Concerns on Seat Leon

[Cupra_Jay]

On idle my car gives a little rumble as if it were misfiring and if you closely look at the rev counter it moves up and down really slowly every few seconds. (I think its still an injector issue). As well as this when its on idle if i say I throttle it a little bit the revs drop below normal then come back again which has a konking sound to go with it which i think comes from the iinduction kit but want to know whats causing that well.

Anyone seen or heard something familiar? I would take it back to the person that rebuilt my car i nthe first place but I work 6 days a week and dont have the time to go there at the moment and want to know if its a minor fix or not . Spoken a couple technicians one refuses to touch my car let alone hear the issue  because of its bad omen and the other stopped responding to my emails .

Regards

Jamie

[rdfcpete]

So everyone can help with accuracy dude, what year and full Cupra model info is it?

What serviceable bits have been replaced since you've had it and may have been replaced more recently etc?....

Too much info is more useful than not enough 

[Cupra_Jay]

Its a Seat Cupra Tfsi 2007 model. Its had a bare engine rebuild with all the old ancillaries put back on the car. Its had some wiring fiddle to suss out a fuelling problem which was related to the injector hence the reason it needed a rebuild in the first place( too much air going in whilst injector runs lean ) That is all the bits replaced as far as im concerned. I dont think any of the injectors were changed so I have no idea if I need a new set of injectors or not and the other sort of konking sound well I was told a diverter valve should sort the issue but I wanted confirmation from a technician or someone who has actually seen this on the TFSI as my mate been experiencing the same sorta konking sound lately when the revs come down

[GrayMK5GTI]

Mine does this, as did my old GTI, as does the guys jetta TFSI at Awesome GTI. . . (Pretty much every TFSI with a few miles on does it).

It's a combination of dirty injectors and dirty inlet valves typically.

I logged mine with VCDS and only counted 2 actual misfires at idle in 3mins of idle (cylinder 3)

Unless it's misfiring like crazy, it's very normal   get it on VCDS and log misfires and report back

[Cupra_Jay]

Mine does this, as did my old GTI, as does the guys jetta TFSI at Awesome GTI. . . (Pretty much every TFSI with a few miles on does it).

It's a combination of dirty injectors and dirty inlet valves typically.

I logged mine with VCDS and only counted 2 actual misfires at idle in 3mins of idle (cylinder 3)

Unless it's misfiring like crazy, it's very normal   get it on VCDS and log misfires and report back

It bothers me because before cylinder 2 died on my car it did something very similar but it wasnt rumbling as hard as it is now. As well as this on the revs coming down the intake does klonking type sound. What could that be? MY mates S3 is doign the same sort of thing and he reckons its his Diverter Valve .

[Scottymon]

Must say, mine did it for a while, I changed to Nology plugs (I know) and it dissappeared, happy days (no pun intended) then my Throttle Body and Alternator died in quick succession (plugs?)
I swapped out to OEM which were fine for a while, but it's doing it again... going to try some new OEM plugs see if it solves the issue.

[GrayMK5GTI]

Have a look at this: http://www.golfmkv.com/forums/showthread.php?t=123845

[Hurdy]

If the sparkplug took out the cylinder when running lean it may be that one of the valves on number two cylinder have pitting or deposits on them or on the valve seat/cylinder head or combination of these. also it could be that the throttle body flap is cracked and allowing extra air on idle into the engine, especially as this can give idle and cold running misfires and uneven idling.

I've had two throttle body valves crack on me as it is due to the combination of extra pressure and volume of air being forced against the valve when letting off the throttle.

[Cupra_Jay]

If the sparkplug took out the cylinder when running lean it may be that one of the valves on number two cylinder have pitting or deposits on them or on the valve seat/cylinder head or combination of these. also it could be that the throttle body flap is cracked and allowing extra air on idle into the engine, especially as this can give idle and cold running misfires and uneven idling.

I've had two throttle body valves crack on me as it is due to the combination of extra pressure and volume of air being forced against the valve when letting off the throttle.

Yeah it was the plug that basically took out the cylinder. If there deposits on the valve seat/ cylinder head thats causing it. What might be the next step ? I wouldnt expect that though. I thought an engine rebuild consisted of rebuilding both head and block  ?

If it is the throttle body im guessing those arent cheap lol ?

[Scottymon]

Rev Q Throttle Bodies are the one to go for, if and when - second hand on ebay for about £50.  (they've come down A LOT since more are becoming available now).

[Hurdy]

An engine rebuild would be down to the builder unless specified by the customer. You would have to ask your builder exactly what was replaced and what remedial work was carried out. It could be anything from a reborn and piston replacement to a "replace and rebuild everything" scenario.

The throttle bodies vary from around £350ish for an OEM replacement to £450+ for a 70mm one. I found the larger one cracks even easier than OEM, so went back to OEM. This is the easiest to inspect for damage as it sits right at the front of the engine and the one to look at first as it is the easiest option. 

[GrayMK5GTI]

An engine rebuild would be down to the builder unless specified by the customer. You would have to ask your builder exactly what was replaced and what remedial work was carried out. It could be anything from a reborn and piston replacement to a "replace and rebuild everything" scenario.

The throttle bodies vary from around £350ish for an OEM replacement to £450+ for a 70mm one. I found the larger one cracks even easier than OEM, so went back to OEM. This is the easiest to inspect for damage as it sits right at the front of the engine and the one to look at first as it is the easiest option. 

On the subject of engine builds. . .

Have you had yours done yet?  all gone very quiet recently John 

[Hurdy]

Not yet, still running strong and going well. The plan was to start the build after the show season and the last show is at the Pod in October. The strength of these engines in stock form has surprised a lot of people, me included as who would have thought you'd be able to put out almost double the stock power on a stock block and run it for as long as I have without any major catastrophes. It is also a testament to my tuner for good mapping and setting the limits with the power and correct hardware to utilise.
Steve Jr at Statller will be at the pod in October with a little taster as to what can be done with a Golf R.   

[GrayMK5GTI]

Oooooo that's worth a watch then 

[Cupra_Jay]

Cheers for the advice boys. Ive just ordered in a diverter valve as Ive found one of the problems . Once Ive had this fitted and it still idles funny. Ill check on the throttle body and see where that lands me