Schrick at 3,000rpm

[emax 0]

Hi there,

 

I've been hearing a funny 'crackling' sound on my car when accelerating hard through 3,000rpm. It maybe only persists between 3,000 and 3,250rpm and only under full throttle.

 

These revs also coincide with the Schrick giving its boost to the torque and I'm wondering if the two are related at all?

 

It is a hard noise to describe but a faint (from inside the car) crackling sound is probably the most accurate description. I don't think it has anything to do with the dreaded timing chain or tensioners as my car had them replaced at around 75,000 and we're now on 108,000. Star Performance also checked my chains recently and said that they were fine.

 

Any ideas?

 

Euan.

[Kevin Bacon 5]

That's pinking mate. If a VR with a VGI is going to pink, it will do it at precisely the revs you described with the throttle wide open. The VGI pulls in considerably more air at peak resonance than the stock manny does. The MAF can compensate to a point, then the knock sensors take a second or two to react and pull the timing back.

 

Is your car chipped? If not, it would benefit from one to dial in a bit more gas at those revs.

[emax 0]

Yes, the car is chipped. Had it done when my Schrick was fitted. I might speak to them to see if they can look at this when it is in for its MOT.

 

It certainly didn't do it when it was first mapped although I have noticed it more over the last few thousand miles. Would this indicate that the car might need another remap??

[dr_mat 0]

Yeah I've been noticing this from time to time recently too. I've been thinking about getting the rechip done.. The pinking is more of a problem in 2nd, which leads me to think it's the rapid build in air flow and the ECU failing to respond to it. In higher gears the build up takes place more gradually, and in 1st gear there's not enough time at those revs for the Schrick to really start doing it's resonance trick..

You will notice that after an incident of pinking once or twice, the car doesn't feel as powerful - at least then you'll know that the knock sensors are doing their thing...

[Kevin Bacon 5]

I find mine pinks on occasion too, but only in this 25+ degree weather we've been having recently. And also when the MAF is having one of it's 'off' days. Mine has also been rechipped. Perhaps the tuners of ours didn't quite pop enough fuel into that rpm range, but AMD did mine and they have years of experience with VGIs.

 

Could be fuel related too. If the chip was set to 98 RON and we pick up a shoddy tank of Optimax..... dunno, what dya reckon?

 

I think the only permanent cure would be to get a map optimised to 95 RON and slightly rich in that rev band.....

[dr_mat 0]

Damn, bit poor if we're all seeing pinking even those with rechips.

I agree mine is worse particularly after sitting in traffic, so I think it's temp related.

I always use BP Ultimate these days though, so it's a nice stable 97 Octane, very little variance cos it doesn't rely on volatile octane boosters. I can't see how I can get better fuel for it!

I wonder if the chip that originally shipped with the VWM VSR was any better in this respect?

[emax 0]

Interestingly, I've only really noticed it in the summer months too.

 

I run the car exclusively on either Optimax or BP Ultimate.

 

Star Performance are also very experienced with the remapping either and I don't doubt their professionalism but I'll mention it to them when I take the car in next week.

 

Interesing what you're saying about "off days". I thought it was psychological but some days my car feels a little down on power and other days it absolutely flies! No real pattern to it but there is a definite difference day on day. I guess a dodgy tank of fuel could cause this too though...

[jedi-knight83 0]

does pinking actually cause any long lasting damage?

[Kevin Bacon 5]

Yeah mine has off days quite frequently. Seems to be 1 week on, 1 week off at the moment! But with the Schrick, when it’s feeling lazy it’s still pretty quick. Whereas with the standard manifold it was seriously gutless during an off day. I often wondered at the time whether the engine is actually 2.9, or 1.9!

 

It could be fuel related but more likely to be a combination of ambient air temp and barometric pressure differences. This is where forced induction is handy as it’s not as badly affected by things like that.

 

Jedi – Yes, if pinking continues for an extended period of time, you will blow a hole in one or more pistons and overheat the exhaust valves. The knock sensors will prevent that though, providing they're working - VAG-COM can tell if they are dead or not.

 

A couple of seconds of pinking won’t kill the engine but if you hear it, just ease of the gas a touch to reduce the load.

[Jim 2]

It could be fuel related but more likely to be a combination of ambient air temp and barometric pressure differences. This is where forced induction is handy as it’s not as badly affected by things like that.

 

Well, not completely. G60's hate the warm weather.. i'm looking forward to winter for some 1 or 2 degree centigrade air temperature :)

 

Sorry to go OT.. won't happen again :)

[Kevin Bacon 5]

Yeah that's true, perhaps I should have expanded on that and said a front mount cooler and water injection isn't affect by air temp/pressure differences :wink:

 

Even so, I found my 16V Turbo was pretty unphased by 30 degree summers and that had fixed timing and fuelling ! It rather enjoy winter air tho :lol:

[Joe M 0]

Could this be a BP Ultimate thing? I got this for the very first time last night after filling up with Ultimate a few days ago. :?

[dr_mat 0]

I suppose it's possible. I'll try another tank of optimax next time and see if there's a difference!

Maybe I'll give it some nasty 95 octane at some point too, and see how bad it can get... :lol:

[Kevin Bacon 5]

Hard to say. I find my engine runs more consistently with ultimate than it does with Optimax. I also notice more low down urgency with Ultimate too but whether that is a pyscological thing or not, I don't know. Optimax certainly gives more clout in the upper rev band though.

 

Seems a number of us get the odd detonation from time to time with the VGI.... maybe platinum plugs would be a better choice, say from an Audi S3, which are better at burning fast moving gas flow? I used to get pinking in my 16V Turbo with the Maestro Turbo NGKs I initially used but sticking some S3 (or any 1.8T plug) plugs in got rid of it completely..... just a thought....

 

Roddy is using my old Iridium plugs with his Schrick so it would be interesting to see if his pinks with those.

 

K

[Joe M 0]

Try some Esso Super Kev. Best fuel ive tried. Even standard Esso seems pretty decent.

[Kevin Bacon 5]

Yes I have tried that and you're right, it is pretty darn good.

 

I agree with Matt in that Optimax isn't very stable. Any benefit of the octane boosters seems to be lost by the time it reaches the pumps. Ultimate and Esso Super are pure, no nonsense 97 and refined to that level, rather sticking spurious chemicals into 95 RON base stocks.

[emax 0]

Hard to say. I find my engine runs more consistently with ultimate than it does with Optimax. I also notice more low down urgency with Ultimate too but whether that is a pyscological thing or not, I don't know. Optimax certainly gives more clout in the upper rev band though.

 

Seems a number of us get the odd detonation from time to time with the VGI.... maybe platinum plugs would be a better choice,

K

 

Got the platinum plugs in mine. I'll try switching over to Optimax or this Esso fuel to see if there is any difference. I'll keep you posted.

 

It's interesting however that quite a few of us with the Schrick are experiencing the same symptoms though.

[Kevin Bacon 5]

Ah OK, the plug choice doesn't appear to make a difference then, thanks for that.

 

There is an Esso 2 mins from my work, so I'll fill up with their 97 Super Unleaded and lunchtime and assess it over the weekend.

[Scruffythefirst 0]

maybe platinum plugs would be a better choice, say from an Audi S3, which are better at burning fast moving gas flow?

 

Plugs wont make a difference to pinking becuase the fuel has started to ignite before the plug fires. This causes the combustion process to try and force a piston down that wants to come up which is what you hear. Common with turbo'd or s'charged cars with high intake temperatures which often leads to melted pistons (especialy if its in conjunction with running lean) or a rod or crank letting go in extreeme situations.

 

The thing with a schrick, or any other sort of tuning that increases the cylinder fill efficency you really need to increase the fueling perfectly, especialy on turbo'd cars, otherwise there's no power gain and more chance of damage, teh ecu and maf will compensate to a point, but its much better having a better map in there in the first place.. Altering the ignition map when pinking is caused by increased cylinder pressures (cos of the schrick) which the knock sensors do won't help much, becuase the det is occuring before the plug fires. You need more fuel to reduce the pinking rather than retarding the ignition. People that live map cossies on the road use det cans, which are specialist microphones that you can hear det begining to occur with. Once you can hear it from the drives seat unaided, you've usualy got a toasted engine. The vr6 will probably be ok, cos its not running such high cylinder pressures and temps, but your not doing it any good.

 

Higher ron fuel will help reduce the chance of det, but is no substitute for enough fuel.

[Kevin Bacon 5]

Looks a like another remap is the answer then.

 

Now do I get Geoff Everett down to throw another Eprom in or do I use one of Stealth's Unichip jobbies, which intercepts the MAF signal and offers infinite adjustment possibilities and future proofing? Kind of veering towards then Unichip at the mo..... just means *another* box sticky taped to the scuttle panel!

 

Mind you, he has done several Corrados with Schrick VGIs, 268s and unichips and they've all given 220 brake or higher....

 

Cheers

[Scruffythefirst 0]

TBH I dont like the sound of either of those. Although its not forced induction and still fairly low specific output so either should do the job. What you really want is a fully mappable ecu like autronic or dta and a nice wideband lambda sensor and someone who knows what they are doing and map it live on a real road and not a rolling one. Although that will be expensive.

 

I'd get an eprom made specificaly for your car, mapped in a simmilar way to a full aftermarket ecu, this will give the best results without having to buy and ecu for £800+. However, if you did more mods, you'd have to start again. There was a great technical essay on what goes into live mapping a car (be it on a aftermarket ecu or eprom) on passionford.com but you have to be a gold member to read it and I'm too tight.

[Kevin Bacon 5]

If you get a DTA you can lose the MAF altogether. It makes a better map than the VW one using just the Throttle sensor and an additional MAP sensor, but obviously you lose the 'live' fuel trimming from the MAF, but they always break anyway, so no loss there!

 

But at well over a grand including fitting and configuration, the DTA is only a viable option if you're constantly getting new EPROMS coded for the stock ECU. That's why the Unichip is handy as it's reprogrammable like the DTA, but a fraction of the cost and can control almost as much.

 

DTA - Excellent bit of kit, but not fit and forget unfortunately.

[Scruffythefirst 0]

the DTA is only a viable option if you're constantly getting new EPROMS coded for the stock ECU

 

There are some other aftermarket ecu's available, some are very expensive and some arent. I dunno if you've heard of megasquirt? its about £100 as far as i can tell and is a fully programable ecu even if you do have to solder it together yourself.

[Kevin Bacon 5]

Megasquirt, LOL! Sounds like it's from a porn site or something!

 

I'm no stranger to soldering, so that wouldn't bother me. Sounds pretty good.

 

On one of the Vortex sites, some guy stripped his VR ECU and replaced all the capacitors and resistors with much bigger telecoms/computer grade ones...... nutter. Think he gained all of 2 hp!

 

K

[dr_mat 0]

I might consider the remap up at Stealth myself, but I guess I'll wait for Kev to report back first.. ;)