Injection timing?

[Volvoist]

I have heard of folks running 1.00mm for injection timing. I am curious what you guys think in terms of a timing setting on a D24 NA... I am wondering if it really will make any difference. I measured my piston height on my engine rebuild today, and determined that it is a 2-notch gasket as per the green book, but that I can safely go to a 1-notch gasket, which is what I will be doing. I want to have an idea as to what to run my timing at for the best performance and economy (economy is more important). Its a BW55 slug, though should be much better with the fresh motor with .040" OS pistons...

[anders]

I have heard of some VW IDI guys running up to 1.10mm. That's too far in my opinion. When I was messing around with the old motor in my 244 I had a total timing advance of 1.05 (my altitude compensator did not have power to causing it to have full advance throughout the RPM range) And it drove fantastic with that amount of advance. A whole lot better then .85mm.

Has anybody here put a pressure gauge on the IP to see what RPM the IP starts to advance? I was thinking of losing the dynamic advance all together and running a static timing of 1.10 (that would be from idle to redline) That way I could get better lower end power and not have the advance to high in the upper RPM range to slowly damage the motor. This is how inline IP's are. Any thoughts???

[Jason]

I have tried many timing settings up to and including 1.1mm on my volvo and my 1.6 jetta TD I had. Any more than 1.0mm gave no increase in mpg, only noise. Extra timing really only starts to make a difference when you pushing alot of fuel and trying to make power at higher rpms. The bigger players in economy are engine condition, especially compression which you have addressed with a rebuilt engine, and injector condition and calibration.


As for the IP advancement, it should start to advance right off idle, and will actually advance in relation to throttle position even at idle speed. That is adjustable as well, but not something you should mess with unless you have lots of experience or a pump bench. "locking out" the timing would only lead to poor performance at lower rpms if your locking it at full advance. As for too much advance up top, the pump is limited by design, the pin that rides on the advance plunger can only travel so far before hitting the body of the pump as the internal assembly rotates.

Jason

[v8volvo]

Interesting stuff Jason... I had wondered about when the advance starts working and how it reacts to throttle position. I assume that is one of the things that is altered with a performance pump build, like Giles etc.

I agree, I would not think about disabling the dynamic advance. I think it is one reason the rotary-pump VW engine designs work so much better out of the box than the Mercedes with inline pumps. A non-turbo D24 is 2.4 liters and makes 82 HP... a non-turbo MB OM616 (240D motor) is the same size but makes 67 HP with an inline pump. The VE design is pretty neat once you get to know it, though of course the Mercedes inline IP is happy pumping river mud, while the VE pump is a little more picky about fuel quality and filtration...

Mike, I usually set mine to around .92. I would not go any higher than about .97 unless, as Jason said, you are using a lot of air and trying to move a lot of fuel. On a stock non-turbo motor, I doubt you will see any advantage beyond about .95.

[sdturbo]

I got my hands on a timing light that clamps to the injection line today. I have suspected that my dynamic advance did not work. When I put the light on I was able to see it advance ~3 degrees with the cold start on and about the same with the altitude compensator. The issue is when I rev it, the timing goes the about 5 degrees the other direction (retarded). This may explain my excessive egts and lack of top end power. I am not sure where to start on making the pump advance correctly as I can hardly find any information on it.

[ngoma]

Did this problem just start happening? Or was it a slow deterioration? What is the condition of the fuel filter?

Was this IP ever opened up? Possibly to reseal one of the little side case covers? It's possible that the spring and washers (part of the advance piston assy.) flew out and didn't get put back in the correct orientation.

Remember that the internal advance mechanism works off of the pressure differential between pre- and post-internal vane pump. If you are feeding the IP (and therefore internal fuel pump) pressurized fuel (as in a pre-IP electric "helper" fuel pump), you may even be reducing that pressure differential and hence reducing further an already weak dynamic advance curve.

Apparently, worn IPs (specifically the IP's internal fuel transfer pump, the rotary vane pump) struggle to provide sufficient internal fuel pressure to activate the dynamic advance correctly. Here is some good reading for you on the methods of measuring the internal IP fuel pressure, and how to adjust the internal pump's pressure output to produce the proper advance: Internal injection pump pressure (http://www.vwdieselparts.com/forum/viewtopic.php?t=5936&start=0)
Please note that that discussion is pertinent to the Bosch VE IP model(s) installed on the VW 4-cyl engines; possibly the D24 version has different specs?

Open question to all: Does anybody know the IP internal fuel pressure specs for the D24/D24T IP?

[745 TurboGreasel]

There/s nothing to make it different from a 1.6 really.
I wouldn't worry about a clicker pump, VE Cummins run a 7-12 PSI lift pump, and worry about the front seal blowing out of the housing if they raise that much past 20.

[sdturbo]

Well I only now just checked the actual timing. I suspect in the time I have owned it, it has never worked properly. The pump didn't respond to adjustments like other VE pumps I have messed with and has always has always been pretty flat on the topend power wise. Even with the compound turbos and shimmed governor its a dog in the higher rpms.

I am going to change the fuel filter tonight just to see (I have doubts, it was new and drove just like this). My only thought is that maybe he diesel cleaned something off the fuel tank and clogged the filter in short order. If that does not get me advance then I will make a adapter for a gauge and set the internal pressure. I suppose if that does not work I am in the market for another pump :-/

I dont think its a problem with the advance mechanism itself since the altitude compensator works perfectly.

[ngoma]

I will make a adapter for a gauge and set the internal pressure.
We will be interested in the results; please post them! (My own hunch is that there are many of these IPs out there running with subpar internal pressure/dynamic timing.)

Take it that you understood you need to tap the pressure reading upstream from the out bolt restrictor orifice? Wasn't that in interesting link?

[sdturbo]

I am interested to see as well. While I suspect there are a lot of pumps running around in this condition (likely not as horrible feeling in a 3000lb sedan as it is in a 5000lb truck). It may be the reason this engine came off the road. I am not sure that it means a "dead pump". It might just be a matter of re sealing the pressure regulator and making sure it operates smoothly.

I replaced the fuel filter at lunch today and it has a smidge more power on the bottomed but still nothing up top. Egts might even climb faster than they were.

[ngoma]

Not so much resealing the pressure regulator as bumping up its preload.

[sdturbo]

Took the regulator out and the seals were all dry and cracked. I replaced those and tried to bump the pressure. I thought it moved a bit but there is no difference in the timing. How hard are you supposed to "bump" that stop? Anyone ever tap is for a set screw instead?

[745 TurboGreasel]

I have a theory the motors which run stronger on veg oil are the ones with way below par dynamic advance, and ULSD makes it even worse.
When I checked mine it wasn't far off spec.
Being on the bottom where grit collects probably doesn't help any.
I also had one apart where the advance ring had worn pretty significantly into the pump housing.

[ngoma]

How hard are you supposed to "bump" that stop? Anyone ever tap is for a set screw instead?
Hard to say, I've never done it; it's still theory to me, but in that link I posted earlier, they hint that there can be some stiction to overcome when attempting to tap in the preload, then finally it moves too much and they have to remove it to push it back out, and start all over again.

Too much internal pressure and it will start blowing seals...

Some sort of a screw-down micro adjuster would be an improvement.

NOTE: I would not attempt any of this without getting baseline measurements of the internal pump pressures at various RPMs. Before and after PSI readings, to be sure. Wasn't that your plan?

[ngoma]

I have a theory the motors which run stronger on veg oil are the ones with way below par dynamic advance, and ULSD makes it even worse.
When I checked mine it wasn't far off spec.
Sounds logical to me. The higher viscosity would be helping build more pressure?

How did you measure the dynamic advance?

[sdturbo]

Well that was the plan except for the part where I am limited on time and and don't have the proper fittings to execute it at the moment. Everything points to low pump pressure so I don't feel I am taking too big of a risk in increasing it. The logic is if i increase pressure a small amount it should be evident in the timing advance (or less retard in my case.) If it blows a seal in the process I wont be devastated in finding another pump to go through and swap in.

I am going to pull it again tomorrow and disassemble the whole pressure regulator. I will measure the stock location of the stop and put some effort into getting it to move one way or another. Maybe I will even make an adjuster for it.

[745 TurboGreasel]

Sounds logical to me. The higher viscosity would be helping build more pressure?

How did you measure the dynamic advance?
Yes, and I didn't, just transfer pressure.

Well that was the plan except for the part where I am limited on time and and don't have the proper fittings to execute it at the moment. Everything points to low pump pressure so I don't feel I am taking too big of a risk in increasing it. The logic is if i increase pressure a small amount it should be evident in the timing advance (or less retard in my case.) If it blows a seal in the process I wont be devastated in finding another pump to go through and swap in.

I am going to pull it again tomorrow and disassemble the whole pressure regulator. I will measure the stock location of the stop and put some effort into getting it to move one way or another. Maybe I will even make an adjuster for it.
Guys on the VW bard are saying their acoustic timers only work right at near idle speeds where advance won't really show.

Don't bother taking it apart just make a punch with a stop, and drive it deeper.003-.005 a shot.

[sdturbo]

The pump sits ~8" under the cowel on the land rover. I have to take it apart to adjust it :-/.

Interesting about it not working at higher rpms. I am going to try it on my 4bt tomorrow and see how that works. That has a brand new pump in it so it SHOULD advance correctly.

[sdturbo]

Tonight I pulled the regulator and used a vise to push the stop .030". Wow its a totally different animal. Pump needs a re tune, nothing but thick black smoke. The egts are still sky high but it now seems very over fueled. Base timing jumped to 17 and it it only goes up a couple degrees when I rev it. Ill sleep on it and make some more adjustments in the morning.

[745 TurboGreasel]

Poor thing was probably starving the whole time.

A wise man would tell you the sweet spot will be right around 12 unless the advance piston is messed up.

[sdturbo]

I put a gauge on it this morning and fuel pressure is high... ~70psi at 750rpm and goes to 100psi quickly. The 1.6 info I can find looks like 44psi at 1000 rpm. Guess I will play with it but it sure is a pain to adjust.

[ngoma]

Base timing jumped to 17 and it it only goes up a couple degrees when I rev it.
How do those numbers compare to your other IP you measured?

[sdturbo]

I set the pump to .090. With the pressure under 70 at idle it at about 12 degrees. Over that pressure it gets into dynamic advance at idle.

I just did a bunch of pump tuning and it has picked up a good deal of power. I am not happy with the higher than stock fuel pressure and while it does advance a few degrees it seems to stop at 15 degrees of total timing. I think the dynamic advance might have another issue that the increased pressure is compensating for.

I really have gained a lot of understanding of these pumps since owing this thing. I really need to get my hands on one to go through. Its just too hard for me to mess with this one due to its location on the land rover.

[sdturbo]

Results after the weekend desert trip. When I left the shop it was running the best it ever has. Lots of power and no smoke. I got the best mileage I ever have out of it but on the way back it really took a dive. The timing seems to be all over the place, it goes from fine to a good diesel knock sound and white smoke under power. Something is just not right with this pump. Not that I have had a taste of what it could become I really need to get my hands on a 2nd pump.