E.G.R. Disconnect.

[davidd]

interesting what you said about the hot egr gas raising the combustion temperature in the cahember. the u.s. blokes are saying they are running cooler with the egr blocked. their story is cooler engine, no pollution, more power and better fuel consumption. mate of mine has a kj and he gets knock at idle when cold, just as i do, when the egr is disconnected.

[MCJK]

Originally Posted by MCJK

Combustion Temp is lowered, it's just the fact that Exhaust gas is hot and is being plumbed in through the instake heating up the Intake side of the head is all.

Originally Posted by davidd

interesting what you said about the hot egr gas raising the combustion temperature in the cahember. the u.s. blokes are saying they are running cooler with the egr blocked. their story is cooler engine, no pollution, more power and better fuel consumption. mate of mine has a kj and he gets knock at idle when cold, just as i do, when the egr is disconnected.

EGR is specifically designed to lower combustion temp to lower NOx, by product of this is the cooling of the turbo, Intake side of cylinder head/intake manifold temperature is increased do to the heat soak from the EGR cooler.

The O2 concentration is reduced in the combustion chamber, Reduced exhaust flow (power loss) and reduction of the combustion chamber temperature as a result of the improved heat collection capacity of the components e.g. water and CO2 which are not actually involved in the combustion but do influence the combustion process.

EGR is active in the lower load and rpm range. the EGR rate depends on engine load and engine speed, it's not all about MAP signal input, there are atleast 9 other inputs in which the ECU uses to calculate EGR activation.

No knock present in my engine, may wish to consider the type of oil your using? im running mobil 1 ESP, although i have no DPF this oil is better suited to a diesel.

[davidd]

thanks mcjk. have only had this egr valve off for a few days about 300klm. truck seems to be improving every time i get in it. i think you are right about the valve being stuck open. there was zero acceleration, no performance at all (totally gutless) under 1800rpm. would still wind out to higher speeds but took a long time. now pulls like a truck from very low revs, anything over 1200 seems enough to get response in intermediate gears and anything over 1500 is plenty in top gear. gets better all the time. i think this thing was just plain clogged up to blazes with soot as well as suffering from excess egr gas. what you say about load makes sense, i have been running round town on short runs and lots of traffic lights for 6 months, empty vehicle. ideal for clogging up. am using hpr diesel 5 oil. is not low ash, but has better dispersant and detergent properties than low ash if you don't have a dpf. have tried alternating with low ash. low ash gives clean oil at oil change. a following hpr diesel 5 run, flushes out a real pile of muck. another run of diesel 5 gives relatively clean oil. has been my experience that low ash definitely deposits more sludge in the engine. but the diesel 5 is a 5w grade on the bottom end so should be fine. engine is still cleaning out after the egr problem, but have much stronger engine showing excellent low to midrange torque, slight power improvement on top end (still down a bit), and so far no noticeable difference in fuel economy. however it takes a much lighter pressure on the gas pedal to get a result so something is going right. have also noticed that if i put the foot down at 100kph it is starting to give a bit of a kick again, instead of just dragging itself up. this thing must have been absolutely chockers with carbon. it is still getting better every day.

[MCJK]

More of an issue i have found is the transmission, seems to me it's mapped for a petrol and not a diesel, the Superchip and a few others deal with this issue, the auto kicks down when it should infact hold the gear.

it's acting apon the modulating pressure (engine load) to soon, the Engine has enough UMF to pull the tits off a bull, why kick down and push the revs up above 3000 rpm when it's not required. the 5 speed is good, just needs a tweak i reakon.

You will find with higher end diesel vehicles on the market, their autos hold the gear longer, makes for a different vehicle all together.

[davidd]

mine is a manual 6 speed, so don't have issues there. it seems most of the blokes with auto issues have added a transmission cooler and the problem goes away. box holds gears longer and fuel economy improves. you may already be aware of that though. steve (redgp) had engine heating problems and transmission problems. added an outo trans cooler and everything fell into place. engine temp dropped and auto trans started working right again. mate with a kj diesel had the same problem as you, and was talking about all kind of mods including changing to a more agressive torque converter. bought the converter (ex u.s.) and then tried a trans. oil cooler and the problem went away. engine cooler, auto trans cooler, and gear changes better, and held gears at lower revs without changing down. just an oil temp problem apparently. the torque converter still sits on the shelf in is workshop.

[EugeJK]

davidd, i was always surprised to hear you running your engine at ~2400. thought something wasn't right there. after my engine bedded in, i rev it unladen at these rpms:

1600-1800 in 3rd through 6th gear cruise on flat,
2000-2100 gear up shift on falt,
2000 in 2nd through 5th gear go uphill (8-10% gradient),
max 2400 gear up shift uphill.

when revving it ~2500 the engine sounds big and hard. in go-stop-go city mode, fuel consumption ~10.6ltr. tried, for experement, to run it at 2000 in city, fuel consumption up to 12.5ltr. interstingly, the engine sounds so happy when 1600 in 4th (60kph), 1700 in 5th (80kph) and 1800 in 6th (100kph).

[tdwrangler]

That is exactly what I do EugeJK. My truck is quick happy chugging along at 1400-1600rpm on a flat road. I haven't seen a hill yet that it won't eat up at 2000rpm, regardless of the gear.