General Pulsing Idle mk2b

[jmckee4]

Hi guys, I have a few questions about my mk2b's pulsing idle.

The car is a 53 plate with just under 55k on the clock.
I have had the car just over 2 years and it has always had an intermittent pulsing idle. (I think) it happens more when its cold) I average 5k miles a year.

I was picking up a friend and I could see my headlights in the reflection of the car in front, the headlights seemed to pulse with the engine.

Spark plugs were changed 5/8/11 at 48k (first time they were changed I believe)
HT leads changed 2/6/12 (didn't record mileage)
Throttle body cleaned 24/8/12 at 53k

I thought that cleaning the tb had resolved the problem but unfortunately it came back. Its beginning to annoy me as I'm starting to believe there may be an underlying problem.

Is there anything that could have gone wrong with any of the above?

I drew this when I changed the HT leads just in case. Anyone verify the leads are in the right order?

Anyone used an ultrasonic cleaner to clean tb and which ones are any good. The cheap ones on ebay look naff but I could be wrong

Any help appreciated, I have provided as much info as I can

 

[s and b]

55 thou tb should be mint
are you sure theres not a split in pipe from rocker cover
i assume no aircon too

sorry hard to diagnose via laptop

 

[jmckee4]

55 thou tb should be mint
are you sure theres not a split in pipe from rocker cover
i assume no aircon too

sorry hard to diagnose via laptop

No, I'll have to check .
How big would the split have to be to cause a pulsing idle?

Yes its an 'Active' so no air con. Can't believe I put all that info and forgot the basics. 1.2 8v Active

 

[s and b]

normally pipe slightly ajar on airfilter underneath
i would connect up a vacuum gauge to ascertain the pulsing mind

 

[Ziggy122]

A possible cause is the alternator belt
I had this ""Pulsing idle"", i cleaned the spark plugs and gapped - no change
Cleaned the throttle body - slight improvement
A couple of days later it was back - along with an annoying squeak

Turns out my belt was slipping a fraction, as a result the revs bounced about, sometimes worse then others and when demand was high

So check its tight - check it isn't shined or cracked

if its shiny - i cheated and buffed it off with a wire wheel on a drill till i can get a new belt

If its cracked - replaced, it'll be ready to snap soon

Ziggy

 

[s and b]

A possible cause is the alternator belt
I had this ""Pulsing idle"", i cleaned the spark plugs and gapped - no change
Cleaned the throttle body - slight improvement
A couple of days later it was back - along with an annoying squeak

Turns out my belt was slipping a fraction, as a result the revs bounced about, sometimes worse then others and when demand was high

So check its tight - check it isn't shined or cracked

if its shiny - i cheated and buffed it off with a wire wheel on a drill till i can get a new belt

If its cracked - replaced, it'll be ready to snap soon

Ziggy

never bought one of these belts
they live the life of the motor and are usually designed to do 100,000 miles these days
thought you had a nice yellow sporting
have you done a history check on the mileage?
something wrong

 

[jmckee4]

Been under the bonnet this morning and had the air filter box off.
There doesn't appear to be any cracks in the breather pipe and it is connected properly.

I can only see the belt on the left side of the engine bay which looks to be in good nick.

TB looks same as after I cleaned it.

Seems to be running fine today, but it is intermittent so will probably be back later today or tomorrow.

Is there any way I can isolate the problem should it rear its ugly head?

I'm wondering whether I should check the spark plugs for any signs of problems.

 

[fingers99]

Problem is, plugs will generally only record a proplem after prolonged running.

 

[jmckee4]

I see what you mean, they've only been in a couple of months.

Would the cause possibly show up with FES? Or does it not do this sort of thing?

Sorry if I'm asking dumb questions

 

[fingers99]

It's well worth a go.

 

[jmckee4]

Ok, I best order a cable then. I've never used it before so don't be surprised when I start asking questions

 

[Ziggy122]

never bought one of these belts
they live the life of the motor and are usually designed to do 100,000 miles these days
thought you had a nice yellow sporting
have you done a history check on the mileage?
something wrong

if its been allowed to slip - its gonna get shiny

It had also been stood - so the belt dried out i believe

As i said i just cleaned it and made sure it was tight = FIXED

Ziggy

 

[jmckee4]

I bought this lead off ebay: http://www.ebay.co.uk/itm/150852545917?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

It arrived this morning and I've just installed M.E.S. Is there anything I should be aware of? Or is just a case of plugging in and that should be it?

 

[cas1]

Let me know how you get on, ive got a similar problem and have a feeling its the lambda

 

[fingers99]

Let me know how you get on, ive got a similar problem and have a feeling its the lambda

Pulsing idle won't be the lambda.

 

[cas1]

Got a mate of mine to plug it in just now and its the lambda sensor.

 

[Ziggy122]

pre or post (euro emission depending)??

a lamba can alter fueling
if the fueling is wrong itll cause odd/off results on a running engine

ziggy

 

[fingers99]

Maybe.

I'd like to see the code. Currently I'd be more inclined to accept the theory that pixies were dancing in the throttle body............

 

[homeward]

...I'd be more inclined to accept the theory that pixies were dancing in the throttle body............

Is this a Punto thing...?!

I've only encountered the odd gremlin, so far....

 

[jmckee4]

Ok, so I eventually got MES working and you'll never guess what?

P0130 - Lambda sensor fault, After Cat from what I can tell.

Doesn't mean anything to me, but whilst playing around I made a graph with the engine running

How big a job is it to change the lambda? Think I'll check any pipework to it first to make sure I'm not doing any un-necessary work. Time to pull out the haynes as I have no idea what I'm looking at