# Running Rich - ECU & injector lag ?



## jackchoo (Jul 15, 2004)

hi, I notice that when I drive, especially during a jam and you have to do a lot of throttle pressing and throttle releasing, the A/F ratio right after each of these throttle release drops drastically (14.6 being ideal ... 10 being damn rich!) below 11 before going back to normal. I know my A/F gauge is prob not accurate but its still its job in terms of calculating the A/F fluctuation.

My guess is when the throttle is released suddenly, the ECU is not fast enough to react to the sudden drop in air (throttle closed) and hence pumps in too much fuel. This is bad for economy right? It takes a couple of seconds (say about 4-5secs) for it to adjust itself back to the correct fuel based on the closed throttle plate.

Is there any way I can make ECU react a little faster to this kind of city driving. Its kinda ridiculous that it doesn't react as fast as it should cos everytime you lift the throttle, it just floods the chamber with unnecessary fuel for a couple of seconds.

BTW I get poor economy on a STOCK S13 auto....about 6.5kms/litre.


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## Joel (Jun 11, 2003)

A vacuum leak can cause this. Look for split vacuum hoses on the engine bay


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## bridrive55 (Aug 26, 2004)

That ammount of richness doesn't sound normal at all. I would check for a big vacuum leak and also test valves such as PCV.


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## Farley_420 (Apr 9, 2005)

It kinda sounds as if its goin into open loop......id also ckeck the o2 sensor


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