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Could a bad lambda signal or sensor cause low boost?

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Old Apr 8, 2011 | 09:52 AM
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Default Could a bad lambda signal or sensor cause low boost?

Hi, just a general query regarding my saph (which i almost forgot I owned ). Last year it went for an MOT but I had a carry on with the emissions being all over the place and it wouldn't boost more than about 12 psi, is it possible the two could be related?

Going to dig it out from storage tomorrow and start taking it to bits to FINALLY get it back on the road, hence why I've actually put up a technical type question/thread for the first time in ages!

Background info-Engine is new, crank/CTS etc sensors are all new apart from lambda probe.
Had the boost issue since it was put back together about 3 years ago and eliminated the obvious things like hoses etc, it has a new 500 cooler that may have a fault, but other than that no obvious symptoms of a leak, I do plan to whip it off and get it pressure tested since that is the obvious and basically only remaining thing to check. (Actuator is fine BTW, been swapped for two others).


Thoughts please?

Last edited by rog; Apr 12, 2011 at 10:47 AM.
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Old Apr 12, 2011 | 10:47 AM
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BTTT, anyone got thoughts on this?
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Old Apr 12, 2011 | 10:53 AM
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Amal valve jetting? What chip is it running?

A lambda sensor couldn't cause low boost, it isn't used on boost (above around 4-5psi)
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Old Apr 12, 2011 | 10:56 AM
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From: Top secret. Mission:Imposible.
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wont be intercooler, as it is a map sensing system
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Old Apr 12, 2011 | 11:43 AM
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Ok I'm confused by that comment ^ what do you mean?
It's running a stg3 Ahmed chip with greens, always has for the last 10 years, ran fine before i took it all apart, maybe i shouldn't have bothered.

What do you mean by amal valve jetting, as in changing the jet size? it's been done already and was fine before.
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Old Apr 12, 2011 | 11:52 AM
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you mean my comment? MAP sensing means it will still work fine with a mojor boost leak, or no intercooler pipework at all, so a minor boost leak will make no odds, this will not be the cause of fluctuating boost, a large boost leak will give no boost, but as mentioned no running problems. Not like a maff/mass system that would leak metered air and cause all sorts of runing probs
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