Technical Flat Spots after service

[klaus23]

Hi all,

Bit of a wierd one. I just picked my Mk2 Sporting up from a mechanic I normally use and who has never let me down. It's a bit late and I can't call him this evening, but I've got a bit of an issue.

It's had a full service: air filter change, engine flush, new oil and filter, brake fluid change, coolant change, new spark plugs and a gearbox oil top up.

Problem is, suddenly (the problem was not there last week) when I accelerate in mid-range there are noticable flat spots, felt as two slight judders when accelerating between 2,500 and 4000 rpm.

I drove about 30 miles this evening and the problem seemed to go away but is still a little noticable. I don't know if it is the clutch because the pedal is fine, the biting point is still normal and the car stalls in 3rd if pulling off in that gear.

The car also idles fine, and the judder is not always noticable. I checked the basics in the dark (air filter box for example) and it all seems fine.

Any thoughts?

 

[T14086]

Sportings are very fussy about spark plugs (I think Denso's are the ones to use,maybe someone can confirm this?) also are plug gaps correct.If these are ok & no breather pipes have accidently been disconnected & plug leads are ok do the usual disconnect battery etc etc etc

 

[klaus23]

Hi T14086 - the car is using Denso plugs (shop didn't have the HGK's) and all the breather pipes and induction bits are on correctly. I would strongly assume the gaps are correct - I don't have a tool to measure them, but my mechanic is pretty good and I'd expect that they're fine.

When you say "disconnect battery usual stuff", can you elaborate?

 

[thefishdude]

by disconencting the battery for about 20 minutes the ecu resets, then when you reconenct, the ecu relearns all the readings from all the sensors on the car engine. this can sometimes get rid of minor problems if changes have been made to engine. this is normall allways done after peope fit better airfilters/induction kits to there cars. as the new unit allows more air. wich unless the reset is done the car wont take fulladavantage.

this may not work for you but its an easy and free thing to do. just remember if you have standard radio you may need the code for it to get it working again.

 

[klaus23]

Hi thefishdude,

Thanks for that - I found the problem today - the problem was one of the plugs which was installed correctly but was faulty. It's going back to the mechanic tonight

 

[thefishdude]

kewl nice find and an easy fix, cant argue with that

 

[klaus23]

And... not only was there a fecked plug, but one of the leads was cracked as well. Both got replaced and the Punto zooms again!

 

[bhinderharminder]

by disconencting the battery for about 20 minutes the ecu resets, then when you reconenct, the ecu relearns all the readings from all the sensors on the car engine. this can sometimes get rid of minor problems if changes have been made to engine. this is normall allways done after peope fit better airfilters/induction kits to there cars. as the new unit allows more air. wich unless the reset is done the car wont take fulladavantage.

this may not work for you but its an easy and free thing to do. just remember if you have standard radio you may need the code for it to get it working again.

when you reconnect the battery after 20mins, how long dose it take the car to get back to normal?
thanks

 

[thefishdude]

dont know exact details but i got thsi from another post that someone said.

disconnect the battery for 30-45mins.
reconnect battery
switch on
leave at idle for 5 mins
switch off
switch on again and then go for a drive
make sure the engine is warm before your drive it hard, but this should be progressive not wheelspinning off the driveway....

it will take a few hundred miles for it to register the new values...


sounds liek guy new more about it that me