Disabling EGR

[dieselman]

i hope im not going off topic but is this necessary for my focus or can it just be blanked off if necessary?

Almost certainly the MAF will monitor the gas flow so the mod will be required.

Will this modification cause a problem when you have to undergo an emission test for MOT?

No. If anything it should reduce smoke output.

 

[turbopete]

Almost certainly the MAF will monitor the gas flow so the mod will be required.

No. If anything it should reduce smoke output.

do you have any info should the need arise? or is it identical to the one for the MB's?

 

[dieselman]

do you have any info should the need arise? or is it identical to the one for the MB's?

The pin outs will probably be different, but the method and resistor values will probably be the same.
All you are trying to do is drop the MAF voltage by 0.4-0.5v when the EGR valve should be operating.

 

[HERBIEMERCMAN]

hi dieselman, this is a very good posting. i had a porsche 911 carrera which had a belt driven pump which forced excess air into the exhaust gasses to get within the usa requirements for "greener" emissions, the pump took up 8 bhp and all the enthuciasts used to take the drive belts off.

i own a 97. e-300. td. 7 seat est. w210. had it from new, now has 200k on the clock, it runs perfect, mpg 26 urban, 34mpg longer runs. engine up to temp inside 5 mins 2 miles etc. SO, should i leave well enough alone? i have no concern for the NOX as it is a drop in the ocean, more bull****.

i know from my development work on combustion appliances that recirculating exhaust gasses causes "vitiation" which causes bad combustion and sooting/ carbonising/ tarfog. etc. i also think IMHO that the amount of exhaust heat being recirculated must have a minimal effect on the engine heat up time, compared to an efficient thermostat and a radiator cover.

i add 200cc's of basic 2t oil to my full tank as i know this modifies the valency of the diesel fuel, ( increases the free radicals) allowing more complete combustion, pluss the increase in fuel pump and inj, valve gear lubrication etc. SO you must be right about the exhaust gasses compromising the complete combustion, sort of a "negative intercooler" where the oxygen content is being depleted as you know.
i relate an mpg improvement of circa 3mpg to the 2t oil, what is your estimation for the EGR removal ? herbiemercman.

 

[dieselman]

what is your estimation for the EGR removal ? herbiemercman.

Difficult to quantify but there is definitely more available low rev torque, so that should equate to better mpg.
My best estimate would be about 2mpg based on long term records.
I have another car which was too early for EGR, but the next model year had it fitted. The manufacturers literature puts the fuel economy difference at 2 mpg.

 

[HERBIEMERCMAN]

many thanks, dieselman, on a 17 gallon tank that equates to 34 more miles per tank, i also like the plasebo effect, feeling like the quality of the engine's combustion is more desireable to the roots of MB owners than the NOX bull**** politicians.herbiemercman.

 

[HERBIEMERCMAN]

dieselman, a silly question, is disconnecting the EGR plug closing the valve completely ? and therfore there is no need to physically blank off the 10mm pipe that feeds the EGR valve from the exhaust pipe. ? could you get let by on the valve. ? longer term due to lack of use. ? i think i understand what the purpose of recirculating exhaust gasses is to reduce NOX, but why can the flow path from the exhaust pipe to the air inlet manifold not be permanently open. ? why does the valve ever have to close? is it somthing to do with cold starting. ? aparently on some older cars the connection was fixed without a valve to interupt the flow. herbiemercman.

 

[dieselman]

dieselman, a silly question, is disconnecting the EGR plug closing the valve completely ? and therfore there is no need to physically blank off the 10mm pipe that feeds the EGR valve from the exhaust pipe. ? could you get let by on the valve. ? longer term due to lack of use. ?

Possibly leakage after some time, but the spring acting on the valve is pretty strong and does press the valve into the seat very solidly.

i think i understand what the purpose of recirculating exhaust gasses is to reduce NOX, but why can the flow path from the exhaust pipe to the air inlet manifold not be permanently open. ?

Because the inert gas would starve the engine of oxygen, hence why it reduces efficiency and causes smoke.

why does the valve ever have to close? is it somthing to do with cold starting. ?

No..See above.

aparently on some older cars the connection was fixed without a valve to interupt the flow. herbiemercman.

Really, can you show us one?

Older cars didn't use EGR at all, it was brought in as a Euro3 requirement to combat NOX output at idle.

 

[soup nazi]

When I installed the shunt I found some vacuum was still passing through the egr solenoid valve. Not much but if left unchecked it would have built up and may have caused the valve to open slightly. I jammed a 4 or 5mm ball bearing in the suction line between the solenoid and the egr valve and put it back on. Its now blocked solid!

 

[oigle]

When I installed the shunt I found some vacuum was still passing through the egr solenoid valve. Not much but if left unchecked it would have built up and may have caused the valve to open slightly. I jammed a 4 or 5mm ball bearing in the suction line between the solenoid and the egr valve and put it back on. Its now blocked solid!

The advice from dieselman re setting up the shunt is to disconnect the electrical fitting on the transducer and tape it up, thus totally eliminating any chance of EGR actaution. I have done that. No issues whatsoever.

 

[HERBIEMERCMAN]

HI dieselman, many thanks for your reply. are you saying that the exhaust recirculation only occurs on tickover. ? to meet the euro3 requirements. SO for 95% of the time the engine is running above tick over the EGR is closed. ? SO we are only eliminating the recirculation for tickover. ? i still agree it is a good thing to do.

i calculated on the premis of a 2 mpg saving on 5,000 miles PA the fuel cost saving is circa £78, based on the current £6/gallon cost of diesel, not forgetting the smoke and taring improvements, engine care etc.

if we are only talking tickover, with the EGR closed the rest of the time, then why are owners, post the modification claiming improvements in performance. ? i think i must be missing somthing here, we cannot just be talking tickover.?

i am immagining me driving along with exhaust gasses compromising my combustion due to vitiation, caused by recirculating "spent" products of combustion, but this cannot be the case if the EGR is only recirculating "spent" gasses during tickover. i love the idea and i hope i am wrong.

with reference to the older cars i have checked this out and you are correct it was not EGR, it was taking heat from the exhaust manifold with a sheet metal cowling and the recirculating this into the air intake manifold, hot air, not exhaust gasses. herbiemercman.

 

[oigle]

HI dieselman, many thanks for your reply. are you saying that the exhaust recirculation only occurs on tickover. ? to meet the euro3 requirements. SO for 95% of the time the engine is running above tick over the EGR is closed. ? SO we are only eliminating the recirculation for tickover. ? i still agree it is a good thing to do.

i calculated on the premis of a 2 mpg saving on 5,000 miles PA the fuel cost saving is circa £78, based on the current £6/gallon cost of diesel, not forgetting the smoke and taring improvements, engine care etc.

if we are only talking tickover, with the EGR closed the rest of the time, then why are owners, post the modification claiming improvements in performance. ? i think i must be missing somthing here, we cannot just be talking tickover.?

i am immagining me driving along with exhaust gasses compromising my combustion due to vitiation, caused by recirculating "spent" products of combustion, but this cannot be the case if the EGR is only recirculating "spent" gasses during tickover. i love the idea and i hope i am wrong.

with reference to the older cars i have checked this out and you are correct it was not EGR, it was taking heat from the exhaust manifold with a sheet metal cowling and the recirculating this into the air intake manifold, hot air, not exhaust gasses. herbiemercman.

My 2 cents worth -
In my experimenting, I found that the EGR valve opened at idle and stayed open when the engine was either off boost or even on light boost. It shut off as boost climbed, probably from about 2 or 3 psi. upwards - didn't measure it.
Thus, the EGR operates a LOT of the time.
The improvement in performance is due, in part, to the cooler more oxygenated air being ingested and also due to a more rapid rise in boost pressure, as ALL the exhaust gas is forced through the turbo impeller rather than losing a sizable proportion through the EGR system. This spins the turbo up more rapidly and thus produces boost earlier. Once on high boost, there is no gain to be had as the EGR would have been shut anyway.
I have found about a 5% gain in economy in low rev, low boost town driving. On open road whilst towing, hardly any difference.

 

[soup nazi]

Oigle
The vacuum that was paasing through my EGR solenoid was with the electrical connection disconnected also. Mine was leaking even when shut which I thought may have cause the EGR valve to open from time to time and thats why I sealed the hose as well.

 

[dieselman]

My 2 cents worth -
In my experimenting, I found that the EGR valve opened at idle and stayed open when the engine was either off boost or even on light boost. It shut off as boost climbed, probably from about 2 or 3 psi. upwards - didn't measure it.
Thus, the EGR operates a LOT of the time.
The improvement in performance is due, in part, to the cooler more oxygenated air being ingested and also due to a more rapid rise in boost pressure, as ALL the exhaust gas is forced through the turbo impeller rather than losing a sizable proportion through the EGR system. This spins the turbo up more rapidly and thus produces boost earlier. Once on high boost, there is no gain to be had as the EGR would have been shut anyway.
I have found about a 5% gain in economy in low rev, low boost town driving. On open road whilst towing, hardly any difference.

That's an accurate summary, thanks.

Early versions of EGR did only operate at idle, usually operated by a switch on the diesel pump actuator, but later ones are more sophisticated and operate as much as possible.

 

[stevesey]

Hi all - haven't been around for a while, but I've recently moved over to satan's fuel - and manufacturer - as I'm now driving a focus TDDI (deliberately went for the TDDI to avoid DMF and common rail issues).

I have been considering blanking the EGR - but in doing some research, there is a very definite school of thought that the EGR operation at part load helps to cool the turbo (it's designed to cool the combustion so less NOx is produced - a side effect is that it cools the turbo - especially at the very lean part load mixture you get in a diesel). Supporters of this viewpoint quote the failure issues with Renault TD engines where (unusually) the EGR would stick closed (not open, like most do) - so owners wouldn't know and would drive for a long time like this (unlike the stuck open case, where the cloud of smoke behind you prompts you to do something).

DM - would be interested in your view on this - especially as you have an EGT fitted. Did you notice an increase in part load EGTs when you blocked the EGR? (I assume it's fitted before the turbo?) Also how do your part load EGTs compare to full load EGTs (a lot of people try to apply petrol engine logic top the argument and that doesn't work for a diesel).

At present I'm swinging towards leaving it alone - partially because it's a ford and built down to a price (even compared to VX's you can see where the pennies have been shaved). So ford may have gone as far as using the lower temps to get away with a less well engineered turbo (mercedes would never do that would they ). Also the TDDI engine has a water/gas cooler prior to the EGR to lower the inlet temp further (and not just by less O2).

Thoughts?

 

[dieselman]

I have been considering blanking the EGR - but in doing some research, there is a very definite school of thought that the EGR operation at part load helps to cool the turbo (it's designed to cool the combustion so less NOx is produced - a side effect is that it cools the turbo - especially at the very lean part load mixture you get in a diesel). Supporters of this viewpoint quote the failure issues with Renault TD engines where (unusually) the EGR would stick closed (not open, like most do) - so owners wouldn't know and would drive for a long time like this (unlike the stuck open case, where the cloud of smoke behind you prompts you to do something).

DM - would be interested in your view on this - especially as you have an EGT fitted. Did you notice an increase in part load EGTs when you blocked the EGR? (I assume it's fitted before the turbo?) Also how do your part load EGTs compare to full load EGTs (a lot of people try to apply petrol engine logic top the argument and that doesn't work for a diesel).

I noticed about a 50C cooling of EGT after disabling the EGR valve.

The Renault issue was nothing to do with heat, they were just poor turbos coupled to over long oil change intervals. Garret supplied ones with modified bearings for alter cars.
I also can't see how the jammed EGR valve could be ignored as it is monitored by the MAF sensor.

Nice to see you Steve.

 

[stevesey]

I noticed about a 50C cooling of EGT after disabling the EGR valve.

The Renault issue was nothing to do with heat, they were just poor turbos coupled to over long oil change intervals. Garret supplied ones with modified bearings for alter cars.
I also can't see how the jammed EGR valve could be ignored as it is monitored by the MAF sensor.

Nice to see you Steve.

Cheers DM - useful info - I'd be interested to know how your part load EGT's compare to full load ones? Useful in assessing some of the arguements put out by others.

Wouldn't be suprised if Renault skipped on monitoring the EGR via MAP/MAF sensors as well?

Still might be tempted - or might go for a restricitor plate to start with.

 

[Alex Crow]

Oigle
The vacuum that was paasing through my EGR solenoid was with the electrical connection disconnected also. Mine was leaking even when shut which I thought may have cause the EGR valve to open from time to time and thats why I sealed the hose as well.

then your EGR transducer was failing, there will be zero vacuum to the valve with zero volts across the transducer when it all works properly.

 

[dieselman]

Wouldn't be suprised if Renault skipped on monitoring the EGR via MAP/MAF sensors as well?

They can't do that for two reasons, firstly they use the standard Bosch ECU and second it's a mandatory requirement to monitor EGR.

Cheers DM - useful info - I'd be interested to know how your part load EGT's compare to full load ones? Useful in assessing some of the arguements put out by others.

Full load EGT is the same as it was, low load is cooler, and I could see the water temperature gauge fluctuate as a result. I wrapped the exhaust manifold to compensate for this so have seen a maximum temp of 820C on a high speed drag up a hill with passengers.

As I've mentioned previously, pre Euro3 regulation there was no EGR.

 

[stevesey]

They can't do that for two reasons, firstly they use the standard Bosch ECU and second it's a mandatory requirement to monitor EGR.

Full load EGT is the same as it was, low load is cooler, and I could see the water temperature gauge fluctuate as a result. I wrapped the exhaust manifold to compensate for this so have seen a maximum temp of 820C on a high speed drag up a hill with passengers.

As I've mentioned previously, pre Euro3 regulation there was no EGR.

Cheers - been reading a little more on the Renault issues - and am back to dismissing the scaremongering I have seen.

However still slighly puzzled by the fact your EGT's have gone down at part load. Part of the logic of the EGR usage is that it reduces NOx production by lowering combustion temps isn't it (as well as there being less O2 around to combine with the N), so with no EGR I'd expect EGTs to rise.

Anyway I think I'll dig out that logging software I wrote a while back, find out what temps I can monitor and and take my laptop for a drive (then stick a ball bearing the EGR vaccum tube and try again). Just to see if I can see any difference in the temps. That's if the TDDI is EOBD compliant - should be by 2004.