4.8 Patrol computer qst
Submitted: Wednesday, Oct 20, 2010 at 13:00
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Member - Beatit (QLD)
Hi Guys,
I've just returned from a Cape trip and had to replace the header pipes
(replaced with extractors due to time constraints in
Cairns) which is a move
away from original. The vehicle drove very
well (and a lot more quitely) all the way home to Brissy but a couple of weeks has passed and on starting the car it idled badly and the engine light stayed on.
I have replaced the air filter and the fuel filter as they were my top suspects
but to no avail. Tried resetting the computer by disconnecting the battery,
this also had no effect - but the car is idling better now. The wiring for
exhaust sensors is just dangling following the extractor installation - they
used to be housed on the engine pipe heat shield. Short of going to Mr Nissan
is there anything I can look at. Any help is much appreciated.
Kind regards
Reply By: Dave(NSW) - Wednesday, Oct 20, 2010 at 13:30
Wednesday, Oct 20, 2010 at 13:30
The guys over here
http://www.patrol4x4.com should be able to help.
Cheers Dave.
AnswerID:
433659
Follow Up By: Member - Beatit (QLD) - Wednesday, Oct 20, 2010 at 14:17
Wednesday, Oct 20, 2010 at 14:17
Thanks Dave,
Found a thread pointing to the O2 sensors.
Kind regards
FollowupID:
704602
Reply By: Robin Miller - Wednesday, Oct 20, 2010 at 13:36
Wednesday, Oct 20, 2010 at 13:36
Hi Beauit
I think you are saying that the oxygen senors are no longer connected (these are the higher up sensors closer to the engine . Or that wires are broken ?
Think yours is auto and has extra sensors lower down in cat as
well i.e. 4 sensors in total.
If it is the oxy sensors that are note connected then the ECU detects this and goes into a pre-programmed basically rich mode. Also engine fault light will come on.
If above correct it is quite likely your spark plugs have gone black.
Can you get manifold worked on to replace the sensors - this would seem to be the right approach.
If you like playing then you can parallel up the to oxy senor inputs on the ECU and with a couple of resistors inject 450mv into the inputs for now - this tells the ECU that its AFR ratio is about right, but engine light would still come on because ECU can detect when senors are not cold on start up.
Still after a while you get used to check engine lights on !
I am surprized you say its quiet - any reasoning why ?
Only reason I never fitted any exhaust mods was because not anyone seems to be able to deliver a product better than Nissan standard without compromise like more noise.
In a side by side match my new auto 4800 can't match my manual 4800 but it sure gets off the line quicker.
AnswerID:
433660
Follow Up By: Member - Beatit (QLD) - Wednesday, Oct 20, 2010 at 13:57
Wednesday, Oct 20, 2010 at 13:57
G'day Robin,
I was hoping you were on line. The Oxygen sensors are still connected but he wires are resting on the extractors and my suspicion is that this may not be good and I guess this could be where my problem lies. Went the extractors path because these were available whereas the genuine article could only be sources out of
Melbourne and a week's delay that we just did not have. Obviously I've kept the header pipes in case I want to go back.
What is interesting is that the car was idling faster (indicating a possible rich mix) but since I've played with the filters and battery it seems to be idling like it used too. But the engine light remains on, I am yet to take it for a drive though.
Kind regards
Theo
FollowupID:
704595
Follow Up By: Member - Beatit (QLD) - Wednesday, Oct 20, 2010 at 13:59
Wednesday, Oct 20, 2010 at 13:59
PS quiter than when it was dumping straight out of the manifold. The exhaust part with the manifold (rusted through)
FollowupID:
704596
Follow Up By: Robin Miller - Wednesday, Oct 20, 2010 at 14:26
Wednesday, Oct 20, 2010 at 14:26
OK Theo
Its possible that a wire has been heated and or broken by exhaust or fittment.
The oxy sensors have heaters that operate for a few seconds on start up (12v applied).
If this doesn't happen then a sensors could go off as
well leading to check light.
Don't know if you have
tools to see if they come up and generate a rough sine wave when warm , a DC voltmeter on 1 volt isn't the best because of slow reaction but can be used a bit to see a varying voltage there.
Because the oxy sensors are duplicated you can wire those two inputs on the ECU together and feed them with volts from just one sensor.
This is how I run
mine - (keeping the other sensor output for a modifyier for fooling the system etc)
This can be used as a comparison test between oxy sensors - also good if looking for a cheap solution as you can get away with 1 sensor.
No 1 plug comes out relatively easily , might be worth a look see.
Check light may keep coming on unless reset or battery off for an hour or so.
FollowupID:
704603
Follow Up By: Member - Beatit (QLD) - Friday, Oct 22, 2010 at 07:46
Friday, Oct 22, 2010 at 07:46
Thanks Robin, I am relatively low tech! I did take the sensors out and cleaned the threads which was also suggested on the Patrol
forum as
well as disconnected the battery for an hour but to no avail. The car appears to be running better so maybe this is still the problem.
I will now have it checked as it has moved past my capabilities - I do appreciate your help.
Kind regards
Theo
FollowupID:
704837
Follow Up By: Robin Miller - Friday, Oct 22, 2010 at 08:18
Friday, Oct 22, 2010 at 08:18
Hi Theo
Did read that thread , but a poor join there is a very unlikely event which really only would affect the heater warm up current anyway.
Also - not many people visit that old patrol4wd these days.
It would be good to extend your capabilities into checking a couple of plugs though.
No 1 is reasonably easy but you need to have good magnetic socket as they are down about 200mm.
The middle 2 (3&4) are a pain and require the throttle body and the part of the connected inlet manifold to come off. the last one against the fire wall is also hard to get to.
The ecu monitors the engine in two banks of 3 cylinders each hence 2 oxy sensors.
So by checking plug 1 & 2 you at least get some idea if either bank is running rich.
FollowupID:
704840