I haven't been on this forum since I dumped my life savings into the truck to get it where it was, but I've been having a problem with what felt like a vac leak between the blower and the heads. Truck stumbles and knocks up to 10 degrees, doesn't built boost like it did, etc. This weekend I decided to start really investigating. I took a trip do the local hardware store and made up a air line adapter that I could hook up to my compressor and attach it into the radix inlet tube. I regulated the air to less than 10 psi (as low as I could really tell) then I just hooked it up to the engine. After not being able to see or hear any leaks, I took a bottle of Windex and doused the whole upper engine and all the vac lines I could find. The good news is I could see the bubbles being made, the bad news is it looks to be all around the seam between the upper and lower housing of the intercooler manifold.

Back when I was building my truck I never heard of that area being an issue. Is there a gasket there or is that metal on metal? Who still exist for magnacharger dealers on the board now? Back when I knew you could send the blower back in and they would over haul it. I also remember there was a 122hh upgrade program going on. Not sure why that area is leaking, but it may be an opportunity to upgrade.

One more thing, when I put the truck all together I forgot to hook the Maf back up and didn't even think about it till 40 miles later. The truck actually iddled better and did not knock under normal non-boost acceleration. I don't understand how the truck was able to run w/o the Maf hooked up. When I realized it I pulled over and hooked the MAf back up Sure enough the truck went back to stumbling and knocking, but it did then add fuel when I went into boost.

 

There is an O ring gasket between the lower intake, and upper intake. There is no gasket between the upper intake and the supercharger. It is just 2 nicely machine surfaces that appears to have red loctite sealing it. It could also be leaking at the fittings around where the intercooler lines go in. I am not sure how they are sealed, but I don't believe there is anything there either, just a locknut, flatwasher and oring (if I remember correctly). I would get the leak fixed before I try and figure out the problem when hooking the MAF. If there is a leak the trims will effect it.

 

iI wouldn't send it in to Magnacharger either. Taking it off will be the hardest part of the fix. it will be easy once you get the two lower halves separated.

 

I sprayed around where the intercooler lines went and didn't see any bubbles there.

 

The PCM uses a combination of MAF and VE tables to do fueling, when you disconnect the maf it uses strictly the VE table, this is called Speed Density (sd). Lots of guys run SD setups when they max out the maf (including me), which is common with forced induction. If you plan to run an SD setup, be sure and have a good tune/ tuner to take care of you since the table needs to be right.

 

I figured that was what it was doing, but I though you had to disable the maf and change the tune to run in SD. I would have expected the ecu to throw a fit when I just unplugged the maf

 

Willing to bet your service engine light turned on...

 

I don't remember it coming on, but the way I have the steering wheel I can't see the top of the dash where the light is. So it could have and just not known it.

 

Ya your CEL would have lit. Speed Density does not respond the same to a vac leak like a MAF setup does. Maf is reading the air that flows through it where as SD goes off of manifold pressure/vacuum. I run 2bar Speed Density also. As Atomic stated, with SD you have to have a really good tuner or know how to do it yourself (Best method) I would NOT do a mail order SD tune.......

 

How much of a leak does it take to really throw off the fueling? My long term trims were from -10 to +9 depending on what I was doing. I'm really hoping this seal on the intercooler was causing all my problems.

What made me finally test for it was I was getting into 4psi and the truck was barely keeping speed on a hill at some times. Other times I'd get up to 10deg of knock with not much of a throttle poke.

I send Tick Performance a message asking about that intercooler/spacer he had going. If I have the blower apart, might as well try it help with the high IATs.