Hi all,
I have an 89 Master Ace Surf and just finished our first road trip with it. This is what I noticed:
When slugging up a hill, slightly gaining speed, about 100 rpm every 10 seconds, with a steady throttle, as soon as it crosses 3300 rpm I hear the turbo spool up significantly and it accelerates faster, maybe 100 rpm every 3 seconds or less. It happens instantly.
Conversely, when slightly loosing speed up a hill, when it drops below 3300 rpm, it feels like I have instantly pulled the parking brake half way and we get out and push it the rest of the way up the hill.
Is this normal? I have not had a diesel or any turbo vehicle before, but it seems to me that since the turbo is exhaust driven that it should provide a smooth power increase.
Thanks for your help - this is an invaluable resource for me as I am in Canada where there are virtually no Toyota diesels.
- (#392) Richard, 29 Mar 05 08:18
Probably the way the diesel pump has been setup. You might try adjusting the boost compensator, it's noted in the archives...
BTW, am I to presume that there's no visible smoke?
- (#392) david miller, 29 Mar 05 08:49
There is some smoke when working it up the hills.
When I recently got the van, I was told to turn in the main fuel adjusting screw until it smokes a little bit up the hills. I turned it too far at first and it had more power and horrible fuel economy. I have been slowly turning it out since to find the best balance between power and fuel economy.
Our last trip was mostly highway driving btween 90 and 120 km/h and we got 28 mpg, but I want to get more than that. In town it gets less.
Also there is no MOT emissions testing here, so there is a bit more freedom in setting up the fuel pump, and I was considering disconnecting the EGR valve - is seems reasonable to think that air will burn better than exhaust and that there should be more power and efficiency there. Is that correct?
Thanks again for the advice, and I will look up the boost compensator adjustment in the archives...
- (#392) Richard, 30 Mar 05 00:22
Yes, disconnecting the EGR is a Good Idea. Especially if the valve is leaky...
That's pretty high revs that the turbo is spooling up at. You should really be seeing the green light coming on at around 1500rpm, with full boost being achieved at less than 2000. It might be worth stripping and cleaning out the hoses from inlet manifold to the top of the pump- especially the little spigot in the manifold, it can get clogged with carbon gunk from the EGR. Might also be worth sticking a boost gauge on (even short term), do this if you can and report back what levels of boost you're seeing and at what revs they are seen.
- (#392) david miller, 30 Mar 05 01:09
Actually, the turbo light does come on around 1500 - 2000, and I can hear it running all the time (the whine is fairly quiet).
If I stop on a hill, manually shift the auto transmission into first so it wont shift up, the rev counter will increase slowly up to 2500 rpm, ( it is quite slow off the line), then it will pick up speed faster until 3300 rpm from which point the engine literally takes off. There are two stages of significantly noticeable power increase as the engine revs up, the most significant is the post 3300 rpm stage.
Regarding checking the turbo's hoses, are you referring to the the large diameter intake and exhaust hoses or are there other smaller hoses that can get clogged. Is the "little spigot in the manifold" the place where the vacuum line from the boost compensator connects to the intake?
I have some photos of the turbo at the following address in case that will be helpful in identifying the hoses I need to check:
http://www.clearcomm.ca/TVP/index.html
To disconnect the EGR, is it as simple as putting a blocking plate at the valve, or should it be blocked at the exhaust manifold side as well? WHen I replaced the head, I was not able to undo the EGR line at the exhaust manifold due to rusty bolts, little access to the bolts, and limited time at the shop I was using. It would be easy to block it at the top though.
thanks again,
richard
- (#392) Richard, 30 Mar 05 08:41
Ah so 3300rpm before hearing the turbo is with it locked in first - that makes more sense. Sounded worrying because personally I normally regard about 3200rpm as my "red line" and the turbo starts much earlier in Drive, as you say.
I suppose that in first the rpm can go up high with little torque and therefore little exhaust to spin the turbo. I recall having this trouble when setting off from cold to go up a hill - not enough power without the turbo and without the power you can't get turbo. In extreme cases I've had to enagage 4WD and "Low" (though with front hubs unlocked) just to get up the hill. One good reason for having the 4WD version.
- (#392) Dave Mason (Sussex), 30 Mar 05 10:27
Simply blocking the egr at the intake is fine.
You've got the right hoses to check, the little ones. But if the turbo light is coming on they're probably OK.
I definitely feel that the boost compensator needs a tweak- might be worth taking it off the top of the pump and ensuring that the linkage isn't sticking (the manual recommends filling the plunger's slideway with oil). Mark the diaphragm's position against the pump body before removing it...
Locked in first, the torque converter will be slack until 2k or so but you *should* have a fair bit of boost at this point and releasing the brake with that many revs on the clock should resuly in a sharp getaway.
I'd definitely try to arrange a boost gauge of some kind, even if only short-term, to help us set the pump up.
What altitude are you at, BTW? Nothing too high?
- (#392) david miller, 30 Mar 05 11:07
We are at about 400m, and the van was originally sold in Tokyo, which is at sea level, I believe. There are times that we would be around 1000m + but only when we are off road.
I will try to find a boost gauge, maybe there is a mechanic around that will loan one out for a while. Does it simply get connected into the boost compensator pressure hose (the only one from the boost compensator). Can I make a gauge with any low pressure gauge and adapting it into that line?
Thanks for your help...
And to clarify the phenomena for Dave, when slugging up a long hill, if I can reach 3300 rpm, we will make it up at speed - the turbo spools higher and the power increases significantly at, for example, 3350 rpm. If we are slowly losing speed when going up the hill, as soon as it drops below 3300 rpm, we will instantly lose a significant amount of power, similar to what applying the parking brake half way or so would feel like.
It is also evident when locking it in first on a steeper hill, with a constant throttle position and it will have slow acceleration until 2500 rpm (not quite needing to be in low range, though I am relieved to find that it is normal to almost need it), and then as you would prepare to shift into second, if you reach 3300rpm, then in a flash you will be at 4500 rpm. I am like you as I regard 3500 as the redline, which is why I was so surprised by the sudden burst of power. The reason I was manually shifting was so I would not have to have my foot so hard into the accelerator in order to keep the revs up before it shifts into second. I guess that I am pretty cheap when it comes to fuel - it is up to 90 cents/litre now.
- (#392) Richard, 30 Mar 05 22:26
Any pressure gauge will do- you only need 0-15psi or so and yes, tap it in to the compensator hose.
At those altitudes, we shouldn't need to worry about derating the motor...
- (#392) david miller, 31 Mar 05 01:12
I finally have a pressure gauge set up in the van and found that the maximum boost pressure I can get is 7.75 lbs. Is that low? I seem to remember 10 lbs being the rated boost.
I have not opened the boost compensator yet. Is it as simple as removing the top of the boost compensator, painting a match mark from the diaphram and housing, lifting out the diaphram, and making sure that there is oil in the guide?
Why is it important to replace the diaphram in the same location as it came out?
Anyway, what do you think I should try in tweaking the pump?
Thanks for your time,
Richard
- (#392) Richard, 2 May 05 00:48
Hmm, that sounds no too bad. Spec is 7.7 to 9.7.
The lid comes off the boost compensator easily, but yes, you must mark the diaphragm. The actuating plunger beneath it has a taper ground in it- it's this taper that controls the fuel increase on boost. But the taper is ground eccentrically (to offer adjustment).
Check that the stop "button" inside the compensator cover is actually contacting the end of the plunger, before marking and removing the diaphragm and plunger. Under the diaphragm you will find a spring and probably a shim.
Gently operate the throttle lever, you should see a plunger/ pin pop out of the front of the "guide". This is what the taper acts on, to control the governor. You'll need a screwdriver or similar to push it back in, but do this a couple of times to verify that it's free- it's not unknown for this pin to seize up causing allsorts of intermittent fuelling problems.
If this is all OK, reassemble, but set the diaphragm so that the taper is slightly deeper at the front (towards the front of the car, where the sensing pin is) than it was. Maybe 1/2" of rotation at the edge of the diaphragm, say 5deg or so. This will increase the fuelling slightly on boost.
Give that a try and come back to me.
- (#392) David Miller, 2 May 05 03:42