01/93 1hz problem

[sup8pdct]

My std 80 has a problem between 65 and 70 kmh in 5th.
While driving along a flat road, engine working only to maintaine speed, the car hunts ie feels like 3 cylinders are working hard, the other 3 only half as hard, ie bouncing foward and back.
The injectors are less then 100,000km old, have checked the valve clearences (was a problem that caused the above all inlets were at 0 clearence or less) The injector pump is the unknown factor here, tho the injectors could be dirty.
Same problem in 4th between 55 and 60.
should I change the pump or the injectors?

james

[Sweeney]

Why are you in 5th while driving at 65-70kmph? This puts undue stress on engine.
You should only use 5th from 80kmph and higher, 4th for speeds 50-100kmph.

[Z()LTAN]

get the revs to 3k at each gear change.

When cruising go to 4th when going under 90kmph

[sup8pdct]

How many people do that?
If that was the case, just about everywhere I go will be in 4th while towing the camper.

James

[oldmate]

I have noticed this on a couple of 1hz. I think it could be in the pump but would also be interested in what others say. i think if it were the injectors there would be smoke.

It seems to happen, as you say, when the engine isn't under load. But it feels to me like it happens at a specific rpm. somewhere 1700rpm ish.

Also what are you saying about the valve clearances 'caused the above'?

[sup8pdct]

I had noted the problem before the injectors were changed, (3 years ago)
It was still there after the change of injectors. So I checked the valve clerances and all inlets were at zero.
So bad that most had groves worn in where the followers wern't spinning.
Changing them and a little settle time latter, did a compression test, all even. The problem seamed to go away.
Now it is back, this time the valve clearences are ok, so there has to be another/same problem.
The pump has never been serviced since I have had the car.
Going on a big trip in july-august. want to get car going as well as I can get it.

James

[Sweeney]

How many people do that?
If that was the case, just about everywhere I go will be in 4th while towing the camper.

James

I have always driven crusiers that way. In the higher gears, I change around 2700-3000rpm to keep the engine in it's comfort range (peak torgue range is around 2200-2800rpm). I also tow in 4th gear.
Driving around in a too low rev range for a particular gear will make the driving response sluggish. In other cases where the revs are too low (e.g. 800-1100rpm in 3rd) can give a bucking sensation (from the engine) or severe resonance through the drivetrain.

Are you getting a bucking sensation?
You mention that some of the intake valves had previously incorrect valve clearance. Are the compression test figures within factory specified range? What are the differences between the cylinders?

[sup8pdct]

How many people do that?
If that was the case, just about everywhere I go will be in 4th while towing the camper.

James

I have always driven crusiers that way. In the higher gears, I change around 2700-3000rpm to keep the engine in it's comfort range (peak torgue range is around 2200-2800rpm). I also tow in 4th gear.
Driving around in a too low rev range for a particular gear will make the driving response sluggish. In other cases where the revs are too low (e.g. 800-1100rpm in 3rd) can give a bucking sensation (from the engine) or severe resonance through the drivetrain.

Are you getting a bucking sensation?
You mention that some of the intake valves had previously incorrect valve clearance. Are the compression test figures within factory specified range? What are the differences between the cylinders?

As I don't have a taco, I cannot give rev range, but would say it is above 1100 rpm. 4th is somewhere near 55kmh. can feel it in 3rd. easy way to make it stop is to put foot down. Light constant load with light throttle is when it shows but only at those speeds.
Yes, is a bucking feeling.
Did it some 2 years ago, but was withing factory range and highest to lowest was about 15 psi.

James

[sup8pdct]

Took it to KM diesel.
At first they said it proly isn't a pump problem.
Then they pulled it out and inspected it.
Many parts stuffed. $2500 to fix..........
Ouch!!!!!
Going to pick it up soon.....


James