When doing stuff on your car yourself, it is *really* easy to do it once and then check it off a list and say that you did it....then never do it again. I have done I think 4 boost leak tests this year. One in Jan, one in march sometime, one about 4 weeks ago, and after tuning my car on my self-installed LC-1 (with much frustration), I decided to get the car on the dyno. Car is scheduled to go on tomorrow @ DB Performance in Rogers, MN.

Well, today (after picking my my iPhone 3G woot!) the car starts to run like crap on the way home. Won't boost past 20psi on pump, 25psi on my alky map. WTF. A million thoughts race through my mind, but it's the wife's birthday so I let them slide away. I tucked her into bed and got a little QT with the evo before its dyno appointment tomorrow. What did I find? A MASSIVE 2" TEAR in the line connecting my IX BOV to my UICP. GAH! All of the frustrations I'd been having on my alky tune are due to this.

The car would NOT lean out at all, I was running literally 17's on my map to get the car to run high 11's on the wideband. Now that this is fixed, the car jumped to running 13:1 AFR's!!! So not only was I wasting my time, maybe hurting my turbo by overspinning it (stock IX turbo on a VIII), my tune was uber unsafe. So, a few quick rips and I got AFR's dialed back in to where I want to start them on the dyno tomorrow.

Moral: Boost leak test: DIY and DO IT AGAIN! AND AGAIN! Amazingly, stuff can go wrong, even if you didn't touch it!

 

+1..very good advice. Never assume something is working correctly today just because it was yesterday.

 

Buy maft pro. You will not have these problems.

Blew my UICP OFF. And it took me 20 minutes of driving to even notice it. Car sounded shrill and the boost gauge didn't move. But I was busy so I got to it the next day. I'll never run a MAF again. I hate the GM's. I hate the mitsu ones. You would not believe how much less frustrating these cars are once you get rid of the airflow meter.

Switch to the heavy rubber nylon impreg fuel hose for your vacuum lines and remove all the 'unnecessary' ones. Like all the soft / hard line junctions over the vc. And all the emissions junk on the back of the IM. Use the round ring fuel clamps. They won't split or tear ever again.

 

Now I'm curious how your dyno tune goes. Be sure to post up your results.

 

Posted just a bit ago

358whp / 348wtq. This is 'big boy' evo IX numbers out of a dyno dynamics with 1.0 correction

https://www.evolutionm.net/forums/sh...d.php?t=357243

I made one more bump in 3 spots and got the afr dialed at 11.5:1, we messed around with the timing and the car picked up a solid 10whp but would knock a bit here and there, so I reverted to my orginal timing map that I had put together on the street

 

Congrats! I can't wait for my alky kit to go in. Its nice to see street tunes being VERY close to perfect when strapped on a dyno these days.

 

Having a wideband in-car was really instrumental in accomplishing this.

 

I can relate to this one.. I run a blowthrough setup with a ford cobra sensor (works better than the GM ones) But I had an intercooler hose pop off and was able to drive it off the road and fix it.

I recently had to put a stock MAF back on the car for awhile, I cannot believe anyone puts up with the quirks the stock MAF in the stock location throws at you when driving, low idle, stalling, wild airflow swings, really bad drivability with the a/c on, etc.. I had forgotten how troublesome the stock MAF is. I took for granted the stable idle and consistent/reliable drivability, plus no quirks with A/C running..

 

Seriously. I was dialing in a GM this evening for a good customer on DSMlink. His last one failed shortly after the car was fully tuned. I've done it a million times, but it never ceases to annoy me.

It just gets old very quickly. I still prefer the simplicity of the stock ecu to / AEM, but god can I just not stomach the MAF. The longer I drive without one the more determined I am to steer clear of them for good.

The driveability, and reliability increases are undoubtedly worth it. The subtle things like tip in, and ease off... all the quirky jerky garbage goes away.

 

There is no truely "plug and play" blowthrough or speed density kit for the Evo, I would be willing to bet if there was something easy to plug in, and has decent documentation, the stock ECU wouldn't be discarded on a whim. People associate issues with the ECU when its MAF related and is easily solved.

 

Either way, the point of this thread is to do a boost leak test before and during tuning if you are having issues. a GM MAF or MAP conversion will only hide this, leave you down on power, and still result in weird problems.