Well I should add...this shop actually builds blown Mustangs...mostly 5.0s, but they work on the new stuff too..so this is not a dyno tuner in a one stall garage in an industrial park like some are...

My other problem is I see many supercharged 5.0s running the PCV to vacuum and a valve cover breather....

ie. Steeda sells this on their website...there is no way a blown 5.0 could breathe only through this with no PCV...

http://www.steeda.com/products/breather_valve.php

 

Just ask him to explain how he would deal with the vacuum leak. If he says that it is not a vacuum leak, then you know right away that he has NO clue what he is talking about or he is only used to carb applications. If he says he will simply enrichen the miture to compensate, then ask how he will compensate for the ever-changing air temp, density, humidity, obstructions in the breathers (which WILL happen with oil mist.) Those are all really valid points and he should be able to explain his methods in fairly simple terms.

Reality is, unless you are either paying a lot of money or unless he is a good friend... he is going to get you a tune that gives you the proper A/F ratio for the conditions that exist at the time. A week or so down teh road, you are on your own.

It's easy to say "stay off the internet" and laugh it off. But if someone did that to me, I'd be wodnering why he didn't answer the question. That's Detective 101. You ask a question and they either rspond with a question or divert the question. (example.. Did you steal the money? Answer: Why would I do something like that?... notice how they never said "no" and never actualyl answered the question.) If he knew what he was doing, he should have no problem answering a simple question from a apying customer who doesn't want to ruin his engine.

We used to have a dyno shop here near me. It was called "F1 Dyno." They had a problem with blowing up engines. They were basically bolt-on boys. they could install the parts, but tehy couldn't tune for **** and they destroyed more than a handful of engines in the process, or at the very least blew some head gaskets due to lean conditions. Don't be afraid to ask questions. In the case of F1 dyno, they did not have to pay for a single engine that they damaged. it's not their problem and it's usually in the fine print.

 

Some of the most reputable shops out there have done what I would call hack work.
And no I am not a professional, this is my hobby...
Wrong is wrong

Ask questions about how they will tune OL vs CL too.



The problem with pcv and boost is that you need to use a valve to keep the intake boost out of the crankcase.

I think the others mentioned this above.

Also, you don't want to run breathers when you can pull air into the intake via the pcv. This is called a vac leak.

These rules apply to all cars, and just because some folks do it WRONG, doesn't mean you should.



good luck,
jason

 

You're forgetting one key point... when you are actually under boost, your PCV valve closes and becomes useless. So when you're running at WOT you car is ONLY going to be able to vent pressure through the valve cover breathers. So even if you leave your PCV system intact, it will not be used at WOT.

And as a sidenote, I have a closed breather on my passenger side valve cover. in other words, instead of an open element, it has a small nipple on the side that connects to a 5.8" tube. i then run that under the rear of my car and vent it into the atmosphere. The driver's side valve cover is completely closed off. i capped it off due to height issues with tall valve covers and an EFI intake. Then there's my PCV valve which also vents into the atmosphere via a 5/8" tube.

So basically I have two 5/8" tubes that run under my car. And with 10 PSI of boost and with the nitrous, I still have no problems with oil or crankcase pressure. Those two tiny tubes are enough to relieve the pressure and keep my dipstick from blowing out. It also keeps oil from spraying out of my valve covers, etc.

So back to what I was saying earlier... If oil and pressure are such a large problem that two open element breathers PLUS an open PCV can't handle it, there there's a bigger underlying problem that should be addressed before it gets worse.

You have a nice setup. Don't let a tuner screw it up on you because he wont give two ****s about your car. Make sure he is able to answer your questions and make you feel comfortable instead of just laughing it off when you express your concerns.

 

I'm guessing that he won't even touch OL. I figured he would just mess with the MAF transfer and tune around the vacuum leak at idle and low RPM in CL and ignore OL. And then when it's time to race and it switches to OL at WOT, then it could get ugly.

 

I will discuss it at length with him...I can unplug the PCV from vacuum in a second and vent the PCV to the amtosphere again....

I hate to beat a Dead Horse(Mustang reference)...but if the car runs decent now, what problems can the vacuum leak lead too?????

 

But you did mention that you get an occasional surge.

The problem is air is entering the engine and it is unmetered so your computer doesn't know it's there. And on top of that, it is unpredictable... so you never know what is going to happen or when. It could be fine one second, rich a minute later, and then lean another mile down the road.

Basically, you have an A/F ratio that can change from minute to minute and your computer amy not know about it until it's too late. That's a bad thing.

 

Let me see.......I've solved idle problems (surging, stalling, too high, etc)......lean conditions at part throttle causing codes 41 and/or 91 to show up,.......fuel consumption issues (not that Mustangs are great in that area, but 9 MPG's is a little low)......+ you may want to check this "Cost of Unmetered Air" write-up someone did on an OBD-II Ford.

In your case, I know he will increase the fuel-trimming to overcompensate via the MAF transfer or the target stoich table.

 

I see...

I just called Steeda and they said it is perfectly fine to run the screw on breather and your PCV on a blown car...this is an annoying issue....I guess only the intelligent members of this board truly understand...

 

If the PCV only works on vacuum and is blocked during boost...then under boost and at WOT the engine should be breathing through the breathers and no unmetered air should get it...Does that sound right?

If so then the only time the vacuum leak is an issue is under normal operating conditions when there is no boost....that does not seem that dangerous to me, but I am an idiot sometimes...