P0171 Driving me Insane!!!

[XJSteven]

Anyone know what Pin the 02 sensor is at the PCM connector on a 96 XJ?

Might not be a bad idea.

I'm in the process of ordering a vacuum tester off Ebay to measure both vacuum and fuel pressure.

 

[XJSteven]

It might be too soon to speak but 3 days ago I cleared the error code twice and at this point it hasn't come back on (fingers crossed!).

Yes I spoke too soon. I just got called in to work and by the time I drove back home the P0171 code was there again.

 

[XJSteven]

Was this reading when fully warmed up?

Hello Skreed, I can confirm the reading was when fully warmed up. I checked again today and got the same result:

At idle - .940 volts constant.
At 2000 rpm - fluctuate from below 0.2 to above 0.8 volts.

If I create a vacuum leak by removing a vacuum hose it drops to .080 volts, when I plug the hose back in it returns to .940 volts steady.

It's definitely an intermittent fault because I went for a drive this morning and got the P0171 code (once on the way there, cleared the code, and it reappeared on the drive back). I drove the same route again this afternoon and got no codes at all.

The mechanic can't get me in to hook it up to his scanner for some live data for another 2 weeks so I've got plenty of time to keep trying if anyone has any other ideas for me to try...

 

[Ecomike]

Based on your last post data, the O2 and PCM seems to be working at higher rpms, cruising, but not at idle. The PCM thinks it is lean at idle and is running it rich at idle to compensate, but it seems the PCM is not seeing the data at idle, but you are, which is odd? If the O2 read low like .2 at idle I would suspect the O2 sensor heater was not working, either no voltage to the heater, or an open heater (bad) in the O2 sensor.

But since the PCM is compensating and running it rich, thinking it is lean, and the O2 sensor shows that at idle, it sounds like the PCM is not getting the O2 sensor data at idle, which is either PCM problem or wiring problem between the PCM and the 2 sensor.

Sorry if I already asked, but have you inspected the O2 sensor wires for exhaust pipe or mechanical damage? It is common!

Oh, and WTF is a "so I cleaned the G101 bolt up anyway", G101?

What are you testing the O2 sensor with? What kind of meter??????

Also, the rich mix at idle indicates a possible fuel injector(s) leak, but that alone should have the PCM calling a rich code error, not lean. I would recheck those wires from the O2 sensor to PCM.

 

[Ecomike]

Order your own scanner if you have a laptop:

http://cgi.ebay.com/Scan-tool-OBD-I...=AU_Car_Parts_Accessories&hash=item43a3aa23e9

Bunch of them on ebay for about $20 net delivered.

 

[casm]

Oh, and WTF is a "so I cleaned the G101 bolt up anyway", G101?

That one's the common ground for the upstream & downstream oxygen sensors on bank 1 (actually, both banks if equipped with CA-spec emissions). Also serves the PCM, TCM, and a couple of other things.

Order your own scanner if you have a laptop:

http://cgi.ebay.com/Scan-tool-OBD-I...=AU_Car_Parts_Accessories&hash=item43a3aa23e9

Bunch of them on ebay for about $20 net delivered.

Yes, but he's in the UK. Things get substantially more expensive when dealing with HM Customs

 

[90xj06]

good old ebay.co.uk

http://cgi.ebay.co.uk/AUTO-scan-too...iagnostic_Tools_Equipment&hash=item43a3ab93ab

 

[Sidewinder CC]

Oh, and WTF is a "so I cleaned the G101 bolt up anyway", G101?

The FSM refers to grounds in the diagrams as "G", in this case it's G101.

Here's a pic of G101 at the oil dip stick tube bracket; I'm sure you are familiar with this trouble maker.

 

[McQue]

Order your own scanner if you have a laptop:

http://cgi.ebay.com/Scan-tool-OBD-I...=AU_Car_Parts_Accessories&hash=item43a3aa23e9

Bunch of them on ebay for about $20 net delivered.

I read through this Ebay auction several times, and it is not clear to me that this product is a real scanner. It clearly looks like it will read out stored diag codes, but I doubt it will display real time performance data based on what I read. I would ask that question of the seller before purchasing.

 

[Sidewinder CC]

Scanners usually run around a 100 bux.

 

[Ecomike]

Yes, but he's in the UK. Things get substantially more expensive when dealing with HM Customs

UK? He ships from Hong Kong, China. Dieselenthisiast and I bought ours last month. I have a friend who tried it on his 2001 Saturn over the week end. It does give live data.

 

[Ecomike]

I read through this Ebay auction several times, and it is not clear to me that this product is a real scanner. It clearly looks like it will read out stored diag codes, but I doubt it will display real time performance data based on what I read. I would ask that question of the seller before purchasing.

Dieselenthisiast and I bought ours last month. I have a friend who tried it on his 2001 Saturn over the week end. It DOES give live data. There are a number of programs available that you can down load to use with the hardware, that do all sorts of cool stuff it seems, including controlling the PCM!!!! The fancier programs are not free, but the main live data reader and code reader is free. The better programs (some have free trials, but they are not free), do graphing...and so. The $20 delivered deal is the hardware and a CD that has links to downloads of a number of programs that work with the hardware and your laptop.

I have a $140 scanner that does not do half the stuff this $20 package does if you have a laptop.

There are a bunch ebayers selling the same package (just search "OBD-II USB scanner Ebay" for all of them), some are specialized for certain vehicles like UK BMWs, one has blue tooth on it instead of USB, and I suspect Iphone and Droid have an APP for it already?party1:

I just randomly grabbed one of many for the earlier post. That is not the guy I bought from, but the same package.

You people do what you want. I would prefer a $20 cable adapter, and multiple upgradable (some free) software choices for my laptop over a limited handheld, not upgradable device for $120 to $200.

http://www.google.com/search?q=ebay...s=org.mozilla:en-US:official&client=firefox-a

Google these and you should find the software sites:

Scantool_net113win
EasyOBDII
OBD2Spy
ScanMaster-ELM

This is the one (seller & auction ) I actually bought.

http://cgi.ebay.com/ebaymotors/ws/e...0709871623&viewitem=&sspagename=STRK:MEWNX:IT

The program lets you perform the following operations: Read diagnostic trouble codes, both generic and manufacturer-specific, and display their meaning (over 3000 generic code definitions in the database).
Clear trouble codes and turn off the MIL ("Check Engine" light)
Display current sensor data, including:
• Engine RPM
• Calculated Load Value
• Coolant Temperature
• Fuel System Status
• Vehicle Speed
• Short Term Fuel Trim
• Long Term Fuel Trim
• Intake Manifold Pressure
• Timing Advance
• Intake Air Temperature
• Air Flow Rate
• Absolute Throttle Position
• Oxygen sensor voltages/associated short term fuel trims
• Fuel System status
• Fuel Pressure
• Many others...

Upcoming Features:
• Data graphing and logging
• Freeze Frame data
• Continuous and Non.

 

[casm]

UK? He ships from Hong Kong, China.

Yes, but shipping's not the issue. It's what the value of the item becomes when Customs receives it in the UK.

Stuff like that, ordered by individuals in the US, is virtually never taxed. The situation in the UK is very different: duty is regularly levied on items of non-EU origin, and they can be taxed at a substantially higher value than the declared one on the customs label at Customs' discretion.

Trust me on this one - I spent nearly 5 years dealing with it when I lived in the UK prior to moving to the US. It really sucked if family on this side of the world sent something to me particularly when I was at school and broke because inevitably it meant that I was going to be taxed on it.

 

[WB9YZU]

So... did you replace the upstream O2 sensor yet?

 

[Ecomike]

Yes, but shipping's not the issue. It's what the value of the item becomes when Customs receives it in the UK.

Stuff like that, ordered by individuals in the US, is virtually never taxed. The situation in the UK is very different: duty is regularly levied on items of non-EU origin, and they can be taxed at a substantially higher value than the declared one on the customs label at Customs' discretion.

Trust me on this one - I spent nearly 5 years dealing with it when I lived in the UK prior to moving to the US. It really sucked if family on this side of the world sent something to me particularly when I was at school and broke because inevitably it meant that I was going to be taxed on it.

How the UK ever get into the discussion in this thread?

 

[casm]

How the UK ever get into the discussion in this thread?

It's where the OP is located - hence the eBay/customs commentary re: the scantool

 

[XJSteven]

Yes, but he's in the UK.

That's funny because I'm not in the UK.

I enjoyed your Ebay/customs commentary though. haha.

So... did you replace the upstream O2 sensor yet?

Yes I replaced it 2 months ago and it made no difference.

But since the PCM is compensating and running it rich, thinking it is lean, and the O2 sensor shows that at idle, it sounds like the PCM is not getting the O2 sensor data at idle, which is either PCM problem or wiring problem between the PCM and the 2 sensor.

Sorry if I already asked, but have you inspected the O2 sensor wires for exhaust pipe or mechanical damage? It is common!

Oh, and WTF is a "so I cleaned the G101 bolt up anyway", G101?

What are you testing the O2 sensor with? What kind of meter??????

Also, the rich mix at idle indicates a possible fuel injector(s) leak, but that alone should have the PCM calling a rich code error, not lean. I would recheck those wires from the O2 sensor to PCM.

I'm yet to check the wiring between the PCM and 02 sensor but according to the 97 manual it should be PCM connector C1, cavity A24 (BK/DG wire). Hopefully this is the same for my 96. It seems weird that the wire would only play up at idle and not at higher revs. What's the best way to test it once I have it unplugged from the PCM?

Yes, I've inspected the 02 sensor wires for damage and they look ok. I did damage a previous 02 sensor by shorting it out on the exhaust but that was about 18 months ago and I've been careful to keep the wires away from it since then. The car was running very rough and barely drivable at the time. This time it is running fine and the only problem is when I go to refuel and see the terrible fuel consumption!

I found the info on the G101 ground by searching this forum for discussions on P0171 codes.

Admittedly I am testing the 02 sensor with a digital voltmeter because I haven't got hold of a high impedance analogue one yet but I can definitely see a difference in the readings between idle and 2000 rpm. Besides, after reading the post below I assumed it would be ok to use a digital voltmeter?

The common analog volt meter most people have will be low impedance; I have a number of them. high impedance analog meters are expensive, and impractical for most home "techs". The majority, if not all, digital VM's are high impedance, and should be used when measuring the voltage of an O2 sensor--even pre-'90 Cherokees. The digital meter will give an adequate indication of voltage values above and below the .450 nominal reading of most common O2 circuits. A reading that varies between 150 and 850MV indicates a good sensor. The other parameter is the ability to rapidly swing above and below the .450v center voltage. This is very hard to test with a voltmeter. As long as the reading doesn't "linger" above, or below the .450 level indicates adequate switching speed. To really test an O2 sensor, you need an oscilloscope, or a good engine scanner that gives you O2 cross counts.

As for the Ebay links to the laptop scanner tool I bought the exact same scanner from Hong Kong about a year ago and had all sorts of trouble getting it to work on my laptop so I sent it back and ordered the basic hand-held one instead (unfortunately it doesn't show live data, it just reads/clears codes). I might have to order another one for my laptop and hope I'll get one that works this time.

 

[casm]

That's funny because I'm not in the UK.

I enjoyed your Ebay/customs commentary though. haha.

Okay, now I'm wondering where I got that idea from. Drives me up the wall when things like that happen :roll:

 

[Ecomike]

The digital meter will give you some data. Like if it reads 12 volts, instead 0-1 volt, you know right away the heater power wire is shorted to the sensor signal wire, or the sensor is shorted internally. If it reads O volts all the time the sensor is dead. But beyond getting a stable voltage, dead, shorted, stuck saying lean or rich and not changing, it is not perfect, leaves questions unanswered that an analog will answer.

The trick with $20 HK package is knowing how to hack the Chinese English instructions, LOL! And having some patience with trying to get Bill Gates junk and Chinese stuff to work together, LOL.

We were missing one step of instructions for 2 days, and finally found it in an email link MS Word file from the seller. It should have been on the CD we got, but I think we got the old style serial port software CD with the USB device version by mistake (wrong CD in the box). But I am use to that sort of agony from working on PC's for 20 years. Not much worse than trying to keep a Renix or OBD-1 Jeep running with just a screwdriver and hammer for debugging tools. hasta

 

[XJSteven]

The trick with $20 HK package is knowing how to hack the Chinese English instructions, LOL! And having some patience with trying to get Bill Gates junk and Chinese stuff to work together, LOL.

Yeah I know exactly what you mean. I've had some very entertaining emails from Chinese Ebay sellers! Last time I complained about an item I bought off Ebay the response I got started with 'Please accept my inconvenience for your life." The rest of the email had me in hysterics too. hahahaha.