Nissan Patrol 4x4 (Africa)

Hi All,

Okay....seriaaas brain teaser:

Just had the Trol into Constantiaberg Diesel to have the injection pump re-calibrated. Got it back on Friday Afternoon.

Initial test drive I noticed that there is an intermittent power loss. With a bit more driving today this is what I discover:

1. The power loss is directly related to the Air-Con compressor cutting in and out.
2. In a situation where the van is accelerating at full throttle/full boost (0.5bar), switching on the air con immediately results in boost and EGT`s dropping drastically. Boost falls off to no more that 0.2bar and EGT falls back by 150-200degrees. Since EGT drops with a drop in boost, I summarize that somehow the fuel is being cut when the air-con cuts in, which causes the turbo to stop spooling. If the air-con is switched on when pulling away, the turbo doesn`t spool up, and there is no power.

I cannot for the life of me think what mechanism could possibly cause these symptoms. Can only imagine something has been connected incorrectly when the injection pump was re-installed after the calibration, however I`m not aware of any commonality between the injection pump system and the air-con system. No funny noises coming from the air-con compressor when it kicks in, and the air-con functions normally



Any thoughts???

If I leave the Air-con switched off it behaves perfectly, and pulls like a freight train.

This is a long shot,

There is a valve on the righthand side of the diesel pump, it pulls the throttle slightly open when the AC is switched on.
This valve is operated by vacuum, check that all vacuum pipes are on properly, you might have a air leak somewhere.

ALSO -- get the diagram of said vacuum pypietjie .. ensure they are in the corrct positions


[referreng to the vacuum pipes here - NOT referring anything about anybody's bedroom .. Cedric !!! gaan slaap]

Ross this is a strange one ....let see what the story is

Okay...a bit more investigating:

The "Idle up" function when the AC switches on is not working (was definitely working previously!!). From what I`ve been reading this is a vacuum system that connects to a diaphragm on the injector pump. I suspect they have not connected this line correctly, which could cause fuel to be cut instead of increased when the AC gets switched on (pulling the diaphragm in the wrong direction).

Will drop the van back there later today and ask them to investigate along those lines. Should be a fairly quick and simple fix, if the current most likely theory (described above) is correct. Here's hoping!!!

Keep us posted ...interesting one

me think something else. Want to hear more before I quote

Oom Mac.... sies .... ek is nie sooo bad nie....

Our trucks are all mechanical, so its definitely not electrical.... but these diesel pumps are really something I know nothing about, ......Baas Frans.... ek wag hier om te leer man....

Ross, can you post a few pics of the offending pipes?

Sorted!!

The Vacuum line from the "Idle Up" Solenoid on the firewall had accidentally been plugged into the port of the altitude compensator on top of the pump, instead of the correct Aircon Idle Up port lower down on the pump. Fixed in 2 minutes (with many apologies!!) by Colin at Constantiaberg Diesel after I had explained all the symptoms and observations. All working perfectly now

Every time I switched on the Air-con....my Trol thought it had climbed Mt Everest!!! At least I know that my Altitude Compensator works!!!

Brilliant Bud !!.... The 'ol beast roars back into action !!