Here's an update on the white smoke issue @ zero/low engine load, which has continued for almost two months now. For those who haven't read about it before: After the engine is fully warmed up it'd still constantly blow white/blue smoke at idle or low RPM part throttle. The smoke pours out both sides of my car, I even got a serious comment from another guy (car) in his 30's in Vancouver saying that my car's "on fire!!!" :roll:
We tried the following with no success:
1) New injectors.
2) Pump timing from 0.85 to 1.15.
3) Fuel screw low/idle screw high and fuel screw high/idle screw low.
4) Swapped pumps.
5) Pulled head. The block & head looked to be in mint condition, pre-chamber cups were ceramic coated.
Here are some of my observations:
1) Driving above 2,000 RPM there's zero smoke. Zip, nada, none. Runs and sounds perfectly smooth.
2) Glow plugs switched on manually at idle = less white/blue smoke.
3) Engine shudders/misfires below 2,000 RPM at part throttle. However, if I go WOT off-idle, there's no shudder and white/blue smoke. I believe this is due to extra fuel = more heat.
4) Stopping immediately after driving, the smoke is not visible until about 5-10 seconds later until the EGT drops. Lowest EGT at idle is 300 degrees F, pre-turbo. 350-400 degrees is more common. However, maybe the reason I don't see the smoke immediately after stopping is because it takes a few secs for the smoke to rise up where it can be seen from the driver's seat.
Most of the above suggest that it may be lack of HEAT, causing the white/blue smoke... just like many healthy diesels blowing a little blue/white smoke when cold starting. I spoke with Giles two nights ago and he suggested that my TD may be consuming far too much air and I'm lacking heat. I'm also boosting approx. 1.5 PSI at idle. Of course! That makes sense. The 1.9TD head intake ports were heavily ported and the deck was modded for extra flow as well. This is such a simple problem and we went through all the trouble of doing other diagnosis for nothing!
I am still consuming oil, but there are a couple leaks at the oil pan, which will be fixed eventually.
Temporary solution (diagnosis): Install 1.6TD intake manifold to restrict airflow, but the head flow mods are still there. Another way is to remove intercooler piping to avoid boost at idle, and have the inlet of the PD130 intake inlet blocked at least 75% to restrict airflow into the engine.
Permanent solution: Bigger turbo to avoid boost at idle
Reinstall original EGR valve to the PD130 intake and have the EGR plate, or shall I call it "throttle plate", be in closed position @ below WOT to restrict airflow into the engine. It should result in a richer air/fuel mixture & more heat.
A blow-off valve would be installed between the turbo compressor and throttle plate to purge excess boost in case throttle is closed at high boost. Who would have expected that a BOV will finally serve a purpose in a little IDI
Now... we tried the temporary solution last night. We took the intercooler piping off and I drove around a little more to ensure that the coolant temp is optimal (approx. 90 degreees C or 190 degrees F). Stopped the car, covered the PD130 intake inlet with a hand (about 75% blocked). Revved the engine in neutral... still lots of smoke
no difference. It was dark but the smoke may have been more grey-ish than white.
DVST8R mentioned that some Cummins use an intake heater as opposed to glow plugs for cold starts. We can experiment by using a heat gun directly into the intake inlet of my IDI. If it works well, then I'll have to make some form of intake heater, with a customized "race pipe". This may be more simple and effective than a mechanically actuated throttle plate + BOV. BTW an electrically actuated throttle plate is a possibility, it can be wired to the OEM WOT switch on the fuel pump so the plate opens completely at WOT.
Another possible problem to consider is that the geometry between the 1.9 head and 1.6 block may be a bit off. Or it could be the deck modification. While the enhanced airflow above 2,000 RPM is phenomenal, fuel/air combustion quality may have been sacrificed at low load. Perhaps the swirl characteristic in the intake ports were reduced a bit too much? Or do these exist in TDIs only? There is an interesting direct injection diesel that has two intake ports routed into one valve. At low RPM only one intake port with maximum swirl capability is open.. when upper RPM is reached, the other port (more straightforward=more flow) is opened. It's like the VNT of head intakes.
Still.. if I go WOT below 2,000 RPM it shudders and smokes less (compared to part throttle) so adding more heat may be sufficient.
Comments?
