I am having great difficulty getting to the bottom of a problem on my 2005, mazda 3, ts2, 1.6 turbo diesel.
Ive been to mazda twice for a diagnostic, had a local mechanic check it over, and also tried myself to find the fault by looking online etc.
After all this i still do not have a definate answer to what exactly is wrong with my car so wonder if you can help?

The fault codes from mazda were-
P0103 - MAF sensor circuit high input.
P0234 - Turbo overboost condition.

My engine management light initially started coming on occasionally and car went into limp mode due to the Turbo overboost condition fault. If i pulled over and turned the engine off for a minute, then restarted, the car would be back to normal and the light was off. This gradually got more frequent, usually after motorway driving. Eventually i found that by hittting 60mph,in 4th,at 2500 rpm the light would almost always come on and i got limp mode,again this reset after restarting car.

My local guy said it was probably due to a leak in the inlet manifold so stripped this down and resealed by him thinking that would fix it. He also said my MAF was coated in oil so he cleaned it up. The car was fine all week around town but at the weekend when i went on the motorway it happened again.

I then booked a diagnostic at mazda where ONLY the turbo overboost fault showed up. After 2 days of head scratching they finally said my turbo "probably" had an internal fault and needed replaced as it was leaking oil into my air intake hose, which was where the oil on the MAF was coming from. I declined due to their high prices and their uncertainty that my troubles would be over after fitting a new turbo.

Next day I checked the MAF myself and it was covered in oil again so i cleaned it.
After investigating, i found the oil on the MAF was not coming from my "leaking" turbo but was due to my oil level being too high which sent excess oil out the relief hose and down into the air intake hose which contains the MAF, so i then also drained out some oil, and since then my hoses and MAF have been clean.

When i started the car up this time it seemed fine on a test drive for 3-4 miles then my light came on as usual at 60mph, 4th gear,2500 rpm,and car went into limp mode. THis time it seemed a more severe limp mode though and had barely any power. I pulled over and cut the engine off, left it and restarted, which usually cleared the light, but this time the light stayed on. I tried again a few times but the light stayed on so i had to drive 3-4 miles home. At this point although the light was on the car seemed to drive normally and the turbo seemed to boost as it should etc.

I went back to a different mazda for another verdict and this time is when it showed up both above fault codes.
They advised replacing my MAF, saying it may have been damaged due to the previous oil on it, which i did with a replacement from a mazda breakers today. They also said that this may or may not clear the turbo overboost fault.

Now my engine light is still on, even with the replaced MAF, and i have black sooty smoke from my exhaust when reving the engine up.
I went for a drive to see how it ran and tried to bring in limp mode by hitting the usual 2500rpm in 4th and it didnt go limp. On the way back though i did feel slightly hesitant, almost as if it wanted to go into limp at times but was fighting it. Also im sure i heard a noise from the engine area, the best i can describe it was like the noise you may get if your engine is idleing but you dont realise and turn the key to start the engine. This was just as i pulled into my street luckily so i soon stopped. It wasnt a continuous noise, it came and went for the last few hundred metres home.

I am now at a loss what to do next.
My thinking was the MAF would fix it but it doesnt seem to have as now i have the black smoke which im sure i never had before today.
Could the car be running lean due to the engine light being on? And do you think that by simply having the fault cleared this would solve this?
I am assuming it is still the MAF fault causing the light to be on as it has not gone off since mazda found it.

I am really hoping the 1st mazda diagnosis of needing a new turbo was wrong and it was all down to the MAF giving false readings, due to the oil, and it now just needs resetting since i have replaced the MAF to clear the fault. Does this sound plausable to you or do you think its maybe something more sinister, i.e turbo?
Surely if it was the turbo then i would have had probems in 1st, 2nd and 3rd gear at 2500 rpm and not only at 2500rpm, 4th gear,60mph which seemed to bring it on?

I have been reading up on erg problems due to dirt and gunk, this was going to be my next thing to check, but i honestly dont know if i should just cut my losses and trade the car in now? I really am now totally stressed out about this and just want my car fixed, or at least i want to be sure of exactly what the problem isso i can decide my next move.

If you can offer any help or advice i would be very greatful.

 

Black smoke typically means an extemely rich condition (too much fuel), diesels are driven by fuel alone. Based on the codes given your maf may have an an intermittent short due to engine tourqe which is why it may only happen on accel. a fauly maf may also cause your overboost condition since the car cannot detect how much air is coming in, im not completely sure on how mazda has there design, i only know the ford crap, this is the best answer i can give.

unfortunately most of the members here are not familiar with diesel vehicles let alone a diesel mazda, i have little hands-on exp with diesels in general, i know how to diag using the proper machines but the advice is more or less a guess.

 

Black smoke is running rich on a diesel.
If the MAF is showing a high input I am guessing that is what it causing it to dump more fuel. Dumping more fuel in may be causing the overboost condition. So, why is it sensing a high input on the MAF? Check for grounded wires. Is there a different intake on this car? A crack in any intakes, pipes, etc?

 

It does certainly feel a bit like it could be a loose or shorting connection giving me te problems. Will test wires from the maf tonight to see if they short out if I waggle it around a bit.

 

Oh and the car is stock, no alterations to it.

 

Finally solved the problem. Saw a diesel specialist in glasgow, he did a proper diagnostic and said both my MAF and my boost pressure transducer were faulty. He replaced both and blanked off my egr valve, now the car runs great, with no fault lights, stuttering or smoke. Can't thank the guy enough, soooo much better than the mazda stealerships diagnosis of needing a new turbo.
Have been in contact with mazda head office to complain, awaiting some form of compensation and my diagnostic payment refunded.

Will never go to a mazda dealer again for repairs or servicing.

Thanks for all advice given here.

 

good, dont know why but ALOT of people have complaints to mazda dealerships, mostly its because they are privately owned and dont hold up to the standards the mazda company holds....i guess