mnypitZ

iTrader: (19)

OK I searched and read a few threads about smelling fuel but mine is a little more than just smelling it.

Jim, maybe you could add something to this.

Background, I have a 98 Z28 with Pacesetter LTs, ORY, unknown catback, Lid, LS6 intake, c&Cd heads, and probably something else I am missing. A freind came by to help tune it. He has HPtuners.

OK so after we installed the cam I was getting a very rich condition, to the point that it would spit and sputter when I took off again after an extended idle. After he put in a tune, We took the car for a long drive and checked it all live but nothing seemed too far out of place. When idling in my garage you can see the black smoke billowing out the tail pipe and it gets bad enough that we had to back out of the garage so it wouldnt fill up the garage, even with a fan blowing.

I do understand that we could have a fuel smell without cats, but this seems accessive.

Any ideas?? Is this normal or are we missing something??

cam specs
DUR @ .004" 290*/ 294*
DUR @ .050" 228*/ 232*
LIFT .551 / .551
OVERLAP 68*
LSA 112*

mnypitZ

iTrader: (19)

Here is cam specs
DUR @ .004" 290*/ 294*
DUR @ .050" 228*/ 232*
LIFT .551 / .551
OVERLAP 68*
LSA 112*

Billiumss

iTrader: (11)

Your have to use a WB 02 to get the VE table close then work on the MAF curve. That should help a good bit.

You will never get rid of the smell, you have a decent size cam and no cats.

JimMueller

iTrader: (9)

I still have a headache from breathing that crap

We didn't have an in-car wideband. I put it in CLSD, disabled DFCO & LTFT & LTIT and reset the fuel trims. We used STFT's to adjust the VE table. The last couple of logs we captured are attached. We only logged through 4000RPM because the MAF was going to get re-enabled, lack of time, and the roads were a little slick due to rain. RAF was tuned a couple of times. Tried adjusting absolute spark up and down to mazimize vacuum. MAP is in the low 50's at idle.

Seems like the car still has a bit of hanging idle and cruise control effect which we can address next visit if John desires.

So far as the odor and fumes, it's the first time I've dealt with a cat-less vehicle. I'm not sure what would be considered normal for odor and fumes. I know I had to walk away from the garage to get fresh air, though. But the fuel trims being off less than 4% at idle doesn't seem to indicate it's a fueling problem unless it's due to a false lean condition.

Eurospec2

iTrader: (2)

I agree and disagree, you right about the WB02 and VE table, but im running an MS3 with no cats and have zero fuel smell at idle..

JimMueller

iTrader: (9)

I did notice that the O2's were lazy at idle. Typically 200-300mV, spiking once in awhile to 700mV. But I didn't want to suggest buying new O2's unless it was guaranteed to make the situation better and/or alleviate the O2 behavior caused by the aftermarket parts. If the fuel economy also stinks, then we can monitor the airflow mode and play with the switchpoints.

mnypitZ

iTrader: (19)

fuel economy is not too bad. A little over 21mpg with the tune Robert put in there. It idled the same way then as it does now.

mnypitZ

iTrader: (19)

Any other ideas?

mrr23

iTrader: (3)

give me a day with it, and i'll get it better. i need jim's cable again and a saturday, or sunday. i have a few ideas to try out.

98Z28CobraKiller

iTrader: (17)

I bet you have a bad O2 and the car is in Open Loop. Go to the Open Loop fueling table and put it all to 1.00. Check the plugs to make sure that you didnt foul them out. Fire it up and see if it is better. The danger here is that w/o the wideband, you cant tell if you are going too lean.

mnypitZ

iTrader: (19)

My thoughts were either bad O2s or fouled O2s and plugs. You were reading my mind.