2.0HDI hunting at idle

[dave_xsara]

There has been an intermittent issue with my 01 Xsara over the recent number of years whereby the rev counter would fluctuate by approx +/- 75rpm around idle (750rpm I think) with an odd blip of +250rpm. There has been a few sporadic incidents whereby the throttle response was noticeably lagging moreso that usual.

The car gets a mixture of driving. During weekdays it travel approx 3 miles in traffic to work and at weekends it would do 50 mile journey on motorways and A-roads averaging around 2500rpm for approx 1 hr.

I'm not sure what causes the hunting as it comes and goes. I'm using standard BP diesel and currently no additives.

I've fired a lot of money at this car recently, so I'm not looking to 'get under the hood' again unless absolutely necessary.

Are there any additives which I should be using on a regular basis? Normally I'd fire in some Redex Diesel System Cleaner on an ad hoc basis.
Should I be using any additive (are the proven to work) or just run a tank of BP Ultimate through the tank on a regular basis?

[Peter.N.]

If this is the 8 valve 2.0. engine the problem will likely be with the pressure regulator on the back of the HP pump, I had this problem myself on a C5. Its fairly easy to change and they can be bought on ebay for not to much money.

The problem is usually with the filter, the shiny bit with lots of very small holes, you can try cleaning it but I haven't found it very successful.

Peter

https://www.ebay.co.uk/sch/i.html?_from ... r&_sacat=0

[dave_xsara]

Thanks - I'll keep an eye on things.

It's not bad enough yet to warrant swapping out the part - only intermittent at present.

[dave_xsara]

I might have to take action sooner with this than I planned.

Was driving into work this morning and there was slight hunting, nothing worth noting about. However, on a few occasions when I put the foot down, the car did not respond for about a second or so and then lurched forward.

Is this a symptom of the same problem or should I be looking elsewhere?

I should also have said that the car was service about 3k miles previously with new fuel & oil filters and oil replaced.

[GiveMeABreak]

Can you get it on Lexia so we can have some codes to go on?

[dave_xsara]

I'd need to take it into an auto electrican to get the codes read.
Do the codes not throw on the engine management light?

[GiveMeABreak]

No, not in many cases. Only specific faults will do this. With this sort of thing there could be a few reasons; fuel supply /pump, MAF, air supply, turbo hose, EGR, etc, so without some sort of pointers from the codes, it will be guesswork really.

[GiveMeABreak]

Dave - I've moved your original post to the diagnostics section as it is probably more suited there:

Please direct all answers to this thread:

viewtopic.php?f=51&t=59992

Thanks.

I was actually talking with my brother about getting our own fault reader. However, we'd want one which covers a majority of cars as he does a bit of home mechanic work.

What are the best diagnostic tools for a home mechanic? I'd be prepared to spend up to £400 for a decent bit of kit that we could get upgrades for as and when needed. IS there a thread on here for this or recommended kits?

[dave_xsara]

Is there an idle control valve on the 90hdi? Or is that a different name for the hp regulator.

EDIT: Looks like the Idle Air Control Valve is only for petrol engines - correct?

What is the fuel pulsation damper (91538325)? https://www.autodoc.co.uk/bosch/677433

Unfortunately I've got noone nearby to get any codes or of the car.

[dave_xsara]

HP Regulator has now been replaced and the car is driving much better. At idle the needle is steady and when taking off there is no lurching or delay. However, looking at the old regulator this does not seem to have failed in the same way as described in this thread.
It looks like there was an impingement on one side of the shaft as noticeable abrasion can be seen from the attached photos. Is this something to continue to worry about with the new regulator? The old one was original and was tightly screwed in.

My understanding was this the HP regulator issue was with a small gauze filter. That is not the case here.
My concern is the the abrasion will now happen to the new regulator.

[dave_xsara]

Apologies for bumping this - it dropped off the first page without a reply.
I was just wondering if the abrasions are expected for a 17yo part or whether they are an indication of something else having gone wrong.

Thanks.

[GiveMeABreak]

As per my previous post above (viewtopic.php?f=3&t=59948&p=606911#p573915), I asked for posts relating to the diagnostic query in this thread to be posted in the diagnostics section: viewtopic.php?f=51&t=59992

Diagnostic posts placed here by some have therefore been deleted.

[Peter.N.]

Not all the regulators were fitted with the filter, in fact I got I best results from one that wasn't. You can buy used ones very cheaply from ebay and that's what I eventually used.

Peter

[dave_xsara]

I managed to get a new Bosch one for £80 but I'm concerned that the wear marks shown in the photos on the old one are due to something internal to the pump which will eventually screw up the new regulator I've fitted.

[Peter.N.]

I think my original had done something like 200,000 miles so I wouldn't worry to much.

Peter