Jerking while accelearating at low revs

[Bomi]

A couple of monhs ago I had installed Powerflex suspension + dogbone mount bush on my vRS (56000 kms). The resultant vibrations did reduce after the bushes bedded down, but on poor Indian roads the ride quality was jarring. So I had the bushes changed back to stock (new ones) by a dealer. The dealer also changed the plenum support (the part on which the dogbone bushes sit). And also my tie-rods as he claimed they were busted.

Now when I accelerate in second gear from low revs of around 1500, the car jerks once (as if the wheels and the engine are disconected for a split second), before picking up speed. Once it crosses 2000 revs, there is no jerking. Similarly, when I lug the engine a wee bit, after braking(revs around 13-1500), this jerking occurs. If I race the engine in neutral, there is no faltering in the RPM rise; also the idle RPM is rock-steady.

Is this clutch slippage? The clutch pedal feels absolutely normal and all gear changes are smooth. If the clutch is slipping, what parts should be replaced (fly wheel, clutch plate, pressure plate)? My charcoal canister also has a broken plastic spout on which I have done a patch job (see attachment-I have used RobClubley's picture), to prevent the ECP light coming on. Is that the cause of this jerking? Appreciate anyones help.

Bomi

[Bomi]

Hi there. Anyome have a suggestion?

Thanks.

[kentphil1]

I had this on my VRS when I first had it a month ago, I sorted it by doing these things in order of seriousness.

1 Check the engine breather hoses especially the y-pipe onto the cambox - my one had a big hole by the y bit.

2 Clean the mass air flow sensor in isopropyl alcohol - made a large difference on my car.

3 Clean the throttle body - this put the icing on the cake and really fine tuned the sorting of the low speed running.

Initially I looked all over the car for loose mountings, clutch faults etc, but this sorted mine so hope it helps

P.S I presume your coils/spark plugs are in good order?

[Bomi]

Thanks Phil. Will check the hoses. Given that the idling is rock steady at 800 rpm I thought that the MAF, coils and spark-plugs are good. Is that a correct presumption?

[kentphil1]

My idle was fine too even though it would jerk badly at certain rpm so in answer to your question, no that does not necesarily mean they do not need attention or cleaning. Have you had a code scan done? - is anything showing in the ecu memory?. If all is clear, assuming your plugs are not due for a change anyway, recheck your plug gaps too. Most of this stuff will only cost you time, so its worth the effort in my opinion.

[Lambie24]

I had a similar problem and it turned out to be a very dirty throttle body. It was pretty easy to sort as I followed this really good guide that someone put on here.

http://www.briskoda.net/forums/topic/129943-cleaning-throttle-body-1-8t-engine/

Hope it helps

[Bomi]

Thanks, Gents. Will do a scan and TB cleaning. Cheers.

[Bomi]

Update :

I had the car scanned at the stealers and they recommended changing the N50 valve as its neck was partly broken. That did no good. Thereafter they changed the fuel filter as I had not changed it for over a year. That too did not cure the jerking. Ultimately, they diagnosed a rogue coil on Cylinder 3 and after changing that, everything is fine.

The stealer was recommending changing all 4 coils but I had had enough of their experiments.

Is there any merit in changing all the coils given that the car has done 57K kms and is now 7 years old?

Thanks

Bomi

[Raf_]

if your car has the original coils phone your local dealers with the number plate and see if its due a recall, you get 4 free coils