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CanadaCraig

Dirty Maf Sensor's Effect On Acceleration

13 posts in this topic

Hi Guys!! :)

I hope you're OK.

Could a dirty MAF Sensor cause a car to have poor acceleration?!

Just so you know.. my car idles fine. [for the most part]

Thanks,

Craig!! :)

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Hello;

The best thing you can do is clean the maf, and check your air filter, to make sure is in good condition. Just go to the auto parts and get electronics parts cleaner, and give a good cleaning to your sensor. Then if the problems continue clean the trottle body, check your throttle sensor, they can cause the same brand of problems also. Need to clean the maf as soon as possible to avoid it getting burned due to the dirt it might has that can cause a short circuit rendering the sensor useless, clean all terminals and metal in the sensor and connector in the engine harness. Disconnect your battery while doing this so the computer ressets. This happened to an Suv of mine the idle was good but had bad acceleration, then all became really bad, it was so, that the SUV literary, limped back to my house and could not even ascend a mild incline surface. Cleaned the maf, checked the air filter TB, which was clean and -puff!- all was back to normal, saving a trip either to the auto parts or to the mechanic and auto parts. I wish to know which of the two would have been worst. Check in the club knowledge for this procedures.

C. PR

Hi Guys!! :)

I hope you're OK.

Could a dirty MAF Sensor cause a car to have poor acceleration?!

Just so you know.. my car idles fine. [for the most part]

Thanks,

Craig!! :)

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It very much can have a huge decrease in performance and milage if dirty

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THANKS C. PR and SKperformance!! :)

I appreciate the responses.

Craig!! :)

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Hello!

Some additional information:

When the engine has reached normal running conditions, the mixture (and thereby fuel consumption) is calculated from the oxygen in the exhaust.

The ECU reads the voltage from the Lambda sensors, and tunes the fuel correspondingly to acheive Lambda = 1.

This means, that if the signal from the MAF is a bit off, the ECU will automatically compensate (as far as it can).

(Many cars have a "window" of +/- 30% or so in the Lambda regulation loop, allowing for tolerances in fuel composition and pressure, fuel nozzles, MAF tolerances etc.

On some Mercedes, the ECU tolerances where too narrow, setting the "check engine" light for no appearent reason. To correct this, we had to replace the ECU's.)

But during warm up, heavy load or acceleration etc. the input from the Lambda sensors is ignored, in favour to (wrong preposition?) MAF input.

Long rant :blushing: , but the point is:

During for instance a long cruise at moderate speed, a slightly "off" MAF does not affect mileage.

Performance and "driveability" will however drop.

/Alexander from Sweden

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Hi Alexander!! :)

Thanks for the information.

So... let me see if I understand what you're saying.

While driving normally [in town - lets say] a dirty MAF isn't really going to effect how a car performs. As long as the O2 Sensors [Lamba's] are OK - the engine will behave itself and drive fine. But as soon as you try to accelerate quickly - the condition of the MAF matters. If that's what you're saying - it certainly makes sense in regards to how MY car performs.

Around town - my car is fine. No problem at all. But as soon as I try to accelerate quickly - the car feels as though it is starving for something. [AIR and/or GAS] Just yesterday - I was driving at around 50 km/h. I pushed the gas pedal quickly to the floor [for one reason or another] and the engine actually STOPPED running for about one full second. It was the first time it had done that. Also - if I push the gas pedal to the floor it will accelerate better IF I ease UP on the gas pedal. To me - that suggests that the car THINKS that there is more AIR coming in than there actually is. Leading me to [once again] believe that perhaps the problem has something to do with the MAF.

So... I'm going to have the MAF cleaned!! [if not replaced]

Thanks!!

By the way...

You wrote, "But during warm up, heavy load or acceleration etc. the input from the Lambda sensors is ignored, in favour to (wrong preposition?) MAF input."

Instead of using the preposition 'to' ["....in favour to MAF input."] you should have used the preposition 'of'. [as in "....in favour of MAF input."]

Craig!! :)

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Craig, check out these attachments. Now they're for the gen 2 model, but I don't think our engines are that different. I'll try and find the one that's titled EG389 as the chart points you to over the weekend!

craig_1.pdf

craig.pdf

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Hi nc211!! :)

I hope you're feeling OK. [A LOT better than I am - at least]

Thanks for the links. I'll look at them again. [and again]

I went to my Lexus dealer today to asked them to clean my MAF. I was told that MY CAR doesn't HAVE an MAF. It has - instead - a Karman Vortex Airflow Meter. [i think that's what they said] NEVER EVER have I heard ANYONE here at LOC mention that the 1st generation LS doesn't have an MAF. Why didn't any of you say something?! Or am I confused? Apparently the Karman Vortex thing can NOT be cleaned. It's set at the factory and that's that. I had my hopes up that FINALLY my car might be fixed. I was really 'P.O'. when I left the dealer. What the hell do I do now?! Grrr......

I better go eat something and calm down.

Craig

PS Do you - nc211 - think that maybe the problem has something to do with the transmission?! [even though it SEEMS to be OK] I am completely lost and confused. Maybe I should sell the car and buy myself a nice pair of shoes. [with laces and everything]

PPS This is why I'm so frustrated with my car. Think of yourself listening to a beautiful stereo system that's playing Mozart. Everything is wonderful - except for an odd tapping noise that's too quiet to define [and locate] and yet to loud too ignore. Because of that noise - the whole experience of listening to Mozart is ruined. That's my car. It's great in all ways but ONE. It's still my dream car in spite of this nearly 2 1/2 year ANNOYANCE!! [but that might change soon]

PPS Alright - time to eat something!! lol :wacko:

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How do you clean MAF

I think you just spray it with some choke/carb cleaner.

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The early LS's used a mass air flow sensor, so in that respect the dealer is incorrect. It is just that its sensor is of a completely different type from the more common hot wire, which Lexus eventually used anyways. The early ones use an optical system, and a mirror which vibrates in the air flow, so the reflected light is used as a means of determining mass air flow. In that respect the dealer is correct.

Hot wire systems do respond to cleaning sometimes, but many of them, like Bosch, have a "burn-off" cycle that heats the wire and bakes any deposits (like a self cleaning oven).

I still don't believe the mass meter is responsible for the low power output.

Don't let it get you down Craig, as frustrating as this process has been for you. There is a solution.

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hi craig

Im still with you on this one.

as u may remember i have the same problem down here.

my maf looks the same as in that post showing the type that uses the vortex thing, so i wont touch it.

The only thing left to my mind is the coils. I havent changed these. Ideally i would like to find a car with good working ones and swap over to try.One at a time and see what happens.

there was a post a while back -some guy said he changed the coils and a engine missfire problem got fixed.No one i have asked seems to know exact symptoms of coils failing on these engines.A very smart auto elec friend, who fixed my wiring harmess problem, didnt know, and said he had no way of testing them.

just a thought-i think some other toyotas use the same coils.

swordfish

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