Jump to content

SDI Hesitation/Judder At Low Revs, Fuel Starvation?


JoeyEunos
 Share

Recommended Posts

As per the title chaps :mellow:

I don't get much of a chance to drive the little SDI these days as it's been in the wife's custody for a while now, took it out tonight and was disappointed to find that there's now a pretty nasty hesitation and/or juddering sensation at low revs, usually the 1000-1800 range. In the past I used to marvel at the fact the car would happily chug along at 30 mph in 5th at around 1100 rpm without complaining, now it seems like 30mph in 4th is too much to ask, it's complaining pretty badly and almost seems to be asking for a lower gear <_< Anything over 2000 is fine...

To make matters more frustrating, I got in this afternoon after driving it and asked how long it had been like, she confirmed it's been a month or so :ph34r:

My first thought is fuel starvation? The current fuel filter is about to hit 2 years old and has covered circa 17000 miles so that seems like a good place to start? I know @Skezza has experience of cleaning the fuel pickup/strainer, worth looking there? Anywhere else I should be looking?

As always any feedback/suggestions would be gratefully received.

Link to comment
Share on other sites

11 minutes ago, Rich said:

cts and coolant flush.

easy task and cheap, liable to fix all at present.

 

CTS, really?

I've got a few spare decent ones about and plenty of coolant too, I'm also prepared to admit I may be wrong but I'm struggling to see how it could cause juddering/hesitation :wacko:

Temp gauge reads true, no codes on my cheap China scanner and the fault is present whether engine is warm or cold...

 

 

Edited by JoeyEunos
Link to comment
Share on other sites

I had this problem and the cause can be seen below

DSC08334.thumb.JPG.2bc8d91628d8a37faa819751f8ecb7df.JPGDSC08337.thumb.JPG.1a305964f036eeac4910affc46c5cdea.JPG

Obstruction of intake

If, when hesitant, the engine exhausts black smoke and the engine noise changes, it is almost certain that this is the cause or the egr does not close well .

For testing cancel the EGR by removing the vacuum hose (plug the hose with a screw to prevent vacuum loss) and  you can apply the same procedure as the hose that fits into the inlet flap ( operation of this flap is closely related to the functioning EGR )

If the engine's performance improves, you've found the area where you need to fix it .

 

  • Like 1
Link to comment
Share on other sites

@lupo 1.7sdi I think you covered this in this thread (I actually commented on it at the time)....

Also covered here...

 

So do you lot think I'm barking up the wrong tree RE fuel filter etc? I must admit this seems likely, the car leaves a sooty patch on the drive upon cold start...

* Are the 'trumpets plastic? Safe to use carb cleaner/Mr Muscle on them?

* Any tips (Or even better 'How To's) RE removing the EGR for cleaning

@mk2, I know you've done this, any guides RE removal of the trumpets/intake/EGR? Also, how did you clean the soot from the inlet ports on the block whilst avoiding debris falling into the cylinders?

TIA.

 

Edited by JoeyEunos
Link to comment
Share on other sites

I knew we had talked about it but I did not know where :D

Yes trumpets are made of plastic but are made of special plastic that is not attacked by petroleum products. I used brake cleaner, WD40 and a thinner.

To clean the soot from the inlet ports on the block I used a sheet-metal spatula

DSC08343.thumb.JPG.7f8cb17b19f84f599dfa10c23f186df4.JPG

After that, to clean the stoot falling on the valves I attached a hose to a vacuum cleaner

  • Like 1
Link to comment
Share on other sites

before you do anything, take it out for a 10 mile run on a motorway... if it's full of soot, or the cats' blocked, a good run will clear it. then if it still judders, it's probably a fuel starvation problem. you could try disconnecting the vac hose from the egr (block the open end with a screw) and run without active egr. is air filter ok?

whats the power like?

edit: i have a feeling it might be stuck egr valve. definitely try egr deactivation- pull vac hose off.

 

Edited by mk2
  • Like 1
Link to comment
Share on other sites

2 hours ago, mk2 said:

before you do anything, take it out for a 10 mile run on a motorway... if it's full of soot, or the cats' blocked, a good run will clear it. then if it still judders, it's probably a fuel starvation problem. you could try disconnecting the vac hose from the egr (block the open end with a screw) and run without active egr. is air filter ok?

whats the power like?

 

Thanks for chiming in fella :)

Funnily enough I had it out this afternoon, only for a 10 mile run on dual carriageway and towards the end (When warm)  hit 70 *cough cough* at circa 4k rpm in 4th for a few minutes. It did feel better afterwards, not 100% but a fair bit better so you might well be onto something... Air filter is 2 years old and had done circa 16k so I will fit a fresh one in the morning (Been meaning to get round to this)

Power seems fine after around 1900 rpm, it happily reaches redline, there's just the stutter/hesitation at lower revs (Almost like engine mounts/bad drive shafts etc but both are fine). This is causing me grief as I know the car will usually run happily and has enough torque to do 1.5krpm in most gears without complaining at all <_<

Perhaps I will give it another longer run tomorrow but with some injector cleaner or Redex.

Interesting that you thought fuel starvation as that was my first thought... If an Italian tune up doesn't work tomorrow  I'll look at changing the fuel filter sooner rather than later too.

2 hours ago, mk2 said:

 

edit: i have a feeling it might be stuck egr valve. definitely try egr deactivation- pull vac hose off.

 

Like this....?

I'd considered simply fitting a generic Ebay blanking plate at the bottom  where it joins the manifold and then re assembling for a stealth EGR delete, but if this achieves the same ends then I'm all for it...

One question though, if the valve is 'stuck' in the open position then surely despite blocking the vacuum hose using the method you describe it would remain stuck open regardless of having stopped the vacuum?

 

Edited by JoeyEunos
Link to comment
Share on other sites

Right, I shall start with the easy stuff first then...

1. Half hours motorway blast at high revs this morning (Possibly with added redex or injector cleaner added).

2. Replace air filter.

3. Replace fuel filter.

4. Blank EGR

5. Remove trumpets/inlet manifold/EGR and clean.

6. Check fuel pickup/strainer.

7. If all else fails then diesel purge and perhaps even chuck a new CTS at it (Long shot though IMO)

I'll do these in order so as to see what effect each step has.

RE EGR, I think simply bunging the hose won't really provide much insight as if it's stuck open then this will have no effect as mentioned.

RE removal, it looks a right pain. The unit appears to be held on by a threaded bar without a nut to spin it off -_- Is it simple a case of grabbing one end of the bar with mole grips? Is the EGR itself threaded inside to house said lower threaded bar? How does it all work?

Link to comment
Share on other sites

yeah, from your symptoms, i'd say it's almost certainly the egr valve is jammed. i'd do that first.

good power/black smoke means fuel and injection system is fine. black smoke and down on power means blocked air filter/cat (unusual).

that threaded bar best attempted with molegrips, or two nuts back to back.

try the vac hose method. minimum effort fix.

Link to comment
Share on other sites

Right, I wanted to wait a few days before coming here and gloating, the issue is now resolved ^_^

A bottle of 'Tunap 984' and 30 miles on the motorway in 4th gear later and job jobbed :) The car is running well and pulling cleanly from low revs so the strip down and cleaning of trumpets/inlet manifold will have to wait for another day... The car's due a service within the next couple of weeks so that will help too I'd imagine.

Thanks to everyone who chimed in on this, you're a good bunch ;) 

Link to comment
Share on other sites

11 hours ago, Skezza said:

I'd do a diesel purge.

If the problems arise again the I will do ^_^

 

10 hours ago, Rich said:

You would do a diesel purge on a petrol.

For any future Lupo bodgers who stumble across this topic, the SDI is derv not petrol!

 This thread doesn't relate to petrol variants ;)

Edited by JoeyEunos
Link to comment
Share on other sites

  • 2 weeks later...

Hope it's still sorted.  If the problem returns... 

I had a similar issue on the two SDI's I've owned;  slight hesitation while accelerating through 2k rpm.

After a lot of frustration on the first SDI, the cure was very simple... I blanked the EGR and the problem went away instantly (a little more mpg too).  So when the second SDI started to develop the same symptoms, I knew exactly what to do, and again problem solved instantly.  (blank panel cost only a few pennies on ebay).

 

 

Link to comment
Share on other sites

On ‎08‎/‎04‎/‎2018 at 8:38 PM, lupo 1.7sdi said:

Yes, canceling the EGR is a good palliative

EGR blanking is a possibility but not at present as all is running well again.

@Lupo 1.7 sdi, have you deleted/blanked yours?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.