Hey Guys,

I've been turbo'd for about 9 months now with an AEM EMS 1052. A couple of weeks ago I noticed the engine falling on it's ass past 6k rpm. So I decided to hook up a buddies wideband to it to see what was what. When the car was tuned, the AFR was a constant 11.8-12.0 under WOT throughout the entire rpm range. Now at wide open throttle, it's at 11.8 until 6k rpm then it dips down to the upper 9s to low 10s. My tuner wont answer his phone for the life of him, so I figured I'd just ask away on here. I was thinking VTEC might not be engaging. Could that be a possibility? I don't know what could of caused this to happen out of nowhere. Here are my fuel system mods. Walboro 255, RC 750s, AEM FPR. I am also running NGK Iridium heat range 8 plugs. Any input would be greatly appreciated.

Thanks,
Jordan

 

Yes vtec might not be engaging, but most importantly, what have you changed or done different since the tune? DO you have any dataloggs? You can go into the map, try setting the vtec to kick in earlier to see if it will effect the a/fs lower than 6k rpms. Set it say at 5k rpms and do a pull while keep an eye on the a/fs. You can also have a spark issue if the spark plugs are old, the iridiums dont last too long. What are you gapping the plugs too?

 

I would start by making sure you have adequate oil pressure before doing much more driving. If your oil pressure is too low to engage VTEC, then you really need to fix that ASAP. If your oil pressure is okay, then I would try raising VTEC to 7K to see if it gets worse. If you find that VTEC is working fine, then I would suspect a boost leak.

 

Iridiums are brand new and gapped to .039. Any way to test the coils? I'll see if I can find my old 9 pin serial to usb converter to hook up the logger. The boost doesn't move from 9 psi , there are no leaks. Is it weird that it started all of these issues shortly after I switch to Mobil 5-30 synthetic? Could engine damage change a tune this drastically?

 

I doubt that you hurt the engine, if that was the case, it would have different symptoms.Simply lower the vtec like i said earlier and try it again. Do you have an oil pressure gauge? If you don't, i would highly recommend you to get one especially with boost. THat oil may be too thin depending on your bearing clearance and could result in lower oil pressure and vtec not kicking in. Also check in the aem how you have the vtec setup. You can send me a datalogg and your map if you would like to my email. corrado_bbm@hotmail.com and ill look at it.

 

also, .039 is a big gap, but that depends on how much cfm the turbo can blow. I would recommend to regap the plugs at .030. I was tuning a k20 turbo crx and it kept blowing the spark at .040. I put it at .030 and had no issues.

 

Lowering VTEC is not the right way to go. If his oil pressure is low, then lowering VTEC could just make oil pressure even lower. It would be safer to raise VTEC, which would also provide more significant changes in the AFR (assuming VTEC is not the issue).

I would also go back to a more appropriate oil, since 5W-30 is thinner than the OEM spec, and you're going well beyond "spec" with a turbo.

 

BTW, who changed your oil, and when was the last time that you checked the oil level? After spinning a crank bearing in an F22 myself due to what I believe must have been a friggin air bubble, I would be totally nervous about your situation. When it happened to me (on the track), the first thing I noticed was power loss. My datalogs also showed extremely rich AFRs when it thought VTEC was engaged (but wasn't).

 

I changed the oil myself. And it reads full on both sides. The only reason I went with the thinner oil was because of the cold Kansas winters. I'm going to change back to 10-30 and see if there's a difference. As far as the tune goes, I believe its due to vtec engaging and disengaging above 6k rpm. I'll also get the gap tightened up on the plugs a few more thousands.

 

For inquiring minds; The problem was a kink in the wire running to the vtec solenoid. Problem solved! Boost happy again!