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Wastegate sound is actaully turbo stall which is not good
I would look into Songman's threads ref his duff DV that caused his turbo to fail (he was running an upgraded IHI turbo but even so
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The wastegate chatter sound is probably just his filter resonating the air as it goes back in, the BMC CDA's can do the same
Yeah I get the same sound with the BMC.
Im looking at getting rid of the sound by fitting a different air feed as its the metal feed that causes that sound
Mood
Guest
so how do i know if my DV (atmos blow off) is working well ? i mean it makes the noise .... i get some power flutter but again ive read up on that and getting the pipes and hoses checked.....
if say im holding 85 - 90mph in 6th , the valve is constantly dumping air while boost is below 0.0bar, above that and you just hear the spool and it only dumps when i lift off ..... is that the way is should be ?
if say im holding 85 - 90mph in 6th , the valve is constantly dumping air while boost is below 0.0bar, above that and you just hear the spool and it only dumps when i lift off ..... is that the way is should be ?
owen1983
Guest
Mood
Guest
Mood
Guest
Its not a case of it damages the engine it CAN just causes conflictions due to how the engine works. AS has been proven it does not always cause problems
Excuse the cut and paste but you asked for an exact response.......feel free to post your views / response
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"No rhime or reason"
But:
(and concentrate, here comes the science bit!)
A modern engine management system, ie the Bosch Me unit fitted to 1.8T's has "adaptive" learning on the fuel, ignition and airflow side.
Because Me is a Torque based structure it's calculation of engine torque verses driver demand is critical to the driveability of the car and it's performance / durability.
When you fit a "leak" in the intake system (open circuit valve) the original calibration of the MAF sensor to manifold and cylinder filling modeling will not corespond. However due to the 20% allowance in the long term adaptive values the ECU will relearn you engine and "leak"
At idle the inlet model calculated airflow will exceed the MAF meters measured output, and depending on the state of your particular components - ie MAF ageing / contamination, throttle plate leakage, Fuel tank purge vapour concentration this may, or may not push the adaptive to it's 20% limit. If it hits the limit the ME unit will run in FMEM mode (Failure mode and effects management) causing reduced system efficiency. The Me unit will use the switching signal from the lambda sensor to return fuelling to lambda 1, storing the correction as a map agaisnt airflow. and add this correction to the fueling calc when operating at non closed loop conditions, ie WOT, fuel injector reenstatment (after overrun shut off, traction control intervention etc.) Now depending on how you drive and how sensative you are this may or may not be felt by the driver during certain manovevers. The throttle plate position will also learn the new airflow to maintain control of idle speed, but you may notice poor engine load rejection, ie turn on the aircon and the engine speed varries etc. or engine speed flares on starts or when operating PAS when parking.
However in all cases this will result in "incorrect" fueling. Now by "incorrect" i mean, not as the manufacturer intended. A post MAF leak will cause rich operation initially, but the adaptives will pull fuel out and become negative. This tends to cause a rich to lean spike on tip outs and other throttle transient. Now it is extremely diffucult for an untrained observer to spot these effects as they occur mainly on throttle transients, when the average drive may not notice. Therefore you could say "why do i care?". Well, any AFR excursion from the intended fuelling set by the manufacturer will result in non-standard engine operation. because of the adaptives this is unlikely to cause immediate engine problems, but over the course of time will change things like catalyst ageing, exhaust and turbo charger valve durability etc. Manufactures spend millions accruing miles on development fleets so hopefully the customers don't get landed with big bills as time goes on, and with most modern cars life'd at 150k miles (min design life) this is a big task.
It is unlikely that this will result in any performance loss, as at WOT the system is open loop, but you may see the result of an open circuit valve oas over fueling on gear changes etc. (a tell tail puff of black smoke is what you can see, a 1200 degC Catalyst is what you can't see, as excess fuel when injection reenstates and excess air from overrun shut off period combine in cat)
Now as you can see this is a seriously complicated subject and i haven't even mentioned the dreaded EOBD or OBDII words yet. Typically Bosch Me units have approximately 9000 calibratable parameters (constants, maps etc) and an engine calibration program will take a team of 8 calibration engineers 18 months to do the basic mapping and OBD validation. These days it's no problem to do the basic fuel and spark mapping, maybe 4 weeks on a midlimit engine on a dyno, but the diagnostics and emmisions devs takes years.
Moral or the story, before you start playing with something you don't understand, find someone who does!(And not just thinks they do!)
(for anyone thinking, "hey what makes me such an "expert" on this subject?" then i'd better mention the last 10 years i've spent as a senior calibration engineer at Cosworth and Prodrive!)
(sorry , another monster post!)
In summary I think the answer is your cars ECU could be tricked into running rich then lean, running lean could cause serious damage to your engine particularly if prolonged. Then again it may all be fine.
The part Bov part recirc valves like Forge Split-R seem to maintain the balance and avoid throwing fault codes this is the way I would go
The part Bov part recirc valves like Forge Split-R seem to maintain the balance and avoid throwing fault codes
this is the way I would goMood
Guest
Cheers RUdd, even tho most of that went right over my head ... the simpler bits made sense ... i think 
the valve was put on by a previous owner , and i was just thinking i should replace it with recirc ... ill see how the funds are doing first if its not that urgent
thank again
the valve was put on by a previous owner , and i was just thinking i should replace it with recirc ... ill see how the funds are doing first if its not that urgent thank again
Mood
Guest
oh btw ...does rich and lean refer to fuel consumption in a way ? so i take it the coil pack and plugs etc would be influenced too ? maybe cause a misfire ?
Running rich means too much fuel is going in and running lean means not enough fuel is going in. Too much fuel isn't as bad as not enough because running lean can cause knocking/detonation
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