Just dynoed...need spark plug/S-AFC advice

[TurboStutr]

I put my car on a DynoJet the other day and had some problems i was hoping to get some help on. First of all, I have a ported big 16g, 2g MAS, FMIC, 190lph pump, S-AFC, RC 550's, 1g BOV, and other supporting mods. My first base run was 262.9hp/261.6tq at 16psi and running very rich. My final run netted 283.7hp/292.2tq at 20psi falling to about 17 at redline with an 11.5 AFR across the board. Am i correct in thinking the falling boost is attributed to my manual boost controller, or have I reached the limit of my stock BOV? And I was running NGK BPR7ES, 1 range colder than stock, but those were running hot so I had to go to an 8ES, is this typical for about 20psi on a turbo of my size? On one run, I hit full boost and then felt a jolt and immediately dropped about 15hp on the dyno readout, could this be from bad knock and the ECU retarding the timing? And one last question, my S-AFC settings are set at 1,000rpm increments and read like this:

3k: 0
4k: -34
5k: -45
6k: -45
7k: -49
8k: -11
(run to about 7,300 on each pull)

That's pulling out way too much fuel, but the wideband reads 11.5...what could be wrong?

Thanks in advance for any help.

 

[CanadianTSi]

You have a Giant Boost Leak. I'm willing to bet large sums of money on it...

 

[andymoraitis]

I would have to agree. When you need to pull such large amounts of fuel to gain a workable 11.5:1 A/F ratio, it means you're way too rich. With the amount of timing added by the amount of air you're subtracting, the knock sensor kicking timiing back could have been the jolt you felt. 550cc injectors should require no more than an 18-20% reduction with the AFC to achieve a solid AFR. It would be a great idea to hook up a logger and see what's happening to your timing as you make a pull.

You may also want to look into using the DejonTool stop leak kit if you find your BOV is leaking. I went the other way and crushed mine to hold 20in/hg with a MityVac and she'll hold 26psi, so consider that as an option as well if you have the right tools to do so. As far as the plugs go, one of the best ways to see what's up is to read them. Run a dyno pull and then remove them (traditional wisdom says to shut the car off as soon as the pull is done, but I don't know if you want your turbo to spin down from a full pull without some cooling). If they're white, then you're very lean. Tan would indicate normal operating temperature and black would indicate a rich condition. The 8ES plugs will load up badly on your setup and you should consider going back to 7's. I'm a bit of a non-traditionalist and while I used to run NGK's, I have seen excellent results running Autolite 63's (stock heat range) gapped to .28. They hold up under big boost on a daily basis and I can pick them up at a local WalMart, Whatever you do, go back to one range hotter though.

Finally, please do a boost leak test and let us know what you find.

Andy

 

[TurboStutr]

Thanks for the help, I'll be doing a boost leak test after work today. That seems to be the obvious problem so after I check that out I'll move on to the BOV and hook up the logger to check for any more possible mishaps. The reason I went 2 ranges colder than stock was because after the dyno run with that jolt from the timing being pulled I yanked out the 1-range-colder spark plugs and they were nice and white. But I'm guessing thats mostly from everything being screwed up by the leaking boost.

 

[TurboStutr]

Well I hooked everything up for a boost leak test and as fast as I could pump the air in with a bike pump, it was leaking out. Filled up the compressor and hooked it up to push 10psi and got under the car to follow the hissing and found out that the underside of my intake manifold is cracked . I never wanted to have to mess with the manifold until I had to upgrade because it looks like a real PITA, but now I have no choice.

 

[TurboStutr]

UPDATE:

manifold isnt actually cracked, just blew out the gasket really good. from all the oil and gunk on it, it appeared to be cracked, but i had to get it out and scrub it clean before i realized it wasnt. while its out i was thinking about gasket-matching the ports on it, does anyone have any opinions on whether this will be good or bad? and then its back to the dyno for some true numbers.

 

[CanadianTSi]

Gasket matching is always a good idea.

Make sure you re-tune before you get on it because things will be totally different.

I bet you'll hold 20psi till redline now, I feel so sorry for that poor turbo...

Compare your hz count now to before the boost leak...

 

[TurboStutr]

Cool, I'll be getting the porting done today. And it'll be re-tuned this weekend before it sees the track again at the end of next month. And I don't even want to know the amount of boost that was going through the turbo while it was pushing that boost with the leak.

What exactly do the hz numbers mean? I've never really paid much attention to those numbers because I don't totally understand it. And the manifold is off the car now so I can't get a count until I get it all back together.

 

[CanadianTSi]

Hz is how the stock MAS measures Airflow.

 

[TurboStutr]

UPDATE:

i got everything back together and continued the boost leak test. first it leaked from my breather filter on the valve cover, then i plugged that up and then it leaked from the oil dipstick hose. i'm guessing its creeping through somewhere and i have to crank the motor to position the pistons or something differenty to prevent the air from seeping through...would this solve it? any suggestions??

 

[exile]

I didn't know that boost could leak from the oil dipstick. Mine doesn't even fit in the tube right =(

 

[Newlogics]

UPDATE:

i got everything back together and continued the boost leak test. first it leaked from my breather filter on the valve cover, then i plugged that up and then it leaked from the oil dipstick hose. i'm guessing its creeping through somewhere and i have to crank the motor to position the pistons or something differenty to prevent the air from seeping through...would this solve it? any suggestions??

Your PCV valve is leaking. Replace it, because your turbo is putting too mauch pressure on the crank case, besides loosing metered air.

Air loss in the intake manifold affects your AFR horribly, since you aren't only loosing air, you're loosing mixture, so now that it's fixed, you should find car much more responsive to tuning.

 

[TurboStutr]

I didn't know that boost could leak from the oil dipstick. Mine doesn't even fit in the tube right =(

i did the ol' "crimp the tube to keep the dipstick from popping out" mod a while back. thats whats kinda confusing, there's no way boost could leak from the point where the dipstick is located(in the oil pan), i'm thinking the intake valves are open letting air through or something.

Your PCV valve is leaking. Replace it, because your turbo is putting too mauch pressure on the crank case, besides loosing metered air.

Air loss in the intake manifold affects your AFR horribly, since you aren't only loosing air, you're loosing mixture, so now that it's fixed, you should find car much more responsive to tuning.

i just replaced the pcv valve about 2 months ago and have only driven the car a couple times at the track since then, could it go bad that quickly?

 

[eclipsegsx1736]

Did you make sure to get a true OEM PCV from a dealer? The ones from autozone etc. ALWAYS leak. Here's a sure fire way to determine if the PCV is leaking under boost: Get the boost leak test ready, and unscrew the PCV from the valve cover but leave it connected to the intake manifold via the vac line. Pressurize the system, and listen/feel for air leaking out from the PCV. If it's leaking, replace it with a true OEM one, or bypass it altogether. I plugged up the nipple on the intake manifold, and have my PCV vented to a catch can, because I was tired of fighting with that stupid thing.

 

[TurboStutr]

yeah i got the valve from the local mitsu dealership. i'll still double check it with the test though. and i just found another leak around the boost controller that i have to figure out

 

[eclipsegsx1736]

It's normal for the boost controller to leak from the bleeder hole. Plug up the MBC or disable it when you do a boost leak test or else the air will always come out thru that hole.

 

[TurboStutr]

It's normal for the boost controller to leak from the bleeder hole. Plug up the MBC or disable it when you do a boost leak test or else the air will always come out thru that hole.

the thing is that i just noticed it today for the first time, and it doesnt do it when i first crank the car up, its only after a drive it for a few minutes, then it emits a hissing sound at idle. and with the front mount i just installed it said to tap into the bov line(not the dump tube, the smaller hose coming out the top part of it) and connect that hose to the boost controller. so when i heard the hissing i just pressed that one hose shut with my fingers and the hissing stopped, is that normal?