155 Q4: From Switzerland to Scotland

[Ade]

After owning a 2.0 and a pair of V6 155s I finally took the plunge and bought a Q4!

I headed down from Glasgow to the English south coast to buy this Swiss import from Pavs.....
A train to London, a train to Portsmouth and then this to Gosport....



Then a quick trip up to Gloucester for an MOT. Got through okay apart from an advisory on both the rear subframe mounts and an oil leak.




A stop over at a mate's in Nottingham..... it's a bit more pink/magenta/orange than I'd like, but I'd always expected to have to get it painted eventually anyway.






The next day I find myself up at Sitech Racing for a shoot after doing over 600 miles in less than 24 hours! Sadly the oil leak had gone from bad to worse.... we found out that the plug seals had burst leaving the bores to completely fill up and overflow!






Got it sorted and the next issue is that the boost is cutting at just under 1 bar. Looks like the boost controller seems to be at fault? Any other ideas about what may be causing this?

Here we have the engine bay...


And a crop showing the boost controller which seems to be troublesome...


After a quick run with it holding boost up to 0.5 bar ok it all went tits up!
Wouldn't go into second, then lots of banging and crunching etc in third.... coasted back to the garage and left it there for diagnosis. It was moved with no apparent problem today, so whatever is wrong is seemingly intermittent anyway....

[WhizzMan]

There is no boost controller in your picture. What I see there is a cam sensor on the exhaust cam.

[Ade]

The part with the blue electrical plug going into it.... not the best angle to see it.
It has a vacuum hose coming from the turbo into it, one going to the actuator and one going into the boost intake hose.

[Brul(tm)]

Try looking a bit better, the boost controller itself would be in the car, but the part that replaces the pierburg is at the end of the arrow



Regards,
Marc

[WhizzMan]

Ah it's next to the pink elephant. I see it now.

[Ade]

....the part that replaces the pierburg is at the end of the arrow

What does this part made by Pierburg do?

[AlfaJack]

What does this part made by Pierburg do?

It is just a solenoid to block the air between the turbo and wastegate.

More info:
http://forum.berlinasportivo.org/showthread.php?t=374

[WhizzMan]

What's missing in that thread is why there are limits on the boost. On lower revs, you don't want too much boost because the torque will kill your big-end bearings, clutch and gearbox. Either you upgrade your pistons, con rods and big end bearings, clutch and gearbox, or you keep the torque down to levels that won't bust your engine.

On higher revs, the amount of rpm the turbo has to make to keep the pressure up, will get too high. You will damage the bearings and it will break to bits. There is a very real possibility that the broken bits will be sucked into your engine, damaging much more than just the turbo. The only fix for this is a bigger turbo or one that can handle the revs.

The pierburg valve controls the pressure to the waste gate by opening/closing 10-15 times a second, or not. The amount of periods it's closed/opened will determine the average pressure the waste-gate valve sees (in combination with the amount of boost pressure you have). This will in turn control the amount of opening of the waste gate. Since there is no linear relation between the amount of open/close commands the pierburg gets (the boost pressure is also involved) it's not simple to tune the turbo pressure using the pierburg and the stock ECU. Basically, it requires a lot of test runs and logging before you can "safely" use the pierburg as a boost system on a modified engine. As said, the ECU also uses the reduction of boost pressure as a safety, so not using the factory ECU with the Pierburg will put your engine more at risk. On the other hand, using an electronic boost controller will help you tune the engine a lot faster.

If I ever get to it, I think there is a way to reprogram the IAW to use a different algorithm to control the Pierburg. If that PID algorithm works, you can actually program the requested boost, instead of opening percentage of the valve. It will require complete reverse engineering of the IAW and rewriting the code that controls the Pierburg. Because of the way the IAW works, the code will have to take the exact same amount of time (clock cycles of the CPU) or less, to finish calculations als the original algorithm. Either that, or the algorithm should be split up in parts so they can run in "spare time" in other places in the sequence.

Probably, if you want to fiddle with this reliably yourself, a decent aftermarket ECU is the best/easiest/cheapest way to do it.

[Q4Jan]

I got the same chinese exhaust manifold. And i really would recommend some heat-shielding to the head.



Also shield the oil-dipstick after that or else it will meld.

[Varypodaros]

where did you buy from? is there any site?

[Brul(tm)]

Looks like a custom build shield.
I am looking for ages now for an original heatshield....

Regards,
Marc

[wrinx]

Or, a slightly more subtle shield



For some reason my manifold was so close to the head it needed spacing out more

wrinx

[WhizzMan]

I think Jan's shield wil help keep the hot air from going up and everywhere under the bonnet a bit better. It's probably trivial since it's not a sealed air thing and the turbo is unshielded, but it may just help. Another thing you can do is wrap the manifold and/or ceramic coat it on the outside. Don't coat the inside. If it starts to flake, the flakes will wreck the compressor of your turbo.

[wrinx]

Considering they are contained in near sealed units the heat dissipation will be almost zero, the shield I made was purely to *try* and deflect some heat from the head because it's too close imho...no idea if it works

I have some 6mm metal to make a spacer for the manifold

wrinx

[jimnielsen]

i had my one ceramic coated on the exterior, it makes an enormous difference to the heat dissipation.

[Ade]

Would wrapping it not being the easiest idea?

And back to my car... Good news! It seems the drivetrain issues are nothing more than a knackered slave cylinder!

Boost cut issue appears to be more complicated though.... initial diagnosis is a boost leak after the MAP sensor. Apparently it's massively over fueling at high boost at the moment for some reason too.... Soon see what happens!

[Varypodaros]

I asked for the manifold.

[Ade]

I asked for the manifold.

Mine came with the car!

[WhizzMan]

They were for sale on eBay a while ago. Maybe Jan or someone else that bought one can check if the vendor still sells them?

[wrinx]

The last batch (where mine came from) was supposed to be the last lot to be made...no idea if he changed his mind.

He's on the Integrale and Coupe forums...can't recall his name though

wrinx

[wrinx]

This is him...

madlyons@tiscali.co.uk

wrinx

[WhizzMan]

I think Jan may be willing to sell his spare manifold? He has his car plus all spare parts up for sale. I bought his spare turbo because I thought mine was busted.

[WhizzMan]

Would wrapping it not being the easiest idea?

And back to my car... Good news! It seems the drivetrain issues are nothing more than a knackered slave cylinder!

Boost cut issue appears to be more complicated though.... initial diagnosis is a boost leak after the MAP sensor. Apparently it's massively over fueling at high boost at the moment for some reason too.... Soon see what happens!

Wrapping would work too, but is a less permanent solution than ceramic coating. I think all 3 solutions have their merit and may work well combined. Not shielding the manifold will cook the oil and coolant in your cylinder head at the exhaust side. Needless to say, that will not be beneficial to the engine.

Good to hear that your clutch cylinder will most likely be the only problem in your drive line.

Regarding the over-fueling. Since you have an aftermarket boost controller and who knows what chip in there, I would recommend you go back to a stock setup, just to see if that cures the problem. If it doesn't, you have the unknown factors out of the problem and you can do a "traditional" fault diagnosis. Once everything is okay, you can put the boost controller and chip back in.

[Q4Jan]

I indeed have a spare manifold laying around.
Probably one of the last ones.

[Ade]

I've completely forgot to update this thread over the years!

Anyway, here's the best bit from the past 4 years...







The worst bit being the last year in which it was at a garage for a year....

But now I've Ffinally got the Q4 MOT'd, taxed and back on the road!
It had been away for ages to have a lot of issues seen too.... Still not 100%, but it had been off the road so long that we decided to just get it back up and running instead of it being the constantly forgotten car that was evolving into a project it shouldn't have been.
So it's had a ton of wiring fixes and various other things like an airbox fabricated for an induction kit, but it's still very much a running project.

Time to get some miles on it, and pinpoint any niggles. Want to get it painted this year for sure....




One thing that still really needs seen to is it's cold start.
It starts then dies, then goes ok.... think it's a bit rich all round too.
I've heard that the Weber Marelli P8 has a reset function which is a good place to start with these types of issues. Anyone know it? I can only find the Escort Cosworth procedure when I google it... Sure it's similar, but don't want to mess it up!