1.6NA Low Power

[joshb]

Howdy y'all,

I bought a 1986 Transporter Doka with a 1.6NA in pretty poor shape. The engine was covered with fuel and oil after running for any significant period of time. Prior to any work, I didn't have any issues getting up to highway speeds (topped out at about 70 mph) but certainly took a while to get there. I've performed the following work:

- New valve cover gasket
- Adjusted valve clearances
- New injectors (all 4 were stuck open and had a bad spray pattern)
- New injector heat shields
- New glow plugs
- New fuel lines, high and low pressure
- New rebuilt injection pump
- New alternator
- New belts all around
- New timing belt tensioner
- New exhaust downpipe
- New oil pressure and coolant sensors

I advanced the injection pump timing to 0.95mm, and the engine starts up without any trouble, no smoke, but feels very low on power and I can only get up to around 20 mph tops. I moved the pump timing back to 0.85 mm, and am getting the same behavior. The engine also seems to have a very slow ramp up when accelerating. In neutral, if I push the accelerator pedal to the floor I can hear it ramp up to what sounds like an appropriate RPM over the course of 3 - 5 seconds.

After installing the new pump the accelerator cable felt very loose, so I adjusted it at the pedal to remove some slack, and set the min/max screws on the pump by monitoring the alternator pulley with a laser tachometer.

Through a stroke of luck I have two rebuilt injection pumps and the original leaking one on hand. The one that's not currently installed has a stuck cold start lever, but I'm considering installing it to have something to compare against.

One other thing, my timing hole plug was missing, and there is a possibility that some penetrating oil / other nastiness found its way down there. Possibly onto the clutch?

This is my first time working on a diesel engine, and I'm a complete noob, any advice or troubleshooting steps would be greatly appreciated.

Just for kicks:


Original Condition:


Most Recently:

[ORCoaster]

Joshb,  Before you swap IPs to the one with the stuck Cold Start lever increases the fueling of your current pump.  That bolt-looking thing above the solenoid with the wire on it is what I am referring to. 

Loosen the locknut on that and turn the screw in by one-half turn.  The idle speed should increase.  Turn the idle adjustment screw out to make it idle slower. 

Now try a test drive.  Any better?   If not try 1/4 turn more and see how it responds.  That screw controls the overall fueling of the pump and it is possible to start dumping more fuel in the injectors than the engine can handle.  That gives you black smoke rolling out the tailpipe as you race the engine.

Let us know if that helps the situation.

I would find some sort of cap or plug to put in the timing inspection hole.  You don't want tools falling in there.  If you don't feel the engine revving up and the vehicle not accelerating then you don't have a clutch slippage problem. 

[fatmobile]

 You probably thought of this but
Does the accelerator go all the way to the stop when you floor it?
 Gonna take 2 people for that test,..
or I guess you could use a camera.

You have access to anywhere with a pulse detector to run a timing light?

[libbydiesel]

I'd increase the max fuel until it has reasonable power or until you run out of idle adjustment.  If you run out of idle adjustment before achieving reasonable power, then jump the accel lever a spline to give more idle and increase the max fuel screw further, etc...   

By 'stuck cold start lever' I take that to mean that the cold start lever cannot be rotated.  If that is the case, then that 'rebuilt pump' is likely damaged beyond where it is even a useful core.  The typical reason a pump has a stuck cold start lever is from water rusting the cold start parts inside the pump and usually that means that other sensitive parts are also rusted and ruined.  Often that happens because the pump was stored in a location with temperature swings and its ports were not sealed airtight.  That allows humid air into the pump and when the temperature drops, the humidity condenses inside the pump.  That condensation usually rusts everything inside the pump very quickly making it a paperweight.  I sure wouldn't take the time to install it without opening the cold start area and removing the pump top to inspect condition.   

[joshb]

ORCoaster - Thanks for the advice! I'll give that a shot and report back. I got a new timing hole cover and got that installed. I was having trouble getting the new timing hole plug surround to thread and 3D printed a dumb hand tool to help get some more force on it. If anyone is interested: http joshbillions.users.sonic.net slash three_dee slash timing_plug_tool.stl

Fatmobile - Good call, I did check this and made some adjustments. I'm getting full travel to the max adjustment screw now, but over did it a bit and the cable tension keeps me about 10mm away from the lowest position of the idle adjustment screw. The laser tach is showing around 1,500 RPM at idle when measuring at the alternator pulley right now. I'll go back and fix this.

libbydiesel - 10-4, I'll report back after adjusting the max fuel screw. Yeah, that first injection pump's cold start lever won't rotate at all even with a considerable amount of force. I originally purchased it from HansAutoParts.com and they shipped it from North Carolina to California in too big of a box and with the bubble wrap equivalent of single-ply toilet paper. When it showed up the accelerator lever had done through the side of the shipping box. I assume that something happened in shipping that damaged the cold start lever. To their credit they were super quick and friendly about getting a replacement pump out to me. Externally it looks pretty good to me, any chance that HansAutoParts.com is sending out good looking but bunk pumps?

If it helps enlightening anything here's that damaged pump:

[libbydiesel]

Hans has a terrible reputation.  I have heard quite a few stories of their pumps not working correctly and haven't heard of anyone who had one run well.  I think the odds are quite low that the pump will work correctly.  Hans isn't a place to get parts from if quality or function is important to you.

Did you get your current pump from them also??  If so, then a better course of action is probably to reseal your original pump (assuming that hasn't passed through Hans also). 

Max fuel affects idle and affects max RPM.  Because of that, it makes sense to adjust max fuel first.  Sometimes you have to switch back and forth, though, in order to get all three set reasonably and be able to test drive.   

Idle should be 850ish.  1500 is way too high and likely to cause the RPMs to hang when you lift your foot off the pedal.   

[joshb]

Whelp, that's what I get for trying to find a low price I guess. The currently installed pump is also from Hans, but the original is unmolested. It seems like with the time investment and potential uncertainty of resealing the original I might be better off talking to Giles about modifying what I have on hand?

[libbydiesel]

Considering it is running right now with the current pump installed, I would start with attempting to get a reasonable adjustment out of it.  Turn up the max fuel, turn down the idle, rinse and repeat.  If you run out of idle adjustment jump the lever a spline and turn the max fuel in more, rinse and repeat.  Not much to lose at this point. 

[joshb]

Point taken. Will report back.

[fatmobile]

 The timing curve could have something to do with the loss of power.
 If you knew someone with a pulse detector they could see if your timing was advancing.
 A thicker fuel can also help the timing curve.
 Some wax in the fuel if it's warm out.
 Or 2-cycle oil is a lube that's meant to burn and will make the fuel thicker.
Got clear fuel lines to and from the pump? See any air?

[joshb]

Adjusting the max fuel screw did absolute wonders. Thank y'all, much appreciated.

libbydiesel - I read past your advice to 'jump the lever a spline'. Is there somewhere I can read more about doing this?

[libbydiesel]

Don't mess with the accelerator lever to shaft orientation unless you run out of idle adjustment (lever bottoms out on pump top) and the idle is still too high.
 If that happens and you still need more max fuel, then jumping the lever to shaft orientation one spine is the thing to do. 

There is a line on the top of the accelerator shaft.  Mark a line on the lever to match that line on the top of the shaft as a reference.  You need to jump in the direction that gives more idle adjustment so the lever goes CCW relative to the shaft.  Loosen the nut on the end of the shaft, lift it up, rotate it one spline, tighten it back up.  The idle screw will need to be adjusted out quite a bit and the max fuel will need to be adjusted in more.  That adjustment will consequently change the amount of slack in the accelerator cable. 

[fatmobile]

 And if you go too far the RPMs will hang.