[josefslezak]

When I drive the revs randomly drop to about 500 for a split second and then it comes back. It'll shake the whole car a lot when that happens.
Also the check engine light, battery and oil light come up.

Usually it starts happening after like 5-10 min of driving.

I've been trying to figure this out for months now but still can't find the problem.

This is what I have replaced so far:

• ignition coils
• spark plugs
• fuel pump
• crank position sensor
• IAC
• throttle position sensor

Do you guys have any ideas what to do about this?
I'll really appreciate any tips and advice, it's so frustration.

Thank you,
Josef

 

[DL175]

Try cleaning the throttle body and MAF sensor.

 

[aVyDe]

Check your entire air intake system. My guess would be that it’s a crack in the vacuum system somewhere that only opens up when you reach a certain rpm and your engine is pulling a certain amount of air. It then reseals once the engine chokes due to lean mixture. I’m no expert, just a guess.

 

[josefslezak]

Try cleaning the throttle body and MAF sensor.

I already cleaned the throttle body. Wasn't dirty at all actually.

And I bough a new MAF sensor a couple days on Ebay. It should be here on Saturday I think.
It would be awesome if that would solved the issue.

Thank you!

 

[josefslezak]

Check your entire air intake system. My guess would be that it’s a crack in the vacuum system somewhere that only opens up when you reach a certain rpm and your engine is pulling a certain amount of air. It then reseals once the engine chokes due to lean mixture. I’m no expert, just a guess.

OK thank you for that idea. I will try that.

I just Googled how to check for vacuum leaks and found a tutorial.
They're using a spray bottle with water and then carb cleaner.

 

[DL175]

I already cleaned the throttle body. Wasn't dirty at all actually.

And I bough a new MAF sensor a couple days on Ebay. It should be here on Saturday I think.
It would be awesome if that would solved the issue.

Thank you!

Just replacing things without really knowing what is casing the problem is really a waste of money. You need to check what that code is for the check engine light. Also test the battery and check the oil level.

 

[josefslezak]

Just replacing things without really knowing what is casing the problem is really a waste of money. You need to check what that code is for the check engine light. Also test the battery and check the oil level.

I agree. The problem is that it doesn't show any codes. The check engine light only shows for a split second when the revs drop but then it disappears. I tried to read the stored codes with my reader but it didn't show any. (it's just a basic cheap code reader though - maybe a better analyzer would show some stored codes).

Ok will check the battery and the oil level.

Thank you!

 

[DL175]

I agree. The problem is that it doesn't show any codes. The check engine light only shows for a split second when the revs drop but then it disappears. I tried to read the stored codes with my reader but it didn't show any. (it's just a basic cheap code reader though - maybe a better analyzer would show some stored codes).

Ok will check the battery and the oil level.

Thank you!

The codes should still be there and they don't go away unless it is erased. Hope you are not reading the codes while the car is running. I think you need to get a better code reader.

 

[AllTerrainOutlaw]

My money is betting on it being a cam shaft code. I just watched a video a few months back of someone that was throwing a flashing CEL and would throw a camshaft code everytime they got on it with their Rav4 2.4. Turns out a piece of metal (can't remember what) broke off the cam and the came would "walk away" from the cam shaft position sensor which would result in it throwing a misfire and a cel light. The light would turn off and engine would run like normal.

 

[Bigphil555]

A better scanner would be able to pull pending or history codes - that would be where to look.

I would cease fire for now on parts too. If the Ebay MAF is not a genuine Toyota, or at least OE then it may not work out of the box

 

[1.8TTony]

"This is what I have replaced so far:

• ignition coils
• spark plugs
• fuel pump
• crank position sensor
• IAC
• throttle position sensor"

A professional diagnosis pinpointing the faulty component costs less than $200.

 

[josefslezak]

Check your entire air intake system. My guess would be that it’s a crack in the vacuum system somewhere that only opens up when you reach a certain rpm and your engine is pulling a certain amount of air. It then reseals once the engine chokes due to lean mixture. I’m no expert, just a guess.

So I tried to check the whole system but haven't found any issues. It all seems to be ok.

 

[josefslezak]

My money is betting on it being a cam shaft code. I just watched a video a few months back of someone that was throwing a flashing CEL and would throw a camshaft code everytime they got on it with their Rav4 2.4. Turns out a piece of metal (can't remember what) broke off the cam and the came would "walk away" from the cam shaft position sensor which would result in it throwing a misfire and a cel light. The light would turn off and engine would run like normal.

I'm thinking about getting a better scanner. Let's see if it shows any codes.

"This is what I have replaced so far:

• ignition coils
• spark plugs
• fuel pump
• crank position sensor
• IAC
• throttle position sensor"

A professional diagnosis pinpointing the faulty component costs less than $200.

I'm thinking about getting a better scanner. I wanted to get one anyway so I think it's the right time now. If a better scanner won't solve the issue I'll probably take it to a shop for a diagnosis.

 

[josefslezak]

The codes should still be there and they don't go away unless it is erased. Hope you are not reading the codes while the car is running. I think you need to get a better code reader.

Ok I'll get a better scanner. Hopefully it'll show the codes.

 

[josefslezak]

Which scanner would you guys recommend?

 

[Bigphil555]

do you have a rough budget in mind at all?

 

[josefslezak]

do you have a rough budget in mind at all?

I was thinking like around $250. I was looking at launch CRP 129E. It has also live data.
What would you recommend?

 

[Bigphil555]

Launch are good, I use the X431 diagun - very happy with that. Autel in the same price band are good. As long as you get decent live data. That 129E does look good

 

[josefslezak]

Launch are good, I use the X431 diagun - very happy with that. Autel in the same price band are good. As long as you get decent live data. That 129E does look good

I just looked at the X431. It looks really cool and also the bi directional feature looks really good but it's way too expensive for me. I just order the 129e on Amazon. It should be here on Tuesday so we'll see what happens

 

[josefslezak]

So I tried to read the codes with the new scanner (Launch 129e) but it didn't show any.

But then something interesting happened. I poured gas cleaner (Techron) to the gas and it looks like the issue disappeared.

Could it be dirty fuel injectors?