I've just fitted a sportex 4-2-1 decat manifold to my s reg 1.7 puma, it has developed a serious flatspot through all the revs, I can have my foot hard down and it won't pull then will fire into life until I take my foot off the throttle then it won't pull again, It ran perfect before fitting the decat but can't put cat back on as it has a hole in it, could the lambda sensor be at fault?
Decat flatspot problem
- Thread starter steelios
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Sjoerd
Member
Definately sounds like a Lambda sensor issue. I've been told that NGK made them to have a lifetime off +/- 130.000km or 80.000miles. It will certainly improve the fuel consumption as they often run a bit rich, to replace them about then.
ScubaSteve
Active member
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- May 8, 2010
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taking the cat out will naturally reduce mid range torque, but if its really noticable like night and day could well be lambda
might be a bit late but,
i bought a manifold, sports cat and backbox second hand, it already had a lambda in the manifold.
when it was all fitted it had some huge flatspots and was overfuelling like mad.
bought a universal sensor (one with no plug) for £35 and its fine now.
the old sensor in the manifold was just worn out i think.
still a few little flatspots in the mid range but im hoping a remap would sort this.
i bought a manifold, sports cat and backbox second hand, it already had a lambda in the manifold.
when it was all fitted it had some huge flatspots and was overfuelling like mad.
bought a universal sensor (one with no plug) for £35 and its fine now.
the old sensor in the manifold was just worn out i think.
still a few little flatspots in the mid range but im hoping a remap would sort this.
Daftgit
Member
Got to agree with the advice mentioned above - if it is seriously flat, it will probably be a lambda sensor problem. As yours is an earlier Puma, you've only got the one to worry about! You could try removing it and cleaning it with a rag and some carb or brake cleaner and then refitting it to see if it's any better. Failing that, your probably going to need a new one (i've also heard about the lambda sensors having a life span). If that fails to cure the problem, it might be worth taking it to a reputable car tuner who can check fuelling, timing etc and maybe sort you out a custom map for your mods!
You may lose some mid range torgue by taking the cat out, but on something like a Puma, the majority of drivers would be hard pressed to tell the difference! Most would just notice the difference in exhaust note!
On a separate note, I had a Citroen Saxo VTR when they first came out (before all the chavs and boy racers started buying them). I fitted a de-cat to it. No massive improvement in performance, just noticed a slight improvement in MPG and it would hold onto a higher gear slightly longer on the banks - not bad for a £30 - £40 mod!
Hope you get it sorted cheaply and quickly!
You may lose some mid range torgue by taking the cat out, but on something like a Puma, the majority of drivers would be hard pressed to tell the difference! Most would just notice the difference in exhaust note!
On a separate note, I had a Citroen Saxo VTR when they first came out (before all the chavs and boy racers started buying them). I fitted a de-cat to it. No massive improvement in performance, just noticed a slight improvement in MPG and it would hold onto a higher gear slightly longer on the banks - not bad for a £30 - £40 mod!
Hope you get it sorted cheaply and quickly!
