20v turbo headache ARRRRGH.

[webbywagon]

I have all the running gear from a 2001 Y leon AUQ engine in my caddy with the six speed box and what a cracking engine it is. I have a K04 and a big front mount I/C and a bmc filter with cold air feed. It has done 239.1 BHP on the rollers so is very quick, well it was. I fitted a turbo smart dump valve and have since removed it after about 300 miles as i started having trouble. I have my forge recirculating one on now instead. What is happening is that it seems to run slightly rich in the morning and can take 20 secs or so to start. It then runs fine untill i park up and leave it any amount of time short or long and it runs flat as a fart. I replaced the MAF and it ran better but still flat or full out rapid. I took it too be vag-com checked and it showed a MAP sensor fault. So i had that replaced and codes cleared, took it for a spin. First off it felt flat and then seemed to clear and was rapid again cool i thought. Went back paid the bill drove off flat as a fart again. This problem just seems to please itself. i Took it to the RWYB at stratford drag strip and first thing in the morning on the way to stratford it felt very very quick as it used to do and then it just decide to go flat out of the blue again. Took it up the strip and it was flat at launch and then boost came in out of the blue (bit scarey) and it is like this all of the time. I have no idea what it is, a second vag-com showed a boost leak but all the hoses are good. Cleared the codes and took it for another 10 minuite run and it showed no faults but still ran flat. HEEEEEEEEELP.

 

[Feel]

Running rich, cold start etc *might* be the coolant temp sensor. Do a search on "green top". It might be worth chucking one in as they're only £12 IIRC.

Exactly what codes are logged? Does it "recover" without cycling the ignition?

Have you checked all the vac pipe under the manifold - boost leak can be a ******* to find.

I guess it might also be the Lambda sensor.

Have you tried cleaning the throttle body (where did your engine come from? how long was it in the open?) and doing an alignment?

 

[webbywagon]

Running rich, cold start etc *might* be the coolant temp sensor. Do a search on "green top". It might be worth chucking one in as they're only £12 IIRC.

Exactly what codes are logged? Does it "recover" without cycling the ignition?

Have you checked all the vac pipe under the manifold - boost leak can be a ******* to find.

I guess it might also be the Lambda sensor.

Have you tried cleaning the throttle body (where did your engine come from? how long was it in the open?) and doing an alignment?

fault codes were n42 came up so i may need one of whatever that is. I was wondering if it was the n72 (is that right) as well. The engine has been in for about a year and has only just started playing up. It is an AUQ out of a 2001 Y leon. What do you mean recover without cycling?

 

[Ljones]

if its n429 valve area they can be replaced or removed there is a guide here

 

[webbywagon]

Where on here? Also i'm pretty sure it showed a fault as low pressure between throttle control valve and the dump valve. Is that the n429 valve?

 

[claudefrog]

its an N249 if your doing a search

 

[webbywagon]

its an N249 if your doing a search

Yes i have had a look and i may divert from the n249 like some of the others have as i have a forge dv. mind you it looks a bit tricky.

 

[claudefrog]

Yes i have had a look and i may divert from the n249 like some of the others have as i have a forge dv. mind you it looks a bit tricky.

get yourself a length of vacuum hosing, its really not difficult at all, i done this mod on my Ibiza, it made a great difference to boost response

 

[webbywagon]

get yourself a length of vacuum hosing, its really not difficult at all, i done this mod on my Ibiza, it made a great difference to boost response

I'll give it a go and see what happens.