Premacy Sport Misfire problem - Dealer cant solve??

[jmdrake]

Hi Guys - having a bit of a problem with trying to solve my cars slight misfire which the main dealer cant solve !!
The car is a 2.0L Sport with 111000 miles and full main dealer history.
The cars previous owners had the 109000 mile service done July this year and the car was fine - the car was garaged for a while and when restarted the alternator was seized and the belt snapped and wrapped around the engine so I was told by Mazda - the car was taken to a small garage to have the alternator renewed and has been running (misfire) since - It has been back to the main mazda dealer 3 times since and they have checked the timing, tried a different TPS, plugs, crank sensor - I have tried a different MAF, cleaned the Camshaft sensor, and replaced the top O2 sensor - its currently back in mazda to see if they can find the fault - I called them this evening and they are keeping the car until tomorrow to run more tests - They said they have tried the coil packs and leads but its still misfiring on idle and off load - if you put your foot down its fine just misfire on idle and if coasting - Any suggestions would be helpful..

 

[Fivo]

Hopefully they have checked the ECU??

 

[SGT_OKINAWA]

Simple...

Simple, dirty fuel injector.
------------------------
Not simple, what to do about it.

(boom07)

1. First!, have a compression check done on your engine, cost medium and if this checks out fine, you probably have a bad fuel injector.

Okay now what to do...

2. The easiest route is to clean the injectors in place because you do not have to remove the injectors! (which can be a real chore on some import engines).

BUY SOME STP FUEL INJECTOR CLEANER, running cleaner through the injectors while the engine is running also removes many of the deposits on the valves and inside the combustion chambers. This eliminates the need for an extra cleaning step if the engine is full of carbon deposits.

The job takes only 10 to 15 minutes, and you can usually tell right away if the treatment addressed the problem (engine runs smoother, idle misfire gone, etc.). I SAY AGAIN, YOU CAN TELL IF IT WORKED IN 15 MIN !!

3. Hard way, and I call it a "wet test", It's messy as hell, dangerous, and ONLY should be done by a certified mechanic, DON'T FOR THE LOVE OF GOD ASK THE 19 YEAR OLD KID working at the Mazda dealership garage to do the test.

THIS IS ONLY FYI FOR YOU - DO NOT ATTEMPT YOURSELF!
Basically you run the car with the fuel injector out of the block, serious chance for fire, mess, damage or worse, DEATH!

You must use pressurized equipment (Do you have that? No? Then don't try some shade tree job to save a buck, it'll make it worse!) So the pressurized equipment is used to feed the solvent directly into the fuel rail while the engine is running. (YES, you heard me right, WHILE THE ENGINE IS RUNNING!)

This means you either have to disable the fuel pump and plug the fuel return line, or install a U-tube so the fuel will reticulate right back to the tank. Disabling the fuel pump can set a fault code on some cars, requiring you to clear the code after the job is done.

Easy as it is, there are some limitations with on-car injector cleaning. One is that badly clogged injectors may not pass enough solvent during a normal cleaning cycle to be thoroughly cleaned. Some baked-on deposits can be very difficult to remove, requiring you to prolong or repeat the cleaning process.

So, translation, AFTER your dealer or repair guy does this difficult "cleaning" it may still not work 100% (sadbanana)

And if on-car cleaning does not work? You will have to remove the injectors and have them cleaned on an injector cleaning machine - or replace them.

YES< replace them. THAT IS NOT CHEAP!

oh BTW - did I mention you should have your codes read either by YOU buying a code reader or take to a place that has a proper code reader. (sun)

Another limitation with on-car injector cleaning is that you may have to do some additional tests to confirm that the injectors responded well enough to your cleaning efforts. A test drive may be needed to see if the drivability symptoms have been eliminated, or you may have to check emissions to make sure HC and CO levels are back to normal. So putting the car back together is required, takes a lot of time and need to get it back on properly.


A power balance test is another way to confirm engine performance and check for weak cylinders (it's like the pressure test before, but there should be less than a 10% power variation between cylinders). An injector pressure drop test will tell you if the injectors are flowing evenly or not.

There may be some risk to the vehicle's fuel system when using concentrated solvent to clean the injectors in place. Most equipment suppliers say to disconnect and plug the fuel return line so that solvent does not circulate back to the fuel tank. Strong solvents may attack rubber and plastic components in the fuel pump, regulator and fuel lines, creating additional problems that you don't need.

On-car injector cleaning also involves some risk to the person who's performing the service. You have to disconnect pressurized fuel lines, make sure there are no fuel leaks, and feed high-pressure solvent (which is just as flammable as gasoline) into the engine while the engine is running. Safety precautions should always include eye protection, making sure there are no open sources of ignition (sparks) nearby, and avoiding direct exposure with the cleaning solvent.

Good luck, that is all I can think of for now, but can't stress enough, SAFETY !!!

Peace!(rei)

 

[MD5]

If it is the injector, they can run from about $35 to $80 each.

What is the year/make/model of your vehicle? I'm kind of confused on what a 2.0L Premacy is since they didn't start making the 5 until 2006 and it had a 2.3L.

If it is the injector, the good news is that you should know which cylinder it is and you will only have to buy one.

 

[SGT_OKINAWA]

If it is the injector, they can run from about $35 to $80 each.

Thanks MD5 I left that out (silly)

I'm kind of confused on what a 2.0L Premacy is since they didn't start making the 5 until 2006 and it had a 2.3L.

The Premacy is the Japan, other nation version of the M5, it has all the neat stuff the USA will not allow or thought to much 'extra' and cut to keep costs down in the USA.

Here tells a lot: LINK

Basically it's a M5 with a 2.0 ltr engine. (RTM)

If it is the injector, the good news is that you should know which cylinder it is and you will only have to buy one.

Yup, after the pressure test and then IF needed the wet test, you'll know right away.


GOSH I HOPE THE STP FUEL INJECTOR CLEANER WORKS.

Peace!(rei)

 

[rweatherford]

One other thing that MIGHT be a long shot. If this car has an external reluctor ring for the timing pickup it could be damaged or slightly out of place. This could cause some problems. Could have been damaged or even slipped to an incorrect location (degree is wrong now) by pulling on the belt before it broke.

Again is is a LONG shot, but something that could be checked.

 

[skyhawk]

Dealer can't solve it? They are supposed to be complete with workshop manuals and testing equipment.. The cars of today is supposed to give out error codes. And on top of that dealer is supposed to have access to higher support from mazda.

If there are no CEL codes, the workshop manual has a section for 'Symptom diagnostics' that they can follow.

Here are some info from the MAZDA5 manual. I don't know if it is similar to that of Premacy.

1. http://www.msprotege.com/members/skyhawk/misfire/misfire1.JPG

2. http://www.msprotege.com/members/skyhawk/misfire/misfire2.JPG

3. http://www.msprotege.com/members/skyhawk/misfire/misfire3.JPG