Contour Enthusiasts Group Archives Forums Modifications Forced Induction Converted to a blow through setup

OK I was running a suck through using a MAF from a 7.5 liter ford truck, I converted to a blow through system using a ported MAF from a v6 tour. To port the MAF I simply removed the aluminum internals converting it into a straight through setup. My idle is much much better before it would fluctuate between 750 - 1500 rpm and when in is coming down to idle from higher rpm it no longer likes to dip the rpm before coming back up. The fuel seams to come on almost instantly now where as before there was a noticeable delay. It seams to spool faster but I think this is probably just my imagination because I don't see any reason why it would. I am still using the SAFC and I am looking at getting the diablo predator instead of the sct setup because nobody in my state does sct dyno tuning. If anyone is considering doing a blow through instead of a suck through I recommend the blow through because I believe it runs much better this way. My Maf is just before my throttle body and after about 12" of straight intake pipe. My IAT is after the MAF and just before the throttle body. Anyone know if they make or can make a diablo predator for the contour ecu or will I need to switch over to a focus ecu? thanks

i agree a blow through might be a better option. I literally have to bring my cruise idle all the way down to about 1,000 rpms until i push in the clutch just so the car doesnt die. Jerry from SCT said this was because the MAF is so far away from manifold.

btw, hacking up the stock maf probably isnt a good idea since, im assuming, your still using the stock maf transfer function.

Odd, many Foci owners using SCT soft/hardware are all going to draw through because of bad idle issues with blow through setups. Also you loose anywhere between 20-30% resolution on the same MAF when used in a blow through setup vs a draw through.

A mystery MAF is a bad idea, you should get one that you can get a set transfer function with. Other wise your PCM is going off of incorrect info and can FUBAR your AFR. A hogged out MAF still "thinks" it only flows a certian amount of air. You are taking a risk at flowing more air than the PCM is seeing, which could run the risk of leaning out under higher load, which = BOOM

The lack of a proper tune would explain why you were having issues with the previous MAF. You were running it off of the wrong transfer function. Just an idea for you....

A draw through is better if possible and cutting the SAMPLING tube out of the maf is a really really bad idea.

It varies on the Focaljet, Blow-thru vs draw thru. Each have pros and cons. TurboTom started with just draw-thru, but last I heard he's gone to just blow-thru. It all depends on the tuning.

You're problem isn't draw-vs blow, its that you have no idea what you're doing and you're just doing trial and error seeing how it works by just how it drives. This will blow you're motor quick. You are a little bit better off since you've gone to the V6 MAF, but you're still just guess-stimating the settings.

Well the sampling tube was already cut off from a previous thing I had tried so it basically was a spare part I had that I used. Since it is the wrong MAF for a zetec ecu anyway it doesn't matter what the flow rate "it thinks it is" because all of this has to be tuned in using a chip anyway. Before I converted to a blow through my engine wouldn't die after coming down from a high rpm because the SAFC has a dec-cel air function to compensate for that. I am still using my safc and resetting the computer every week to make sure it gets enough fuel. Although its not a wide band o2 I am monitoring the o2 voltage and it reads .95 at WOT under boost which is way to rich but that beats a blown engine until I get the diablo and I have added a wideband o2 sensor to my list of needed parts. There were a few on ebay that were only $60 from bosch that claimed to be wideband O2 sensors any one else see these?

It does matter what the flow rate "it thinks it is" is because that's what's used to determine timing. Granted a lot of things go into figuring timing, but the ECU looks at the MAF signal as it's number 1 source for timing/load values. Not the crank position sensor, not the o2 sensors, not the water temp. The MAF voltage signal.

I'd stick with the SCT. Like I said, 6hrs one way to find a tuner is a cake walk. Or just get the tuning software and do it yourself. You obviously like tinkering, at least this way the SCT is supposed to be so user friendly, you'll know with more detail what's going on.

Not to mention that in NO time you're gonna coat the sampling wires in oil and crap and it'll run like ass.

If you left it as a draw-through and tuned the damn thing, you wouldn't have to resort to hack jobs like this.

Well many people are using a blow through setup without problems. It seams like I was told that a suck through system was a bad idea on this forumn and was given certain reasons why now that I am doing what was originally reccommended I am told that it is a bad idea for certain reasons. I know that turbo tom at focus fanatics reccomends a blow through setup and this guy actually makes and sells turbo kits for zetec focus cars. Tom has probably turboed more zetec focus cars then there are turbo contours in existance in the US so he knows his stuff. I agree that the timing issue presented by a mystery maf is not good so I am just going to get another maf housing at the junk yard. As far as oil on the maf wires my intercooler piping is clean and I have been turbo now for 3500 miles so I don't think that is an issue with a good turbo.