Here's one for all the supertuners. I have deleted my air injection system and now am getting a lean condition. Since the stock system is calibrated assuming there is air being pumped into the exhaust won't it try to lean out the mixture to try and maintain that level? Do I need a custom chip to eliminate this ? Could I install a resistor inline with the O2 sensor to fool the ecm into thinking it isn't getting enough fuel? What should I do? :smash:


[Modified by jeffie86/96, 2:34 PM 8/29/2002]

 

Trying to think of what is really going on. Only 2 things I see. Less load on the serpentine belt and no air being pumped to the Cat. The cat should be far enough downstream that it shouldn't change the readings on the O2 sensor. And at normal conditions, the "excess" load of the smog pump deletion really wont put that much less load on the engine.

Are you sure that your EGR system vacuum lines didn't get messed up during the smog pump removal? How about your canister purge lines?

I don't have any before or after data with my smog pump delete but I would be pretty impressed if it created a noticable lean condition.

Rule #1...never trick the ECM by manipulating the direct sensor inputs. People have been known to do it on the knock sensor and the coolant temp sensor. It is all in vein though. The guys at GM have tables to account for almost all of the calibration that needs to be done. So keep your O2 there and if you haven't done it yet, you might just go with a heated O2.

Good luck. Are you running '86 electronics? If you were using a scan tool, are you sure it was in the right mode? One thing with the deletion of the pump is you do NOT want to run rich...you will toast your convertor if you still have it.


[Modified by HighHopes85, 5:31 PM 8/28/2002]

 

I think he's talking about his AIR pump, not his A/C pump. So NO air is being introduced into his cat, if it's still there.

The only way to really find out the cause, is to scan the car. If you have an Ease or Diacom, you WILL find out what's causing it to go lean.

 

h rocks, I am glad we are on the same page ;) :lol:

 

I think you guy's are ingroing the air injection that occurs at the exhaust manifolds. The 86 should have air injection at the cat and the Ex manifolds.

I'd suggest looking for an exhaust leak. The air ports are blocked and tight, right? The O2 sensor is how old? As I recall, you only have one. Where is it located? Dri/Pass side? Stock/aftermarket location?

 

The exhaust manifolds have been replaced with headers, no provisions for air injection, the O2 sensor is located in the drivers side collector. My main question is concerning the fact that since the air pump is injecting air into the exhaust at the ports under normal stock condition won't the computer be factory calibrated to expect said parameters under normal operating conditions. Air is not being pumped into the exhaust now therefore the unburned hydrocarbons will make the computer think it is running rich and try to lean out the mixture. I am wondering if I could fool the computer by installing a resistor on the O2 sensor and make it think it needed more fuel.

 

Dunno about yours, but on mine air injection at the exh port only occurs on start-up (to light the pup cats before the ECM goes closed-loop). Hence the ECM doesn't have to make any compensation for AIR.

If yours is a recent header conversion, it seems more likely to be an O2 sensor problem IMHO. Is your heated O2 sensor working up to spec?

DrJ



[Modified by DOCTOR J, 8:01 PM 8/29/2002]

 

jeffie, unless you scan it and collect some data, you are whistling in the wind. I don't think that it's your problem, but again, in the absence of DATA, it's just a guess.

 

DOCTOR J is correct about this! The ports near the head ONLY get air injected at startup/warmup. Not after the engine is fully warm.

So the removal of the AIR pump and related piping will not cause a lean condition.

When is the lean condition occuring? Idle, part throttle, WOT? More details please.

-Tom


[Modified by tommelton, 8:00 PM 8/29/2002]

 

We are having trouble with computer communication, the reader doesn't want to talk to the computer. I will obtain more data as soon as possible. Thank You all for your help, you are most considerate. Jeffie

 

What reader? If DIACOM, it is HIGHLY dependant on the actual PC in use. The parallel port MUST be set to Uni-directional, and then, still on some PCs (laptops, whatever) it will not communicate. I have 2 laptops, one works, the other does not.

-Tom

 

I have a hand held scanner(autoXray). My friend has a nice Snap On scanner and it communicates well with it. Jeffie