Model Specific Questions and Info > MK2 Golf/Jetta and Audi 5k
White Exhaust Smoke - Bad Fuel Injectors?
soma56:
Consistent with a couple of other posts here on this forum, that the awesome community here has been courteous enough to point me in the right direction, I'm considering new injectors. 1.6 TD.
The problem: I have white smoke (un-burnt diesel) from the exhaust - not horrific but enough to have the neighbors shake their head and more then I'm comfortable with. It especially shoots out when raising the rpm. It's definitely not coolant.
Some things that I've done leading up ponder on why I think this is a faulty fuel injector(s) issue:
Bent valves? The cylinder head was recently replaced after being machine and in excellent shape. No cracks between valves. Tested for leaks with it sitting upside down and leaving a puddle of wd-40 on each valve. 7 out of 8 valve stems didn't budge with the 8th having a very, very slow minor leak that I'm not even concerned about as the compression test came back as 410 PSI for this piston.
Bad HG? Fresh head gasket (1 hole) after measuring the protrusion of the piston from multiple points.
Bad compression? Compression was tested - it's excellent (between 385 and 410 PSI) considering the age/use of the motor. Little blow-by (and no smoke) from the top of the valve cover.
Turbo issue? I rebuilt the turbo (new seals, etc.) but for good measure - I bypassed the turbo (direct air into the engine) and yet I still have the same amount of white smoke.
Too much/little fuel? I'm familiar with the 'max set screw' on the IP and have adjusted it relentlessly. Recently put in some fresh seals in the top of the pump (no leaks - she's good to go and working correctly). In one case I set the max fuel down to the point where such little fuel goes into the system that it hardly goes above idle when flooring it. My logic was 'less fuel, less chances of smoking' - this isn't the case.
Timing? I have the special timing tool and done it on several occasions. She's bang on.
Fluid levels (oil/rad/etc.) are all consistent. This leaves me with only one other possibility: the fuel injectors. I should also point out I've been running on waste veg oil for years. It's my understanding this can have an impact on injectors (let alone other parts of the system). I have no means of 'testing' the injectors. Although I did take note of one ingenious method in which someone 'turned' the fuel lines 90 degrees from the IP so that the injector was 'accessible' to see if they were spraying. Each one is 'spraying' but they seemed more like a hose pattern and excessive. I have no benchmark to go by so I don't know if it's 'excessive' or otherwise healthy. I suspect it should be more like a 'mist' with this engine.
With all that said everything is pointing towards replacing all the fuel injectors to 'hopefully' take care of this white smoke issue. I honestly don't know what else it could be at this point. She runs just fine, lots of power and kick for what the old 1.6's are worth (especially with the turbo). Fuel injectors are expensive (let alone seemingly rare as I'm discovering) so I'm reaching out to see if anyone has any insight. Is there something I've missed? Thoughts? Experiences? Suggestions? Or (I've done everything you would do) and just go ahead and spend the money on new injectors?
ORCoaster:
As you know sometimes the specs for timing are not what they seem to be. Yes the tool says it is 90 mm but the engine is worn or not and sees the fuel coming at a different time then what the specs would have us believe. Try putting the timing back and then forward from where you have it now.
I know its work you would rather not do but it could change the smoke issue just enough to save ordering 4 new injectors or having them rebuild with new nozzles.
I didn't see where you tried changing the timing; just that it was correct as per label on the car fender or Bentley.
Try it and let us know if it helped any.
libbydiesel:
Make sure you have a clear line on the supply and return from the pump. When you start it, are there any bubbles in the line? Air in the fuel will cause it to smoke white.
Does it smoke constantly? Just when cold? Just at low rpms? Just at high rpms?
Have you made sure the cold start lever was pushed in when you timed it?
It is NOT "too much or too little fuel". "Too much" fuel makes the engine accelerate. "Too little" makes it slow down. Neither one makes it smoke abnormally. All the accelerator pedal does is add more or less fuel.
soma56:
--- Quote from: ORCoaster on September 18, 2018, 11:05:20 pm ---Try putting the timing back and then forward from where you have it now.
I didn't see where you tried changing the timing; just that it was correct as per label on the car fender or Bentley.
--- End quote ---
Good point. To be even lazier then I am right now - I'm wondering if I can plug in the dial gauge (after setting everything to TDC) and simply shifting the IP back a few degrees from a dialed-in zero position as opposed to going through the whole timing process. I suspect the advanced timing lever on the IP is something else I should have tried running on for a bit to see if there's an improvement as well. Thanks for the perspective - I'll give it a shot this weekend.
--- Quote from: libbydiesel on September 19, 2018, 12:49:53 am ---Make sure you have a clear line on the supply and return from the pump.
--- End quote ---
Supply has clear lines. The return doesn't. However, as a desperate measure at one point, I disconnected it to ensure there was flow from the IP and there was. I'll look into getting one this weekend.
--- Quote from: libbydiesel on September 19, 2018, 12:49:53 am ---When you start it, are there any bubbles in the line? Air in the fuel will cause it to smoke white.
--- End quote ---
None from the fuel filter all the way to the injectors. I installed a check valve just after the tank as well. It seems the lines between the injectors have some small bubbles that appear when running. On one occasion, with the max fuel turned way down (low) the lines between the injectors went 'dry' or emptied of diesel after a short run. I wouldn't say the fuel system completely 100% primed but closer to 85%. I primed it the best I could with the tools I have - enough to get it to fire up in 3 seconds. There are no obvious signs of external diesel leaks anywhere within the system and all hoses are tight let alone brand new.
--- Quote from: libbydiesel on September 19, 2018, 12:49:53 am ---Does it smoke constantly? Just when cold? Just at low rpms? Just at high rpms?
--- End quote ---
Yes, good point. Smokes constantly even when hot and in idle. A burst in rpm's will see a burst in smoke in which black smoke is visible. If I drive slow and shift gears at a lower rpm it's not so bad but bad enough to cause the neighbors to raise their eyebrows.
--- Quote from: libbydiesel on September 19, 2018, 12:49:53 am ---Have you made sure the cold start lever was pushed in when you timed it?
--- End quote ---
Yes, learned that a while back the hard way. Good call for thinking of that though.
--- Quote from: libbydiesel on September 19, 2018, 12:49:53 am ---It is NOT "too much or too little fuel". "Too much" fuel makes the engine accelerate. "Too little" makes it slow down. Neither one makes it smoke abnormally. All the accelerator pedal does is add more or less fuel.
--- End quote ---
10-4 on that. I've reset the max fuel screw to the default position.
ORCoaster:
You can do just that. Be sure that cold start lever is all the way forward towards the pump face. You don't want that engaged doing the timing. You can't really run on it as it only does its job at idle and the first few hundred RPMs after that. Once the pump builds up some internal pressure that mechanical part loses its function.
Some might say to just loosen the pump and bump it towards the engine for a bit of advance or pull it towards the radiator for some retarding. If your engine stops smoking one way or the other then measure what that number is with the gauge. Write it down and drive on it for a while, see how it rolls at that point.
Navigation
[0] Message Index
[#] Next page
Go to full version