[Coolshrek]

Hi,

When the problem appeared was not easy to hear it from inside the car (I was outside, near the engine, wife was going to work) but now that I know what to listen for, I can hear it every time.
I just noticed that on cold starts only, the engine ... how should I describe this... hunts/ rattles/ looks for, the idling revs! Starts easily, hits idling revs then engine speed drops a little then gets up again to set point then drops a little again. There are some 2 to, say, 5 little waves in some 2-5 seconds, then idling speed is smoothly regained and maintained again.
Anyone noticed something similar? What could it be?   

George

[Lorian]

What Engine?

[Shambles]

What Engine?

... and what's your mileage?

[Coolshrek]

Diesel 19000Km build Nov 2008

[2i30s]

dirty fuel filter.?

[Coolshrek]

Thought at that, very possible but most unlikely since the issues is only limited to cold start. Any other time low engine speed and idling is rather smooth... Will have to be some sensor/s that controls some process in the first few secs. Of course fuel supply will be one of those processes!

[2i30s]

does a diesel have an idle solenoid [tps] like a petrol engine.? the wife's cw Had one changed that was faulty,and the symptoms where similar to yours. 

[Coolshrek]

No idea mate whether or not there is such solenoid, but you may be on to something!!! And also make sense in terms of being a very  time specific issue.

[Shambles]

does a diesel have an idle solenoid [tps] like a petrol engine.?

Fair question 1i60

https://www.i30ownersclub.com/forum/index.php/topic,4171.0.html

[2i30s]

partially answered,Steve. 

[Lorian]

IIRC found the schematic for it on the Ceed tech CD, which I don't have to hand at the moment.

[Coolshrek]

That informed vaccum explanation Shambles seem to refer to normal running, don't you think? Not even sure if the Turbo system gets into play at all at start up, does it?

[2i30s]

even at 1000rpm a turbo is still under some load.

[Coolshrek]

very true i suppose if the engine turns most likely so does the turbine...

[Shambles]

One thing you could try, before seeking expert guidance, is resetting your ECU.

It's been covered many times on this forum, and others, no doubt.

Disconnect the battery -ve lead and allow 30 mins for any residual current to dissipate (some say to depress the brake pedal, but I'm not an advocate of that).

General opinion is that you give the ECU the chance to re-learn your starting/stopping/driving style it will adjust accordingly and behave in a way better suited to your modus-operandii.

Hey, it's just a cheap way of changing things to see if it makes a difference....

[2i30s]

the diesel engines we fit to fire pumps at my work get tested before being delivered.some of the big 300hp engines we run non stop for an hour and the whistle of the turbo is amazing.the turbos glow bright red,I've even seen one glow up allmost transparent.it ended up blowing up because the wrong injector pump was fitted and it ran to lean.   cummins where very apologetic.  

[2i30s]

One thing you could try, before seeking expert guidance, is resetting your ECU.

It's been covered many times on this forum, and others, no doubt.

Disconnect the battery -ve lead and allow 30 mins for any residual current to dissipate (some say to depress the brake pedal, but I'm not an advocate of that).

General opinion is that you give the ECU the chance to re-learn your starting/stopping/driving style it will adjust accordingly and behave in a way better suited to your modus-operandii.

Hey, it's just a cheap way of changing things to see if it makes a difference....

is that only a crdi reset,or it also works on a petrol engine. ?

[Shambles]

One thing you could try, before seeking expert guidance, is resetting your ECU.

It's been covered many times on this forum, and others, no doubt.

Disconnect the battery -ve lead and allow 30 mins for any residual current to dissipate (some say to depress the brake pedal, but I'm not an advocate of that).

General opinion is that you give the ECU the chance to re-learn your starting/stopping/driving style it will adjust accordingly and behave in a way better suited to your modus-operandii.

Hey, it's just a cheap way of changing things to see if it makes a difference....

is that only a crdi reset,or it also works on a petrol engine. ?

I believe it's an ECU reset, regardless. Must be worth trying...

[2i30s]

to save dissconecting the battery,could you just pull the plug out of the ecu.? [sorry about going off topic]

[eye30]

oil and fuel delivery possibly from cold as oil will have drained to the sump and fuel -Who knows!

[JohnT]

I've had exactly the same symptoms, on cold start only.  Like a slight 'miss' every couple of seconds, but only lasts about 10-15 secs, then runs perfectly.  It hasn't bothered me particularly, but I'd still be keen to know the cause if anyone finds it.

Cheers,
John

[LuciferDarklord]

The ECU controls idle by varying the fuel quantity injected.  My car does the same thing - I think it might be a slight air leak and the fuel drains back to the tank overnight.  Dont think its anything to be concerned about, bring it up at the next service.  If it blows blueish white smoke at cold start its probably a glow plug.  And in the other post, reecho is correct, there is a vacuum pump driven off the camshaft I believe to power the brake booster and other vacuum operated devices.  There is no Idle Air Device as the engine speed/load is controlled entirely by varying the amount of fuel delivered by the injectors.

[Coolshrek]

I cannot agree more. When a Diesel starts, well, it stars and runs reliably assuming that the fuel supply is consistent and above all else, air free. Never noticed significant blue smoke but some black at start up and under heavy acceleration, which of course is normal.