Please help me shed some light on this!! I have a my99 classic fully decated with a 2.5 inch system and a panel filter.Car is standard apart from these mods. On track after 5 or so laps the boost is starting to creep upto 1.5 bar then dropping off to 0.5 bar. Lift off throttle and reapply shoots upto 1.5 bar and back to 0.5 and so on. im not getting any fuel cut at all jus as car gets hotter boost creeps. Ive checked actuator with a mitivac. Its working as it should ive checked the wastegate hasnt stuck or any signs of sticking! Where do i go now????? Please help ive had this problem at every trackday i go to

 

Anyone ? Im thiking ive either got a sticking actuator or a boost solenoid problem? Surley reaching these levels of boost i should be hitting fuel cut?

 

Yes you should be, assuming a UK car and a standard ECU. Fuel cut is 1.22 bar, so if your boost gauge is telling you 1.5, one possible explanation would be a broken gauge, or, possibly, reaching a little, oil getting into the MAP sensor pipework.

Explanation for the boost control funking out on the track could be oil blowing into the solenoid - have you tried pulling any of the boost control pipework off and seeing if it's gunked up?

 

Ive had the gauge checked and its reading ok. Car is a V plate turbo 2000 with standard ecu. The cars 100% fine on the road and only ever has these problems on track after the engine bay temp is up. Im really stuck with it all. I havent tried cleaning any of the pipes as yet so i will try that. Can i run the car on track with the boost solenoisd disconected to eliminate the boost solenoid? I was gonna Blank the pipe to boost solenoid and install a manual boost controler to set the boost to 1.1 bar and see if it still creeps up after ive cleaned all pipes?
Cheers for your help, really apreciate your advice.
Steve

 

bttt

 

The fact that it happens on the track is significant. The engine bay temp thing probably isn't the factor you initially suspect. The bay temp will really start to rise when you stop the car. When you're running it, the airflow through the front will keep the general air temps under control.

As a matter of interest, what sort of oil level do you see if you pull the dipstick when the engine is hot?

Definitely. Certainly worth a look to see whether there's a lot of oil in them at the moment. First thing I'd try is taking the pipe off the compressor nipple and sticking a cotton bud down it. If it comes out oily, you know you're onto something.

The short answer's no. If you disconnect the solenoid's electrical supply you'll leave it "open", so your boost will be restricted to actuator pressure only. If you disconnect it by removing the pipe to the wastegate actuator you will end up with uncontrolled boost, and a fight between your turbo and engine over which can expire first.

I wouldn't try that yet, one step at a time. Always better to understand and fix a problem rather than try and skirt around it (creating the risk of making things worse). Aside from anything else, if your MAP sensor isn't reading properly (as 1.5 bar of boost without cut suggests), your ECU probably isn't setting the fuelling properly - and this will continue or worsen if you switch to an MBC.

Incidentally, do you know which ECU your car has? Label could be black, brown, green, or, possibly, pink. Any ideas?

 

Hi Buddy, i never check the oil as soon as i come in off the circuit so i dont know as i check it just before i go back onto circuit. I run the oil level halfway up the disptick in a aid to not overfil it and get the boost surge problem.

Ill look into the pipes now as ive collected the car from having a new clutch fitted, if the pipes are oily, if they are would a cleaning of the pipes possibly cure the problem of the overboost?

Ok i wont take the mbc to next trackday ill clean these pipes out and see where that takes us, il also have a look at now at the ecu. Cheeers again
Steve

 

The pipe off the top of the actuator is clean inside as is one of the pipes going into the boost solenoid, I dont know which pipes these are as im not a mechanic but i think ive checked the right ones. I can get to the ecu as its behind a cover in the footwell and all my tools are at work. Whats the map sensor and where is it located? My best mate has exact same car so where thinking we can take the boost solenoid and map sensor and try his at Oulton Park. Is that a good idea?
Thanks again.

 

Boost solenoid, pressure (MAP) sensor and the pressure source change solenoid are fixed to the bracket on the front of the offside suspension turret. The pressure sensor is the one at the top of the bracket, with the black three pin plug. Have a look inside the pipe between that and the change solenoid underneath it.

If you want to swap yours over with your mate, just undo the three plugs, three pipes and three bolts and the entire bracket with all three devices comes out. Although, there might not be a huge amount of value in doing so. If your mate has exactly the same car, for example, it might suffer the same problem if driven at speed on the track, so your ability to learn from the control pack swap might be limited!

From what you've said, it sounds like this is exactly what you've got. Might be interesting to have a looksee in your breather pipes and intercooler to see how much oil there is in them.

 

Is there any value in checking the operation of the w/g actuator, by temporarily bypassing the BCS with a bit of vac line direct from comp. cover nipple to w/g nipple???

That way, if it boosts to 1.5bar then you know you have a prob. with the w/g actuator diaphragm/rod/flapper... (I think a correctly functioning w/g mechanism should only allow around 0.5bar.)

 

I dont think its boost surge from overfill as ive had that before. If the car is hot an i hold it WOT the car spools upto 1.5 bar and drops off around 0.6 bar and doesnt come back up untill i lift off the throttle.Once its overboosted it drops to 0.6 and stays there not 1.5 then 0.6 then 1.5 if that makes sense?Its very hard to explain the boost goes up way to fast and even if i hold it part throttle im still hitting 1.5 bar, maybe even more my gauge only goes to 1.5 bar and the boost is going right to the max on the gauge. When this happens the exhaust note barks up and then drops off when the boost goes like the cars being held back. No matter how you drive it ie smooth, part throttle, wot, the car still overboosts. If i continue to drive hard it the car wont boost over 0.5 bar after 10 or so laps like its being held in limp mode. I hope this helps so more its very hard to explain on the internet.

Joz8968 i may try this on the circuit to elimintae t for certain, ive had them checked by a mechanic but its definantley worth ruling out for certain.

 

mine did this exactly same thing after this same mod cos of more air flow etc the ecu cant keep a steady boost target so it fluctuates only on WOT in 4t n 5th gears...i put a dawes in till i had it re mapped
maybe on the track the zaust gasses are hotter so even more flow through out? you might get it on the roads when winter air temp really drop

 

Cheers Andy, ill maybe take mbc to next trackday and if all else is doing no good plumb it in and try it!

 

BTTT
Any more on this guys? Booked to do Oulton Park on 18 Nov. Just want to try as many things as i possibly can while im there to stop this. Cheers

 

bttt