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Discussion Starter #1
Hey All,.. hoping someone can point me in the right direction. I have a turbo SVT that I’ve self-tuned with Pro Racer. Car runs and drives amazing. No issues with WOT,... but occasionally after getting on it and coming to a stop my AFR swings rich (.70 lambda) and then creeps up and over to lean (1.25 lambda) before settling back to 1 lambda. More annoying than anything else but id like to get it solved. Any suggestions on where to look in the tune?

Thanks for any help!
 

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Maybe a duh question, but is your BOV is before your MAF or recirculated if not? It could also be that it's evacuating air that has already passed the MAF and goofing it up, but that can probably be tuned out a bit. Knowing your MAF/BOV setup and locations could be helpful.

Otherwise, how are your failed MAF tables? If the MAF is closer to the throttle body of BOV, that could be getting things boggled and without those tables it'll get funky.
 

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Wouldn't load be goofed up on a boosted vehicle in these if hitting failed MAF tables?
 

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If the BOV is causing enough turbulence in the tube that the ECU thinks the MAF is broken. Also transient fuel events can hit this table on other Fords, but perhaps the SVT doesn't do this.
 

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The BOV lets off the psi built in the piping between Turbo and TB , once the psi is is equaled out the BOV closes

For the BOV to work the throttle blade has closed or come close to it , it takes 2 things for the BOV to open , Vacuum and psi in the piping if the BOV is adjusted properly

When this happens it doesnt cause the MAF to see any turbulence , reverse flow from the BOV opening unless some one has places the BOV right beside the MAF , The BOV should be no less then 12 inches from the MAF

If the settings are correct in the SVT Focus Tune you should never hit or need to change the Failed MAF Tables , If you do then you have something set wrong

Back in late 2000 when I was one of the first to do a blow through MAF on any engine we had the MAF at the filter , we still used a BOV and dumped metered air and never changed the Failed Maf Tables

Tom
 

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Right, that's why I was asking originally how the piping was setup on the vehicle. Getting that way too close could cause some funk.

But for the failed MAF tables, does the SVT not read the load from this for tip in tip out to predict fueling?
 

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Failed MAF is TPS /RPM not load based in the X/Y norm

Predicted fueling is a completely different discussion as well as tip in and tip out fueling

Tom
 

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Discussion Starter #11
Thanks for the replies!

Mods,.. log manifold with T3 super60 turbo. Turbonetics evolution wastegate. Turbosmart Kompact BOV before the front mount inter cooler. 60 lb deka injectors. 3” diameter straight charge pipe before stock MAF housing. MAFia. CFM 67mm TB. CFM ORP. J&S ultrasafeguard

Tom, thanks for the offer. I’ll shoot you over a log file showing that event
 

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Discussion Starter #13
Blow thru MAF,....

why no J&S? I thought you were using them in the past for knock prevention? I’ve got the knock sensor turned off and I’d rather have something in case of bad gas or something else. Other than picking up some stray false knock it hasn’t appeared to cause any issues,...
 

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I guarantee you you dont have the J&S set properly to work on the SVT , I HIGHLY RECOMMEND removing the J&S and Turning your KS back on in the Tune

There is no such thing as false knock on the SVT , you do need to set up the KS properly in the Tune but its much much better then the J&S is

Back before it took SCT 4 years to get the KS logable we did use the J&S sense 2007 there hasnt been a need for it

Tom
 

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Discussion Starter #15
I didn’t think my version of pro racer could make the proper changes for the knock sensor. I only see the ability to change the amount of knock retard,...
 

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Discussion Starter #17
Ok,.. so to confirm between Max amount of spark retard and max value of slow correction I have enough adjustment to get the knock sensor dialed in?

I’ll see if I can get that datalog over this evening
 
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