Terrano ERG saga continued

I disconnected ERG on my 92 terrano diesel but has not idled properly until well warmed up and then can idle to high after decent run - any ideas why ?

Edited by mals69 at 8:43 pm, Thu 9 Apr

mals69 wrote:
I did it on my 92 terrano diesel but has not idled properly until well warmed up and then can idle to high after decent run - any ideas why ?

Diesel have egr flow only at idle and it closes at half load unlike petrol where egr is off at idle ,
if your diesel has No electronic pump then the only way the idle gets changed is by the actuator controlling the aircon.
it knows when egr should be on and changes idle with that divise , so you would need to remove that controll function so it dont starts to change idle .
So we will assume yours has been deleted befor this LAW was passed so techically your delet is not illegal .

Quote
intrade (402 402 positive feedback) 9:05 pm, Thu 9 Apr #6

I did it on my 92 terrano diesel but has not idled properly until well warmed up and then can idle to high after decent run - any ideas why ?

depends on if its EFI. if it is its probably the injection pump playing up.
if not EFI then you probably bumped something off. check if they have idle up or cold weather timing advance.
intrade wrote:

Diesel have egr flow only at idle and it closes at half load unlike petrol where egr is off at idle ,

not many diesel run egr at idle. generally speaking off at idle and full throttle. but not all, some its on full time.

EGR is useful on petrol engines as it can help reduce throttling losses. they don't use anywhere near the amount of EGR diesels use (especially late model ones).

Quote
tweake (26 26 positive feedback) 9:34 pm, Thu 9 Apr #12

Cheers

No EFI - its one step up from a Massey Ferguson in design.
If it was EFI the chances of the injector pump failing directly after
disconnecting the ERG valve would be rare in my view.

I was under the understanding the ERG valve is to recycle unburnt fuel, so would it not make more sense for it to be open at idle ?

Many eyes have looked over it so doubt anything bumped apart - should of added I disconnected it at-least 5 years ago.

Think intrade onto it - any ideas where to start looking for the below
re intrade post - would it be a vacuum operated solenoid, mechanical or
electrically operated ?

No electronic pump then the only way the idle gets changed is by the actuator controlling the aircon.
it knows when egr should be on and changes idle with that divise , so you would need to remove that controll function so it dont starts to change idle

Id be suspecting low compression and blow-by causing the problem.

If it's the aircon's idle-up it can be cured by turning the aircon off. If it was the aircon though, it wouldn't account for no/low idle when cold.

i tell you what egr is there for.
Its to reduce the "ultra high nox levels" diesel make from the lean burn. As you know diesel do not have a intake throttle to shut the air off at least that is how it would be on a old diesel! designs do change.
diesel run up to 160+ to 1 air fuel ratio in idle OLD MECHANICAL DIESEL!
New diesel use electro mechanical ecu controlled intake runner flaps to reduce the air fuel ratio among things its used for some more then this on some but that would deveate to far from the subject now. Some also have electronic ecu controlled exhaust valves that open up again to suck exhaust fumes back in to the chamber before it stays shut for compression ignition again.
these 2 problems for emission exist on diesel NOX and particular matter
another huge subject i can tell you loads about also of its problems and why.
The egr is there to reduce nox ! nox is is made when it burns lean= at idle. because a diesel makes its rpm from the amount of fuel it dumps in to the engine and because there is no throttle plate to reduce air at idle means its ultra lean burning and the higher the rpm and load on the engine the more fuel is dumped and the air fuel ratio gets less then at idle.
This is why diesel have egr run at idle and part load and shut off at higher rpm because the air to fuel ratio comes down by loads compaired to what it is at idle .
Exhaust gas displaces air and cools the piston chamber , exhaust gas egr "cooler" are used later on to cool the exhaust gas some more to have colder air and displace more of it during idle and part load

you should be able to cure it if it is the idle air controller by simply unplugging what ever changes the idle on the pump this will mean the idle wont change and it will struggle when you turn the aircon on

EGR is often electrical silanoids vaccume operated .
here is a strory i encountered years ago on a 1992 toyota corolla non turbo 2 c diesel
it was to come in for a rocker cover oil weep or drip i should say
anyhow i went to pick it up ratle the ratle and it was hunting at idle
similar petrol cars hunt on vaccum leeks.
Hmmm scratched my head for a bit as it made no sense and the aircon was dead years ago on that thing .
in my shop i looked closer as the only thing that could do this would be a faulty pump or the idle up motor for raising the rpm in idle when the aircon was on.
I could hear some vaccume leeks somwhere and the hoses everywhere so i done the rocker cover plastic one with a new gasket and it still leeked the same as before . the plastic crap had twisted and worped over time so i fitted a aluminium cast one from a 2c van engine i had and that was solfed.
Diesel need vaccume for the brakes and since this OLD! one had no aircon and the egr crap was blanked off since ages i removed all vaccume hoses and put em in the trash and plugged the holes so propper vaccume for the brake was there, after all its better to be able to stop then try and have lower nox levels with the poor design idea of slapping a egr valve on to engines.
i also had the intake from the van engine same engine no egr on that so that got fitted to this thing also to correctly delet the egr and you could now see the engine with almost no vaccume spaghetti lines enywhere.
System design needs to be knowen befor you do these sort of things it becomes more complicated as soon as electronic parts controll the injector pumps timing and fueling

old diesel have a mechanical vaccume pump because they make insufficient vaccume at idle, because there is no throttle butterfly restricting the intake like on older petrol engines. I hope everyone did know that? as it explains the high nox levels at idle.
Have a look on this picture i said this befor on newer cars egr has to be programmed out of the engine managment system to correctly delete it
and no that is not a job for any diy , these fueling maps are sold as offroad use only tuning items in the uk ,usa etc
This shows what is used to controll and check egr its from a bmw and i just googled the immage i know how it works but system designs dont always are the same there is loads of ways to get to rome.
http://www.bmwforums.info/attachment.php?attachmentid=10314&d=1374579288&thumb=1

Low compression ? It only son 170k - just run in for td27

Cheers very much in trade - I'll come back to you on this one as short on time but could you answer this please ? Got problem at the moment of the rear master cylinder brake line outlet not pumping any fluid - the after-market cylinder was replaced 18 months ago - brake company think machining fault with cylinder - before new cylinder ordered could the problem be related to lack of vacuum ? (Front brakes were working good but now pedal going to floor most of the time)

(Wanted to replace EGR valve at the time but one of the bolts
was seized so cut pipe and squashed ends and sealed with exhaust sealant)

Looking back rear brakes passed plenty of WOF when
put on brake roller after blocked egr pipe off must be faulty
master cylinder

brake comes down to system design usually 2 brakes are togahter either both front , or on right front and on rear left etc. follow the brake lines to see what you have and conclude from there.
vaccume is just a assitence it has nothing to do with pushing any fluids on brakes . you should check on master if it squirts fluids to the line not t pumping any fluid the filler bowl usually also has 2 inlets on master for these 2 circuits make sure there is no obstruction or the bowl empty or blocked on one chamber . Also fluids are extreem corrosive plenty warm water as soon as possible if you squirt it on to the car somhow is how to clean it off.

if no fluid squirts on master and no obstruction on inlet then i would say the part has gone faulty again.

how did you disconnect the EGR ?
one problem i've seen a few times is people put ball bearing in the vac line to the egr valve. what can happen with that is the egr valve gets stuck open a little bit and can't close because of the ball bearing.
egr on when cold can cause rough idle.

Cheers intrade - good in-depth post this morning - had lunch with a mechanically minded mate - he had a read and was right impressed.

Yeah you are correct about the obstruction in one of the master cylinder chambers - had a leaky hose couple of months ago and run the reservoir dry which ended up ripping cylinder seals out of their placement - all fixed now.

I disconnected it the cowboy way in the end tweake (as above) did not have lot of cashflow back then - needs must, need by blow torch to apply heat for such situations.
What intrade said about aircon actuator makes sense re idle problem.

Cheers all for your time posting :)