Missing when foot is down

[Anonymous]

Hi, for some reason yeserday my R just started to miss when i put my foot right down on boost only, it doesn't miss when idling or normal running, only on full boost. I don'e know if this is relevant as well but after it messing around i notice that the boost gauge doesn't fall right back to -7 on idle and i thought it used to.
It has had new leads, plugs and it hasn't rained for a while.
The only time it has done anything similar is when the bleed valve was out too far, but doing it up again solved it but now it's doing it again so i've had to do it right up, STD Boost ( i don't have an aftermarket gauge though. I always use either optimax or similar.

Cheers

B

 

[geetee]

As your not making as much vacuum on idle I would suspect a leak sowhere on the inlet / vac pipes / boost pipes.

You say you've had problems with the bleed valve before - they are know to have probs leaking air at idle. Try taking ur beed valve off entirely. I preume you have bypassed the standard boost solenoid so just take the pipe that runs from the plenum to the bleed valve and whack it straight onto the actuator. This should give you about 0.4 - 0.5 bar.

Other possibilities for investigation are MAF and Throttle Position Sensor.

I would suspect a split or loose hose somewhere though... god knows there re enuff of them.


Have a look at
http://www.mummachummas.co.uk/pics/BoostControls.gif

Cheers
GeeTee
8)

 

[Anonymous]

So is the gauge meant to return completley to -7?
Sooooo many pipes :shock:

Cheers

B

 

[Anonymous]

oh, and if the boost is too high will it start farting and stuff?

 

[geetee]

It was you who said it used to go to -7 :?

I think the standard gauge on mine reads about -5 / -6 at idle - but it varies.

The standard boost gauge is cr@p - if you have increased the boost with a bleed valve, you MUST get a decent after-market gauge. How do you know what boost you're running???

If the boost is too high you'll blow the engine up - so I wouldn't be too concerned about it farting or not.

If you have suspected your bleed valve b4 I would replace it, preferably with an electronic boost controller. If your bleed valve has a problem and you have no accurate boost gauge you can be in very very expensive trouble. e.g. break a conrod and watch it explode out the side of your crankcase taking ur bottom end internals with it. Do you have £4K to spare for an engine rebuild?

Makes the boost gauge look cheap eh!


Cheers
GeeTee 8)

 

[Anonymous]

True true...
I said

boost gauge doesn't fall right back to -7 on idle and i thought it used to.

Got a gauge ready to go on but have not done it yet, (More pipes) a job for tonight me tinks..

I don't know what boost i was running as it was done on the rollers by the previous owner, now i have wound the bleed valve right in and wont have a clue how to get it back to the 276bhp it says on the print out and it feels soooo slow

Don't really wanna blow it up to be honest..

Cheers

B

 

[geetee]

Get the boost gauge fitted first.... you'll need to use the T piece in pipe marked no. 4 on here to get both Vac and Boost readings.

http://www.mummachummas.co.uk/gtir/BoostControls.gif

If everything else was standard, 276bhp would probably be about .9 bar.

It may be worth investing in a new fuel pump to make sure you don't run lean at the top end and / or do a rolling road session with a good tuner like Powerstation who will make sure there's no detonation or leaning out of the mixture.

I've been running about 1 bar on a bleed valve for about a year with no probs at all - but am just installing a Profec B EBC for peace of mind after reading a number of horror stories about bleed valves.

Have you done a fault code check when you have the stumbling / missing problem?

Cheers
GeeTee 8)

 

[Anonymous]

Powerstation is where it was rollered at last time, as it now runs properly at std boost i guess it shouldn't lean out if i push it back up. i'll set it back to 0.8 and put up with it. I'll slap electronic boost controller when i have a few spare notes.

Cheers mate

 

[geetee]

Just cos it runs fine on standard boost doesn't mean it'll be ok on increased boost. Increase the boost and ur pulling more air through... therefore u need more fuel.

It may have been ok last time it was rollered - but how long ago was that and can you be sure the fuel pump hasn't detiorated since of the fuel filter clogged more??

Better safe than sorry.....

Cheers
GeeTee 8)