Where to stop?

[TonyJetta]

I hear that the Snap-On tester shows significantly lower numbers than a Harbor Freight tester, for example.

I think this is what you are leading up to: I would expect the Snap-On tester to be more accurate out of the box.

You could always replace the HF gauge (use the HF adapters and hose) with a known good model, of the same pressure range.

Tony

 

[TDIJetta99]

it also depends on where the check valve is located... I think the snap-on tester has the check valve located in the quick-connect coupler, which is 8" away from the adapter that screws into the glow plug hole.. That means that the volume of space inside the adapter and 8" of hose is included in the combustion chamber volume, which lowers the indicated readings on an engine with such a small combustion chamber..

The harbor freight setup has the check valve located in the tip of the adapter, as close to the combustion chamber as possible.. This should result in more accurate readings, but the gauge quality is inconsistent from harbor freight..

The solution would be to get a known accurate gauge and use it with the harbor freight tester as Tony suggested

 

[IndigoBlueWagon]

Not saying the Harbor Freight gauge is reliable or unreliable, don't know. Just that I've heard the Snap-on gauge reports lower numbers, which TDIJetta99 explained. 420 with one tester might indicate hard starting, but with another, not.

 

[oldpoopie]

Not saying the Harbor Freight gauge is reliable or unreliable, don't know. Just that I've heard the Snap-on gauge reports lower numbers, which TDIJetta99 explained. 420 with one tester might indicate hard starting, but with another, not.

My SnapOn tester repeatably tests at a lower values than the Harbor Freight unit I used to have. It doesnt matter though, as long as you know what a healthy motor will test at.

 

[Keebler145]

SNIP!

ALH injectors had a steady light haze of white smoke at idle and would make large clouds of white smoke at 2000 RPM in neutral. I didn't think to try this with the PP502's.

SNIP!

Well I've seen this plenty of times, I wished I could help you here. The only fix I ever had for it was to buy new nozzles, or get the old ones balanced and cleaned.

If you ever looked at my train wreck of a thread I had the same issue with smoke, but mine was actually partially misfiring when smoking like that. Is yours doing this also?

I gave up fighting the issue and took the car back to stock. Still has lower compression. But stock injectors/turbo/tune and no smoke or misfire.....

I'm interested to see if you figure this one out. Best of luck though!

 

[Fix_Until_Broke]

I'll take the gauge off and put it on the deadweight tester tomorrow - Accuracy not withstanding, I believe it to be repeatable.

It smokes white both with my DBW setup PP502's and another set of stock ALH injectors.

 

[silverbox]

is the engine consuming any oil?
How long does it take for rings to seat?

 

[Ski in NC]

Didn't you put lower CR pistons in this build? That will make for white smoke on cold starts.

 

[runonbeer]

A good question to ask yourself at this point may be "where to stop"?

 

[Fix_Until_Broke]

The engine has consumed some oil - ~1/4" on the dipstick over the last ~1000 miles since I changed the break in oil out. It was at the top kink in the dipstick (overfull) and now it's at the top of the crosshatch.

I did put PD150 pistions in which are supposed to be ~18.5:1 CR, however with my additional ~0.005" pistion protrusion and the reduction in valve volume the CR is ~18:1

A puff of white smoke on startup does not hurt my feelings (I'd rather it wasn't there, but...) however the steady stream of white smoke for the first minute after startup and the fact that it will generate large clouds of white smoke even when fully warmed up at a high idle (2000 rpm) is a bit concerning.

 

[Fix_Until_Broke]

A good question to ask yourself at this point may be "where to stop"?

Yeah, I think I had that thought about 3 months and $12k ago...

 

[Fix_Until_Broke]

Some data from this weekend...Video's coming shortly

Slopes were taken between the data points in the red circles.

 

[Fix_Until_Broke]

Compression gauge reads ~5% high and is repeatable.

Cal Reference = Gauge Reading
100 = 105 +5%
200 = 210 +5%
300 = 320 +7%
400 = 425 +6%
500 = 530 +6%
600 = 635 +6%
700 = 735 +5%
800 = 840 +5%
900 = 940 +4%

 

[silverbox]

Compression gauge reads ~5% high and is repeatable.

100 = 105 +5%
200 = 210 +5%
300 = 320 +7%
400 = 425 +6%
500 = 530 +6%
600 = 635 +6%
700 = 735 +5%
800 = 840 +5%
900 = 940 +4%

Do you mean reads low?

 

[Fix_Until_Broke]

No - 500 actual PSI reads as 530 psi on the gauge so the gauge reads higher than actual pressure.

Post edited for clarity

 

[ArturCosta]

I was reading the topic and dont have much to say only about the white smoke , my engine did that also , solution was advance timing on pump and remap... never had white smoke any more , start up or 2000rpm in neutral.
Engine is now 42k after rebuild.

 

[Keebler145]

^ I've hear similar responses. I never got around to trying it, but I did confirm the only time it did this was at idle or higher revs with retarded timing. But, I was able to remove the issue by having new nozzles isntalled or old ones cleaned and rebalanced...

try getting the tune adjust so you never have retarded timing haha see if it solves it?

 

[ArturCosta]

I had white smoke with Pp502 and stock injectors , and Pp764 and transporter injectors.. both where calibrated before install. Only solution was advancing the tune (where it smokes) and pump.

 

[JFettig]

log MB4, both WOT and where it smokes.

 

[Fix_Until_Broke]

Timing is in the data in post 342

I'll have to do a no load data plot with a video

 

[Fix_Until_Broke]

Not sure if there's anything to see here - the more retarded the timing got, the more it smoked.

 

[Fix_Until_Broke]

I lengthened the glow time of the glow plugs this morning - it's ~6 seconds at 8C instead of .91 seconds. It helps some but is not the cure all.

Takes 2-3 engine revolutions before it lights instead of 5-6
Starts on ~3 cylinders instead of 1-2 and runs on all 4 in ~1 sec instead of 3-4 sec.

Injection timing is spot on in the center of the graph still.

 

[TDIJetta99]

Look at what the timing is doing... It's staying at 0* and going towards -1... It should be advancing.. try changing group 4 in the adaptation to 32900, or even 33000 and see if it changes anything..

Don't leave the adaptation like that if you still intend to heavily load the engine below 2000rpm though..

Your pump timing is retarded for a performance application as well.. Get it just ABOVE the green line... That, along with the longer glow time, should make it fire up a lot faster when it's cold..

 

[Fix_Until_Broke]

Will mechanically advancing the timing (while still within the control range of the ECU) actually change anything? Won't the ECU put the timiing where it wants anyway? Or is this a 1st or 2nd revolution thing before the ECU has a chance to correct the timing?

Looking at the data in post 342, the timing is in control and meeting the request by the ECU.

If I advance the mechanical timing it will be on a different slope of the camplate in the pump (I don't know if it's a steeper or flatter slope though)

 

[Ski in NC]

Camplate moves with advance piston, so as long as ecu is in control range, effective slope profile should be the same. Advancing mechanically helps with starts, as advance piston is bottomed at start, only moves once fuel pressure rises and ecu gets control.

Changing adaptation does change running advance. You can see that in the vcds data pre and post adaptation. Try small changes in adaptation, only a degree or so more advance makes a big diff in no-load smoke. Just advance enough to get it to clean up.

 

[JFettig]

I looked at the first couple graphs in 342 and missed the rest.

Where is your mechanical timing set? From what I've seen, when you advance it at the pump far enough, it cannot adapt far enough to let it get retarded. When I say far enough, to the top line on the graph. Mine won't go btdc as far as I've seen.
DBW claims that when it is advanced to the top line, you are in a better place on the camplate and more fuel gets injected sooner.

Jon

 

[Whitbread]

Agree with everyone else, green line or even slightly above for the timing graph.

With NoJoke's wagon, Mike had to modify the timing maps like crazy because of the very low CR. The motor absolutely does not like to be retarded past 3* BTDC. The factory maps have areas where the timing advance goes to minimum possible under low throttle, light load conditions. By keeping the timing 3* or higher at all times on the map, it quit smoking blue/white under light throttle/light load conditions.

 

[Fix_Until_Broke]

To be clear, I'm never operating the engine at 2000 RPM no load for minutes at a time, I was just providing this info to help troubleshoot the IDI sound and hard starting - might be a piece to the puzzle.

Mechanical timing is set right on the middle line - I'll advance it to the top of the range and see how it goes.

 

[TDIJetta99]

Agree with everyone else, green line or even slightly above for the timing graph.

With NoJoke's wagon, Mike had to modify the timing maps like crazy because of the very low CR. The motor absolutely does not like to be retarded past 3* BTDC. The factory maps have areas where the timing advance goes to minimum possible under low throttle, light load conditions. By keeping the timing 3* or higher at all times on the map, it quit smoking blue/white under light throttle/light load conditions.

Yeah mine kinda does the same, although my CR isn't super low (18.0:1).. I have my mechanical timing set above the green line about 1.5 degrees before it sets a timing control code.. It fires instantly when cold no matter how long it sit

 

[Keebler145]

Yeah mine kinda does the same, although my CR isn't super low (18.0:1).. I have my mechanical timing set above the green line about 1.5 degrees before it sets a timing control code.. It fires instantly when cold no matter how long it sit

I also had best results doing this. It didn't slve my 2k rpms missing issue completely but made it better. If I hadn't started my new job and needed the car to be smoke free I would have spent more time and money on resolving the issue.

It's definitely a timing issue. Just wished I had learned this before taking my car back to stock . Guess it's a good thing I'm getting back in the game with pd .

On a serious note, Fix, how bad does your car smoke just at idle? light haze or like billowing?