Replaced PCV and FPR on VR6. What a difference.

[aclwalker 3]

Hi all,

 

I've had a long running saga with rough idling and poor, hesitant acceleration. Well the last couple of things I replaced have made a massive difference and I think the problems are now solved.

 

Firstly I replaced my PCV valve (Positive Crankcase Ventilation). That's the little disc-shaped piece that is attached to the breather outlet and joins the main air ducting. Here's a picture of my original one (sorry it's a bit fuzzy):2.8l 24v Climatronic system.pdfP8010112.JPG[/attachment:80khs0f5]

 

Note the badly shredded hose part that connects to the breather outlet, where unmetered air has likely been leaking in to the air intake. You can also see jubilee clip damage here, but this is really just because I deliberately tightened it up to try to seal as best as possible while I awaited the new part. Clearly I had an air leak here. You can also see that this hose part is peeling away from the disc part. It wasn't as bad as this as I had peeled it back a bit, but it was definitely leaking here too. It took almost no force to open it up wider than that.

 

VW dealers won't sell you this part alone. They will only sell the entire ducting, including this part and the connecting hose and it's £75 (plus VAT, I think). Ford sell this part alone though. I thoroughly inspected my main ducting and the connector hose and came to the conclusion that I needed this part alone. It's £28 (including VAT) from Ford. Just tell them you've got a Galaxy V6.

 

While I inspected the air ducting, I cleaned out the throttle body (it was quite oily and was sticking slightly) and the ISV. I also tested the ISV with the VAG-COM output tests. It seemed to be working fine. I also inspected the dashpot and it seemed to be working fine but needing adjustment in order to damp the throttle a bit more. I checked the throttle angles with VAG-COM and they seemed to be out a little bit. You sort this by adjusting the dashpot positioning.

 

I reassembled and ordered the PCV from Ford. The work above with the throttle body, dashpot, ISV, and trying to minimise the effect of the holes in the PCV with careful jubilee clip positioning resulted in an immediate improvement. The car was much more responsive and smoother.

 

However, the hunting idle on cold start and the hesitation were still evident.

 

When I got the new PCV valve a few days later (Glasgow Fair bank holiday 'n' that), I replaced that. I also used a much flatter jubilee clip to try to be kinder to the new PCV. What a difference with the idle. The hunting was almost totally gone. I'm not sure if the very slight remnant was just because of the mappings being used to the old setup (I didn't do an ECU reset). One thing I noticed is the design of the PCV is such that it seems to sag a little, even with the flexible hose underneath. This is likely why it bursts eventually. It doesn't look the best of designs.

 

So I had seemed to cure the idling problem but the hesitant acceleration was still there. So I bit the bullet and got a new FPR (Fuel Pressure Regulator). I have been wanting to replace this for a while. Eurocarparts wanted £75 for it (including VAT, I think). VW wanted £68 including VAT, so I went with the dealer. They also got it the next day, which was good.

 

Firstly remove the fuel pump relay and try to start the car to remove the fuel pressure. Even with doing this, I still had some residual pressure when I took out the FPR, so have rags and a jar ready to catch any petrol. Removing the old FPR is very difficult. It is in VERY tight and the slight corrosion you get over the years doesn't help. I had to virtually destroy my old FPR to get it out. Here's a picture:P8010108.JPG[/attachment:80khs0f5]

 

Petrol enters the FPR just to the left of the bigger black plastic ring on the left of the the picture. A spring closes a valve inside the FPR, preventing the fuel from leaving (and hence maintaining pressure behind it), until the pressure of the fuel overcomes the strength of the spring, whereupon it leaves the FPR through the smaller bit on the far left of the picture which then goes to the return line and back to the fuel tank. The vacuum line at the top right of the picture also tweaks this so as to compensate for the vacuum that the injectors experience at the cylinder so that the fuel pressure is constant throughout. At idle you have very little air in the cylinders (i.e. a high suction) so fuel is sort of sucked out the injectors, so this suction also pulls on the FPR, meaning that the spring inside it has to overcome not only the fuel pressure but the suction, resulting in it opening the valve quicker in this situation and hence lowering the fuel pressure to compensate for the sucking effect at the cylinder. Sounds complicated and I've probably not explained it very well.

 

Anyway, if the spring is weak in the FPR, then your pressure will be too low, leading to fuel starvation as the valve will open too soon. If you have a broken vacuum line, then the compensation at idle will not be there and the fuel pressure will be too high. It seems to me that it's possible to have both faults at once and therefore to have too much fuel at idle, but too little at full throttle. I guess it's also possible to have a leaking valve (pressure drop) and also a leaking diaphragm resulting in petrol entering the engine via the wrong route, but don't quote me on that.

 

I also noticed with my FPR that the metal part on the right of the picture was spinning round relative to the rest of the FPR, so I guess I could have had a vacuum leak there too.

 

Anyway, once you have the FPR out, you need to be extremely careful to clean up any corrosion on the fuel rail where it contacts the FPR. I had a surprising amount here, and I was taking no chances after my experience of a shredded seal with my crack pipe, in similar circumstances. So I carefully blocked the fuel rail holes to prevent particles entering and carefully cleaned it up with emery paper. Be very careful as it's easy to remove more than you expected. I was worried I had done that, as the paint was right off. I had no spare seals for the FPR so I took my time and only attempted to fit the new one once I was certain that all corrosion was removed and smoothed down.

 

Unfortunately I slightly bent the vacuum pipe on mine while trying to squeeze the new FPR in with a G-clamp and a bit of wood, but it's still perfectly functional. In the end I had to hit it in with a block of wood and a hammer, which didn't feel good. Getting the horseshoe clip in can be tough, especially if the fuel rail mountings are mangled a bit like on mine. Somebody must've been in at mine in the past.

 

EDIT: I forgot to mention about the vacuum hose. I noticed on another post about the G60 that the length of the equivalent hose is critical (100mm I think for the G60), so I looked up ETKA and it said that for the VR6 it should be cut to 175mm. I had corrected my short hose some time ago before this FPR replacement. Anyway, I think that you should check the condition of this hose and also its length.

 

Anyway, I got it all back together, re-fitted the fuel pump relay and pressurised the system. No leaks. Then I started it. No leaks, but a bit of rough running until it worked the air bubble out of the system and got the pressure back up to normal.

 

However, I went for a test drive and the difference was literally incredible. The hesitation was gone, but I could feel little echoes of it, probably due to the ECU mappings trying to compensate for it in the past. I have now had quite a long run with it (yesterday and today) and my car has never run better. It never conks out. The idle never dips under 650. The idle is very, very smooth, with just a hint of the occasional miss (the plugs are a bit sooty due to all the previous running problems though). Acceleration is smooth and without any hesitancy and the power is back.

 

Best of all, I have got a massive improvement in fuel economy. I reckon I'm getting 20% more mpg. I was driving today at motorway speeds (not slouching) and got 32.5 mpg for the whole trip. I would struggle to get 26-27 before.

 

I know this is a massive post, but I'm just really pleased that I finally seem to have nailed these running problems and driving the car is a joy now. It's very smooth, powerful, responsive now. Not bad for a 202,000 miler!

 

I hope others find some inspiration in my ramblings.

[zak 0]

congrats, its nice when the old vr's running sweet! Did you drive the car after you changed the pcv or only after you had changed both the pcv and the fpr? Im curious which of the two were most responsible for your results.

[Jim 2]

I hope others find some inspiration in my ramblings.

 

Great post - and well worth a read. I'd really like to see a definitive check list for all models on how to improve certain issues like this. Having similar lumpyness with my car and i'm sure you'll agree that it just takes enjoyment out of driving it when it is consistently stodgy!

 

Anyway - as I say, nice post and thanks for writing it up.

[G60SC_Stoney 0]

agree with the above, we really need some sort of easy checklist to sort these problems out. My VR is running a bit dodgy and from what ive read, i need to replace the MAF, but nowe it looks as though i may as well replace the FPR as well. oh and give it an oil change, plug change and basically give it a good service, oh dear.... :pale:

[easypops 8]

Great post - and well worth a read.

 

As Jim said ^^^

Well written and understandable for the mechanical novices (me) :D

[mattkh 0]

I hope others find some inspiration in my ramblings.

Hi

What a great post. Well done and thanks especially for the photos.

[steve @ 0]

Good going. One of the most noticable things on mine is having the injectors cleaned and flow tested(http://www.injectorcleaning.co.uk), made quite a big difference, mind you they had covered 150k.

[boost monkey 0]

I'd say the PCV would be directly responsible for the hesitant acceleration as it's to do with the airflow and ventilation, considering how such pipes can lead to similar problems on other corrado engines.

 

Edit: Injectors are actually service items, and need to be checked/cleaned every 75-80k! Don't think many people know that :salute:

[craigowl 0]

Yes - good story.

Good of you to take the time to write it up. :salute:

[aclwalker 3]

congrats, its nice when the old vr's running sweet! Did you drive the car after you changed the pcv or only after you had changed both the pcv and the fpr? Im curious which of the two were most responsible for your results.

I did drive between changes, but only a couple of times (I don't drive much these days). I'd say that the PCV change (along with the throttle body and ISV clean) sorted out the lumpy idle, although there's was still a bit of roughness. It seemed to smooth out the car, but I noticed a performance difference with the new FPR. The FPR definitely seemed to address apparent fuel starvation at full throttle. But it also smoothed out the remaining idle roughness. The main change is the 20% better fuel economy.

 

If there's one thing I've learned in my 6 years of Corrado ownership it is

Never assume there is only one cause of your problem!

I might put that in my signature.

[-Neil- 0]

2.8l 24v Climatronic system.pdfP8010112.JPG[/attachment:wvx0i1w1]

 

I dont understand where this piece is.. can someone help please.

[Critical_Mass 10]

I'd say the PCV would be directly responsible for the hesitant acceleration as it's to do with the airflow and ventilation, considering how such pipes can lead to similar problems on other corrado engines.

 

Edit: Injectors are actually service items, and need to be checked/cleaned every 75-80k! Don't think many people know that :salute:

 

So going by what boost has said above, it WOULD matter if the PCV was missing all together. My 93 VR didnt come with one, I think others also have it missing. If i fitted one, would it make a difference?

[aclwalker 3]

2.8l 24v Climatronic system.pdfP8010112.JPG[/attachment:2ia4hgel]

 

I dont understand where this piece is.. can someone help please.

 

Firstly, make sure you have a VR6. :)

 

Look at the air intake. Follow the curved bit round from the MAF and you'll see a much smaller pipe that joins up to the main air intake pipe. Follow this smaller pipe along and you'll find this piece attached to rocker cover. It's at the back left of the engine (as you face the engine from the front of the car). You might need to remove trim parts to see it, or look from the driver's side of the engine (UK spec).

[aclwalker 3]

I'd say the PCV would be directly responsible for the hesitant acceleration as it's to do with the airflow and ventilation, considering how such pipes can lead to similar problems on other corrado engines.

 

Edit: Injectors are actually service items, and need to be checked/cleaned every 75-80k! Don't think many people know that :salute:

 

So going by what boost has said above, it WOULD matter if the PCV was missing all together. My 93 VR didnt come with one, I think others also have it missing. If i fitted one, would it make a difference?[/quote:3ejt0mfd]

If it's missing but the pipe going to the much larger diameter pipe is properly sealed off, then I don't think it would affect performance, except I don't know what happen to the oil vapours that would normally be burned off.

 

Are you sure you're not thinking of the charcoal canister? I'd be surprised if lots of people had this breather valve missing (unless, of course, they've simply replaced it with a normal hose). Many people have removed their carbon canisters. I still have mine.

[Critical_Mass 10]

Yeah i definately mean the pcv valve. There is one pipe coming off the head that attaches to a plug, which then goes into the intake pipe. Its not air tight where it meets the plug if that makes a dfiference.

[-Neil- 0]

Well im currently trying to sort out my running issues and got somewhere today, replaced my ISV with a known working one and my car seems to be running fine at the moment!

 

But when i accelerate i notice the car kind of ever so slightly judders as i accelerate, this may be the FPR, where do i find this to replace it?

 

Also, i looked at changing my PVC, but i DONT HAVE ONE! :s

I've got a 1993 VR6 coilpack

here are 2 pics of what i have..

 

 

i met with another CF'er and he had a 1995 VR6 with a 4 pin MAF and his PCV looked liked this...

 

can someone tell me if mine is correct or if i should have this vavle thing?

[Danny B 0]

good post.....I replaced both of these last summer and the biggest difference I found was with the PCV, I found the differences very subtle but very worth it.

[Critical_Mass 10]

The top pic is how mine is set up. Maybe its just on the late VRs... would it be worth fitting one to an early VR?

[-Neil- 0]

The top pic is how mine is set up. Maybe its just on the late VRs... would it be worth fitting one to an early VR?

 

Very good question, i managed to get the thin pipe from a VR6 golf, so all i need now is a vavle from ford, but i am unsure if this is worth it?

[Critical_Mass 10]

Well it must do something especially if VW decided to fit one later and if people are saying they notice a vast improvement, id give it a try.

[-Neil- 0]

Tonedef very kindly dug out his paper work for me and gave me some part numbers for this valve from ford..

 

F7364573 N/STK 002881/VALVE A

It was 24.98 inc VAT

 

Hope that helps anyone who want to get one. I'm going to try and get one and fit it and see if it makes any difference.

 

Can someone tell me why there is a plug on this when its blanked off??.....

 

 

[Critical_Mass 10]

Whats the plug for?

 

Cheers for the part no. Neil going to try get a pipe too.

[-Neil- 0]

Whats the plug for?

 

I'd like to know this too, maybe etka or whatever its called can help?

 

I got that rubber pipe that goes from the throttle body to this vavle thing then to the blue plug for the CC from a golf mk3 vr6, just to give you a heads up.

[Critical_Mass 10]

The T shaped one in the bottom pic? Do you have to fit that pipe too, or is that unrlated to the PCV valve? I gather then that another pipe will be needed to connect the PCV to the plug thats connected to the intake pipe?

[Chris Smith 0]

Tonedef very kindly dug out his paper work for me and gave me some part numbers for this valve from ford..

 

F7364573 N/STK 002881/VALVE A

It was 24.98 inc VAT

 

 

Is that the code for a PCV valve from ford?