85Iroc-Z

iTrader: (4)

I have been doing my ve learns to get my car running better (383 tpi running ebl p4 flash). The blms are getting closer with the learns but one area doesn't seem to be changing. When engine braking, or coming down steep hills off the gas, the engine is popping from the exhaust and the o2 sensor reading on the Whats up Display is reading anywhere from 0-90mv. It has a surging/high idle problem at idle as well with the IAC steps reading 0. Could these problems be tied together is is there an adjust to the tune I need to make? Brand new o2 sensor and IAC valve as well.

RBob

iTrader: (1)

Check whether the ECM is in DFCO or if the popping is prior to that.

If the popping is prior to DFCO, it is either an exhaust leak, or the AFR is too lean. If too lean need to increase the VE at those RPMs and 20 KPa MAP.

If the popping occurs while in DFCO, there is fuel getting into the chamber(s). When it shouldn't be.

Could be a vacuum leak.

RBob.

85Iroc-Z

iTrader: (4)

The light is not coming on for dfco so I will try adjusting the low end ve tables a little bit and see what that does.

CORV3TT3

Hi!

So here's a bunch of questions...

• Did you set minimum idle air?
• What is you idle speed set to?
• Do you have a wide band? If so... what are your AFRs showing at idle?
• Are you in closed loop at idle?
• What BIN did you start with?
• What injectors are you running?
• What is your fuel pressure?
• Cam specs?

That should be a good start for folks to chime in on.

85Iroc-Z

iTrader: (4)

I actually just tried setting the minimum air. After jumping the aldl terminals and letting to IAC go for thirty seconds I try to start it to set the minimum air. When running it is at about 1500 rpm and doesn't seem to go down even when I turn the idle screw.


I believe idle speed is around 850 900 I'd have to double check again.


I have a Zeitronix zt2 wideband. It is showing low 13's at idle when warm and then rises to 14.7 when hitting closed loop.


I started with a bin RBob made for me.


Siemens 60lb/hr. injectors


Fuel pressure is 43 psi


224/230 @.050, .566/569 lift, 112 LSA


I cant figure out how to start doing ve learns using a wideband. I check wb under preferences for the ve learn, select the zeitronix unit non linear with 0% filter, and turn the cts threshold up to 150 degrees celcius. Am I missing something here?

CORV3TT3

Could be a vacuum leak... 1500 is pretty high.

Ok... so... once you have the IAC fully out, you did unplug it, right? Just making sure...

85Iroc-Z

iTrader: (4)

Yes it was unplugged

85Iroc-Z

iTrader: (4)

My IAC counts at idle are 0. Shouldn't they be around 10-15?

CORV3TT3

IAC counts should be relative to your minimum idle speed. If your idle more closely matches your minimum speed- then you'll have less counts. If your minimum is a lot less than your commanded... you'll have more counts.

If you already have zero, it's not going any lower. So, it's not going to be able to lower your idle.

If RBob programmed your BIN... and your idle is high / hunting... could be a vacuum leak.

85Iroc-Z

iTrader: (4)

I haven't been able to locate one but I will look again. It idles so much nicer when cold.

85Iroc-Z

iTrader: (4)

I cant find any vacuum leaks. I increased the ve tables where the popping and 0-100mv is happening and it hasnt changed anything. I retried setting the minimum air and cant get it below 1-1100 rpm. Are there any other things that can possibly be causing this? I am running out of ideas.

CORV3TT3

Linkage- is your linkage binding?

Is your IAC working right?




I'm wondering if the TB blades are closing all the way... if you don't have a leak... something is adding air.

85Iroc-Z

iTrader: (4)

I'll check for binding. The IAC is brand new but I may try another one as well. I am looking at the BLM's and INT when the 0mv and popping is occurring and they are both sitting right around 128. I had the idle screw all the way in when setting minimum air and it still wouldn't go lower than 1100 rpm. It doesn't always idle that high when cold though. It sits around 850-950 rpm.

85Iroc-Z

iTrader: (4)

I keep increasing the ve tables during those rpm ranges but it is not fixing the problem. Plus when i'm doing the learns it pulls what I increased right back out. I am unsure how to post a datalog but I made one if someone would like to view it.

85Iroc-Z

iTrader: (4)

Rbob informed me that I was having a problem with my VSS signal as my ECM wasn't seeing anything from it. I just re-pinned the wire for it. We'll see what effect that has on it.