Pinking At 3500rpm - Anyone Else?

[anorak 0]

Been a bit concerned about running lean so went to Stealth yesterday for a fuelling check from Vince - or so I thought!

Turned out his new apprentice had booked me in without Vince knowing and not only was he too busy to have a look at my car but he doesn't have any software for the Chipstar at the moment.

As usual though, Vince was very helpful and spared the time to have a chat about what the problem could be (if there is one).

The symptoms are when dropping down a gear when cruising if the revs are between 3500 and 4000rpm I can hear a definate 'pinking' which disappears after 4k.

If I accelerate from lower revs (in any gear) there is no pinking right through the rev range.

It seems as though not enough fuel is getting through if I lift off at 3500 and then plant it.

Vince said that because that's the peak torque region for the Schrick it's not uncommon.

He also said that my fav fuel, Optimax, can go off in the petrol station tanks because it's not as popular as the cheaper stuff and suggested I try running on normal unleaded to see if the problem is still there.

Another possibility is because I'm running an 11psi pulley on the 'charger and it was originally mapped with an 8.5psi one.

I've pm'd Mina to see if he had any remapping done when the new pulley was put on but just wondered whether anyone else had the same thing - especially anyone with a Schrick.

I'll find out if the fuelling's off at the RR Day next week. It just seems weird that it doesn't happen when pulling right through from 2k.

Any ideas?

[ Edited ]

[mightyvr6 0]

I have heard of cars with schrick pinking even after remapping so I suppose it's possible. Could be just a matter of increasing the fueling at that point in the rev range. Have you tried a tank of bp ultimate?

[jcorallo 0]

[blockquote] Another possibility is because I'm running an 11psi pulley on the 'charger and it was originally mapped with an 8.5psi one.[/blockquote]

Sounds like the culprit to me.

If you are mapped for 8.5psi, the charger would not have produced any boost until about 4k normally. Now you will be boosting earlier - hence pinking.... and the Schrick will be further amplifying this boost as well with its resonant effect.

By the way - knock control only happens up to 4k, as there is too much mechanical noise from the engine after this point...

Jules

[anorak 0]

Cheers, chaps

I'll give BP Ultimate a go see if it makes any difference.

Vince did say he'd had some Schricked cars with the same problem.

So I should be ok if knock control is working up to 4000rpm?

mightyvr6 - how's yours with the Vortech kit?

[mightyvr6 0]

It feels good and is v. smooth. The charger is audible at idle but when the engine is revved it's drowned out by the vr6 roar. The z-charger was silent at idle and noisy when revved so a bit different in character. The vortech does get hot though which was never an issue on the z.

[VR6Pete 1,455]

I've got a schrick and it still pinks after a dastek + remap.... its a rite tricky bugger to map

[anorak 0]

It feels good and is v. smooth. The charger is audible at idle but when the engine is revved it's drowned out by the vr6 roar. The z-charger was silent at idle and noisy when revved so a bit different in character. The vortech does get hot though which was never an issue on the z.

Yeh, I found out the hard way how hot the 'charger gets the first time I took the top off the water injection reservoir which is low down in front of the blower. Still got the scorch mark on the back of my arm! &|

Sounds much better than the Z kit doesn't it. Does it feel any stronger?

Pete - I presume you've had no problems with yours pinking.

I s'pose as long as it's just at fairly low revs it should be ok.

Just a bit paranoid after melting an engine already this year.

[Nerih 0]

all this talk about superchargers, what is the real difference between the z and vortek? Apart from the supercharger howl? Price difference?

[anorak 0]

mightyvr6 is probably the best qualified to answer that one, having had both kits on his car now.

As far as I'm aware the ZR2 is fine for 250bhp or thereabouts, whereas the Vortech kit is more upgradeable with different pullies. Both run about 8psi as standard I think.

The Z kit has its own oil reservoir which needs checking and topping up occassionally and the Vortech has a feed from the engine.

Been told the Vortech is more robust. Mines done over 30,000 miles and still works (keeps fingers crossed). I was advised to get the Z reconditioned after 15k.

Think you can get a Z fitted for under £2k now. Don't know about Vortech prices - mine came with the car.

Please feel free to correct whatever of the above isn't true

[mightyvr6 0]

A difference which probably accounts for the smoothness is the fact that the vortech has internal gearing and the z is belt driven. The belt actually oscillates slightly which means the impeller isn't driven quite as smoothly as it is by the internal gears.

There is a lot to be said for the z- charger. It is cheaper to buy and easier to install than the vortech and is capable of a lot more than 15k between rebuilds. Because it is driven by a cogged belt, there is very little load on the impeller and therefore little stress on the bearings. It uses its own oil reservoir rather than engine oil for lubrication so it never gets v. hot so the boost stays cooler which gives more power. The impeller spins more freely than the vortech so it starts making boost earlier in the rev range. It is capable of good power too, producing between 250 and 275 hp on a standard engine with stock injectors.

They are both good units, the main difference being the fact that the vortech is capable of producing higher levels of boost.

[ Edited Mon Oct 25 2004, 12:16AM ]

[antera309 3]

I believe the Schrick switchover point is set to 3500rpm on Supercharged VRs (as opposed to 4000rpm for N/A ones). Sounds like the fuelling is just failing to keep up now you've upped the boost..

Maintaining the fuel-air mixture is a really exact science, but I'm sure Vince will be able to sort it for ya.

[Eat this 2]

what injectors r u runnin would stock injectors be able to keep up? you r runnin serious mods (mina told me what ages ago but iv forgotten hehe)

[anorak 0]

Thanks again guys, appreciate your help.

The switching point for the Schrick is 4000rpm apparently (see full spec on www.minas.freeuk.com/page3.html).

It's running green injectors and the 11psi pulley now though.

Like you say - I'll know more after Sunday but it definately sounds like it's to do with upping the boost in the midrange.

Mina never had any pinking as far as he knows though.

mightyvr6 - thanks for the better informed info on the 2 kits

[FishWick 21]

I see you have your MAF down-stream of the charger. Shouldn't it be up-stream (ahead of the charger) otherwise the MAF readings will be false?

But that aside, pinking is common on Schricked VRs because the engine comes on the cam aswell as being at peak resonance by 3500rpm.

I've found using 268s (or 248s if you're SC'd) moves the cam breathing away from the critical 3500 zone, ergo removing the pinking at best, reducing it at worst.

The trouble with chipping it out is the reduction in ignition advance and therefore a reduction in torque. It's a tricky one to get right.

I'd say if the knock sensors pull it back withing half a second of the pinking occurring, don't worry too much. If the pinking is prolonged, the sensors are struggling like hell and the timing needs backing off slightly, plus a pinch more gas.

Try a different fuel as suggested (Esso SuperUnleaded is stable and very good) and see how the car responds to a more progressive throttle action, as opposed to jumping on it.

[ Edited Mon Oct 25 2004, 08:06PM ]

[anorak 0]

Cheers, Kev. As helpful and clued up on here as you were on the Corrado forum, mate.

The MAF doesn't seem to be causing any problems on the Golf like it did on my Z kitted 'rado (lumpy idle, jerky light throttle response & occasional stall when hot) so I'm taking the "if it ain't broke..." approach.

The pinking lasts for a second or two and as you say a more progressive throttle application eliminates it.

Perhaps I'll just have to not change down so often for overtaking and use torque instead of power.

You going on Sunday?

[mightyvr6 0]

Mark, is your car obd1 or obd2? I'm asking as it has the obd 2 style maf (but was also fitted to late obd 1 cars) This could explain why your car runs smoothly with the maf after the charger, or it could be something to do with the spirals of air created by the vortech being less turbulent than those form the z onto a less sensitive maf (?)

[FishWick 21]

I find the 2.8 is better than the 2.9 for low rpm responsiveness and isn't as jerky by far! Could be due to the bigger throttle on the 2.9?

Cool, if the MAF seems to be behaving, leave it, but if you ever up the boost, you might want to relocate it ;-)

I'm sure Vince can iron out the pinking, he's the master!

Can't make it on Sunday, sob sob :-(

[anorak 0]

Ben - how do you tell if it's OBD1 or 2 (apart from year - May 94).

Thought 2's weren't around 'til 95.

[FishWick 21]

Mark's got an OBD2 MAF according to the pic, so guessing the car is OBD2 compliant too?

OBD1 MAF = hot platinum wire. OBD2 MAF = heated film

[ Edited Mon Oct 25 2004, 08:33PM ]

[mightyvr6 0]

I think your car might be obd 1 with the heated film obd2 style maf which is less sensitive than the obd 1 maf. Late corrado vr6s had this maf too.

[anorak 0]

Dunno - I just drive it! %-6

Have a look on Sunday, Ben.

[anorak 0]

I find the 2.8 is better than the 2.9 for low rpm responsiveness and isn't as jerky by far! Could be due to the bigger throttle on the 2.9?

quote]

Mines got a 2.9 big valve head and enlarged t.b. but is much smoother than the Corrado. Probably due to the Vortech being internally geared and the fact that it was originally set up and mapped by Vince.