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Still overboosting

skendrick

skendrick

New member
Had my car fixed over xmas replacing the fuel pressure regulator and the car is running great, so I thought it might be time to put the boost enhancer back on the car. I have it turned right down to it's lowest setting but one and the car has started to overboost again and cut out on me.

If I accelerate hard from around 3000rpm the engine cuts out at around 4-4500rpm. I can still drive the car but as soon as I slow down or stop at a junction and go to accelerate again the engine cuts out.

What could it be as it looks like my car will have to live without the boost enhancer?
 
I`m certainly no expert but the ECU cuts the engine when it detects knock/detonation. This is either weak fuelling or timing advance.

Did it do this without the boost enhancer?

Is the ignition timing out a tad?

Is the fuel pressure adequate ie; accurately metered?
 
You haven't inadvertently set the BE fully the opposite way to your intention, have you?[FONT=verdana,geneva"] [FONT=verdana,geneva"]Basically if I read your post correctly the car was fine until you fitted the BE and now it isn't, so it has to be the BE causing the problem either because it's set too high, fitted the wrong way round or is faulty.[FONT=verdana,geneva"]
 
The car never overboosts with the BE removed.
At xmas I had the car serviced and all items checked, even the ecu was sent away and tested, all was well.
The BE is set at its lowest not it's highest, this I know, can they be faulty that I'm not sure of?
What is the cycling valve and how do I know if this is running?
 
The cycling valve sits under your inlet manifold (between No3 & No4 IIRC) is about 50mm diameter with 3 vacuum hoses attatched. Follow your vacuum hoses & you will find it.
 
have a look here: http://forums.gururacing.net/viewtopic.php?t=9

Although it's for a reliaboost (functions the same as a BE, just looks different), and I doubt that you set it in the same way, the instructions on where to fit it, and what to remove are pretty good. I just reckon you've got it hooked up wrong, so this should help.

There's a pdf file on the first post in that thread which is the fitting instructions. I know what LR's can be like....... Not to clear IIRC! [&:]
[FONT=verdana,geneva"] [FONT=verdana,geneva"]
 
As I understnd it the BE is designed to work in conjunction with the cycling valve. It's a very quick add-on for an otherwise standard car. I certainly ran mine with the cycling valve back when I had one.
 
ORIGINAL: Fen

I certainly ran mine with the cycling valve back when I had one.
Click to expand...

Me too, with no problems.

Are you sure you have a BE (its blue and red) as opposed to a Reliaboost (which is brass coloured and is best run with the cycling valve bypassed)
 
Was it new or second hand? I have read of upgrading the spring to allow more boost. Otherwise there could be some dirt in there, or a leak in the boost line that goes down to the wastegate (or the cycling valve).
Tony

PS also worth checking the earth points are clean and the plugs are gapped correctly.
 
Hi all, sorry I haven't replied but i've been off.

I don't know what boost I am running but the dial on the dash without the BE on goes upto 1.8bar and with the BE on around 2.0bar + I guess.
The BE was on the car when I bought it and I have checked it's set up and it is the same as shown on the promaxsport website. I have the BE 7 turns away from the red bolt and it is still overboosting.
I will take a photo of the engine bay and show you tomorrow.
When the car was serviced and repaired the BE was not on the car, if this makes a diffrence?
I have found the cycling valve but what does it do (sorry for being green about this)?

 
The cylcing valve is controlled by the KLR computer and manipulates the pressure the line to the wastegate is allowed to see to allow a form of electronic control over boost.[FONT=verdana,geneva"] [FONT=verdana,geneva"]It's not a great system an proper boost control replaces it much more satisfactorily.[FONT=verdana,geneva"]
 
Try adjusting the BE.

IIRC it should be 4 turns out (I am sure Andrew will correct me)

I don't know what boost I am running but the dial on the dash without the BE on goes Up to 1.8bar and with the BE on around 2.0 bar + I guess.
Click to expand...

I think the over boost protection operates at about 1.9 on standard chips.

The new fuel pressure regulator might be adding more fuel than the old one and is setting off the over boost. Fuel mixture does affect the point at which the knock sensor operates, this could be why you did not have problems before.

Mike[:'(]
 
When I put the BE on the car after xmas I set it up to 4 turns from lock but the car was overboosting so I dropped it down to 8 turns which stopped it but it felt like there was nothing there so I turned it up to 7 turns and it now overboosts.
To give you an idea of what is happening if I am in 2rd gear and put my foot down I can use the whole rev range with no problem but if I put my foot down in 3rd or 4th or 5th overboost cuts in around 4000-45000rpm.
 
That's exactly what mine was like when I tweaked the BE up slightly too much. It's definitely the BE to blame, either because it's set too aggressively or it's faulty somehow. [FONT=verdana,geneva"] [FONT=verdana,geneva"]To be honest my BE made little discernible difference out of the box. When I tweaked it I got to the point where the car was fine in all but extreme periods of WOT in 4th (probably 5th too, but where is there enough road to try that?) so long as I used Optimax and it was noticeably quicker. It was almost undriveable on 95RON though.[FONT=verdana,geneva"]
 
With mine each turn makes a considerable difference, if I was to turn the BE up to 4 turns from the bolt it would be like having a second turbo strapped to the car.
 
My Turbo S had the same symptoms & the cycling valve was diagnosed as being faulty, I expect your BE is just amplifying the problem.
 
if I am in 2rd gear and put my foot down I can use the whole rev range with no problem but if I put my foot down in 3rd or 4th or 5th overboost cuts in around 4000-45000rpm.
Click to expand...

Strikes me that you reach max revs quickly in 2nd gear therefore it isnt overboosting for long enough (I'm sure I'll be corrected but I believe if you get overboost for 6 secs or more its cuts off the fuel) so in 3rd and 4th which take longer to achieve max revs the system is detecting longer periods of overboost and reacting accordingly.

I could be wrong of course..........................
 
That's absolutely right, in lower gears the revs rise quickly enough that you don't trip the knock sensor. I'm not sure about 6 seconds delay, but you need to hold boost long enough for things to get hot and boost pressure to climb enough that knock starts and in lower gears you hit the redline before all conditions are met.
 
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