EGR and air intake temperatures.

[jed the spread]

So I am about to block off my EGR (1.9tdi afn). I have read and am aware of the pros and cons of keeping the EGR but I was lay under the van the other day and it got me thinking that it must really raise the air intake temperatures. I have seen a liquid heat exchanger on some other TDI models that cool the EGR intake temperature but looking at my charge cooler it cant really be much help if the hot exhaust gasses are being forced in too. Its got to give you more power if its blocked off and you just have the air intake via a charge cooler hasn't it?

Jed

[ewenmaclean]

Hi Jed,

you're right about the EGR for more power - not just because the air intake temperature is raised slightly but because there is a slight drop in boost pressure when the EGR is opened. You could just blank off the vacuum supply to the EGR first and it'll disable it as long as it's not too full of gunge and will close ok. You might be able to tell the difference. The ECU knows about the drop in boost pressure when the EGR is activated but not the temperature change as the inlet manifold temperature sender is normally located before the EGR. Once you do block it off it's a good idea to change the EGR adaptation so that it expects the EGR to open less frequently - that way you're likely not to get any error codes.

If you want power and not to have to clean your inlet manifold then blocking off the EGR is a good thing to do, but I think if you want mpg then it will help a bit as it recycles some of the incompletely combusted diesel. Even if you do keep it driving to redline now and again should stop the build up in the inlet manifold.

Ewen

[keith]

I vag commed my intake air temps on Monday night...as I had had a problem with something else.

I drove my van really hard for 45 mins (to check out a boost related fault)...and the highest peak temp was 44 degrees....which quickly dropped to an average of 30 ish under boost....and low twentys at idle.

so...I think my charge cooler is doing what its supposed to do.

my egr is blocked off too.

[syncroandy]

It may seem a bit contrary but I'm toying with fitting EGR to mine, allegedly its worth 2-3mpg. I'm only getting low 30's mpg and if I can get it to over 35 I'd be happy.

[lloydy]

I got rid of mine as I didn't want all that crap running in my inlet manifold. Personally, I think the only time you really need cold inlet temps is when your drag racing. Mine hovers around 35+ when on extended boost, and I have seen 60 odd on some of the mountain passes last year ( ambient temp of around 40). Pottering around town I get 20-30.
I've officially given up on recording mileage figures, life is too short. I get 29-30mpg, sometimes a lot less depending on my driving. I'm happy enough with that (for the power I have). End of the day I could turn down my fuelling.
I'd get rid of it jed, it's not as if you can't put it back on.

[jed the spread]

Thanks for the replies guys, very good of you.

I was getting quite high MPG compared to most and I am now thinking its because I kept the standard nozzles and the EGR? Anyway I got a blanking plate sorted that just slots in,



I will pop some gasket stuff on both sides and see how it goes. I will keep all the pipe work on and just sandwich the blanking plate in and If my MPG goes miles worse I will take it out again because I have enough power anyway. I was talking with Lee the other day and his thinking was if Linford Christie ran with a pipe up his a**e and breathed it in through his mouth while running he wouldn't do very well

Fair point

Jed

[mrhutch]

never mind that, cut your nails shagger..

[jed the spread]

Proper mans hands them, you can see I work for a Living

Jed