Need help with prob. mazda cant fix or wont

[Corvette_Brett]

Alright here goes.... since day 1 there has been issues with my wifes ms6. they have replace a couple different "valves"... but i still have a miss..

The prob... right now is if u start the car and its cold u can hear the motor missing (is this a sound they make because of cam profile or whatever)... next if u take off easy through 1st and 2nd gear then ease down on the gas in 3rd to spool the turbo it studders on the way up through the power band almost like the turbo is stalling or engine is missing..

car has been in the shop 8-9 times since it was new for probs.(and its 2hrs 1way driveto dealer) the last 1 they "fixxed" they "replaced a valve that tells the computer that the motor is getting boost" im assuming this is a map sensor or somethin to that affect

it did stop back firing and detonating and then blowing a puff of black smoke out of it the size of the car.. but i still have the studder i have gotten the manager over 2 dealerships involved and we r now getting some service but everytime i go get the car it runs good for a few days and develops new issues ... sorry for the long write up any help would be appreciated

im not new to faster toys or workin on them i have a 02 lightning pushing 18lbs of boost with all bolt-ons makin 468hp and 533tq at the rears and a c5 vette with full bolt ons makin 364hp and 373tq at the wheels that i done all the work on... but i am lost on the DI turbo motors

im thinkin maybe that it dumping all the fuel when it was det. may have fouled the plugs.. but hell i dont know

 

[Corvette_Brett]

well i tryed the test to see it the turbo seals were bad.. started and drove it for 10 min normal driving let sit for 10 min idoling while i hooked up a scan tool. got back in the car while datalogging and 1st gear easy 2nd easy shiftin at about 3000 went to 3rd and eased down on the gas going to take it to 6000rpms at 4234rpms i aborted the pull because the turbo sound like it was going to come through the floor board when i eased out of it i looked in the rear view and there was a cloud of white smoke as big as the car...

sounded like someone throwing rocks up inunder the car... scan tool on play back had no knock or codes or anything out of the normal... so im guessin i have a turbo prob.

 

[coyfish]

Well this only happens when your hitting boost???

If your turbo seals were gone you should have been smoking white clouds like a chimney.

 

[Blendercloud]

It sounds like an ignition problem from what you've described. Surely the dealerships have examined the plugs and checked the function of all the coils, but I wouldn't assume they have. If you want to do it yourself, you should pull the intercooler off (very easy, don't let it intimidate you) and check out the plugs. If they are fouled, replace them with a Denso ITV20 (stock) or ITV22 (1 step colder). If the problem persists, my instinct tells me you may have either a bad coil or a wire leading to a coil has become disconnected or severed.

 

[Corvette_Brett]

shouldnt a miss throw a code cause it didnt hickup on the playback... just no power under boost when it acted up.... loud noise like some1 put a hand full rocks in the turbo... and a white cloud... as soon as i turned around and headed back it ran fine with no prob. at all.... people that were standin around thought i had blowed the motor from the sound and the white smoke

 

[Blendercloud]

If it's only under boost, it could be the type of fuel you're using. Are you putting 93 octane in it? Also, does the fuel you use have 10% ethanol?

From your further description it's starting to sound like massive detonation (outside of the white cloud; I don't know what to think about that).

 

[Corvette_Brett]

i agree with it sounding like detination but no codes no retard nothin in the playback... i thought maybe the impeller may have had enough oil on it to throw it out of balance and make it chatter...and ive tried every 93 octane in this town .... my lightning and vette both r tuned for 93 and no probs out of them at all from the 2 places we normally fill up

 

[bova80]

it takes 3 misfires to throw a code

 

[Corvette_Brett]

if these were missfires there were 20 of them

 

[TheMAN]

I've seen #3 fuel injectors go bad on these engines... maybe it's that?

 

[Blendercloud]

I'm with Bova and TheMAN on this one, Brett. It really seems like something with ignition and fuel delivery and less likely that it's a turbo issue. Without being able to get under the hood myself, it's hard to say for sure though. I wish I could be more help.

 

[Alladin]

I have been fighting this problem as well for about 6 months now. I stopped going to the dealership and am planning on going to a new one to see if they can help.

On my car, they replaced the turbo, updated the ecu and claim they did the TSB for the fuel pump.

I'm at a loss also so if you get an answer please post it up here Corvette Brett

 

[Corvette_Brett]

as bad as i hate to say this im glad im not alone.. if u get an answer let me know what the hell is up...if it was missfiring or an injector going down would that not throw a code... the more i think about what it did the more it sounds like its prob. to start with that they fixed for a while by replacing a "valve that tells the ecm when its getting boost".. the only difference is the color of the smoke and this last time i was going by what the people said that was standin around cause i couldnt see it as i capped the hill... but no knock retard with that much det. thats crazy

 

[Corvette_Brett]

i did notice fuel pressure never got above 215psi is this normal

 

[Blendercloud]

No, that's terrible. If you're seeing less than 1200psi during wide open throttle, you're not getting enough fuel.

My stock pump runs at 1750-1850psi. I think you just figured out your problem.

 

[Corvette_Brett]

reallywell that may be it ill get them to check that friday.. at idol its at 58psi accordin to the scanner

 

[Blendercloud]

Direct Injection requires a boatload of pressure from both pumps and then the outlet of the injector is also used as a restrictor/controller.

To be honest, if your car is under warranty I would be concerned with the long-term effects of this problem on the engine.

 

[Corvette_Brett]

like i said ive been tryin to get this prob. fixed since pretty much day 1.. its got 39xxx on it but its their baby till 100xxx so they r goin to fix this..

 

[Corvette_Brett]

my question is what should fuel psi be at idle and 4200 where i aborted the run....the purge valve is what they replaced before

 

[Corvette_Brett]

no one knows?