choinga

I've got a Vitesse MAF installed - just went under my intake and replaced just aobut everything...new ICV, TPS, TB rebuild, venturi delete, all new hoses and vacuum lines, new DME temp sensor, cleaned ALL my grounds, etc...

Cold start - car comes up great...always idles great - right at 840 +/- 20RPM and sticks right at 14.7.

If I just let it sit and get completely warmed up the A/F ratio on my Zeitronix wideband starts to slowly tick rich until it stops around 12.8 or so. It will bump around from the mid 13's and back down in the mid/high 12's.

Even with the Vitesse PB, I can't dial out enough fuel at idle to get the A/F ratio back up to 14.7. I can dump fuel in and get it to choke, but won't do anything the other direction.

This is totally repeatable. I can go out in my garage tomorrow AM and every day after and do this.

My voltages seem marginal/OK - I run 12.7V across the battery with the car off - around 13.8 with the car running and will back down to no less than 13.1 with heavy load.

Vacuum seems OK as well - right at start up I see ~15hg and when warmed up between 17-18hg.

I cleaned all my negative grounds and pulled the connectors off the starter tonight and cleaned them up as well.

Any ideas here? I've got inspection coming up in a few months and want to get this straightend out before then. I don't think I'll be able to pass anything running 12.8 A/F at idle.

All that said, the car runs like a bat of hell...holds boost well and has a pretty steady idle RPM regardless of AFR. If the car was two years older I'd just apply for antique status and not have to worry about it anymore but I've got two more years to deal with here in TX.

JohnKoaWood

Is your zietronix output for NB connected to the DME? Sounds to me like your NB is off, if it is connected to the DME, open Zietronix, and change the switching point....

If not, try hooking it up and play with the switching point for the NB output...

Andy1212

Intake leak? Did you put new injectors/fpr in?

Airflite40

yeah it should be the other way round.... richer when starting cold.

choinga

I have the ZT-2. Are you referring to the purple wire which is a simulated NB output? No, I don't have that connected to the DME. What wire on the DME do you connect that purple wire to? I was looking at the ZT-2 manual and that is definitely interesting. Be curious to see if that works in my scenario.

The only thing connected to the zeitronix is the vitesse PB. The 0-5v wire out goes into the PB to log AFR voltage...but I just realized after reading the manual that maybe you have to use their PB to change the settings so that it actually outputs the voltage to that wire...I dunno, I haven't been looking at it real close in the vitesse PB yet.

I don't know that Vitesse software that well - I haven't seen any feature like that but would be nice if I could control everything from one piece of software...

choinga

I had the intake off - put it back on w/ all new gaskets and put in new injectors when I installed the MAF several weeks back.

I took a can of carb cleaner and sprayed it around the bolts and flat areas where the intake connects to the block and never felt any idle surges. I've sprayed it around the TB as well and a few hoses and "T's" that and can't find any obvious leaks.

The only thing that I found weird was when I sprayed soapy water on my Evo BOV and the idle stumbled. It definitely wasn't the clamps or connection points - if I spray water right on the valve itself it's sucking the water in. Not sure if that's normal or not? I pulled it off and blew in the holes and it wasn't letting any air through - so it seems like it's working OK.

choinga

exactly. It will usually start a little rich but then backs down to 14.7 pretty quick (doesn't take much for the car to get warm - it's been 100+ for over a month where I live now...). Once it's really warm (fans are coming on) then it slowly starts ticking down and settles in right at 12.8 usually bouncing around a little but never getting back up into the 14's.

At cruise though, it runs nice right in the 14's and the AFR's look pretty normal, albiet a little rich, but according to John - that's by design. At WOT I'm in the mid-11's. Occasionally when I'm driving it around and it's not just idling in the garage it will idle in the 14's - but for the most part once it's good and warm it likes to be in the 12'.s

Airflite40

did u clock the MAF like john suggests?

choinga

EDIT - I didn't know the term 'clock the MAF', but looked it up.

John never made any suggestions about the controller orientation. I have it sitting pretty much straight up 12:00 which according to a post I found was right where another lister said John recommended it to be located. I guess I could move it around a little, but for a car that otherwise runs pretty well except for this issue - is this really going to make that much difference??

Airflite40

it could make a difference especially in your case where the issue is at idle... i have read past posts where clocking the MAF has solved weird idle issues like smoothness it wouldnt hurt to try

choinga

I'll try moving it around and see if that changes anything - doubt that it will. It's almost like a heat issue on the stock negative to the bellhousing or something crazy like that...as the engine gets hot and heats that cable up it's eating up voltage and causing some weirdness.

I'm new the Wideband AFR - is it supposed to bounce around when you rev the engine at idle? Mine sure does. It always settles back to wherever it was idling fine but whe you gas it and hold it at various RPM's the AFR changes pretty significantly. I'm certainly no expert at AFR's...but doesn't seem like the car ever needs to be in the 10's when you goose the gas at idle.

I've got a negative kit from Robby coming - maybe I just bite the bullet and buy the whole thing and get the alternator out and replace all those cables.

Now, that's certainly not going to hurt anything to do that - probably fixes a lot...but not 100% sure it fixes this issue.

Definitely weird though that the PB won't let me dial any of it out at idle and coax it back up to 14.7...

Airflite40

u won't need to remove the alternator to install that kit, but.... get ready for this... u will probably have to remove the intake... im pretty sure i had to pull mine off....

for the alternator part u just need to pull off the shroud

choinga

Just for grins this AM I pulled the DME out and adjusted the FQS to position 2 which cuts fuel. Same effect, car idles great at 14.7 until it's really warm and been driven around for awhile and then it settles back in around 12.8 at idle. *sigh*

I actually like the AFR's a little better though...I'm at 12.4 at WOT instead of 11.2 which I think is really rich. I dialed my boost down to 14PSI in the interim, but a few test runs in 3rd went well.

I'm waiting on word back from JohnKoa on that simulated narrowband output from the Zeitronix. Their directions don't indicate where you'd tie that into the DME. I may try using that and see if I can get the car to default to 14.7 in a closed loop.

My gut tells me it has something to do with a ground - probably the battery negative that goes to the bellhousing...once it's good and warmed up it's old and nasty enough that it just starts to eat voltage.

V2Rocket

try cleaning your WB02 lol

doabarrelroll

Did you ever figure this out? My AFR numbers are identical.