QD32T Driving with Timing Advance Solenoid ON

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Carnage
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QD32T Driving with Timing Advance Solenoid ON

Postby Carnage » Tue Aug 23, 2016 2:36 pm

Hey guys, first post but loooong time lurker. I've been working on my rig (ZJ) for almost a year, (Grand Cherokee '98 Limited). I've swap the 5.2 V8 for a QD32T (was a QD32ETI but swapped the IP from a TD27T), the tranny is a RE4R01A+ATX14A transfer case. Last week I'd finally finished most of the electronics so the rig was (finally ) ready to drive. I drove it around, but was not much impressed, as it needed some tweaking. I had trouble starting it up (winter here) so I figure that I should connect the other solenoid of the IP, Wow, I was amazed, the vehicle with the Timing Advance Solenoid ON drove smoothly had a ton of power and really was a change like from night to day, so I wanted to try it further and got on the road, drove around 200KM max speed 120KM/H and when I arrived home to check everything, I was amazed, the engine was way cooler than I expected, oil was good and everything seems fine. So here is my question. Is there any long term problem (to the engine) to drive it with the Timing Avance Solenoid always ON? I ask that because for my experience it was all PROS and no CONS.
Thanks for your help Guys.
Nathan from Chile

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tweake
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Re: QD32T Driving with Timing Advance Solenoid ON

Postby tweake » Tue Aug 23, 2016 6:41 pm

Carnage wrote: Is there any long term problem (to the engine) to drive it with the Timing Avance Solenoid always ON?

quite possibly.
i'm not sure on the way those ones work. i suspect its a block the return flow setup. constant use means the IP won't get proper cooling.

how did you set the pump injection timing?

if you need to advance the timing to make it run, i suspect your base injection timing is way off.

Carnage
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Re: QD32T Driving with Timing Advance Solenoid ON

Postby Carnage » Wed Aug 24, 2016 4:28 am

I got this from the FSM:
DescriptionTo improve startability, a solenoid timer is used on models for cold
areas. Its purpose is to advance fuel injection timing in relation to
coolant temperature for a certain period after starting the engine.
This timer is controlled by the signal from the glow control unit. The
glow control unit sends a signal to activate the advance mechanism
of the fuel injection pump during cold starting.

timing_operation.JPG
Timing Advance Solenoid Operation

OperationPart of the fuel in the return line returns to the fuel injection pump
inlet, when the solenoid timer is OFF. When cold starting, the solenoid
timer comes ON to stop the return of fuel to the inlet. This
increases the fuel pressure in the fuel injection pump so that fuel
injection timing advances. The duration of fuel injection timing
advance varies with changes in coolant temperature.
The figures show the differences in fuel injection timing in relation
to engine speed when the solenoid timer is both ON and OFF.
When the solenoid timer turns ON, fuel injection timing advances
by approximately 2°. Thus, cold engine starting in cold weather is
greatly improved.

QD32_timing.JPG
QD32 Timing Curves

It doesn't need the advance solenoid in order to work, but it work much better (power, temperature) with it ON.
So tweake you are correct as it block the return flow, however I don't see how this can cause damage, my background is electronics not mechanics so please bear with me, thanks

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tweake
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Re: QD32T Driving with Timing Advance Solenoid ON

Postby tweake » Wed Aug 24, 2016 8:09 pm

Carnage wrote:So tweake you are correct as it block the return flow, however I don't see how this can cause damage, my background is electronics not mechanics so please bear with me, thanks

it sounds similar to what mitsi (i think) uses.

injection pumps pump a large amount of fuel through the injection pump and back to the tank. this is for lubrication but also cooling.
when the solenoid is on and is blocking the return to the tank (to increase the timing) the fuel is not going back to the tank to cool down.
thats ok when the engine (and injection pump) are cold. but using the solenoid all the time will mean the injection pump won't be cooled by the fuel, which will cause increase wear and possibly out right failure. i don't really know what will happen when you cook an injection pump.
i know one diesel engine that doesn't return the fuel back to the tank and the fuel goes back to the inlet, but that has a fuel cooler on the pump inlet and i think it has a bonnet scoop to get air flow to the fuel cooler.

i would advance the static pump timing a couple of degrees.
fit your dial gauge and read the lift of the pump. keep record of the settings and try different amounts.
advance it until it has loads of injection rattle then back the advance off a bit.

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Re: QD32T Driving with Timing Advance Solenoid ON

Postby Carnage » Thu Aug 25, 2016 6:11 am

Tweake, thanks for your reply and help, however there is something that still confuse me. The advance solenoid when ON just cut the internal flow in order to stop the return of fuel (to increase pressure) to the inlet but not to the fuel tank, fuel is still being returned to the tank. After searching for the operation of the "normal" IP (not for cold areas) it looks that is doesn't have this internal flow, so it appears that it works just like the "cold areas" IP with the advance solenoid ON, being the only difference the timing calibration of the pump.
So I could guess that if the avance solenoid is ON when the timing calibration occurs it won't act different as a "normal" IP. What do you think, again please bear with me as my background is electronics not mechanics, thanks

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tweake
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Re: QD32T Driving with Timing Advance Solenoid ON

Postby tweake » Thu Aug 25, 2016 5:40 pm

might pay to check the operation of the solenoid or what fuel goes where.

if solenoid is open in normal use (engine hot) then theres probably a restriction on the return to the tank.
this may be a setup for cold areas only.
having hot fuel go straight back into the pump inlet is not good in a warm-hot country.

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Re: QD32T Driving with Timing Advance Solenoid ON

Postby Carnage » Fri Aug 26, 2016 4:05 pm

Tweake it appears you are correct, as this is for cold areas only, as having hot fuel go straight back into the pump inlet on warmer weather areas will cause a sever diesel degradation (not to mention when this hot recirculated % get back into the tank, what a mess it will cause.
I guess this is why it's working much better with the Timing Advance Solenoid ON, guess the pump is really for cold areas only.
Thanks a lot for your help, I'm having another question that I made a new topic:
viewtopic.php?f=25&t=46606
Hope you can help me out

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