2885 Boost Deviation Plausibility Error
Mini Cooper 2885 Boost Pressure Control Deviation Plausibility Error
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Here are some items that we have found cause this error. please feel free to contact us if you have any questions or want to add to this list.
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Turbo Exhaust housing Failure, seen at 60k.
If the waste gate actuator is not operating properly it can cause a few different errors. Make sure that the waste gate valve is open about ~5/16” or ~8mm when measured on the shaft. Make a reference mark on the turbo and waste gate actuator shaft and pull the shaft towards the vacuum canister. It should only move ~5/16” or ~8mm, if it moves more you will have low boost pressure if it moves less than the ~5/16” or ~8mm the turbo will go into over boost and alarm.
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Also make sure the exhaust housing actuator is tight in the exhaust housing, it may stick due to wear damage. The shaft should move back and forth smoothly without binding, also if you pull up and down on the shaft the waste gate should feel tight in the exhaust housing. Too much play in the turbo exhaust housing indicates that there is excessive wear in the turbo exhaust housing causing it to bend and get stuck open or closed.
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They wear out quickly because the waste gate is on a duty-cycle meaning rapidly opening and closing when in boost. We typically see failure starting at about 60k miles or sooner if you have an OEM turbo and are running high boost pressures. Click here to see turbo exhaust housing.
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.Blow Off Valve Failure
Remove the BOF and test it by applying 12dc and ground to the two leads. The piston should move in when 12dc power is applied. Also remove it and check the diaphragm is not ripped or torn and leaking. Click here to see BOV or Blow Off Valve.
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Vacuum Waste Gate Failure
Use a vacuum pump connected to the waste gate actuator vacuum canister to test for leaks, it should fully close the waste gate when vacuum is turn on and fully open it at atmosphere. If you don’t have a vacuum pump it can also be tested by blocking the vacuum port and closing the valve to see if pressure builds or closing the waste gate and blocking the vacuum port then releasing the waste gate to see if the vacuum canister sucks in air. If it fails in either direction it will need to be replaced. Click here to see Vacuum Waste Gate.
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Vacuum Line Failure
Checking all vacuum lines for damage, wear, holes, soft collapsible tubing due to oil damage or restricted. (check vacuum pump also)
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Boost or Turbo Failure
Boost or Turbo Failure
If the turbocharger is not making boost and is noisy and/or the car blows bluish smoke out the exhaust when you accelerate it is may need to be replaced. The turbocharger should be replaced or when the turbine hits the housing it will shed aluminum flakes into the intake system and metal flakes into the engine oil. This type of failure is due to the catalytic converter being so close to the turbocharger that it burns the oil inside the turbocharger after the engine is turned off.
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And this is why. As the shaft spins it wobbles which compress the C-clip into the turbine shaft. The burnt coked oil prevents the C-clip (what you would call the oil seal) from expanding once it is compressed around the shaft. When the C-clip is compressed around the turbine shaft the exhaust gases can enter the turbo and oil can enter the exhaust or catfold. When oil enters the catalytic (catfold) converter it blocks the air flow due to all the particles in the oil and creates back pressure. This back pressure pushes the turbine shaft into the thrust bearing causing excessive wear, pushes more oil into the exhaust, and/or pushes oil into the intake piping. Eventually the compressor touches the compressor housing which stop the turbine from spinning or worse completely breaks the turbine shaft. We typically see turbos fail from 30k to 60k miles due to the oil coking around the turbine shaft.
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The result of this is either catastrophic turbo failure, failure of the turbo to create boost pressure, varying boost pressure, turbo works when hot but not when cold, works up to 8psi then car goes into error, works at low boost but engine sputters and stalls, or one combustion chamber failure due to oil coating the spark plug, or worst of all the oil can prevent the piston from fully closing causing the piston to crack. We have even seen pre-ignition due to the extra oil lowering the octane rating and/or the gases prematurely igniting due to the extra pressure in the chamber (igniting kind of like a diesel). This has caused pistons to crack or the pre-ignition to burn a hole in the piston and has also lead to the myth that there is an issue with the pistons on the N14 engine.
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To see if the turbo is not making boost pressure because of turbine contact with the turbo housing pull on the nut on the compressor side of the turbine shaft. If the thrust bearing is warn enough to allow the turbine to touch the housing it will move in and out ~1mm. The compressor is probably rubbing up against the turbine housing preventing it from spinning. If it is not rubbing and there is play in the turbine shaft it still means that you have thrust bearing wear due to back pressure in your exhaust.
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Also if you can pull the turbine shaft assembly up and down more than ~1mm the compressor and/or exhaust turbine can rub against the compressor and/or exhaust turbine housing preventing boost pressure to build. If the oil was not changed often enough (meaning it was changed as recommend by Mini Cooper ever 10 or 15k miles there could be excessive wear in the sleeve bearing. The oil on a Mini Cooper 4cly should be replaced before 5k miles and with only ACEA spec. A3/B3 oils). Both of these issues can cause the turbo to fail (meaning boost pressure failure due to the turbine is touching the compressor or exhaust housing) prevent in as soon as 40k. Click here to see our full line of turbochargers.
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Inter-cooler/after turbocharger Leak
Inter-cooler and post turbocharger leaks can cause your turbocharger to fail due to it over spinning to reach boost pressure. The leak will not allow the turbochargers to reach boost pressure and it can cause the compressor to grenade throwing aluminum chunks into your engine. Always fix any intake leaks immediately. Click here to see our high flow intercooler.
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Clogged air filter
A clogged air filter can cause your turbocharger to fail due to it over spinning to reach boost pressure. The clogged air filter will not allow the turbochargers to reach boost pressure and it can cause the compressor to grenade throwing aluminum chunks into your engine. Always replace your air cleaner as recommended by the OEM manufacture.
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Rear Crank Case Ventilation System, Pre-ignition (known as piston failure or bad pistons).
Due to a bad design of the rear crank case ventilation system on the Mini Cooper N14 07 to 10 (or to 12 for the JCW) the engine is susceptible to pre-ignition (knock). This engine has a rear crank case ventilation system that vents right into the intake through the “noise maker”, on direct injection engines this is absolutely the worst place ever to vent hot oil vapors. The reason is because the hot oil gases build up on the hot intake valves and block the air flow.
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In as little as 15k miles the valves can coke up with oil and block the airflow into the engine. This leads to an uneven distribution of air flow into each combustion chamber and this is one of the worst things that can happen to a turbocharged engine. Not only do you lose power because you now are getting more air in one combustion chamber than the other but even worse the air to fuel mixture is not correct and that leads to pre-ignition.
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This has lead to the myth that the pistons are weaker turbocharged N14 engine than the N18. Yes there were some changes to the pistons but this had to do more with the new dual vanos system than the quality of the cast pistons. The actual problem is the improperly mixed fuel due to the air being blocked by dirty valves. This improper mixture causes the pre-ignition which burns a hole in the piston. To fix this the valves will need to be walnut blasted than the rear ventilation needs to be block off with a cap. click here to see our secondary crank case vacuum block off cap.
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HPFP Failure (high pressure fuel pump)
Mini USA has an extended warranty on the HPFP for the 2007, to 2009 Minis with the N14 engine with less than 120k.
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Turbo leaks
Check all connections to the turbo for leaks on the turbo inlet, outlet and tubes to inter-cooler. Don't forget check the connection at the tube on the cold side coming off the hard tubing from the inter-cooler located just past the MAP sensor.
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Turbo Upgrades
If you don't have boost until you reach 3000rpm you will get this issue, you can flash you ECO or drive a little differently.
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Vacuum Reservoir
Check the vacuum reservoir under the manifold is not full of oil water, dirt, or has leak or restriction.
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Other things that might cause this issue:
Pressure/Temperature Sensor failure
Map Sensors leak or failure
Vac Pump not working
Cold Side pressure sensor failure
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