Can a faulty crank angle sensor cause one bank to run rich?

[Nick JD]

G'day,

My VS was misfiring badly so I replaced all the leads and plugs, and while doing this noticed that the drivers side bank were all black and super rich.

From searching heaps I was pretty sure I had a faulty O2 sensor on that side's exhaust ... but after checking the fault codes I'm getting a 47 (no signal on the crank angle reference) followed by a 76 (variation of air/fuel ratio on both banks). The 76 is clear from the plugs, but the 47 has got me stumped.

I was waiting for a 13! Grrrrrrr.

So my question for the gurus is, will a faulty crank sensor cause one bank to run rich?

Is the DFI Module stuffed?

Any help would be greatly appreciated.

Nick.

[Brett_jjj]

Oxygen sensors usually only set an error code if they stop working altogether.If its still sort of working buit giving bad readings it can cause problems like yours.Most oxygen sensors should be replaced every 100,000 km or thereabouts to keep the engine management system running as it should.Also a vacuum leak can cause similar problems to what you have described.Maybe check the vacuum hoses around the engine and the vacuum reserve tank under the front left guard.It looks like a black ball thing.If the code 47 wont go away, Id try checking the wiring and connectors that go to the CAS (Crank Angle Sensor).If they show nothing wrong,then replace the CAS.Try to use genuine holden sensors if possible.Ive seen a few problems happen with some cheaper sensors.

[Nick JD]

Cheers, Brett.

The thing that's puzzling me is that if it's something to do with the CAS or the DFI, why would all three plugs on one side be fouled? Does the EFI system get mixed up when the CAS or DFI is hiccuping?

[Nick JD]

I replaced the RH O2 sensor and it's running way, way better, but it still bogs down a bit when I plant it. I haven't done the fault codes again, so it's looking like it might have had multiple problems...

A question: can anyone point me to a thread that tells fools like me what to do, using a multimeter looking for correct voltages on the ECU terminals? The Gregorys says to do this, but I don't know exactly what to jam the meter's (+) and (-) into ... sounds like I can zero in on exactly what's ailing the old girl this way, or at least focus on the CAS or the DFI.

Should I reset the fault codes and drive it again?

[Not_An_Abba_Fan]

Bogging down when you plant it is normal, you are asking the car to go from current speed to flat out WOT at an instants notice. It won't do that as it takes a moment for the PCM to adjust the fuel according to the throttle postition, and it also has to tell the transmission to change down a gear if it has to.

That is if it doesn't bog down to the point of coughing or almost stalling.

[Nick JD]

Sorry, I probably worded that wrong - it bogs down under a bit of load - it's kind of a shudder/stutter ... if I put my foot down a little more it sometimes clears.

I haven't driven it up a hill, but a long hill might be a bit of a challenge. It's fine as long as I cruise all the way up to 100.

[Brett_jjj]

My VS V6 just accelerates away cleanly when its floored from standstill.Theres no lag or bog down or stuttering at all.(maybe some wheelspin,depending on the road surface).Id be checking the coils by getting a known good one (borrow a mates) and trying it in each of the 3 positions where yours are,one at a time, and then driving it each time to see if theres any difference.

[Nick JD]

I'll check the resistance of the coils tomorrow - but I'm starting to think it might be the DFI. The Gregorys pretty much says fault code 47 is either a faulty ECU or a faulty DFI.

I really don't want to to be a CAS problem, or it has to go into the shop.

BTW - I paid $80 for the Oxygen Sensor, which was the cheapest I could find (NGK). Holden said $135. Seems quite likely now that I had two seperate problems at once - freaking diagnostic nightmare.

Can anyone tell me how to read the voltages off the terminals in the ECU? I've searched and can't find anything.

[Brett_jjj]

I'll check the resistance of the coils tomorrow - but I'm starting to think it might be the DFI. The Gregorys pretty much says fault code 47 is either a faulty ECU or a faulty DFI.

I really don't want to to be a CAS problem, or it has to go into the shop.

BTW - I paid $80 for the Oxygen Sensor, which was the cheapest I could find (NGK). Holden said $135. Seems quite likely now that I had two seperate problems at once - freaking diagnostic nightmare.

Can anyone tell me how to read the voltages off the terminals in the ECU? I've searched and can't find anything.

I wouldnt take to much notice of the coil resistances.Ive seen them show up ok on a multimeter but still cause misfiring.Thats why I recommend getting hold of a known good coil to try in each place.

[Nick JD]

Thanks, Brett. Will do. One of the coils is new and the other two are old. That probably says a lot. It'd be nice if it was just a coil.

I just found the section on how to test the ECU voltages too!

[Vr5speedv6]

G'day,

My VS was misfiring badly so I replaced all the leads and plugs, and while doing this noticed that the drivers side bank were all black and super rich.

From searching heaps I was pretty sure I had a faulty O2 sensor on that side's exhaust ... but after checking the fault codes I'm getting a 47 (no signal on the crank angle reference) followed by a 76 (variation of air/fuel ratio on both banks). The 76 is clear from the plugs, but the 47 has got me stumped.

I was waiting for a 13! Grrrrrrr.

So my question for the gurus is, will a faulty crank sensor cause one bank to run rich?

Is the DFI Module stuffed?

Any help would be greatly appreciated.

Nick.

I had the same problem as this (minus the crank sensor code), changed dfi and coil packs and still the same. Did a bit of searching and found its an earth fault with the O2 sensor. If yours has the 4 wire O2 sensors simply cut the pink wire on the drivers side O2, it makes an amazing difference

[Nick JD]

An update and a thanks for the help.

Since it's so easy I did a resistance test on the coils and the 2-5 coil was giving no resistance reading at the lead connections - the other two were in the mid-5KΩ range. Got a new one and 3 minutes later - running like a DREAM!

Cheers.

[Vr5speedv6]

Good to hear
But if all the plugs on the driver's side were fouled I'd be snipping that pink wire anyway, as one coil can't be to blame for that.

[Brett_jjj]

Good to hear
But if all the plugs on the driver's side were fouled I'd be snipping that pink wire anyway, as one coil can't be to blame for that.

I doubt all cars are effected by this,mine has 4 wire heated oxygen sensors and runs fine,the plugs always look ok when removed.I wouldnt go cutting wires for nothing,not until you are 100% sure the heated oxygen sensors are actually causing problems.

[ephect]

check your codes in a week or 2's time and see if any codes are logged.. if your still getting 76, this is your fix: How To: Fix the VS V6 4 Wire O2 sensor earth problem – Known Holden Problem

[Vr5speedv6]

I just did the simple pink wire snip and its never run better
I know Dr Bob thinks it's all that is necessary.

[Nick JD]

Thanks fellas! The pink wire will get it if it's still saying "76". I suspect it won't be though - that RH sensor was only logging "3mm of soot - very voltagey" every microsecond.