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Mike, Technician
Category: Mazda
Satisfied Customers: 39198
Experience:  Tech Expert
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I Have a 57 plate mazda6.It does not run is constantly

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I Have a 57 plate mazda6.It does not run is constantly surging . pulling away seems slightly delayed and does not have enough grunt to get up steep hills without having to change down to 4th gear. car has been in mazda garage, but could not find the fault. There has been no management lights coming on. It has been plugged in, nothing found. A new lambda censer has been fitted plus new plugs. Just been on 780 mile journey and car averaged approx. 35 to the gallon. Even though it runs erratic, put it in 3rd and 4th gear and it will pull away very quick. Please can you help. Pete.
Hello and Welcome - My name is ***** ***** Im happy to help / advise..
Hello and Welcome - My name is ***** ***** Im happy to help / advise..
Exactly what engine does the car have?What mileage does the car have ? Did this happen suddenly - or gradually ?Has the car been on any diagnostic equipment - other than basic fault code testing?
It seems you are not online right now - please reply here - when I receive your reply , I will get back to you asap thereafter - Rgds, MIKE..........................
Customer: replied 2 years ago.

Reg YT57XJE - MAZDA 6-2.0 TS 147 5DR HATCHBACK. MILEDGE 40000. The car was erratic when I bought it at 38000. Has been put on basic diagnostic equipment and fault finding .

Hello again Pete -
Thank you for your reply and info..
Just further to that as above then.. I need to just ask, what is its service history like?
Do you happen to have a list of what parts were used/ replaced on the last service?
When was the last Full service caried out - date / mileage.. if you know..
Last - please just clarify if it was a Mazda dealer you used?
Rgds, MIKE....................
Customer: replied 2 years ago.

it was fully serviced when I bought it in October last year. When I took it to the mazda gagage they replaced the lambder sensor and plugs cleaned the e.g.r valve. As far as I know a full service was done in October when I bought it, approx. 38000 miles.

Customer: replied 2 years ago.

The mechanic who I have my cars serviced by found me the mazda6 last October. He sorted it all out and serviced it ready for me to drive. After a short while I noticed it was not running smoothly so I tried to get in touch with him but he had become ill so I took the car to the mazda dealer in Cheltenham where they checked it over and fitted the lambda sensor and new plugs.when I had the car back it still was not performing right.I took it back but they could not get to thebottom of what was wrong. I then took it back to my usual mechanic who is trying to get it right.He thinks it may be weak on fuel but as no management lights have come on he is unsure.He has been told by another engineer he might try and put a resister on the fuel line to get a slightly richer output.While at mazda they did look into a few other things but obviously nothing has worked.Sorry for the short story but that is all I know. Pete

Hello again Pete -
Apologies for the delay.
OK - given all that you have said - and with the initial issue as described, I feel that your issues are down to fuel or air starvation.
The first thing to check is the air filter - ( just in case ).. I have seen thick black air filters that have just been "serviced" before - even by garages, so check that - and check the air supply pipe for any blockages / kinks etc or even leaks.
If all ok there then fuel filter is next. The fuel filter is an item that "definitely" gets missed -even by garages.. If you cannot find evidence that its been replaced in the last 12 miles / 12 months.. then its a 99% chance that this is your fault..It needs renewal. That should clear this fault for you..
All the symptoms you describe - and the fact that the garage went for petrol system related issues - ie, o2 sensor and plugs etc... PLUS, no EML ( light ) - all points to the fuel system as the fault... and Im reckoning on the filter as above.
IF you find after doing the filter its still the same ( and you must do it to be sure ).. then you could well be looking at an exhaust restriction - ie, cat blocking etc. This is a common fault on low mileage cars -- so, again IF the fuel filter replacement doesn't cure this for you - then you need to be looking down that line. You would ideally need a garage equipped with a "back pressure tester" to check the cat operation -
One way of the other, thats the way forward on this.
I take it the garage has tried injector cleaner part of their checking for the fault.. If not - then I suggest after fuel filter replacement, a bottle of that should be added to the tank also -
Let me know how you go..and / or let me know if you need anything further on this..
~~~~ Meantime - Please do click on the "Exc / Ok rating" for me at this time.. "Thank you" in advance for that .
.. Note that you can get back to me anytime at all after doing the rating - it doesn't close you out --
Best Rgds, MIKE.
Mike and 2 other Mazda Specialists are ready to help you
Customer: replied 2 years ago.

Hi Mike, Pete, Mazda 6 problems. My mechanic is going to have a look at the recommendations you thought might help. Can you tell me where the filter is situated and if there is more than one. Also what does the second sensor on the Cat do, and does it have anything to do with the problem. Thank you for your input so far. Pete

Customer: replied 2 years ago.

I have been asked by mechanic , can you get a replacement filter for inside the petrol tank. Pete.

Hi again Pete -

. - There is a filter in the tank Pete - but this is just the pick up filter on the end of the suction pipe - they dont generally ever get replaced or need doing.

The main fuel filter is an inline one... depending on exact version you have Pete - its either under the car..or, in the back left corner - hidden under stuff..up by the bulkhead.. ( back left as sat in drivers seat )

Tell the mech to simply follow the fuel line from the tank -easy way to find it. Its a silver cylinder so he cant miss it.

The post cat sensor monitors output from the cat telling the condition of the output gases etc - it doesn't tell you if the cat is blocked or not. If there is a fault with the sensor or its circuit a fault code will usually be set for that.

I hope that helps you further - All the best Pete - MIKE.

Customer: replied 2 years ago.

Hi Mike, Pete, Mazda6 problems. Have checked cat. seems okay. Have checked fuel filter and pump. There is only one filter inside the tank. At the moment the fuel pressure is being looked at. If there is anything else at all you can think of it will be very much appreciated. Thanks again for your help. Pete.