<span class="highlight">Wiring</span> up a Turbo Timer in GU 3 litre Patrol

Yes, quite right Ross. I must admit I am a little bemused by the concept behind a turbo timer. As you pointed out it is illegal to leave the vehicle running so why not just let it idle down for a couple of minutes while you make sure your hair is combed and the nail polish is dry. (;-))

I'm assuming here that drying the nail polish is why some drivers, male or female like to hang one arm out the window while the vehicle is in motion.

Cheers
Pop

Hi Ross: Thank you for your input.

The MAF sensor is used because it has high co-relationship with engine speed and thus assumes that high engine speed probably means that the turbo is working hard too. The integrated circuit monitors the voltage from the MAF and compares it with a threshhold voltage many times per minute and uses this info to work out how long the engine needs to idle for cool down, giving more weight to the last 25% of the data stored in any 5 minute block.

This is a fairly crude and very brief overview as to how it works but you can get the general idea.

It is supposed to be an "intelligent turbo timer" only allocating cool-down time if the engine has been working hard, overcoming the annoying habit of engine run-on even though it hasn't done any work. ie starting the car and backing it out of the garage then turning the engine off!

I do take your points but in essence by monitoring my EGT and scan gauges along with the ability to adjust the threshold voltage that the unit uses it is easy to set up and surprisingly accurate in its automatic allocation of time reqd to get down to 175 degC, which is my temperature of choice.

I just have to get it working with the Patrol ignition circuit now.
Thanks for the description of what is reqd it is very helpful and makes great sense.

warm regards
Thommo

503
I can see the relationship of the MAF and the theoretical speed and load inputs BUT I can't see how it can then tell how hot the turbo IS or how hot it will remain hot for, OR how long it needs to run at idle to allow the required cooldown amount.

A simple temp sensor located near the turbo will always do it every time with no variations.
Every vehicle will be different with relation to the airflow around the turbo and the heat dissipated by the turbo during the cooldown period.
Therefore the MAF involvement , while a trendy/unique way of sensing, really won't mean anything as it can't tell if the turbo has cooled down or not.
It is the turbo you are trying to protect isn't it?
The involvement of more electronics will only complicate things and I wouldn't be placing my trust in it to save a turbo.

Simpler the better, or just wait a minute or two.
I used one for 25 years and usually just waited until time passed meant cooling had occurred, the timer only ran sometimes but I didn't rely on it.

Ross M

Thanks Mike, I appreciate your guidance.

I have taken a jumper from the MAF sensor and compared the results with the Scan Gauge read out before and after and can see no difference, volts for given RPM according to the genuine Nissan Manual.
It really is very easy to keep your MAF honest thru the use of ECU talk and the real time voltage readout from it.

eg
Engine - ignition ON engine stopped Maf voltage approx 1.0 volt
Engine idle- normal op. temp Maf voltage 1.6 - 2.0 volts
Engine idle - 4000 RPM Maf voltage 1.6 - 2.0 to approx 4.0v

cheers
Thommo

Hi mate I have a boggard turbo timer and it will only engage the delay shut down if the car has been running for over ten seconds so in your situation if you started the car and it was in gear you would just turn it off as per normal with the key, not sure what brand you have but this should of been something yours should of had? With your handbrake applied even with the car in gear it should of stalled anyway? I don't believe they are unsafe as long as you use them sensibly. I always rock the gear stick before turning the key if in your situation but I can see how you can get busy trying to pack up and overlook this. Glad no one got hurt and can see how the scare made you remove yours.

Hi Peter:
Thanks for taking the time to reply.
That was indeed a close call, but as "jacent" pointed out that wouldn't have happened if you had an "intelligent" T/Timer.

Thanks again for sharing this incident with us. It highlights a very dangerous practice which I'm sure most of us are guilty of doing at some time or another, starting the car from outside the vehicle through the open doorway.

This is exactly what killed outdoor legend "Malcolm Douglas".

He stopped close to a tree. When he tried to start the vehicle standing outside but inside the door it lurched forward, still in gear, and he was crushed between the door and vehicle as the door pushed hard against the tree.

We should all learn from this!

Thanks again
Thommo