Narrowband and wideband disagree. PL files inside.

[gunslinger]

I was just going to bump an old thread back up to the top, but I can't seem to find it.
Last year I had a lean condition that I was trying to track down. The fuel pump was failing, so I changed it, and I got my fuel pressure rise back. O2s were still in the 600s. I wired up a new heated O2, same problem. I found that the O2 ground had a high voltage drop, fixed it, same issue. Cranked up the fueling in the chip, same issue. Added a couple lb of fuel pressure, same issue.

So I decided to pick up an AEM wideband and see if it really is lean. I turned off the alky system, turned down the boost, and reset the chip, and the wideband says it's 14.5-15.3 while cruising, and at WOT, its buried at 10:1, but the O2 is still hanging in the 600s. At idle the O2 will go up to it's normal 780s. I don't like how static the O2 is at hwy speeds either.

I know that the Batt voltage reads low, it always has. I've verified 14.5V at the fuel pump, and going into the ECM. I'm starting to think the ECM is failing.

WTH is going on with this thing?? HELP!!

Two logs attached. One with alky and one without.

 

[gunslinger]

Anyone?

 

[Paul Lohr]

It sounds like the narrow band oxygen sensor's output is not changing even though the proportion of oxygen in the exhaust stream should be changing. So the narrow band sensor is staying at 600 millivolts under all conditions?

Someone more familiar with Scanmaster / Powerlogger oxygen sensor readings might help us here.

From a look at the Scanmaster instructions, it sounds like your narrow band sensor is out of its normal range (750-770 mv).

http://www.fullthrottletech.com/attachment.php?attachmentid=172&d=1135610103

What about taking measurements with a digital voltmeter at the narrow band sensor's output wire? This might spot a faulty ECM or Scanmaster.

 

[Slow91z]

Not trying to play Mr. Obvious or anything but have you changed the o2 sensor...I've seen old ones do this.

 

[TurboBuRick]

I agree. Throw a new denso o2 in and see what happens.

 

[Chuck Leeper]

" I wired up a new heated O2, same problem."....................

 

[Slow91z]

" I wired up a new heated O2, same problem."....................

Missed it.

 

[fastblackracing]

#1 check the voltage going to the signal side of the o2 key on engine off, I think it should be 450 millivolts. #2 if the car is really running at 10.0 as the wide band says i would think it would be in rich misfire condition throwing even more raw fuel into the mix. #3 can you explain the voltage drop on the ground side a little better as to what you found? #4 I thought the o2 at idle should be 450 always crossing over up and down not hovering at 780.

 

[TT/Ameasap]

I was just going to bump an old thread back up to the top, but I can't seem to find it.
Last year I had a lean condition that I was trying to track down. The fuel pump was failing, so I changed it, and I got my fuel pressure rise back. O2s were still in the 600s. I wired up a new heated O2, same problem. I found that the O2 ground had a high voltage drop, fixed it, same issue. Cranked up the fueling in the chip, same issue. Added a couple lb of fuel pressure, same issue.

So I decided to pick up an AEM wideband and see if it really is lean. I turned off the alky system, turned down the boost, and reset the chip, and the wideband says it's 14.5-15.3 while cruising, and at WOT, its buried at 10:1, but the O2 is still hanging in the 600s. At idle the O2 will go up to it's normal 780s. I don't like how static the O2 is at hwy speeds either.

I know that the Batt voltage reads low, it always has. I've verified 14.5V at the fuel pump, and going into the ECM. I'm starting to think the ECM is failing.

WTH is going on with this thing?? HELP!!

Two logs attached. One with alky and one without.

Read your plugs. That will tell you for sure.

 

[gunslinger]

#1 check the voltage going to the signal side of the o2 key on engine off, I think it should be 450 millivolts. #2 if the car is really running at 10.0 as the wide band says i would think it would be in rich misfire condition throwing even more raw fuel into the mix. #3 can you explain the voltage drop on the ground side a little better as to what you found? #4 I thought the o2 at idle should be 450 always crossing over up and down not hovering at 780.

A TT chip uses an open loop idle, so that's why the voltage at idle is high. That also tells me that the sensor is working, and capable of getting up into that range. At the same time, the WB is reading around 13:1, which seems about right to me.
The voltage drop was across the ground ckt for the O2 sensor. Key on, engine off, I had 6mV drop, and once I started the engine, the drop went up to 40mV. I cleaned the grounds on the back of the block, and the voltage drop went away.
What really bugs me, is that at WOT, the ECM is in open loop, doesn't use the O2 for fueling. Why is the WB so rich? Chip issue? Cam sensor??
And at hwy speeds, the fuel trims, are 117, and 136. What's up with that? I've checked them a bunch of times and they're always skewed like that.

I changed the plugs last fall, and they looked prefect, which to be honest, I was shocked. I drive 18 miles each way for work, all hwy, and I've only been able to get 16mpg.

 

[gunslinger]

Well....Blew a head gasket today. No knock, 20psi.
I had knock issues last year when the fuel pump was failing, so I can't say I'm really surprised, but damn it was loud...pop...pop..pop...BANG! Scared the sh!t out of me.

 

[fastblackracing]

Well....Blew a head gasket today. No knock, 20psi.
I had knock issues last year when the fuel pump was failing, so I can't say I'm really surprised, but damn it was loud...pop...pop..pop...BANG! Scared the sh!t out of me.

Damn that sucks, thanks for the update and schooling me on how you chip works. Appreciate it good luck on your new project. I used to have a stack of used head gaskets 2 inches thick from ones that we worked on. I always wondered if buick sold more gasket sets than they sold turbo cars?

 

[Pronto]

That sucks. I know you just freshened it up a little while ago too. I think I got a spare ecm if you want to try it after you get everything back together. While you have the heads off you might want to do the Casper's ground kit and also check the O2 wiring back to the ecm for issues.

 

[gunslinger]

The heads are back on. I found two bent push rods, so the rest will have to wait to go back together till tomorrow. I did a cylinder leakage test, and all 6 were around 20%. Not too bad for a 130k mile cold engine.
When I had the engine out last time, I lengthened and relocated the grounds. I'm definitely going to recheck all those.
Once it's running again, I'm going to check the actual O2 input against what powerlogger and scanmaster say it is. If the numbers are off, it's getting a new ECM.

 

[Pronto]

There's an ornament for your garage.

 

[Ttype6]

What really bugs me, is that at WOT, the ECM is in open loop, doesn't use the O2 for fueling. Why is the WB so rich?

You stated that you richened the fuel in the chip and raised the fuel pressure. Did you reverse these adjustments after seeing the 10.0/1 on the wideband?

And at hwy speeds, the fuel trims, are 117, and 136.

Are you saying that your BL numbers bounce from 117 to 136 and back again in repetition?

Well....Blew a head gasket today.

Were you injecting alcohol when this happened?

 

[gunslinger]

You stated that you richened the fuel in the chip and raised the fuel pressure. Did you reverse these adjustments after seeing the 10.0/1 on the wideband?

Are you saying that your BL numbers bounce from 117 to 136 and back again in repetition?

Were you injecting alcohol when this happened?

In the logs attached, the chip is back to base-line settings, and the fuel pressure is at 43psi line off.

Integrator and Block Learn are skewed from each other. Cruising on the hwy, BL is 136, and Int is 117 every time. You'd think that if it had a history of adding fuel, it wouldn't always be trying to correct for the fuel it has added. ??

And yes, I did was injecting alky when it popped. Everything is just about back together. I could see on the deck of the block where the compression ring on the HG, had been distorted for a while.

 

[Ttype6]

In the logs attached, the chip is back to base-line settings, and the fuel pressure is at 43psi line off.

Integrator and Block Learn are skewed from each other. Cruising on the hwy, BL is 136, and Int is 117 every time. You'd think that if it had a history of adding fuel, it wouldn't always be trying to correct for the fuel it has added. ??

And yes, I did was injecting alky when it popped. Everything is just about back together. I could see on the deck of the block where the compression ring on the HG, had been distorted for a while.

In your alky log,you can see that when your wideband moves in a rich direction,so does your narrowband and vise versa. The only times there are great differences is at full throttle/boost and fram253,where the narrowband goes rich to .650 with a corresponding very rich reading from the wideband. They both move to rich,but the wideband shows richer. I think the wideband is sending different voltages to the powerlogger than the Powerlogger is programed to receive in the AEM setting. If the voltage sent to the powerlogger,for any given A/F ratio,doesn't match the number programed for that A/F ratio,the displayed number will be wrong. If this is the case,the Powerlogger will give a different reading from reality. It should read 14.7 to 1 during closed loop operation,but it reads much richer. I think your narrowband is dead because it isn't bouncing from .800 to .100 in a rapid pattern as it should during steady,closed loop,light throttle operation.Do you have the appropriate AEM gauge connected to the wideband controller?

 

[gunslinger]

In your alky log,you can see that when your wideband moves in a rich direction,so does your narrowband and vise versa. The only times there are great differences is at full throttle/boost and fram253,where the narrowband goes rich to .650 with a corresponding very rich reading from the wideband. They both move to rich,but the wideband shows richer. I think the wideband is sending different voltages to the powerlogger than the Powerlogger is programed to receive in the AEM setting. If the voltage sent to the powerlogger,for any given A/F ratio,doesn't match the number programed for that A/F ratio,the displayed number will be wrong. If this is the case,the Powerlogger will give a different reading from reality. It should read 14.7 to 1 during closed loop operation,but it reads much richer. I think your narrowband is dead because it isn't bouncing from .800 to .100 in a rapid pattern as it should during steady,closed loop,light throttle operation.Do you have the appropriate AEM gauge connected to the wideband controller?

I do have the gauge with the WB, and it agrees with what PL and SM are showing.

I got it all back together and running tonight. It runs okay.
When I first started it, and the chip allowed closed loop idle, the narrowband and the wideband were cycling together just fine. The battery voltage was also reading correctly. I shut it off, and restarted it, and with an open loop idle in park, the narrowband sat at .840, and the wideband sat at 12.8-13.2. The battery voltage also started reading low again.

Tomorrow, I'll hook the laptop up, and take it up on the hwy to see what's going on. I'm also going to hook a multimeter to the O2 input to the ECM, and see if what PL and SM are telling me is true. If it's not, I can only assume that the ECM is junk.

 

[Pronto]

The junkyard in Lowell has a ecm there. I think they want $35 for it.