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Running Lean?


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OK guys, the saga continues with my tuning mission!! After travelling 250miles from Leeds to Colchester last weekend to visit Mark, pick up a Milltek and six branch from him and have it fitted, my car is now not running properly.

If I boot the old girl when it's quite hot, it's like it's missfiring but not, if you know what I mean?

I get a kind of intermittent baaabaaabaaaa flatspot thing going on above 4,500rpm - max rpm. Thing is, it doesn't always do it. When it just gets up to full running temp, and I floor it it runs like hell high ho!!!

Which kind of backs up what Steal-th said.

I've spoken to Vince and he has told me that he thinks it's running lean because of the increase in airflow, as I only had a stock system on the car before with just a Remus rear silencer. (for those that don't know it is supercharged). He mentioned that it needs more fuel as the engine gets hotter. He now wants to sting me for 200 notes to just adjust the fueling and he ****ing knows that I can't take it anywhere else.

Any suggestions would be appreciated before he pulls my pants down and bends me over my bonnet!

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I hate to keep on about it, but are you running a maf or not? If your on one of his mafless maps then the engine has no way of knowing about a change in airflow, in which case what he's saying could be right.

If you have a maf then this extra flow is accounted for.

In the meantime if you think its going lean back off as soon as it does it (or better dont let it!) as going lean on boost melts stuff VERY quickly.

Hope you get it sorted,

Tom.

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Yes mate, I do have a MAF. I haven't got a clue if it is running lean tbh. It just sounds like it's popping off the limiter when infact it does it around 4.5k. It just seems to have all the signatures of a fueling issue.

I was wondering if it had anything to do with the lambda, as it was obviously removed and put back in the new exhaust - fault code maybe?

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Yeah running a maf then should add fuel for any extra air its taking in, so long as the fuel map is right that shouldnt be causing you a problem.

A missing lamba or "implausible signal" etc will show up on vagcom. also if theres no signal then it will add fuel, so you'd be running rich - but to a point the symptoms can be similar.

Would make sense if its the lambda i spose... Only way to tell really is with a wideband or vagcom - see whats going on.

Tom.

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