cavellm

Hi all,

I've got a '93 that has less than 10k miles on rebuilt engine (big streetport) and new BNR stage 2 (we think) turbos.

I went to the dyno a couple months ago, and had a weird problem with it showing running very lean up past 6k rpms. Very rich up until then, but the a/f ratio would skyrocket. The strange thing is, the a/f curve was exactly the same at 12 psi as it was at 16-17 psi. I haven't had the time or money to get it taken care of, but while changing the oil yesterday I found an exhaust leak coming from the turbo to downpipe. I'll attempt to tighten it up today, but would that cause the dyno to read that lean? Nobody could figure out if it was a fuel delivery, fuel pressure, or tuning issue. Does an exhaust leak cause lower than normal vacuum and an erratic idle, sometimes shaking the car? I've checked all vacuum lines that I can see and haven't noticed anything amiss.

Also, when replacing my intake thermosensor, I noticed a flow of air coming from behind the UIM. Putting my hand back there, I can't exactly pinpoint the area where its coming from. But it gets stronger when the RPMs get higher. It's cool air, not hot. Is this normal? I never noticed it before.

Yet another, there is oil leaking from the turbos. It's looking like its coming from the oil return lines. I've tightened the bolts as tight as they should be, think replacing the gaskets would fix the issue? I'm hoping its not the seals.

The strangest issue of the bunch, there is what appears to be soot on the driver's side area of the engine bay. Covering the front of the strut tower, the hood directly behind the black plastic headlight cover, and by the Diagnosis box. Area around the engine and pass side are perfectly clean. I can't find out where the hell this is coming from. I've cleaned it off once before, but it came back.

Thanks for any help!

Cavell

mad_7tist

yes an exhaust leak before the o2 sensor can effect readings. because of the pulses in the exhaust it will draw in air sometimes which change the readings. i'm not saying that is your prob but... the air flow is prob coming from the acv you still have the air pump?

cavellm

This was a tailpipe sniffer sensor on the dyno. Unfortunately they didn't have an o2 one.

Air pump has been removed. It's a straight through exhaust. Would or should it have been blocked off from the removal of the air pump?

It's in a bad position to get my hand down there and see where I'm actually touching. It feels like its blowing towards the firewall, not too far above the top of the tranny.

cavellm

ttt

GoodfellaFD3S

iTrader: (213)

Hey Cavelly,

the exhaust leak will definitely show incorrect AFRs, but from what I know will show you running richer than you are, not leaner. Fixing that exhaust leak will solve alot of your problems I think.

As far the oil leak, it may not be coming from the return lines, may be leaking down to that point. Prolly clean the turbos up, drive it a bit, then inspect and see where the highest oily point it on the turbos. Unfortunately, the old style BNRs are rebuilds/upgrades, and we now know that they are inclined to leak. The Hitachi cartridges dont like to be rebuilt (one reason why I went with some brand spankin new BNR turbos, no rebuilding at all).

When I am back in texas (like 10 days) maybe I can meet up with you and poke around in your engine bay with a spotlight to see if I can help ya out......

cavellm

I'm not too sure, my reasoning behind it showing me running leaner than I actually am is that if some exhuast is escaping from the dp, then not all of it is reaching the tail pipe, hence less exhaust at the tip where the sensor is.

But then again what do I know, I'm just a computer guy

You went back to NJ for a little bit?

dgeesaman

iTrader: (7)

Just a suggestion: probe around using a lit bug punk - one of those little incense sticks for keeping away mosquitoes. With a bright light, it's easy to watch the smoke get sucked in / blown away from a leak.

Now I need to figure out how to test my LIM with the stock airbox/turbos in place.

Dave