E.G.R. Disconnect.

[davidd]

mcjk. i get rattle at idle when engine cold (with egr disconnected) can you give me a clue there as to why? also are you saying that without the egr valve operating the maf sensor helps compensate for the lack of gas flow or is it simply compensated for by the map sensor calling for a bit more boost and getting the airflow valve opened a bit more? if you block the egr and the airflow valve doesn't open more you choke the engine and lose power, not increase it as is happening. also my engine idle revs don't change, still steady at 800. but much stronger at idle. if the air flow valve is an issue with the egr blocked, is that problem solved by removing the airflow valve or are there other issues as well?

[MCJK]

Originally Posted by davidd

mcjk. i get rattle at idle when engine cold (with egr disconnected) can you give me a clue there as to why? also are you saying that without the egr valve operating the maf sensor helps compensate for the lack of gas flow or is it simply compensated for by the map sensor calling for a bit more boost and getting the airflow valve opened a bit more? if you block the egr and the airflow valve doesn't open more you choke the engine and lose power, not increase it as is happening. also my engine idle revs don't change, still steady at 800. but much stronger at idle. if the air flow valve is an issue with the egr blocked, is that problem solved by removing the airflow valve or are there other issues as well?

ECU is the chief, it must be tricked by the fact the EGR is inoperative and doesn't actuate the throttle body at all or it would be more noticable.

MAF sensor is only a messanger, ECU decides what to do with this message in relation to it's point in the mapping. the EGR is activated (although inoperative due to being blocked), no change is found as per the O2 sensor data in relaxing to MAP data, so ECU must not actuate the throttle body to compensate, the end result is the ECU ensures Smooth running in regards to mixture formation <- this is the only logical explanation.

As for noisey cold start, if it's a tappet bleed up type rattle, it's either a full set of cam followers (unlikely) or incorrect oil.

[davidd]

could the rattle at cold startup be advanced injector timimg, caused by removing the egr gas ?

So MCJK your saying no need to remove Air Flow Valve as ECU will pick up via O2 sensor that EGR valve hasnt opened, if thats the case i'd expect the 'Check Engine ' Light to come on? Wouldnt do any harm removing the Airflow Valve as i know others have done it.
Do you know the Max Exhaust temp at Turbine for the 2.8lt VM Motor?
Im looking at a Cummins spec chart now and states 430Deg C for Turbine out temp & 592Deg C at Manifold but doesnt list a Max Temp. I do know of another that listed 650Deg C Max temp.
Do you know? Are you a Motor Mech?

[MCJK]

Best get a quote on a new VVT turbo guys, if it goes pop.. not cheap..
either is the engine.

Ive found diddly squat advantages of disconnecting it, i only disconnected mine as it was busted and noisy, fuel is the same, power barely noticable if anything. Software is what is needed to properly rectify the EGR to gain the full benifit of the modification. remove it completely.

Davidd's EGR must have been stuck open, this explains the massive difference he has achieved from disconnecting it.

Best way to save Alot of fuel is free wheeling hubs, pulling the front axle due to breakage on trail has dropped my fuel by over 4L per hundred city traffic. (will be back to normal once axles sorted)

Davidd, shouldn't rattle at all, must be another issue. there is a knock sensor, but being a diesel the knock threshold is very high

[MCJK]

Originally Posted by ShortStuff

So MCJK your saying no need to remove Air Flow Valve as ECU will pick up via O2 sensor that EGR valve hasnt opened, if thats the case i'd expect the 'Check Engine ' Light to come on? Wouldnt do any harm removing the Airflow Valve as i know others have done it.
Do you know the Max Exhaust temp at Turbine for the 2.8lt VM Motor?
Im looking at a Cummins spec chart now and states 430Deg C for Turbine out temp & 592Deg C at Manifold but doesnt list a Max Temp. I do know of another that listed 650Deg C Max temp.
Do you know? Are you a Motor Mech?

No Engine light, Engine mixture formation must being running within specific values, EGR only works at idle or decel, the variables of the specific values from sensors are Wide. Looks like it sucks it up.

[MCJK]

Originally Posted by ShortStuff

Do you know the Max Exhaust temp at Turbine for the 2.8lt VM Motor?
Im looking at a Cummins spec chart now and states 430Deg C for Turbine out temp & 592Deg C at Manifold but doesnt list a Max Temp. I do know of another that listed 650Deg C Max temp.
Do you know? Are you a Motor Mech?

Personally i do not have a spec sheet nor know the specified temp for the 2.8L VM, but in saying that a Garrett turbo is a Garrett Turbo regardless of what it's bolted to, over 750 degrees longivity will be an issue, if you can boost it up at a max 650 degrees with a nice power gain, which there would be, go for it.

I know ppl run higher temps, but this is a daily driver here, if your manual you can kiss your clutch/gearbox good bye if there is a huge gain in power lol