tb42 not return to idle (hanging)

[bobbrumby]

most of the time after driving and coming to a stop the idle will hang up arround 2000rpm then drop to idle. It seems to do it more once its heats right up the idle will hang at 2000rpm for ever it sparatic though sometimes it will return to idle. No ammount of throttle jabbing helps and this happens on both gas and petrol, once when i closed the hood the idle increased (the air cleaner rubs the hood becuase of lpg ring). Would this appear to be a vaccum leak of some sort, maybe carbi base or the joint between the lpg ring??

[YNOT]

EFI or carby?

If it's an EFI engine check this thread; http://www.nissanpatrol.com.au/forum...erature+sensor

and this thread; http://www.nissanpatrol.com.au/forum...eed-adjustment

Tony

[bobbrumby]

nope carbi sorry

[patch697]

It very well could be & I'd be checking that out for sure but the fact its happening on both fuels suggests its more like a vac leak somewhere.

Grab yourself a can of CRC or WD40 & with the engine running slowly spray a little around the vac lines (one by one, the carby & the inlet manifold where anything joins to it including where it bolts to the head.

If at any point the idle charges then you've isolated a vac leak that needs to be fixed.

Get back to us & let us know how you get on with this.

[bobbrumby]

i could not find any vacuum leaks but did find out the when it actually happens, you dont need to put the motor under load, its just when rolling. Like when your on a hill, clutch in, take off with gravity and the idle increases in both the forward and reverse directions.

[gec]

I had some thing similar with mine when it had the TB42 in it, I found that when I rolled up to a stop sign or intersection in neutral or with me foot on the clutch then it would hold the revs up until after I stopped, but if I rolled up in gear and depressed the clutch just before stopping then it didn't do it, I never found a reason for it and it never made any problems that I saw so I just changed the way I drove because it used to pee me off.

[bobbrumby]

the pvc filter (i am guessing) in the side of the air cleaner was very oily is this meant to be washed occationally?

[patch697]

the pvc filter (i am guessing) in the side of the air cleaner was very oily is this meant to be washed occationally?

you can block the PCV off to see if there's a change in your problem & if its the issue then replace it rather then clean it. Its not an expensive part so well worth just replacing if faulty.

[Silver]

there is electric and vacuum controlled anti pollution gear on TB42s that is meant to keep revs up when decellerating. It is intended to prevent unburnt fuel going out the exhaust.

This can play up, and since I don't understand how it works, I don't know how to fix it. Maybe one of the better informed and more experienced of us can assist.

I had a similar issue with an MQ L28 motor, and I couldn't sort it out, nor could a couple of mechanics I spoke to

[bobbrumby]

Just reading throught the manual are you refering to the "ANTI-AFTERBURNING CONTROL SYSTEM" p249 of the manual?