Can anyone offer advice on where to check next before I start just throwing new parts such as coil packs at my car?

 

When the engine is cold it shudders a little under very light acceleration, such as maintaining 30 or 40 mph, whether on cruise control or just my right foot. If I accelerate harder, it's fine, no misfire.

 

So far I have put new plugs in it (when did plugs get so expensive by the way?) and run 2 bottles of injector cleaner through it and the issue still persists. I only use super unleaded and buy it from several fuel stations, so I doubt it's dodgy fuel. Any ideas on what I can try before blindly buying new parts that I may not need?

 

 

Hi Mate

I have been researching the same, I concluded it wasnt electrical, or fuel - My symptoms - Worse while cold - upto 3k rpm.. above this - pulls smooth! 

 

I changed the DV valve - no change and had it smoke tested - no leaks

 

I'm aiming towards the inlet manifold being gunked up at present - just dont fancy removing it!!

However one thing to consider, which was recommended by the guy smoke testing - E5 petrol only - hes had numerous older performance petrols in with E10 issues!

 

If you resolve before I do, drop an update in here and I'll do the same

 

Andy

 

 

Carbon build up on the valves causes cold start and running issues. I assume you've scanned it and have no codes? If not, look at getting a carbon clean. Injectors, plugs and coils 'should' throw an engine light

On 25/04/2023 at 14:35, AScoff said:

Hi Mate

I have been researching the same, I concluded it wasnt electrical, or fuel - My symptoms - Worse while cold - upto 3k rpm.. above this - pulls smooth! 

 

I changed the DV valve - no change and had it smoke tested - no leaks

 

I'm aiming towards the inlet manifold being gunked up at present - just dont fancy removing it!!

However one thing to consider, which was recommended by the guy smoke testing - E5 petrol only - hes had numerous older performance petrols in with E10 issues!

 

If you resolve before I do, drop an update in here and I'll do the same

 

Andy

 

 

Not resolved yet sadly. Mine is only when cold, once the engine is fully up to temp it's smooth under all loads.

 

I'm not sure how I feel about removing the inlet manifold, it's the only car in the household at the moment, so being without it for an extended time is not appealing; I've never taken one off before and if it goes wrong I can't get to the parts shop easily!

 

It only has E5 Super fuel in it, I used a tank or 2 of the E10 and the car hated it, the difference in fuel economy alone makes up for the c. 10-15p a litre price difference too.

 

14 hours ago, Black vRS Oct said:

Carbon build up on the valves causes cold start and running issues. I assume you've scanned it and have no codes? If not, look at getting a carbon clean. Injectors, plugs and coils 'should' throw an engine light

 

I'll look into that, thanks. No engine light shown, I'll grab my little OBD dongle and see what the Torque app shows in the way of codes. I assumed none given there was no engien light on...

10 minutes ago, tufty1974 said:

Not resolved yet sadly. Mine is only when cold, once the engine is fully up to temp it's smooth under all loads.

 

I'm not sure how I feel about removing the inlet manifold, it's the only car in the household at the moment, so being without it for an extended time is not appealing; I've never taken one off before and if it goes wrong I can't get to the parts shop easily!

 

It only has E5 Super fuel in it, I used a tank or 2 of the E10 and the car hated it, the difference in fuel economy alone makes up for the c. 10-15p a litre price difference too.

 

 

Sounds like we are looking in slightly different areas, as mine is worse when cold.. but it still happens at full temp!

I've got no error codes to go at either

 

I dont fancy the inlet manifold removal either.. it looks like a days job if you have not done it before, plus the element of surprise!!!

 

Garage is getting booked today, need this sorting its annoying and clearly something wrong and not healthy!

 

I was advised against a carbon clean on an old car, can end up too clean and rattling! Thats from a mechanic, I've not looked into it any more than that as this stage.. 

Best of luck...

On 27/04/2023 at 11:25, tufty1974 said:

 

I'll look into that, thanks. No engine light shown, I'll grab my little OBD dongle and see what the Torque app shows in the way of codes. I assumed none given there was no engien light on...

I've just had mine diagnosed as the Evap purge valve

I disconnected it and the hesitation went, new one going on tomorrow! 

On 24/05/2023 at 12:39, AScoff said:

I've just had mine diagnosed as the Evap purge valve

I disconnected it and the hesitation went, new one going on tomorrow! 

 

 

I was delayed in looking into this further by a house move and warmer weather making the problem go away! Did the purge valve replacement fix your issue? If so, I will grab one, it looks relatively easy to fit from that photo, was that the case?

4 minutes ago, tufty1974 said:

 

I was delayed in looking into this further by a house move and warmer weather making the problem go away! Did the purge valve replacement fix your issue? If so, I will grab one, it looks relatively easy to fit from that photo, was that the case?

Hi mate

 

Oh no!! lol

Turns out I needed a full intake clean, that sorted it.. then an injector went.. so intake off again... then a swirl flap issue.. which is ongoing!!!!
Main problem was intake carboned up... been running on E5 too... so if youre on E10.. worth a look - and dont bother with those companies who will come out and do a carbon clean.. utter rubbish...

 

Good luck

Yikes, I hope your ongoing issues get resolved soon!

 

How did you go about the intake clean? Self-service or a mechanic? If mechanic, what sort of cost was it if you don't mind me asking?

11 minutes ago, tufty1974 said:

Yikes, I hope your ongoing issues get resolved soon!

 

How did you go about the intake clean? Self-service or a mechanic? If mechanic, what sort of cost was it if you don't mind me asking?

I looked at it, but got my garage involved

They did a full strip and walnut blast clean... was just shy of £500! then same again for Injectors!!! 

 

Swirl flap and injector went after a carbon clean... I'd be asking some tough questions on the garage to be honest.