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Vectra Z18XE P0170 Fuel Trim +15.6% (Read 6208 times)
Steve Parker
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Vectra Z18XE P0170 Fuel Trim +15.6%
14.06.11 at 21:26:50
 
Have picked up a cheap Vectra as a runabout for my stepson. A bit of history supplied with the car shows problems about 6 months ago at MOT with MIL on Kiwkf*t fitted a new top Lambda (appears to be Bosch unit). The car hunts at idle has very slight hesitation at times and MIL came back on driving back from Auction.

Code P170 Fuel Trim logged and no other codes long term trim listed at +15.6 which i assume is weak mixture. Checked all hoses and sprayed around inlet manifold with carb cleaner and no signs of a air leak and cleaned MAF with carb cleaner.

Live data shows MAF reading of between 3.6 and 3.9 g/s at idle. I know that these are known to have issues with MAF but wth it unplugged idle does not improve.  Are MAF figures about right or would this point to a duff unit
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UncleAlbert
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #1 - 14.06.11 at 23:28:17
 
These have the "Idle Control Valve" don't they...in that case I'd obtain a New Gasket remove it IIRC T20's and clean it with Carb Spray and "Scotchbrite" Needle Plunger is quite robust.
Also the Throttle "Butterfly" could have a Carbon "Gunge" Ring on the Venturi and is stopping it Fully Closing, IMO

P.S I know you shouldn't but I didn't have a New ICV gasket so I carefully re-used with Smear of RTV sillicaset..sorted Idle cutting out prob, Sister-in-laws Vectra 1.8 code No Idea, years ago Cleaned Her MAF too Grin
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horse
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #2 - 14.06.11 at 23:46:38
 
classic maf sensor fault, but do check again  for vacum leaks first, live data i normally find unreliable in the real world and vauxhalls , once again, like the fiesta heater valve mentioned earlier spurious ebay parts are not recomended
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Fatboy Finn
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #3 - 15.06.11 at 00:18:56
 
Quote:
Have picked up a cheap Vectra as a runabout for my stepson. A bit of history supplied with the car shows problems about 6 months ago at MOT with MIL on Kiwkf*t fitted a new top Lambda (appears to be Bosch unit). The car hunts at idle has very slight hesitation at times and MIL came back on driving back from Auction.

Code P170 Fuel Trim logged and no other codes long term trim listed at +15.6 which i assume is weak mixture. Checked all hoses and sprayed around inlet manifold with carb cleaner and no signs of a air leak and cleaned MAF with carb cleaner.

Live data shows MAF reading of between 3.6 and 3.9 g/s at idle. I know that these are known to have issues with MAF but wth it unplugged idle does not improve.  Are MAF figures about right or would this point to a duff unit


Hi Steve your kind of on the right track assuming weak mixture, however a Lambda sensor only looks at oxygen content of the exhaust gas (thats not strictly true Lips Sealed), anyway you are looking for any reason that might cause excess oxygen. Such as.

1. air leaks after the MAF like vac/breather hoses etc

2. low fuel pressure/short injector duration

3. Exhaust leaks (particularly manifolds on Vectras)

4. MAF problems (does the value rise when you blip the throttle)

5. o2 sensors (have they fitted the correct part) I have seen sensors fitted to Vauxhalls that are the wrong type
(the common type switch at approx 1v and some Vauxhall ones switch at 5v) Lips Sealed

6. the other thing to bear in mind is that when combustion takes place in a cylinder most of the oxygen will be used in the "explosion" (for want of a better word) if clean combustion fails to take place this "unused" oxygen will be in the exhaust gas, so any kind of misfire be it mechanical or ignition related can also cause p0171.

Start with the basics if it has a misfire Smiley

http://en.wikipedia.org/wiki/Oxygen_sensor
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Steve Parker
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #4 - 15.06.11 at 13:27:05
 
Quote:
Hi Steve your kind of on the right track assuming weak mixture, however a Lambda sensor only looks at oxygen content of the exhaust gas (thats not strictly true Lips Sealed), anyway you are looking for any reason that might cause excess oxygen. Such as.

1. air leaks after the MAF like vac/breather hoses etc

2. low fuel pressure/short injector duration

3. Exhaust leaks (particularly manifolds on Vectras)

4. MAF problems (does the value rise when you blip the throttle)

5. o2 sensors (have they fitted the correct part) I have seen sensors fitted to Vauxhalls that are the wrong type
(the common type switch at approx 1v and some Vauxhall ones switch at 5v) Lips Sealed

6. the other thing to bear in mind is that when combustion takes place in a cylinder most of the oxygen will be used in the "explosion" (for want of a better word) if clean combustion fails to take place this "unused" oxygen will be in the exhaust gas, so any kind of misfire be it mechanical or ignition related can also cause p0171.

Start with the basics if it has a misfire Smiley

http://en.wikipedia.org/wiki/Oxygen_sensor


will double check for air leaks but all hoses appeared ok and no change in idle when pinched/blanked off.

02 appears to be switching live data (on cheap ELM cable at thats all i have that will talk to Vaux)  shows switching between 0.15v and 0.35v and no 2 sensor showing a near constant 0.35v

No visible signs/sound of exhaust leak but will look again.

will see if i can get fuel pressure reading and injection duration when i next get to look at the car at the weekend.

MAF data does raise when throttle opened but think i need to double check output with volt meter.  TPS and CTS live data appears valid so i dont think it has the common earth fault.

May stick a MAF on it anyway to see what happens as lots of people have problems with them.

Also need a closer look as i have been told its a bit hit and miss on these having EGR. I did not notice EGR valve but was not looking for one as i thought they all had no EGR

No signs of any missfire and no faults logged may try another coilpack as i think i have one lurking in the garage somewhere

If no improvement will also check inlet manifold again for leaks
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mac 54
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #5 - 15.06.11 at 17:19:10
 
You can spend the best part of a day tracking down these sort of problems even with all the equipment and experience,  especialy if its multiple faults.
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #6 - 15.06.11 at 22:05:43
 
Quote:
will double check for air leaks but all hoses appeared ok and no change in idle when pinched/blanked off.

02 appears to be switching live data (on cheap ELM cable at thats all i have that will talk to Vaux)  shows switching between 0.15v and 0.35v and no 2 sensor showing a near constant 0.35v

No visible signs/sound of exhaust leak but will look again.

will see if i can get fuel pressure reading and injection duration when i next get to look at the car at the weekend.

MAF data does raise when throttle opened but think i need to double check output with volt meter.  TPS and CTS live data appears valid so i dont think it has the common earth fault.

May stick a MAF on it anyway to see what happens as lots of people have problems with them.

Also need a closer look as i have been told its a bit hit and miss on these having EGR. I did not notice EGR valve but was not looking for one as i thought they all had no EGR

No signs of any missfire and no faults logged may try another coilpack as i think i have one lurking in the garage somewhere

If no improvement will also check inlet manifold again for leaks


Should the peak voltage not be higher, like up around 0.8v or so?
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Fatboy Finn
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #7 - 15.06.11 at 23:41:20
 
Quote:
Quote:
Hi Steve your kind of on the right track assuming weak mixture, however a Lambda sensor only looks at oxygen content of the exhaust gas (thats not strictly true Lips Sealed), anyway you are looking for any reason that might cause excess oxygen. Such as.

1. air leaks after the MAF like vac/breather hoses etc

2. low fuel pressure/short injector duration

3. Exhaust leaks (particularly manifolds on Vectras)

4. MAF problems (does the value rise when you blip the throttle)

5. o2 sensors (have they fitted the correct part) I have seen sensors fitted to Vauxhalls that are the wrong type
(the common type switch at approx 1v and some Vauxhall ones switch at 5v) Lips Sealed

6. the other thing to bear in mind is that when combustion takes place in a cylinder most of the oxygen will be used in the "explosion" (for want of a better word) if clean combustion fails to take place this "unused" oxygen will be in the exhaust gas, so any kind of misfire be it mechanical or ignition related can also cause p0171.

Start with the basics if it has a misfire Smiley

http://en.wikipedia.org/wiki/Oxygen_sensor


will double check for air leaks but all hoses appeared ok and no change in idle when pinched/blanked off.

02 appears to be switching live data (on cheap ELM cable at thats all i have that will talk to Vaux)  shows switching between 0.15v and 0.35v and no 2 sensor showing a near constant 0.35v

No visible signs/sound of exhaust leak but will look again.

will see if i can get fuel pressure reading and injection duration when i next get to look at the car at the weekend.

MAF data does raise when throttle opened but think i need to double check output with volt meter.  TPS and CTS live data appears valid so i dont think it has the common earth fault.

May stick a MAF on it anyway to see what happens as lots of people have problems with them.

Also need a closer look as i have been told its a bit hit and miss on these having EGR. I did not notice EGR valve but was not looking for one as i thought they all had no EGR

No signs of any missfire and no faults logged may try another coilpack as i think i have one lurking in the garage somewhere

If no improvement will also check inlet manifold again for leaks


Has the sensor got a proper plug on it or has it had the plug "attached" with heat shrink or crimped connections?
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Steve Parker
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #8 - 16.06.11 at 17:15:02
 
Has the proper 4 pin moulded plug on it so im sure its a OEM/Bosch unit just can't quite get part number without removing it.  I'm sure that pre and post sensors are the same so if the MAF don't fix it i may swap them (Sure sensor is OK as idle still poor with it removed).  May also see what the warranty is for Kwikf*t as i have the bill and sensor was done about 6 months ago
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mac 54
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #9 - 16.06.11 at 17:23:55
 
raise the revs to 1,500 and hold, watch what the trims are doing ,then raise and hold at 2,500 and note the trims, this will tell you if you have electronic fuel control lean or rich,
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Steve Parker
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #10 - 16.06.11 at 18:21:28
 
mac 54 wrote on 16.06.11 at 17:23:55:
raise the revs to 1,500 and hold, watch what the trims are doing ,then raise and hold at 2,500 and note the trims, this will tell you if you have electronic fuel control lean or rich,



Thanks will try that when i see the car again hopefully over the weekend
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UncleAlbert
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #11 - 17.06.11 at 02:53:15
 
mac 54 wrote on 16.06.11 at 17:23:55:
raise the revs to 1,500 and hold, watch what the trims are doing ,then raise and hold at 2,500 and note the trims, this will tell you if you have electronic fuel control lean or rich,


Also if you have Live Data on the O2 you should see it Drop to a Lower level Reasonably steady..only saying this cause my Autel MS 509 (Chinese I do Believe Shocked)  doesn't show Live data on the O2B1S1, just Her B2 Downstream.

Oh found this might be of interest to you:

http://www.airmassmeters.com/

Their Advice regarding Cheap Copies I'd endorse..."Asian Tiger" meoooow!!

And with all due respect to the Forum's Master Mr Nobster may like this.... Smiley

http://www.youtube.com/watch?v=VBdSqk78nHw
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Steve Parker
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #12 - 20.06.11 at 21:30:39
 
Have fitted new genuine  MAF and also changed Thermostat (as it was slow to warm up). Don't have the code reader to clear adaptation data co just cleared codes and the vectra now drives and idles a lot better. long term trim still shown as 15.6% after a 10 min drive but short term now 0.0% and now running closed loop unless accelerating and 02 switching in live data so i assume fixed.

Will long term trim  reduce with use if problem fixed.

Can i clear adaptation/long term trim by leaving battery disconnected overnight?

Oh how i miss the tech2 and other diag equipment i used to use when Luton plant was still there
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mac 54
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #13 - 20.06.11 at 21:50:45
 
it probably has codes still logged your scanner cant read so ltft not cleared, try running it a while.
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Steve Parker
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #14 - 20.06.11 at 21:56:40
 
mac 54 wrote on 20.06.11 at 21:50:45:
it probably has codes still logged your scanner cant read so ltft not cleared, try running it a while.


Thanks will tell him to run it around and see what happens
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Steve Parker
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Re: Vectra Z18XE P0170 Fuel Trim +15.6%
Reply #15 - 03.07.11 at 20:45:06
 
Cars now been used on local runs to/from work about 15 mile round trip. 60 mile trip to see us today. Still no codes logged or MIL and LTFT now 0.51% and car runs well. So looks like MAF was root cause of problem. Thanks again for help/advise
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