[PeterB]

Have you checked the fuel cap and oil cap for sealing?

Hi,
I did try cleaning the rubber seal on the fuel cap, and no noticeable smell of fuel near it (not sure how else to check if it's ok)
and the O-Ring on the oil cap (can't notice any leak and no oil smell - and I didn't notice any change in engine speed when I was checking around the air intake, pipes and rocker cover with a butane/propane mix blowtorch).

Also ran tank full of Wynns Total Action fuel system cleaner through, and now running Powatec fuel system cleaner through (did find slight leak of dirty liquid where air intake connects to throttle body, but tightened clip but makes no difference).

One thing I wasn't sure about was when I disconnected the Fuel Evap Resevoir pipes in the wing, when I blew into the one to the engine, I didn't notice any air blowing through, but when I tried blowing into the pipe into the Fuel Evap Resevoir (one to engine reconnected), i wasn't sure if there may have been a bit of airflow.
But, I would have thought if I had a problem with the Evap Tank Resevoir, that it would show up as a permanent air leak.
When I check at Idle and 2000 rpm, it looks as if there could be an air leak when cold - short term fuel trim goes noticeably opposite direction to revs (though as yet I have not been able to find it), but when it warms up it seems to be more stable.

What I'm really not sure of is if the rear o2 sensor should start making large changes after a few minutes driving (see Front02vsRearO2 screenshot above), had expected it to stay around 0.45v as when it is cold - but when I look on the internet it seems that some engines are different, and not sure if the z14xep is one of these (I did try swapping the front and rear o2 sensors, but it still seemed to do the same thing and after a while the P0170 came back - their now back in their original positions).

 

[PeterB]

Can you feel any suction when removing oil cap with engine running.

Mm,
Just tried, initially thought there was a slight suction just as I removed the cap - but not all that much. Cleaned again and put small amount of vaseline on o-ring to see if would improve, if anything suspect loses any suction slowly whilst removing cap now.

BUT - when put palm of hand over oil cap position, there doesn't seem to be all that much suction (at tick over) - should there be ?

 

[PeterB]

Can anyone confirm whether its ok for the Z14XEP rear o2 sensor to start varying after a few minutes as per the FrontO2VsRearO2 screenshot above (as if the ECU might be over-adjusting or something, but at a lot slower rate than the front o2 sensor), or should it be maintaining approximately 0.45V even when the engine is warmed up -- are there any known causes for this type of problem ?

 

[PeterB]

Hi,
Are you saying that in normal driving the Rear o2 sensor should vary occasionally when the engine is warm (it seems to change from approx 0.45V during first couple of miles to varying between 0.1 V and 0.7 V occasionally when warmed up).

Should I try finding somewhere where I can do a reasonably constant 19 mph when warmed up to see if it stabilises, would I then expect it to be about 0.45 V and to stop varying so much ?

 

[PeterB]

Hi,
Are you saying that when the engine is idling, warm, with all auxiliaries off I should expect the rear o2 sensor to be toggling between low and high occasionally ? Any indication of the frequency, or should it just be occasionally ?
-- I read the Front 02 sensor should be changing regularly to keep the cat happy, but it was very unclear what the Rear O2 sensor should do -- Is there some reference I can refer to to see what it should do ?

 

[PeterB]

I checked the EGR solenoid resistance, and when I disconnected its connector it gave an EGR fault code, which I assumed meant it would know if the EGR valve was not operating properly.
-- Tried running tank of Wyns Total Action cleaner through, hoping would solve if EGR valve was sticking (it claimed to clean and lubricate both inlet and exhaust, including EGR valve) --
Car scanner shows it passes EGR test (whatever that involves) in its emissions section - but don't know if its telling the truth - it says it passed all the other tests as well - which obviously is not true as I get about 14 drives from resetting the code until the engine management light comes on again.

Do you mean fuel tank ventilation / evap valve ? Not sure, if its the one in the pipe from the Fuel Evap Resevoir in the wing to the rear of the throttle housing
- I did disconnect the Fuel Evap Resevoir pipes in the wing, when I blew into the one to the engine, I didn't notice any air blowing through, but when I tried blowing into the pipe into the Fuel Evap Resevoir (one to engine reconnected), i wasn't sure if there might have been a bit of airflow occurring - did wonder if the fuel evap resevoir tank might have a leak, but as there's no petrol smell I guess not.
-- BUT --, I had assumed the air would have somewhere to go to the other side of the valve, I now realise with the throttle closed there is a slight possibility I may not have noticed if the valve was leaking if there was no backward path from the inlet towards the air filter - is it a test I need to do again - would removing the oil filler cap during the test make it valid ??

 

[PeterB]

Just tried tapping it with pliers when got home, while engine still warm and running, then let cool down and tapped again.
- I thought it had potentiometer feedback of actual position as 5 terminals, but did read that vauxhall sometimes turned EGR checking off if they'd had car for light in the past -
The ECU light came on again on way to work, so will probably try and do some more ODBII results before resetting it again, and maybe look at some of the 'All Sensors' data I screenshot from CarScanner the other day - I think it shows readings and limits (even though on standard version it doesn't show a pass / fail result).

 

[PeterB]

Hi,
Not intermittent - repetitive but not immediate - I just have a tendancy to reset the code a few drives after the light comes on.
Seems to be better to reset it when the engine is running (if reset with engine not running I think it has to re-learn everything again and runs rough for couple of drives before settling).
-- Sequence is :
Reset P0170 code from car scanner with engine running, light goes off.
Start using car, after warming up short term fuel trim sometimes going way out of range, seen up to 25 when pull up and idle for a while.
Short trim starts stabilising (maybe +/- 5 when warm) after couple of drives as long term adjusts (long term usually ends up in -2.78 to +2.78 range, altering occasionally).
After maybe 3 or 4 drives it's got a pending P0170 code again (can be seen with pedal test without connecting ODB II).
After about 14 drives (from resetting) decides pending code is valid and turns on light again.

- Are you suggesting I should reset code, and try doing a few test drives with EGR valve disconnected to see I get the EGR valve code only instead of the P0170 fuel trim code ?
Regards, Peter

 

[PeterB]

OK, tried with EGR connector off and fault codes reset.
Got 2 EGR fault codes (P0403 egr solenoid circuit and P1405 sensing circuit) and service light on instead of ECU light.
It didn't seem all that happy, seemed to go up to Short term +25 a lot at idle (know it does that after reset codes, but seemed to be taking longer to stabilise).
Did couple of test drives, but with short term trim as it was it would probably throw the code, so reconnected EGR again, and now the short term has recovered to approx +/- 5 when warm.

What I did notice, and seemed a bit strange, was car scanner non-continuous info is showing a monitor rich to lean / lean to rich threshold voltage of 0.627 V for O2 sensor 2 (whereas it's showing about 0.446 V for O2 sensor 1) . If it's actually true, sounds a bit suspicious.

Also, not sure it's toggling the O2 sensor 2 properly at warm idle, just seems to be wavering a bit (though probably need to let it re-adjust after resetting the codes as may still be re-adjusting itself) - it is giving 0.45 V for couple of miles, then 0.7 V when accelerate and 0.1 V when decelerate, just not sure about the idle (or should that be at 19mph, in which gear ?).

 

[PeterB]

Hi. OK, will try your test.
At moment am monitoring the situation, after tapping the EGR valve and doing about 20 miles at 4000 rpm am waiting to see if get code back again.
If anything, I've noticed idle goes slightly low when brake pedal pressed, recovers to normal when brake pedal released. Had presumed this was normal, just hadn't noticed it in the past.

 

[PeterB]

Hi Ross,
Suspect you could be right, think will have to compare with another car - don't like the sound of this elephant -
1/ checked pedal went down more when started engine - ok
2/ put foot on pedal then turned off engine, waited 30s and it did not start rising under my foot - apparently ok
3/ tried your test, ran engine, stopped engine, waited 30s, then checked pedal - did not notice it being particularly soft and rising on each press - sounds as if failing the test -
4/ Idle slows down slightly when press brake pedal (from about 800 to 700), not sure if this is normal or not
Does this mean that either the valve in the brake vacuum line or the servo seal are likely to be faulty ? - if so, I expect I will get the fuel trim light again soon.
Peter.
PS : I did try swapping the O2 sensors, didn't seem to make much difference to the waveforms on car scanner, so put them back again. Tried cleaning the MAF valve, looked ok (but not sure if 4.5 KG/s is ok at idle, couldn't find out what it's meant to be)

 

[PeterB]

Hi Ross,
Will check again in morning. Initially didn't think there was any hiss, but with ear really close to the pedal area I think there may be a very slight hiss that stops when press the pedal.
Are you saying there should be absolutely no sound, not even air maybe moving inside the servo or something ? - will maybe try and record it with mobile phone tomorrow, try and be more sure what I'm hearing.
I was also intending to try and check the one-way valve in the pipe tomorrow (if I can work out how to get the pipe off the manifold, it seems to have a yellow clip but I'm not sure how it comes apart). I presume the other end is just press fit into the servo ?
-- As you've done the job before, is it possible to change the brake servo without emptying the air-conditioning (Haynes manual mentions getting the air conditioning drained before starting work) ?
Presumably the brake pipes need to be removed from the master cylinder, doesn't look as if the servo will come out otherwise ?
Does the wiper motor need to come out to get access ?
-- Any idea how long the job takes, got an awfull suspicion having A/C is going to mean I will have to get the job done, don't fancy messing around with the A/C myself.
Peter

 

[PeterB]

Hi Ross,
Ok, done a couple of recordings with phone near brake pedal, think there may be a slight hiss when pedal is up. (had to convert them to videos so could share on utube - so may have to unmute in utube)
Audio recording 1 (as an MP4) - pressing and releasing pedal at about 5 s intervals, then slowing to about 10 second intervals near the end.
Audio recording 2 (as an MP4) pressing and releasing pedal at about 5 s intervals.
Took me ages to work out how to share them, as can't add audio or video to this forum - hope they work.
Like to know what you think.
Peter.
(Also have taken number of pictures of the master cylinder area, still need to go through them to find suitable ones, but maybe you can see if the layout looks similar to the 1.8 so I can get the servo in and out without draining Aircon).

 

[PeterB]

Hi Ross.
Idles reasonably well considering. Have to be quite near the pedal to hear the hiss, phone was really near the servo, near the top of the pedals when recording.
At moment am still waiting for the P0170 to re-appear since tapping the EGR and run at 4000 rpm, though guess it will come back.
Any idea how the vacuum connector is released from the inlet manifold, don't want to force it as manifold is plastic - do I need to squeeze the 2 small yellow bits part way up the connector sides or something ? it's completely different from the connections to the evaporation tank I had apart before.
Guess the connection at servo end is just a bit of leverage to remove from grommet, bit awkward to get to, may have to remove whole pipe to blow into it. - Does it just press back in afterwards, or does it need vaseline or something on it when reassembling ?
Peter.

 

[PeterB]

Hi Ross,
I can try that, but when I had a breather hose to the manifold off the other day, I don't remember being able to blow air into the inlet manifold through it, had thought it would get past the throttle valve a bit. Manual suggests removing both ends to check the valve, not sure if there's a reason why (and I'm not sure how to get the manifold connector with the yellow bit off - if anyone knows, please advise).
May have to use car to get to work tomorrow, and meant to take cousin out on Friday, so I'd better try not to break it before then - also think I should try and listen to servo on couple of other cars, maybe at work - so may be bit of a delay before next test.
Please see attached photos from my car, hope they make some sense. Unless it's the vacuum valve it's looking as if the brake servo may need changing sometime, and really need to know if it's like the 1.8 where the servo can be manouvered in / out without degassing the AirCon.
Any thoughts would be appreciated, can take more pictures if something is unclear.
Thanks for your help, Regards, Peter.

 

[PeterB]

-- PS, what's Rubber Grease, is it the stuff that used to come with brake cylinder seals years ago ? Might I know it by another name ? --

 

[PeterB]

Thanks Ross,
Will let you know when have time to do more tests and what the results are. Need to convince myself it's the servo and not the valve, and that I don't notice a slight hiss on other cars - though I suspect your right the brake servo is probably to blame.
Ok, no more vaseline (had noticed petroleum jelly used for injector seals), think we use silicone grease at work.
Can you clarify 'The manifold end comes off by pushing the fitting onto the manifold and pulling the yellow tab towards the body of the hose fitting', it looks as if the yellow tabs at the bottom are already mainly compressed, are you saying it will press down more, and then to pull up on the 2 yellow tabs at the bottom (and that it's nothing to do with the 2 small yellow bits higher up) ?
Peter

 

[PeterB]

Sorry Ross, One more question,
In the Haynes manual it mentions when Aircon to 'undo the bolt securing the pipe block connection to the expansion valve and withdraw the pipes from the valve' , with a picture with 2 Aircon pipes going into a block on the rear engine bulkhead being the inlet manifold.
Am I correct that this is going into a valve hidden behind the bulkhead, and if one does not Degass the Aircon that one does NOT undo this bolt to remove the block and pipes from the bulkhead ?
Peter

Do Not Remove ???????

 

[PeterB]

Ah OK - I had been thinking this might do (use it or its equivalent at work) - but as you say, maybe should use the correct stuff -