Acura TSX K24 positive Short and Long trim fuel

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6 months 1 week ago #201373 by raresvintea
Hello, I'm located in Europe and I have a Honda Accord CL9 2008, like the Acura TSX in USA with K24a3(without egr and 190bhp) My car has aprox 160.000kn(120.000 miles) and i have an issue with positive short trim fuel and long trim fuel(sometimes p0171). My car has also LPG, and when car runs fine on lpg it's still want to compensate in stfl and ltfl.
I've tried several items:
-sprayed brake cleaner on every hose to find a vacuum leak, no found, if i spray directly into intake immediately the values drop and goes negative
-make a profi valve adjustments
-block vacuum from brake booster and the pipe coming from purge valve
-block front mount engine support that is vacuum actuated
-check air valve that closes when antifreeze gets hooter
-replace fuel filter inside the tank

What to do next:
-check fuel pressure
-change the gasket between exhaust manifold and down pipe and then it comes lambda sensor, if it's leaking it can give false readings?! but it's no dark sports visible, like exhaust smoke
-change first lambda

Any ideeas?

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6 months 1 week ago #201375 by relative4
Replied by relative4 on topic Acura TSX K24 positive Short and Long trim fuel
What are your trims at idle, 2500, and 4000?

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6 months 1 week ago #201380 by hondaguy453
Replied by hondaguy453 on topic Acura TSX K24 positive Short and Long trim fuel
Inspect your PCV valve and fitting. Also check to make sure the fitting area isn't cracked. It's threaded into the valve cover, correct? I can't remember lol. Definitely check fuel pressure, but you should also ensure that your fuel injectors are actuating. They could also be stuck closed or plugged with crap too.

If it ain't broke, don't fix it
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6 months 1 week ago #201383 by raresvintea
Replied by raresvintea on topic Acura TSX K24 positive Short and Long trim fuel
2500 and 4000 under load, or in parking position?

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6 months 1 week ago #201384 by raresvintea
Replied by raresvintea on topic Acura TSX K24 positive Short and Long trim fuel
I've changed pcv valve and checked the hose from it to intake manifold. The pcv valve on this engine is plugged in a rubber grommet. I will check fuel pressure if it's a problem with the pressure regulator or injector problems.
I still thinking if it's a exaust leak before O2 sensor, engine will sound fine but o2 will see more oxigen, but why no signs of exaust leak.

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6 months 1 week ago #201386 by relative4
Replied by relative4 on topic Acura TSX K24 positive Short and Long trim fuel

raresvintea wrote: 2500 and 4000 under load, or in parking position?


Good question. I'd expect them to be the same, but definitely worthwhile to look at both.

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6 months 1 week ago - 6 months 1 week ago #201389 by raresvintea
Replied by raresvintea on topic Acura TSX K24 positive Short and Long trim fuel
800 rpm LTFT 7.8% and STFT 7.0%
2500 rpm LTFT 7.8 STFT 6.2
4000 rpm LTFT 7.8 STFT 4.7

Second run after a grocery store visit
800 rpm LTFT 8.6% and STFT 11%
2500 rpm LTFT 7.8 STFT 7.8
4000 rpm LTFT 7.8 STFT 4.7

Both measurements are done with coolant on the operating temp 90C, while parked, in parking position. For 2500 and 4000 rpm i've waited for 15-20 sec before take the readings.

If would be a vaccum leak at higher rpm would dissapear at least STFT
if would be a fuel delivery issue on higher rpm should increase
If would be an exaust leak should look like a vaccum leak
Correct me if i'm wrong please to leave behing a good info

How it's a aged O2 sensor? The fuel consumption is a little bit high
Last edit: 6 months 1 week ago by raresvintea.

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6 months 1 week ago #201390 by relative4
Replied by relative4 on topic Acura TSX K24 positive Short and Long trim fuel
I agree with your analysis, except I don't know what exhaust leaks do to the trims.
At this point, I'd suspect MAF sensor or upper O2 sensor. Have you cleaned the MAF sensor?

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6 months 1 week ago #201399 by raresvintea
Replied by raresvintea on topic Acura TSX K24 positive Short and Long trim fuel
This engine, in my variant, has only MAP.
I will check fuel pressure and change o2 sensor

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6 months 3 days ago #201524 by raresvintea
Replied by raresvintea on topic Acura TSX K24 positive Short and Long trim fuel
Changed o2 sensor and donut gasket from exaust. Still the same positive short and long trim values

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