Diesel injection timing

[markp2]

Can anyone tell me whether the injection timing on a Gen 3 Surf is purely mechanical or whether it is adjusted by the ECU?
Reason for asking is that after fitting an intercooler set up from another Surf along with the intercooed ECU, the engine makes a very rough noise if you use more then 30% throttle.
If it was a petrol car, I would decribe the noise as similar to extreme pinking/detonation due to ignition timing being too advanced. The truck runs very quietly and smoothly up to 30% throttle opening and then changes tone dramatically when you open it up.
There isn't any smoke and performance is good (better than pre-intercooler) but I would like to get to the bottom of the problem before I potentially damage the engine.
Any info would be helpful,
Thanks,
Mark

[surfenstein]

Can you not refit the original ecu and see if you have the same problem.?

[markp2]

Yes, that was going to be my next move. Just trying to avoid dismantling the glovebox to get at the ECU again, if it is likely to be something else!
Thanks,
Mark

[Gazbo]

ECU i would of thought. Different air pressure and readings

[TonyN]

Too advanced timing results in loud knocking on diesels, you can't over lean a diesel, and to much fuel just makes black smoke so it must be a timing issue.

The timing is decided by the Crank position sensor, speed sensor, TPS, fuel/air temps... etc, all pretty complicated and the ECU then tells the Timer control valve when to squirt fuel.

The only thing you've really altered is the air temp, I wonder if the Air temp sensors are different, or read on a different scale and its confusing the ECU.

Or maybe the pump isn't calibrated to work with that ECU, and can't cope with the timer control valve signals.

Lots have people have just fitted intercoolers with no problems, I don't anyone yet who has tried an Intercooler ECU with a non-intercooler pump.

I'd try the orginal ECU first, if it goes away you'll know its a pump/ECU compatabilty issue. The only real option then is to just run it with the old ECU, or try the Pump off the intercooler truck (I still have it) but is a lot of hassle for unknown gain.

[markp2]

Thanks for the info. Timing is the conclusion I had come to as there isn't any smoke.
I have tried the old ECU. If anything, it is worse and the engine check light has come on.

The air temp sensor (black plastic widget in the black plastic pipe near the flexi hose) is between air filter and turbo so this shouldn't have changed.
I have connected the pressure sensor to the underside of the intercooler. On the normal manifold there is a takeoff pipe close to the PAS reservoir. However this is downstream of the throttle body whereas the intercooler is upstream so this may make a difference.

What does the smaller throttle valve do? It is connected to a diaphragm valve of some sort. The std 3.0 has two of these but the I/C engine only has one. I have connected it to an outlet at the base of the throttle valve but don't really know whether it is vacuum or pressure operated!

There is also a grey sensor on the underside of the intercooler itself. Not sure what it does. I have nothing in my loom which fits this and am wondering if I should!

Tony, I sent you an email at your toyota address as your inbox here was full (popular chap!) - have you received it?

Thanks,
Mark

[NiftyNev]

What does the smaller throttle valve do? It is connected to a diaphragm valve of some sort. The std 3.0 has two of these but the I/C engine only has one. I have connected it to an outlet at the base of the throttle valve but don't really know whether it is vacuum or pressure operated!

It's partially closes it at certain times for EGR operation and closes completely at engine shutdown. It's vacuum operated. Where have you connected it? Got a pic?

Nev

[markp2]

Hi Nev,
Thanks for the comment about vacuum operation. I had assumed that the inlet manifold would have a vacuum (like a petrol engine) and had connected the actuator for the small throttle butterfly to the underside of the throttle body.
I had another look at the engine yesterday and spotted what looks like a vacuum pump attached to the power steering pump with a tiny metal tube leading up to the cylinder head. Hooked the actuator into that and it now runs better and shuts down smoothly although the idle is now rather low.
I also swapped to the Intercooler ECU again but this produced clouds of black smoke (overfuelling) and no idle at all (swapped straight back). Strange that it had the opposite effect before I connected the vacuum supply!
My experience with diesel engines is largely with 1970s and 80s agricultural tractors which have no throttle bodies or butterfly valves. It is surprising how different a mid-90s 4x4 'electronic' control engine is.
Sorry no pics - keep forgeting to take the camera when I go to my workshop.
Mark

[NiftyNev]

Hi Nev,
Thanks for the comment about vacuum operation. I had assumed that the inlet manifold would have a vacuum (like a petrol engine) and had connected the actuator for the small throttle butterfly to the underside of the throttle body.

No the inlet manifold is usually under pressure especially when the turbo is boosting. Does get a very small vcacuum at idle and on engine shutdown.

Where is this you connected the hose to previously? Not where the turbo sensor is, or should be? Was unaware of any other manifold port on the 3Ltr.

Nev