Turbo help please

[curtklze]

spark plugs in a rich engine are black with carbon, in a lean engine they are clean or white, in a proper engine they are a very light brown.<p>I think you may have killed your o2 sensors when you were running the 2.5 injectors with the K8 vaf and computer for so long (befor the turbo)

[mrspanky79]

thanks for the answere curt. As for the vaf in the turbo system every turbo'd or supercharger probe/mx6 i have looked at has it in the same spot, even the the few 2.5l turbo mx3. BATTOSAI were are you planning on putting your vaf?

[mrspanky79]

So im almost convince that my o2 sencers are gone and im running rich. On my way to the show last night i turn my base fuel pressure done even more and on the highway the odd time the a\f gauge would jump to say rich then fall back to lean. So Im going to change them. I want to keap the 2.5l injectors in (and dont want to go to all that work to change them right know)so could i use the fpr off of the 1.8l on the 2.5 to bring the pressure down a bit more or are they the same?

[curtklze]

The fuel pressure regulators are the same on all k-series engines. You should be running an adjustable regulator insted of the stock one, with an FMU (rising rate regulator) to rase pressure when the boost comes on.<p>Just a guess but I would start with 3-5 psi less than stock at idle.<p>I think there are some Rising rate regulators (FMU) that can replace the stock regulator, and also raise the pressure under boost.

[BATTOSAI]

I have my VAF as you say, the closer to the manifold. I don´t think that the Vaf won´t work right under boost, as when in full boost the car is supposed to be at WOT, where the cone is at it´s fully open position,and then the car operates by preset fuel maps ( correct me If I´m wrong). An advantage of this location is the IAT. When It reads hot air, it retards the ignition timing, so when the charge will be hot,( boost going in) it will adjust in function of the temp. which is really a thumbs up for the Vaf after the turbo!!

[OsoSlo z28]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by BATTOSAI:
I have my VAF as you say, the closer to the manifold. I don´t think that the Vaf won´t work right under boost, as when in full boost the car is supposed to be at WOT, where the cone is at it´s fully open position,and then the car operates by preset fuel maps ( correct me If I´m wrong). An advantage of this location is the IAT. When It reads hot air, it retards the ignition timing, so when the charge will be hot,( boost going in) it will adjust in function of the temp. which is really a thumbs up for the Vaf after the turbo!!<hr></blockquote><p>full boost at WOT is one thing. i seriously doubt that every time you have + manifold pressure you're at WOT. i know i hit low to moderate boost just driving around town. just my take on the situation.

[sampsonmx3]

I don't have my turbo set up yet but in Maximum Boost the vaf should be before the turbo not after the intercooler

[mx3TT]

The VAF is saposed to be measuring how much air is going into the intake manifold. Theres where I had my MAF when I had it. Now i am getting a VAF because I got the GTX harness and ECU. Unless the VAF going in a different place then the MAF is should be after the intercooler. Correct me if im wrong.

[OsoSlo z28]

it "should" be after the intake and before the tubo.

[tiburon]

oh the confusion... here is my take on the situation<p>MAF's and VAF's do the same thing using diffrent methods. MAF uses a trap door to messure air flow and a VAF uses a heated wire. Neither one of thease were designed to messure pressurized air flow. They can mesure the volume of air that passes by them but not what pressure that air was when it passed. All signals they send are assuming that the air was at atmospheric levels.<p>AS an example picture a 300psi SCUBA tank, it's what? 3, mabey 4 cu/ft? Now if you opened that tank and let all that air into a baloon you would have about 80cu/ft of air. Thats a big diffrence and thats the diffrence that your VAF is seeing.<p>Proof: look where the MAF is on a GTX. Do you doubt the all knowing mazda gods? <p>MAP's are the only meters that were desiged to messue pressure and should be the only meters that ever see compressed air.<p>Note: This is what I know and I'm not saying that I'm right. If anyone has a better explination I'd love to hear it so I can correct my mistake<p>I say move your Meter then see how it runs. tracking down the other problem will be easyer then.<p>[ June 26, 2003: Message edited by: RiceRocket666 ]</p>

[OsoSlo z28]

not all maf's are flapper-door. the 94+ mx-3s are hotwire.

[mrspanky79]

all v6 modles cars run on VAF they didnt come out with a hotwire MAF for the v6 untill 97 and that would only be on the 2.5l (since the mx3 was no longer made) along with other changes bring the 160hp up to 170hp.
Jeff Abrams havnt heard from you, what is your oppinion on where the VAF should be?

[maldo]

Clearly non of us FI guys have the answer you are looking for. I suggest you go to the egroup as both Jeff and Vaughn hang out there more than they do here. Maybe they will give the answer than that you are looking for since we don't seem to know what we are talking about. Maybe go on Probetalk or MX6.com and see what they say.

[mrspanky79]

maldo what are you going on about? you seem to get touchy about things no one said you didnt know what you where talking about. As for my problem i have already found out what it was and in the prosses of fixing it. For one my stock fpr was holding to high of a base pressure so i had to opean it up and take out the spring next my o2s are gone so they are sending mixed signals to everthing changing them this weekend. As for the vaf/maf just trying to shed some light on those that dont know much about the v6 and i was just wondering if jeff was going to comment on anthing because he knows more then me about it. And the last time i look at jeffs motor or sean page or some of the turbo probe they have the vaf in the same spot but i have read some info on here that makes me think alittle. But like i said no need to get touchy all the info and piont of views the better.

[maldo]

I am just stating the facts, plenty of tuning/troubleshooting tips have been given to you but each has been shot down by you without trying them. It seems that you have been unwilling to try them yet we have been willing to help. My suggestion to go to the other egroup was simply because that is where Jeff hangs out mostly (trust me on that) and would be able to see your message much quicker than here as he is hardly ever on this UBB. <p>Oh well, I'm done, problem solved, all is good.