VP20 advance issue, swapped to full mechanical pump

[dylan1978]

Hi all. Great forum, forums like these really keep us weekend warriors going.

See what you think to this.

I've recently aquired a peugeot 1997 806 1.9tdi, with a DHX engine and a VP20 ECU diesel pump, (wire from the 2nd injector). I've always been impressed with diesel pugs and found them to be quick smooth and quiet, (and cheap). Anyway this one isn't, in fact it sounds like an old transit in contrast to the 1.9d non turbo old school partner I use which is super quiet.

When driving under load up to 1500rpm the car vibrates alot and is generally unrefined and tractor like, above 1500rpm it smooths out a bit but it's still LOUD. It starts well enough, doesn't seem to smoke much and is quite nippy above 2000rpm.

Step 1 - full service no change

Step 2 - Liqui moly diesel purge on a closed fuel loop 2 litres, another oil change, still no change

Maybe the engine mounts I thought?

Step 3 - change all of the engine mounts and that one underneath the engine is a pig - still no change.

So then I saw the diagnostic plug, oops, I thought I'd bought something without an ECU, my bad.

So my mate has a car repair business with two ramps and lots of kit and he owes me some favours. He plugged it into a bosch diagnostic and it refused to read it. The snapon DID read it however and showed the following faults.

4 pedal position sensor circuit
3 coolant temperature circuit
19 barometric pressure sensor circuit
14 injection begin sensor
32 glow unit

The live data showed the temp was reading 140 degrees

We tested the resistance of the lift sensor - 107 ohms

I replaced the temp sensor, (the green one behind the fuel filter) and it made no difference. We read it with the snapon again and it showed the same codes interestingly with No live data available and were unable to clear the codes, the diagnostic machine just freezes up.

Interestingly if I unplug the wire coming from the 2nd injector this makes no difference and it still sounds like an old transit. Not that I'm disrespecting old transits I think they're great but they do have that distinctive sound. PLUS there is NO K light coming on at all even with the lift sensor unplugged, the K light comes on with the ignition so I know that the bulb's ok.

So I've Spoke to a helpful chap at an ECU repair place because I'm starting to wonder if the ECU is at fault but I feel like I'm chasing my tail a bit here. I just want it to be smooth and quiet, I have family all over the UK and drive alot. He said it could be the ecu but maybe not. Typical ECU repairs seem to range from £50 to £150 with no guarantee that the problem will go away.

SO

Option 1 - Fix this automatic advance issue with an ECU repair etc.

Option 2 - Bodge the pump in a fixed position so that it's quiet, (I don't now if that's possible)?

Option 3 - Replace this semi ECU pump with an old school mechanical one and forget about sensors, ecus and fault codes and go back to living my simple life in my cave.

Or maybe I'm missing something?

Your thoughts greatly appreciated, I promise to keep you up to date on progress.

[Peter.N.]

These engines are not normally all that noisy - by the standards of the time. If its diesel knock you are experiencing the pump timing could be over advanced, it will normally get quieter as the engine warms up. I have not experienced the electronic pump but the mechanical one you can adjust by slackening the mounting bolts and turning the pump, in the direction of rotation to retard.

If the pump is faulty I would be inclined to fit a Bosch fully mechanical pump, an early one without the armour, but if you do, change the pipes as well because some have a different output positions.

Peter

[dylan1978]

Thanks Peter

Do you think I could use the existing injectors or would I need to aquire a set to match the mechanical pump?

Yes it does quieten a little when it gets warm. Also I had a voucher going out of date for Sainsbury's so I bought a load of veg oil and stuck that in and topped up with diesel, about 60/40 diesel/veg oil. I don't think this engine's ever seen veg oil before. A 40 mile round trip later and it seems a little smoother but still knocks away.

Out of curiosity I took the ECU off to check the connections and tried starting the engine. Now THAT was loud like "Turn that racket off!" so I'm puzzled, the ecu must be doing something but the system's gone wrong somewhere.

Maybe there's away of fixing the pump timing manually and bypassing the ecu. I go on the princible that anythings fixeable.

I

[Peter.N.]

Other people have said so but when I changed a Lucas pump for a Bosch one on a BX some years ago I used the original injectors. I can't see that there would be any other difference than the opening pressure. Mind you the BX went like a rocket with its Bosch pump and Lucas injectors

Peter

[Dommo]

Assuming the opening pressures are the same you can use the old injectors id have thought..

Using the wrong pressure injectors makes the timing go to pot. You have to imagine the fuel pressure in the fuel line as a curve on a graph (hard to describe), once the pressure reaches the break pressure of the injector, it is allowed into the engine. If the pressure of the injector is lower than is specified for the pump, the fuel starts being injected much sooner and over a much longer duration so there is no burst of atomised fuel that the pump intends to give.

[dylan1978]

Thankyou that's interesting, and critical by the sound of it.

Yesterday I picked the pug up from a party where I'd left it, pulling out of a tight spot it stalled, when I started it it sounded awful. Clatter beyond Clatter like when I tried disconnecting the ECU to see if it made a difference to the already there noise, (it did). So turned it off, checked the ecu connection and under the bonnet for anything obvious and turned it on again, the same. Drove it , (slowly) up the street, the same, started it this morning, the same... uh oh.

So it's going in to my brother in law's garage for an inspection. He had a listen and reckon's it might have jumped a tooth on the belt, that shouldn't happen right? Either way it's not driveable. I'm going to borrow a car and get myself over to the scrappy and see if there's a mechanical bosch pump I can scavenge and do that at the same time. We'll see.

I know what they'll say, "It's getting on a bit Dylan, is it worth spending the money?" But the thing is it's a one owner, rustproof, 100k totally useful vehicle that can carry 7 in comfort to Scotland one day and be a van with 2 sliding doors the next. If I can get around this I should have a reliable motor for the next 100 - 150k miles.

With reference to the injectors Dommo I'll see if I can get a set with the pump I'll (hopefully) find at the scrappies.

[Peter.N.]

If the timing is out its normally retarded - difficult for the sprocket to jump forwards. Opening pressure will affect the timing but not very much, the pressure drops with age anyway and as it gets lower the combustion becomes quieter and yet theoretically the injection point advances - answers on a postcard.

On the old Perkins 4/108 engines that I used to do conversions you could actually adjust the pressure with the engine running, if you took the injector cover off there was a screw and nut adjustment like the old tappets, you could hear the effect of increasing and decreasing the pressure - I wouldn't try it with a common rail engine though.

Peter

[dylan1978]

Thanks Peter

I try to steer clear of common rail stuff after a bad experience with a mercedes Vito, black death anyone? But the more I learn about diesel engines the more I want to find out, especially the big stuff and marine engines.

Anyway, I now have an IP which I removed from a 157k clean 405td at the local scrapyard, I'll get it fitted in the next few days with a new cambelt and see what happens...

[Peter.N.]

I felt exactly the same way about common rail engines which is one of the reasons I have continued to run the XMs but I must admit that the Hdi 406 I have has changed my mind, not about all common rails but the 8 valve 2.0L particularly. It had done 189K when I bought it and didn't look as thought the engine had been touched, its now done 202k and hasn't missed a beat.

There are quite a few advertised with 300k+ miles and are still running fine, it was seeing this that changed my mind about them, this is XM territory plus 60 mpg. I still wouldn't trust some other CR engines although many of the problems I believe are brought about by the extended oil change intervals.

Peter

[dylan1978]

Pump from the 405 installed along with a new cambelt kit. The Cambelt had jumped 2 teeth. I guess I was lucky that no damage was done. With the mechanical bosch pump fitted it runs like a dream with no ECU to go wrong I'm a happy bunny.

If you have the semi electronic pump and you're having issues with it then swap it, there's no school like the old school and you won't need someone with a computer to tell you what's wrong with it.

Case closed.

[Peter.N.]

Well done, pleased you have fixed it.

Peter

[CitroJim]

Well done, pleased you have fixed it.

Peter

Indeed I very much second that.

Only problem is that VP20s are now becoming rather scarce...