Diverter valve mystery

[rallychief]

Ok , when I bought my Cupra 2001 180 auq , it had a shiny alloy diverter valve fitted, the guy I bought it from said he had tried fitting a forge 007P but it wouldn't run right, it would only work with an atmospheric valve, the 007p was in the boot, which on closer inspection is an e.bay copy, so VCDS was giving me a boost leak suggest DV, so I thought return to standard , so been running it for ages atmo, as weather and being poorly didn't let me address it.

So sun shining this morning, got a nice new 710P valve, fitted it, oh dear I must have lost at least 50 bhp, the car was proper quick before, everything on here suggests these engines will not run properly atmo, so what the hell is going on, as this one won't run properly recirc


Cheers Chris

 

[Sprogpole]

Post some pics, so we can check your plumbing

 

[Hobbiniho]

if it isnt running right with the new (genuine??) diverter valve then i suspect the original problem wasnt the valve but something else, you do have the val;ve the right way around?? boost into the side and the bottom to the tip?

 

[rallychief]

Yep the valve is plumbed into the hole in the TIP ( standard )This spill on the TIP had an alloy bung in it, I removed to fit DV in the correct way around, the original pipe from DV was in the boot attached to 007P copy, so used that to go across back of engine, to the fitting on the metal pipe, the atmo valve was connected to, then the small 4mm pipe, which now by passes my N249 going to inlet manifold, so the car is now as factory recirc, but with a better standard valve.


Cheers Chris

 

[Sprogpole]

Are the unused pipes from your N249 bypass blocked off or removed?

It sounds like the previous owner has done some messing about to me.

 

[porter555]

Hi, dont know if this will be any help but sounds similar to something iv experienced on my auq 180. I too brought mine with an atmospheric valve fitted (forge splitter) and when I fitted a new forge 008 dv, it ran awful, down on power and everything. Narrowed it down to an issue with all the little pipes connected to the n249 and vac resevoir etc, so I got some new vac Line, did the n249 bypass (as per a guide in the faqs), and then it ran great. Might be worth a try

 

[rallychief]

Hi porter 555, is the 555 a Colin Mcrae tribute, anyway have already by passed N249, it ran fine after that, the pipework around the N249 was a right mess, as was the valve itself, I do however still get a returning N249 mechanical fault on VCDS cleared twice but still returns, did notice fuel consumption dropped a fair bit after by pass, is their anyone near me that could have a scan over it, suspect its something done by a previous owner, and unless someone looks at it that knows how it should be, I am rather in the dark.

Cheers Chris

 

[porter555]

It is indeed rallychief, one and only. Was also my favourite livery of any rally car, and favourite car in fact (i know thats probably classed as swearing on here!).
Have you plugged the n249 back in? Some people remove all the original pipework, do the bypass, then plug the n249 back in, and if your lucky, the EML doesn't throw a wobbler. think iv read somewhere its luck of the draw if it stays off or not, but i could be wrong (happy to stand corrected if anyone can help).

 

[rallychief]

Yep, both plugs are connected on the N249 block that was replaced once all the pipework, valve etc were stripped off.


Cheers Chris

 

[wildrides]

Your fault is most likely that the car has been chiped with custom code to run a vent too atmosphere valve . People often dont admit the car has custom code when selling . Get it re flashed to run a recirc valve and it will probably be okay.

 

[rallychief]

Hi wildrides, if it has neen mapped to run an atmo dv valve, a couple of questions occur

1 why would you map for atmo, is their any advantage in it

2 if it is mapped for atmo, would it not just be sense to refit it

3 any easy way to tell if it has been mapped for atmo


for info, it does have a stage 1 remap


Cheers Chris

 

[wildrides]

some people like a very noisy blow off noise ( personally I like steath ...... the cops can hear you coming quarter of a mile away with a noisy one and have time to get thier hand held ready )

if it runs good with a blow off I would refit another .

There is no power or running advantage to either but some say recerc warms the intake temp so speeds heat sink and knock sensor ecu fuel trimming . I am not really convinced it is a material change to intake temps.
Has it been done ? -only the coder will know . if its standard APR , revo etc then I very much doubt it has been done , but some tuners offer totally bespoke maps and thus it could have been done . Another thing they do sometimes is disable the knock sensors ! Great until you melt a piston crown ragging it up hill on a trip to the thin air of the Alps or a trip to the ring!

 

[rallychief]

Hi Wildrides, ok plot thickens a little, been out driving the car today, prob 15 miles, and some of the power suddenly came back, its not all there, but much better than yesterday, does the ECU need a period of time to learn, the new running parameters ?


Cheers Chris

 

[wildrides]

It does have a learning ecu, but I dont think it would trim a really large amount of power unless it had gone into a limp mode .
Also I dont know if the coding thats been done retains the function to trim the fuel in the same way as stock ecu coding does.
I think the only way to tell for sure if it is the DV causing the HP loss is to substitute swap the two parts back and forth and monitor the changes

 

[rallychief]

should have said, have not EML on at any point, VCDS continues to throw up N249 mechanical fault, but doesn't throw on EML, nor did the boost leak, check DV fault throw it on.


Cheers Chris

 

[rallychief]

Ok update on this one, have been up tp to my ears working on a motorsport event, anyway been driving the car with standard 710P, and have used it really hard down some really bad country lanes for lots of miles, anyway the power is all the way back, as it was with the atmo DV, absolutely at a loss to know what's gone on.

Have another issue now prob a new thread.


Cheers Chris