacho occasionally dips, at one point it went to zero for maybe half a second. I could hear the engine still going round. I was actually accelerating through this, so I know it's a dodgy reading, rather than the engine intermittently stopping. The engine note was changing with the dips, but seems more like the engine is interpreting it somehow and changing settings to compensate, rather than the other way around (I may be wrong on that though).

So what should I be checking? Is there a specific wire that would sense this that I might have knocked and made a loose connection?
I made a short wiring harness to convert the engine 8 and 3 pin plugs to a single IP 10-pin plug, but kept all the original plugs, so that it could be changed back if required, could a dodgy connection here do it?
Or is the fuelling set wrong on the IP, so that the hammer mod could fix this?

These are the only things I can think of, but not sure where to start checking.
All help greatly appreciated,

Thanks in advance.
 

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Discussion Starter #3
Thanks, I didnt think the fuel pump would have too much to do with it.

I took both the small wires out of the alternator, and the engine multiplug out and then put copper grease on all the terminals and plugged them back in. I also loosened the alternator, retensioned the belt and tightened back up. Took it for a twelve mile test drive and didnt have the problem happen during that. Hopefully it's better, but I'll give it a week and see.

Im hoping one of three things happened:
1.Maybe some fuel spilled onto the alternatr contacts when I took the old IP out, which messed them around
2.I could have nudged the engine multiplug when reaching down to the bell housing TDC marker.
3.not enough tension on the alternator belt (had to take this off as I dropped a bolt down into the lower timing belt cover - doh!), though I find this least likely as theres a big spring that tensions the alternator.

As I said, Ive addressed these 3 issues so hopefully no more problem.

Thanks for your hint zmok, much appreciated.

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