Part throttle surging and wierd noise

[Rising]

Okay so I've been meaning to get some feedback on this issue for awhile, but it just hasn't seemed to be a big problem till tonight. I've noticed with this engine that I've been getting some throttle surge as I accelerate. Mostly noticeable in 1-3 as they are shorter gears. I.E. throttle position is static and the engine seems to climb to a certain rpm, then it feels like a goosed the throttle for about 150 rpms and then goes back to normal acceleration. This is pretty annoying when driving around casually in 1-2 around neighborhoods and also when trying to save gas and being light on the throttle. 

But tonight it started to worry me because right at that rpm it starts to accelerate and makes an awful noise. Like BAD. Grindy knocky sounds. So now I'm worried that another engine is going to fail me Is this slight runaway? Failing pump? Failing engine? What's going on here?

I just got home and I'm too tired to write more. I'll try to get a video and investigate more tomorrow. . . hopefully someone has some insight on this.

[ORCoaster]

SURGING the man says.  Wait while I apply the cranial enhancer mega force analyzer.  Chin strap on and powered up. 

So, I think you are on to it somewhat in that it may be related to fuel.  But not from an outside source like crankcase.  Although I wouldn't rule out that possibility until you yank the hose off the intake for a couple days and see if that helps.

I am going with fuel pump here.  It is sticky in side and when it lets go the pressure builds and you get a bump in the advance.  It may very well be that advance piston it self.  Ever have the IP apart?  How about those little bitty pieces of metal that slide in and out of the vane pump.  They sticking?  Don't tell me you have an air leak on the pump. 

The grindy knocky sounds would have me looking at the transmission and axles for worn or binding parts.  They hold then pop out and all is good then bind up again some how.

Transmission full of oil? 

OK that is all the battery life I have in the thinking cap for now. 
Anyone else care to thow knives at the woman on the rotating wheel? 

[fatmobile]

Surging is usually caused by loose injection pump bolts.
 Either the 4 that hold it to the brackets or the others that hold the bracket to the block.
 Look down behind the pump and see if those two bracket bolts are still there. I blue lock-tite those now.
 
 Usually occurs with a vibrating accelerator peddle.

[rs899]

^^ x2, from personal experience....

[Rising]

Okay excellent work with the cranial enhancers. A. The fuel pump makes sense. I will check the bolts today but I don't feel like that is it. Its very consistent to be loose bolts. Its always the exact same rpm range. But a sticking advance piston makes tons of sense. I actually thought that as soon as I woke up this morning with a clear head.

Okay so I've never done anything to my injection pump. The biggest thing I've done besides setting the timing is adjusting the fuel screw and the idle set screw. (For reference I turned the fuel screw down a 1/4 turn to save some more fuel ) How do air leaks form/how would I know? They are some bubbles at my injector return hoses but i always thought maybe my hoses were weird or something.

What about running something through the injection pump? Should I run atf or sea foam straight through it? How could I unstick some stickiness? Or maybe its time for a Turbo diesel pump ;D;D

As for the grinding to clarify. It happens in neutral parked with me at the front of the engine and only as the rpms do their surging gig. But nothing at idle or slight throttle.


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[TylerDurden]

Bubbles in the injector returns are normal.

Clear fuel lines from the filter and to the return line will show if/where air is entering the system. About 3' of tygon tubing will cover both runs.




The grinding noise is a concern... does this happen even when the engine is cold?

I'd take out the IP OUT bolt and look for grunge in the screen, then clean it with brake parts spray.

Then I'd run a can or two of Diesel Purge - stick both tubes from the IP into the can and run it till the cleaner is consumed. The cleaner will circulate back to the can a lot while the engine is burning it as fuel.

[Rising]

Okay well as usual I'm dumb and missed something obvious. Haha. Fat mobile hit the nail on the head.  The back bolt by the oil dip stick was missing from the injection pump and after sourcing a new bolt and tightening everything up. The surfing and the rattling noise are gone.

Grinding was a bit of a stretch on the noise i guess as it was definitely caused by the loose IP. Glad I caught this though.

Anyway I still want to run a bit of diesel purge through it for the heck of it. I just replaced my return line with solid line. But my supply line is already clear. No bubbles coming from the filter.

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[8v-of-fury]

The biggest thing I've done besides setting the timing is adjusting the fuel screw and the idle set screw. (For reference I turned the fuel screw down a 1/4 turn to save some more fuel )

FWIW, you have saved no fuel by doing this modification. . This is a diesel with no throttle plate, there always needs to be x amount of minimum fuel for y amount of RPM. So if you are still turning the same RPM, then you are still injecting the exact same amount of fuel you just have to push the pedal further now.

If you REALLY want to save more fuel, take the right foot 1/4" off the pedal at all times. this will save more than you think haha.

[Rising]

The biggest thing I've done besides setting the timing is adjusting the fuel screw and the idle set screw. (For reference I turned the fuel screw down a 1/4 turn to save some more fuel )

FWIW, you have saved no fuel by doing this modification. . This is a diesel with no throttle plate, there always needs to be x amount of minimum fuel for y amount of RPM. So if you are still turning the same RPM, then you are still injecting the exact same amount of fuel you just have to push the pedal further now.

If you REALLY want to save more fuel, take the right foot 1/4" off the pedal at all times. this will save more than you think haha.

Surprisingly I believe I knew this already haha. But good info for everyone anyway.

I understood that right foot = fuel injection quantity. However when I added a 1/4 turn to the fuel screw my fuel mileage took a hit. Presumably due to added fun factor. Haha. Backing off a 1/4 turn has netted me my highest mileage tank yet  at 48 MPG. . . So somehow I need to learn to control myself haha.

But until then I've physically limited my fuel consumption in my quest for 50 MPG. Ill probably get tired of it in a week and bump it back up. Baha.




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[8v-of-fury]

Are you driving slower?? As I said it takes the same amount of fuel regardless to hold a 1.6L engine at a certain rpm.

Congrats on the tank mileage, but I think its just because you are driving slower lol.

[ORCoaster]

And the magic word is???

Smileage. 
a Hagarism if you didn't already know.

Slow and easy always wins the MPG race.

[TylerDurden]

Are you driving slower?? As I said it takes the same amount of fuel regardless to hold a 1.6L engine at a certain rpm.

There is the issue of overfueling...

[8v-of-fury]

I don't think so. For if he has lowered the max fuel, the same fueling can be achieved by pushing the pedal a little further. 1/4 turn is not really surmountable in terms of overall fueling, and the throttle could easily overcome that amount.

I don't think he was near 48mpg if he were cruising in the higher RPM's where over fueling is more likely.

[burn_your_money]

FWIW, you have saved no fuel by doing this modification. . This is a diesel with no throttle plate, there always needs to be x amount of minimum fuel for y amount of RPM. So if you are still turning the same RPM, then you are still injecting the exact same amount of fuel you just have to push the pedal further now.

I partially disagree. When accelerating you hit max fuel quite often, even if you aren't trying (50HP, what do you expect?). By limiting the amount of max fuel there is the potential to save fuel. It really depends on driving style though.

[8v-of-fury]

I was not accounting for acceleration to be part of the equation, I don't/didn't accelerate my 1.6TD/1.6D at full fueling (the most amount of pedal with no smoke belching) from stop lights lol.

I assumed it was a pure basis of cruising said car at said rpm, at said speed. Same speed/rpm will require the same fuel regardless.

Limiting max fuel upon acceleration would help to save some fuel, but enough to noticeably bump up a tanks average?? and by only turning 1/4 turn? Skeptical I am.