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Welcome, what are your problems, and what did you get year/engine wise?


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Welcome to the forum!

Are you getting any engine codes? That would definitely help us diagnose the problem.

Unfortunately, however, they didn't sell the 2.0L Diesel in the states, so many of us won't be of much help.
 

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Discussion Starter #5
No it is a petrol 2.0l.

it failed the inspection 2 times in the week i owned the car because very high co, hc.

I have got p2088 and p2178 only, but they are intermittent and also they came on yesterday for first time.

I failed first inspection with only high on CO, so i did clean and also replace MAF, I cleaned the spark plugs, replaced front o2 sensor, changed oil and filter but on the second attempt i did get VERY high on CO. HC, lambda was 0.8.

Today i removed the throttle body for cleaning, and o my god how much carbon build up there was behind and inside the intake manifold, it was wet inside the intake manifold.

I have checked for vacuum leaks with spray but nothing found.
 

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Discussion Starter #6
Cleaned the intake manifold and thottle body, now the car runs much more stable, but still the RPM moves a little bit up and down after increase the RPM. I have to take a test drive and see.

But i dont think the problem was the cleaning, there is a problem that make all that junk in there or is it a common problem for Mazdas like the VW/Audi engines have with carbon build up?
 

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I’m not very familiar with the 2.0 but I’ve never seen build up that bad before, I’m not even really sure what would cause that. Have you checked the PCV valve?


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I’m not very familiar with the 2.0 but I’ve never seen build up that bad before, I’m not even really sure what would cause that. Have you checked the PCV valve?


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Agreed - That's a tremendous amount of buildup. Definitely look into the PCV valve and hose - they're like $6 each and not a bad replacement (at least on the 3.0L).

p2088 is a Camshaft Position Actuator Control Circuit Low Bank 1 and is p2178 is System Too rich off idle bank 1.

How bad were the plugs when you cleaned them? It seems, with that buildup on the TB, that p2178 is your more likely culprit - you're running way too rich.
 

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Discussion Starter #9
I’m not very familiar with the 2.0 but I’ve never seen build up that bad before, I’m not even really sure what would cause that. Have you checked the PCV valve?


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The throttle body was even worse, it was 100% closed, when filling with fluid for solving the fluid did stay in place. No not yet, i have to take of the intake manifold for that i believe? I have to do it outside and it is a bit cold here so i thought getting some advices here first
 

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Agreed - That's a tremendous amount of buildup. Definitely look into the PCV valve and hose - they're like $6 each and not a bad replacement (at least on the 3.0L).

p2088 is a Camshaft Position Actuator Control Circuit Low Bank 1 and is p2178 is System Too rich off idle bank 1.

How bad were the plugs when you cleaned them? It seems, with that buildup on the TB, that p2178 is your more likely culprit - you're running way too rich.

I will check the PCV and hose.

The camshaft sensor was a bit dirty and the magnet was not as strong as a older sensor i have, maybe thats not important but maybe the sensor is bad. I will replace that.

The plugs where really bad, i have orderd new ones but wanted to try cleaning first with ultrasonic cleaning and sandpaper. Also i did a stupid mistake that could answer why the second inspection had way to high CO and HC, when replacing the front o2 sensor, i cut the wires because it was the easiest way to take it off under the car, and i joint the "new sensor" with old cables.

The reason i thought the o2 sensor was the problem is that when measuring the sensors i got the value on sensor 1 = 6500μA and on sensor 2 = 0.8v. And because i thought the o2 sensors only measuers in Volts i thought the o2 was bad. When replacing i got the same values so i understood that the sensor was normal, however no i can not read the sensor 1 value anymore, it say "not supported". But still i had high CO before cutting so the rich problem i somewhere else.

Could the engine temp sensor show in the middle in the car but send wrong temp to ECU?

Next step is to replace/clean the PCV and also clean the intakes, is there anything on Mazdas that i could do when i am doing all this?
 

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Discussion Starter #11
Car runs almost 100% better, almost perfect idle now. For anyone that want to know, i cleaned the throttle body in a ultrasonic cleaner with electronic upwards not touching the water. I used water + ultrasonic cleaner and soap.

I filled up with 98 octane (usually i used 95 octane before). I noticed that the car stalled in the highway one time, as if it got choked but automaticly started back up again.

Could the fuelfilter be clogged and the ECU notices preaussure loss and forces more fuel to engine and makes the car go rich?
 

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Car runs almost 100% better, almost perfect idle now. For anyone that want to know, i cleaned the throttle body in a ultrasonic cleaner with electronic upwards not touching the water. I used water + ultrasonic cleaner and soap.

I filled up with 98 octane (usually i used 95 octane before). I noticed that the car stalled in the highway one time, as if it got choked but automaticly started back up again.

Could the fuelfilter be clogged and the ECU notices preaussure loss and forces more fuel to engine and makes the car go rich?
With how much garbage you had everywhere else, it's worth checking at least. that, or the ECU is used to having everything clogged up and needs to re-learn what it's like to be properly maintained lol.
 

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It seems that the car has its fuel filter inside the gastank with the fuelpump so i will jump that step for now.

I took off the intake manifold and surprisingly it was very clean and inte intake valve chambers, the valves are very very clean, no buildup at all. That is little wierd i think. Also the PCVhose was in good shape no cracks, the PCV valve, injectors (i think i will replace them any way with partnumber 0280156154 hope they will fit) and the fuel rail ( fuel rail when blowing in it it felt clogged) in the ultrasonic cleaner.

I have cleaned the intake manifold and setting it to dry.

Next step will be engine temp sensor, CPS, o2 sensor, catalytic converter, sparks and coils.

Do anyone know if Mazda 3 o2 sensor will fit mazda 6 (same engine, but the sensors have diffrent partsnumber, i belive it has to do with the lenght of cable but not sure) so if anyone had tried and could tell me would be nice
 

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I have not tried, but I would assume the same as you - the numbers differ so something physical is likely to differ as well.
 

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I have not tried, but I would assume the same as you - the numbers differ so something physical is likely to differ as well.
I found a Mazda 3 2.0 in a scrapyard, the o2 sensor had only 4 wires, 2 grey 2 white if i remember right, but my mazda 6 has 5 wires, think it was 2 white, 1 grey, 1 black and 1 blue and 2 connectors. So it seems to be more complicated o2 sensors on the mazda 6.
 

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After removing the intake manifold for cleaning, the car now hesistates when accelerating wich made me think of 3 scenarios,

1. I damaged the throttle body (have read that not move the plate by hand wich i did)
2. Ignition problem, spark plug or coil but here i think missfiring would be more reasonable.
3. Vacuum problem - Hose that i have forgot to connect or something, but more likley the canister valve hoses that are wrong put. If anyone have a picture that could guide me on how to connect the hoses i would be very thankful.
 

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After removing the intake manifold for cleaning, the car now hesistates when accelerating wich made me think of 3 scenarios,

1. I damaged the throttle body (have read that not move the plate by hand wich i did)
2. Ignition problem, spark plug or coil but here i think missfiring would be more reasonable.
3. Vacuum problem - Hose that i have forgot to connect or something, but more likley the canister valve hoses that are wrong put. If anyone have a picture that could guide me on how to connect the hoses i would be very thankful.
@DrFeelGood, I've observed that you always have a picture or reference for something like this.
 

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Vacuum hose routing diagram

@DrFeelGood, I've observed that you always have a picture or reference for something like this.
The Dr. is here for you.
I can't remember what vehicle specifics you have (perhaps making a signature with the info would help) but I am going to assume you are v6.
With a hesitation I would bet you dislodged one of the connectors on the coils. If I know anything about how these things work I bet it is one of the ones on the rear bank.


As far as the TB is concerned, I have moved that thing countless times without issues so I am skeptical about that.
Good luck mate.
 

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Discussion Starter #19
Thanks both Archerfish and DrFeelGood.

Unfortunatly i have a 2.0 petrol engine. I tried to move the hoses and noticed that there were alot of preassure in one hose so that was wrong fitted, the car didnt hesistate as much but it started to after a wile, this problem was not there before removing the intake manifold so i am sure it is some faulty connections.
 
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