Oil burner engines with EGR
Discussion
If the EGR valve is noisy and slow to react it may be coked up, they are notorious for that. Easy enough to check if it's not in a horrendous location. It could have been made on a Friday as well. You are correct that EGR doesn't effect fueling it is simply a valve that lets exhaust gas into the combustion camber when commanded.
A clogged air filter will defo make it run rich. Especially when you stomp on the go pedal, once you empty the plenum it will take a while for intake air to squeeze past the trapped dirt.
I recommend countering these conditions with 1 bottle of nitrous and 1 bottle of propane.
A clogged air filter will defo make it run rich. Especially when you stomp on the go pedal, once you empty the plenum it will take a while for intake air to squeeze past the trapped dirt.
I recommend countering these conditions with 1 bottle of nitrous and 1 bottle of propane.
egr return signal on hdi citroens and pugs connects directly to engine idle control system through ecm, so you could possibly find disconnecting will alter idle speed or cause stalling,
Have tried same with many diesels, only seems to work on older type (pre HDI)systems.
most systems now (OBD) seem to switch on engine management light, your car is def OBD.
If egr is vac controlled,most are electric now, try altering vacumm to egr by fitting adjustable valve inline like type fitted in turbo vac pipes and keep adjusting until it gets better but very small amounts of adjustment at a time(no such thing as a quick job!!)
with modern management systems all sensors/input are factored into software so by unplugging you are denying that input to the ecm, it is purely for emissions reasons that egr`s are fitted but then the most part of modern ecm`s is for emissions purposes any way,fuelling and ignition is quite simple software but making it clean is harder and the main criteria nowadays for any diesel manufacturer. thats why ecm`s are huge or there are multiple ecm`s doing one job.
even if you do manage to disconnect egr with no problems, on its own you probably wouldnt notice any difference anyway, but unplug and try. good luck
Have tried same with many diesels, only seems to work on older type (pre HDI)systems.
most systems now (OBD) seem to switch on engine management light, your car is def OBD.
If egr is vac controlled,most are electric now, try altering vacumm to egr by fitting adjustable valve inline like type fitted in turbo vac pipes and keep adjusting until it gets better but very small amounts of adjustment at a time(no such thing as a quick job!!)
with modern management systems all sensors/input are factored into software so by unplugging you are denying that input to the ecm, it is purely for emissions reasons that egr`s are fitted but then the most part of modern ecm`s is for emissions purposes any way,fuelling and ignition is quite simple software but making it clean is harder and the main criteria nowadays for any diesel manufacturer. thats why ecm`s are huge or there are multiple ecm`s doing one job.
even if you do manage to disconnect egr with no problems, on its own you probably wouldnt notice any difference anyway, but unplug and try. good luck
Un-plugged mine, a friends, and my older brothers (all 306 Hdi's) on the vacuum switch, and all have stop the EGR functioning and resulted in superior response to the throttle and no dodgy idling or engine lights coming on etc.
Seems to be quite a popular modification to these cars. Considering it's so badly designed/implemented to start with it's no wonder people un-plug them.
The implementation just seems so crap, it's active even when pushing on, change gear and the EGR activates for that brief period... lift mid-bend and on it comes. It's just lame. Fair enough on a motorway for hours on end, or tootling at 30mph through town, but the system just can't determine when your not tootling but pushing on and want quick response.
I guess you could always block up the vacuum pipe to the EGR, but if unplugging it works then all good I say.
Dave
Seems to be quite a popular modification to these cars. Considering it's so badly designed/implemented to start with it's no wonder people un-plug them.
The implementation just seems so crap, it's active even when pushing on, change gear and the EGR activates for that brief period... lift mid-bend and on it comes. It's just lame. Fair enough on a motorway for hours on end, or tootling at 30mph through town, but the system just can't determine when your not tootling but pushing on and want quick response.
I guess you could always block up the vacuum pipe to the EGR, but if unplugging it works then all good I say.
Dave
dickkark said:
all good stuff but it does put undue pressures on the rods/crank over a period of time and then!!! many cars particularly shoguns/pajeros have bit the dust because of this and there is no warning.good luck though.
How can turning off a valve that just lets exhaust into the intake manifold in only certain circumstances do anything to the bottom end of an engine?
Dave
because the egr valve is factored into fuelling as stated, pressure from the turbo still spooling on overrun is still being forced into cylinders under lean conditions as no exhaust gas is recirculated,which is used to assist combustion on overrun.
as you should know running lean causes rapid heating of the air in cylinder (which is excactly the opposite of what is required and why you have intercoolers)which then is transferred into the reciprocating parts,the piston carries alot of heat away from the cylinder but transfers some of that through the rods to the crank/bearings.
this is something that has been discussed at a recent diagnostics seminar I attended recently and was debated but the overall feeling was that it would lead to significant engine wear over time,plus the factor of personal experience changing/repairing engines that have had blocked/removed/unplugged egr valves.
manufacturers spend time/money developing these systems to work with an egr valve if you remove it from the equation there is going to be a negative reaction somewhere in the long term.
as you should know running lean causes rapid heating of the air in cylinder (which is excactly the opposite of what is required and why you have intercoolers)which then is transferred into the reciprocating parts,the piston carries alot of heat away from the cylinder but transfers some of that through the rods to the crank/bearings.
this is something that has been discussed at a recent diagnostics seminar I attended recently and was debated but the overall feeling was that it would lead to significant engine wear over time,plus the factor of personal experience changing/repairing engines that have had blocked/removed/unplugged egr valves.
manufacturers spend time/money developing these systems to work with an egr valve if you remove it from the equation there is going to be a negative reaction somewhere in the long term.
dickkark said:
because the egr valve is factored into fuelling as stated, pressure from the turbo still spooling on overrun is still being forced into cylinders under lean conditions as no exhaust gas is recirculated,which is used to assist combustion on overrun.
as you should know running lean causes rapid heating of the air in cylinder (which is excactly the opposite of what is required and why you have intercoolers)which then is transferred into the reciprocating parts,the piston carries alot of heat away from the cylinder but transfers some of that through the rods to the crank/bearings.
this is something that has been discussed at a recent diagnostics seminar I attended recently and was debated but the overall feeling was that it would lead to significant engine wear over time,plus the factor of personal experience changing/repairing engines that have had blocked/removed/unplugged egr valves.
manufacturers spend time/money developing these systems to work with an egr valve if you remove it from the equation there is going to be a negative reaction somewhere in the long term.
Fair point I suppose, but if you sit with the car idling the effect is the same.
Lean burn, EGR inactive, lots of heat?
I seriously doubt that engine designers built the engine to a point where they would suffer harm from EGR not functioning. The 1.9 XUD9 engine that Peugeot used actually moved from no EGR to EGR, and in doing so suffered lots of big-end failures!
Considering this engine worked perfectly well generally with and without you wonder why the modern engine's can't manage to operate without the heat reducing abilities of EGR under only steady state low power demand situations. If you sit in traffic all day or cruise at speed on a motorway EGR will never be active anyway.
The newest PSA units use sheep p*ss filters or something, so I hear, and do away with the conventional cat converter and EGR. Where does the heat go in these 16v high output units?
I think perhaps the failure of these engines is not due to EGR being removed but because the engine's were poorly maintained. I could go into examples of XUD9 service life, EGR application and service schedule's, but I won't bore you. The fact in that engine's case is that ignorant manufacturers specified longer intervals (almost X2) while adding a device which adds increased strain onto the lubrication system (EGR).
I'd go as far as saying that EGR actually makes an engine more likely to suffer from damage because when it begins to operate out of specification it causes problems like black smoking and rough idle which overheat the turbo exhaust impeller (stuff bearing and send water temps up very quickly) or the rough idle puts increased strain on the engine bearings.
Yes I may well accept the EGR should and does work great on a brand new car, but since disconnecting mine I've reduced random engine noises, pauses, power loss, increased response and driveability. It's just a liability much like a CAT on a 10 year old car can mean owners send them to the scrapyard when they hear it'll be £500 for a new one fitted, even though there is nothing wrong with the car!
Considering that most tuners of the PSA DW10 and XUD9 have all removed the EGR and I don't think one person has yet had bottom end failure or overheating, and they are running engine's tuned, which I expect means running higher EGT??, but lower combustion temps (richer mix)...
If it was really a problem that EGR was always active, you'd think it would be a feature on the service record for the cars, to make sure it was working effectively and within parameters?
Considering of the 4 cars I've owned that had EGR as a feature, not one mentioned it's function in any of the service manuals or maintainance guide. Considering it is *seen* as essential to engine temperature control and bottom-end longevity then why is it ignored by manufacturers? It's not checked on even a major service on my car!
I think they are designed, like any GOOD engine would be, to operate perfectly well without the EGR there, much like they are designed to run under arduous conditions with long service intervals and with alot of built in slack and still operate effectively.
Just my 2p anyway.
Dave
dickkark said:
because the egr valve is factored into fuelling as stated, pressure from the turbo still spooling on overrun is still being forced into cylinders under lean conditions as no exhaust gas is recirculated,which is used to assist combustion on overrun.
I think that you may be extrapolating a little far here... under overrun conditions on a diesel engine there is no fuel being injected...
dickkark said:
as you should know running lean causes rapid heating of the air in cylinder (which is excactly the opposite of what is required and why you have intercoolers)which then is transferred into the reciprocating parts,the piston carries alot of heat away from the cylinder but transfers some of that through the rods to the crank/bearings.
this is something that has been discussed at a recent diagnostics seminar I attended recently and was debated but the overall feeling was that it would lead to significant engine wear over time,plus the factor of personal experience changing/repairing engines that have had blocked/removed/unplugged egr valves.
EGR richens the mixture, true, and reduces peak temperatures, but these are momentary events in the cycle, and will not affect component wear. At high-full load the EGR valve is held closed and so does not affect combustion under these conditions, and the temperatures here will be far] higher than those experienced when the engine is running part load with EGR.
dickkark said:
manufacturers spend time/money developing these systems to work with an egr valve if you remove it from the equation there is going to be a negative reaction somewhere in the long term.
The only negative reaction will be an increase in emissions and the breaking of the law. It is illegal to tamper with emissions control equipment on a car! However, the engine will perform more or less as before assuming the diagnostics don't put it into limp home!
I am not really sure of the value of disconnecting it though - arguments in favour of retaining it:
1. Legality.
2. No performance detriment (assuming the manufacturer has tuned the control terms well!)
3. Significantly better emissions (NOx reduces massively)
4. Quieter
Arguments against retaining it:
1. Maybe, slightly, detrimental to fuel consumption (but we are talking a tiny amount)
2. Possible coking of valve - especially if the engine only ever gets used for short journeys, but then why would you buy a diesel for short journeys?
3. Masks that diesel clatter than everyone loves...
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