Motor Vehicle Maintenance & Repair Stack Exchange
Motor Vehicle Maintenance & Repair Stack Exchange

Questions tagged [lean]

A condition where the air fuel ratio is not optimal and the engine is not receiving enough fuel from the fuel system

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Symptoms of Lean or Rich carb settings on a motorcycle

I have a 1981 Yamaha XS650. I recently put in K&N stock replacement filter (ie, they are in the airbox and conform to the size of the original), however they may be leading to a leaner mixture because they purportedly let through more air. I want to…
user460
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What's the meaning of a "lean" vs "rich" air fuel mixture

I'm learning about vacuum leaks on engine intakes and I'm hearing this terminology of lean air fuel mixture. I thought I heard of a rich mixture before too. What's a normal mixture referred to as? A balanced mixture? Also just for clarity, this…
jxramos
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Strange surging and like it's going to stall, hesitant whilst idling

I have been having an issue with my Peugeot 207 (2008 model) 1.6L VTI petrol engine. The cam cover was replaced by the garage but hasn't fixed the problem. I have lost faith in them. I have managed to record and upload an example of the noise it…
Mike Rouse
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Fuel Trim Readings

I have a 2002 Toyota Corolla (1ZZ-FE engine) and I am trying to understand the fuel trim values I am getting in real driving conditions from my scan tool. I have P0171 code (lean condition) that comes on and off. I posted earlier about this, but I…
Florent
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Can a permanently stoich or lean running engine ruin a catalytic converter?

It's known a cat can be burned by an engine running too rich for too long, but i wonder what the effects are of constantly running lean. Will the cat just be uneffective because of the lack of CO, or will permanent damage be done to it? Would you…
Bart
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2009 Aprilia RSV1000 - Piggy Back ECU, Should I get one?

I have an Aprilia Tuono, 2009. It seems to run lean after putting an Akrapovic exhaust on it. It makes exhaust popping sounds on deceleration. My boyfriend said I need a power commander on it to make it richer. I thought Aprilia ECU's support…
Ppoggio
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Engine lean issues

Vehicle is a 2006 Ford Courier, started having hesitation/loss of power after fill up at a gas station that I'd never been to before. I depend on it for transport so I'm forced to still drive it, which does work, but it refuses to go above ~3000 rpm…
Aaron Patrickson
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Is there a chemical limitation to the mixture an engine can maintain?

I know that the question/title is a bit ambiguous, but I couldn't wrap it in a single sentence, so please let me elaborate. You can change the mixture of an engine for whatever reason. Because of multiple reasons, it's unwise to go either too lean…
Bart
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How much leaner can you responsibly run an old engine?

I've got a '76 Triumph TR7 and I was wondering this after I got its carbs tuned after its restoration. As many of you may know, old engines are initially not capable of running as lean as modern engines, due to less (local)cooling capacity, and…
Bart
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Help on diagnosing positive Long term fuel trim

My vehicle (Ford Fiesta 2014 Petrol) always have a positive long term fuel trim, which means its running lean mostly. The log data that I recorded using torque pro can be downloaded here : Torque Pro Log LTFT always quite unstable, and swing from…
hudarsono
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2012 Audi Q5 P2177 Code "System Too Lean"

My wife's 2012 Audi Q5 has recently popped its check-engine light, and my scan tool reports: "P2177 SAE System Too Lean Off Idle Bank 1" She says that it appears to run & drive without issues and in the 30-min drive I took it on it seemed to…
brhans
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Emissions per mile of high MPG lean-burn gas-powered cars versus standard gas-powered cars

I am wondering if there have been studies or calculations of the NOx emissions per mile of high MPG lean-burn gas-powered cars versus standard gas-powered cars. Honda made some great lean-burn cars in the early to mid nineties. But the lean-burn era…
user25009
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I have a code for 3 misfires, fuel tank ventilation, and car running too lean on my 2004 BMW 325ci

My car has been eating up coolant but is not overheating. There is white exhaust smoke coming from my tailpipe when idling and heater on. I have low engine performance and sludge. Rough idle. Loss engine power especially when going up hills. I was…
Erica Bojorquez
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Can fuel dilution significantly lower oil pressure?

Low oil pressure light flashes at idle when the engine is warm. It doesn't do that when the engine is cold and it flashes more frequently the warmer the engine gets. The light doesn't flash or isn't on under load. Oil level is halfway between min…
Masza
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How to fix Check engine error P0171 on VW Tiguan?

Took the vehicle for service after the usual 7000km.Parts that were changed during the service are Spark plugs, engine oil type 5W-40, Oil filter, Air cabin filter and Air filter. Two days later l got check engine on further diagnosis with OBD2 l…
Duncan O. N.
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