Not acheiving full boost when hot

[Tart]

Hi, Bought an R last month running 265bhp and it runs lovely... When I got it, it was setup to run at .8bar through a bleed valve. After letting the car warm up, booting it sends the boost straight up to .8 and it flies.... prob is after sitting in traffic for a while, if I then boot it, it feels slugish and does not acheive boost over about .65bar... The eng temp is still normal and the oil temp is still quite low (normally 3rd mark). Full boost is normally only acheived when the oil temp is reading between the first two marks on the oild temp guage.... Does anyone have any ideas why this is and what I can do to solve it....? thought maybe a dodgy sensor!!!! any thoughts would be appreciated... Cheers. Matt

 

[robinsongtir]

as you say after being in traffic it seems sluggish this points to one thing the top mounted i/c suffering from heatsoak the only way of stopping this front mounting it or getting a front mounted i/c kit.Although some people will say fit water injection I wouldn't if you are running on a std engine a front mount is more benificial

 

[Tart]

I did think bout that but didn't think it would be very likely since it only punching 265 bhp and the boost isnt that high.... Im prob wrong but thought that front mounts where really only needed above about 300bhp??? do u think the front mount (as well as lookin real nice) would solve all the probs then..... ???

 

[Edd]

Personally it sounds like the det sensor is kicking in and cutting the boost hence you see a boost cut from 0.8 to 0.65

Sounds like it's running lean or detonating somewhere most likely, best get it set up on the rollers.

Mine was doing this when i first bought it, kept going slow when hot and cutting boost, got it set up at powerstation where they fitted uprated pump and checked timing and it never did it again :lol:

 

[J-GTi-R]

as you say after being in traffic it seems sluggish this points to one thing the top mounted i/c suffering from heatsoak the only way of stopping this front mounting it or getting a front mounted i/c kit

Not quite right, a front mount would certainly help the problem but not necessarily cure it (and it's a bit of an expensive way to try). What is happening is the car is going into safe mode, causing the boost to be cut and the car to over-fuel. It's a safety thing built into the ECU when it detects detontation. There are two things that need checking, first do a fault code check (details in the how to section) to make sure it's not a faulty det sensor and second check the timing, as it is probably too far advanced for UK fuel.

I get the same problem from time to time in the summer, but rather than back off the ignition any further, I run octane booster when I know I'm going to have the problem occur (my timing is pretty much spot on, but when it gets really hot outside I know it'll happen anyway).

 

[Tart]

Thanks for the advice, thats great. Will try the fault code check and timing first..... I am running optimax but may try adding some octane boost as well. Let u all know how it goes. TA

 

[Tart]

Right, did the fault code test and sure enough Im gettin a detonation failure circuit...... thanks for that..... nxt question..... any good way of sorting it out....? wud having the cars timing adjusted be the best option???

 

[J-GTi-R]

Unfortunately not, you have to replace the detonation sensor, which isn't the easiest of jobs (what job is bloody easy on the 'R???). Adjusting the timing won't do anything.

 

[Anonymous]

Where bouts is the sensor? I have the same prob on my R...

 

[Fast Guy]

Adjusting the timing won't do anything.

Are you sure? I thought retarding the timing a few degrees should take you out of the det area? the down side being you'll lose abit of power.

 

[J-GTi-R]

Adjusting the timing won't do anything.

Are you sure? I thought retarding the timing a few degrees should take you out of the det area? the down side being you'll lose abit of power.

It would if the det sensor was behaving and triggering the safe mode as it is supposed to be doing, but if his det sensor is shagged and that's causing the problem, then adjusting the timing won't do squat.

 

[Fast Guy]

Gotcha!

 

[Tart]

This may seem a bit dim but how do u know if the detonation sensor is failing or doing its job properly??? when it comes up failure on the fault code checking does that mean its knacked or that its lowered the boost for a reason?

 

[J-GTi-R]

That's not dim it's actually a very good question, I've been thinking about that one.

The thing with the det sensor is if it has triggered safe mode, most people can just turn the car off, let it cool for a few mintues (when mine does it, turning it off then back on again usually suffices) and the ECU resets and the car is fine again. If you do a fault code check you have to turn the engine off first, then turn the igntition on without starting the car. As a result, you're essentially resetting the ECU, and the car will come out of safe mode, and a fault code check should show if the DET sensor is faulty or not, not that the car is in safe mode. However I can also see the point that, if the car doesn't reset immediately upon turning the engine off (I think some people have to wait a while) then does the det sensor circuit fault code just mean it's in safe mode, triggered by the det sensor?

I have to say, from experience, it has turned out to be the det sensor on other cars that have had the same problem, but do as a precaution check the timing first (rather than shelling out £180 on a new sensor!!).

 

[Tart]

Cheers thats great.... I'll defo get the timing checked this w/e first... see wot we come up wiv. Let u know how it goes...

 

[J-GTi-R]

Yes please do, as it would be interesting to find out what happens to your car.