CRD overfuelling ?

[Jamiepatrol]

Hi guys. Happy new year from Jamie.

I have a feeling that my CRD is overfuelling. Is there any way to adjust fuelling / air rations, other than a chip ??

I believe my boost is just right, so I don't know how adjusting boost will help. I'm about to do the NADS< but other than a faster spool up with the needle valve, i don't know how a dawes valve would help me? But please smebody correct me.
My reasoning behind this is the following.
@ 100km/h my EGR sits on 400 - 450C boost hovering around 10-12, I believe this is the way it should be boost , btu albeit that its still EGT too high? This is on 33" all terrains, not towing no NADS and no EGR blocked with an ambient temperature of around 26-28. I believe this is a bit too high in terms of EGR after my brief research on these forums.

Around town it's 200-350 etc... A bit more if I give it to it.
Also, the cat of my beautidert exhaust begins rattling once it's heated up, for example after a brief run on the ring road at 100km/h. I'm told this could be due to too much unburnt fuel accumulating in the cat and it burning off in there instead of in the chambers?
Wil the NADS helpe me if it is overfuelling or, is this another sinister problem?
If so, how could it be controlled?

Thanks. Jamie.

[threedogs]

The rattle will more than likely be your heat shield , you
could block your EGR so exhaust gas escape quicker lowering your EGTs.

check all hoses are tight, clean MAF

[Maxhead]

@ 100km/h my EGR sits on 400 - 450C boost hovering around 10-12, I believe this is the way it should be boost , btu albeit that its still EGT too high? This is on 33" all terrains, not towing no NADS and no EGR blocked with an ambient temperature of around 26-28. I believe this is a bit too high in terms of EGR after my brief research on these forums.

Around town it's 200-350 etc... A bit more if I give it to it.


Thanks. Jamie.

These look very much like my temps and boost. I can get to 650degC towing if I let it...LOL I have no nads.
You will find most CRD's will have similar figures. You can drop EGT by blocking the EGR but might get boost issues.

Whats your fuel economy like? I get around 12-13lph

[Winnie]

The engines do run hot like that from factory... Surely they are built to withstand the temps.

[Maxhead]

The engines do run hot like that from factory... Surely they are built to withstand the temps.

Yep, They are designed like that and those temps are normal

[Jamiepatrol]

@ threedogs
The rattle is 100% at the cat. Once it heats up a bit and begins rattling, if i jump out and hold it with something it stops the rattle. All mounting points of the exhaust are super tight and its not up against anything. Once EGT's drop below 300 or once at idle, rattling stops.*
I have a brand new MAF installed and it made stuff al difference. I'll block the EGR when my nads get fitted. That way i can at least manage any consequent boost issues.*

@ Nisshead
I noticed a few people having such temps and boost, but then i've also noticed a few have lower EGT's even when towing.*
Fuel economy i dont know yet as my tyres are fresh so still going through a tank but the 33"s definitely are felt on the foot i had to adjust my driving / acceleration and gearing to suit.


To be honest I'm not fussed one bit about the fuel economy. My main concern is if it is overfuelling, that supposedl can leat to warped */ cracked EGR tubes and or exhaust manifols which is a ton of $ to fix up. I'd like to preevent that as much as I can because this car is a long term family car for us. Big trips planned.*

Thanks for the replies.

[Maxhead]

Is the cat discoloured due to heat? Does it glow red on a long run??

Also any smoke???

[Jamiepatrol]

Is the cat discoloured due to heat? Does it glow red on a long run??

Also any smoke???

Not glowing red or anything. Just rattle noise coming of it felt. Throughout the car.
Also no smoke unless I really gun it. Even then nothing much. The other thing I forgot to mention is sometimes it drops dark patches on concrete under exhaust outlet. Multiple droplets of crap. It didn't do this prior to getting the exhaust fitted.

[Jamiepatrol]

Also all the power is there I don't lose much power unless its really hot and air con running. But for example I'm doing 90-100kmh in 5th its manageable once I hit cruising speed. But if step on it to gain some speed or overtake the engine feels like its labouring. Or under stress hard to describe.

[threedogs]

Maybe the guts of the CAT are blocking the exhaust flow ,
Fit a sports/ racing CAT, or Gut yours and re weld

[the evil twin]

Be a tad wary when trying to compare EGT's with other vehicles.
There are HEAPS of variables that will give different readings for different vehicles.
Someone else may simply have their EGT probe an inch or two further away from the turbo for example.

Your temps don't sound all that far off the mark really... what is your fuel consumption like?

Oh and of the 3 "rattly" Cats I've seen it has been the heat shield. Try temporarily jamming something between the Cat and Shield and see if that fixes it... if so then you can sort out a permanent fix, if not then continue to look at other issues

[threedogs]

As per your headline you say over fueling this to me would suggest belching black smoke.
The CRD can handle much higher temps than the DiD , and as ET suggests never compare two
Patrols as there are so many things that could be different. 650 degrees is not out of the question,

[Hodge]

G'day Jamie.
As others have suggested these temps aren't that drastic. I too have pondered the same mate. I have very similar results to you. But I have a 2 & 3/4 Beaudesert fitted and like you NO nads or EGR block yet.
I had a rattle which turned out to be the turbo heat shield slightly resting on something even though it was tight. I got the grinder out and cut like 5mm off the culprit side and now all is well.
I haven't taken a closer look at my exhaust around the cat area, but i there a heat shield above it ???? Maybe check that.

If the car temperatures behave that way on normal driving. I'm wondering what it'll like when towing and/or going up a hill ? I'd love to see it gunned up some tracks up the high country and watch the EGT go off the charts.

[Rumcajs]

High EGTs means there is more fuel going in or less air getting in. While everyone is saying sitting on 400°C at 100k/h cruising on flat road is normal that doesn't mean its OK. It isn't not on the flat road cruise, maybe climbing a moderate hill perhaps. Goal is to keep them (temps) down not hoping that engine was designed to cope with those. The hotter it gets the quicker it wears out.

This is good reading --> Why EGT is important (http://www.bankspower.com/techarticles/show/25-why-egt-is-important)

I also know I'd not trust Nissan with anything after the ZD30 debacle.
So if you have higher fuel consumption as well (averaging over 14 L per 100) than either the fuel system or induction system has an issue.

If the "cat" is rattling that means it is possibly causing restriction in the exhaust which will increase load on the engine and higher EGTs.

Alternative ways to keep EGTs down are not cheap but bigger/more efficient intercoolers (Nissan unit is a joke, a cheap mass produced barely sufficient minimum) better free flowing less restricting induction system will improve/lower EGTs.

Cheers

[Jamiepatrol]

Thanks again for replies. So if it is over fueling, and if boost is fine how can this be managed if at all ? Only way to intercept messages to injectors is a chip right ?

[NewDan]

Hey Jamie, those are the sort of temps I'm getting, and I've got a bigger intercooler and 3" exhaust (but no egr block) and at present running on 31s
Dan

[the evil twin]

Thanks again for replies. So if it is over fueling, and if boost is fine how can this be managed if at all ? Only way to intercept messages to injectors is a chip right ?

The Chips that I am familiar with will only add fuel not reduce it by either or increasing pressure or injector opening time... but there could be some that will allow you to take fuel away.

Having said that... I would still confirm that it is indeed over fueling and find out why. There is something wrong if it is and you need to find out what.

[Hodge]

Thanks again for replies. So if it is over fueling, and if boost is fine how can this be managed if at all ? Only way to intercept messages to injectors is a chip right ?

I've been wondering this my self. I often see people mention the DI's and CRD's getting dyno tuned. I mean, what the hell can you tune / adjust on these things, other than adding a chip?

Besides that Jamie I wouldn't worry about it too much. Just drive the bloody thing. I've got similar itches on my patrol, but I'm over it. I'm just gonna add the NADS, EGR block, and just drive it, because I bought the patrol, the patrol didn't buy me. If it blows up, it blows up.

[the evil twin]

I've been wondering this my self. I often see people mention the DI's and CRD's getting dyno tuned. I mean, what the hell can you tune / adjust on these things, other than adding a chip?

Besides that Jamie I wouldn't worry about it too much. Just drive the bloody thing. I've got similar itches on my patrol, but I'm over it. I'm just gonna add the NADS, EGR block, and just drive it, because I bought the patrol, the patrol didn't buy me. If it blows up, it blows up.

A Dyno is a tuning tool not a definitive yardstick in most cases (at least not without a whole heap of extra work to ensure repeatability).
Essentially it gives you a snapshot of before and after a mod or what happens when you tweak this or that.
Thats why the same vehicle on two different Dyno's won't necessarily give the same results.
For example setting a chip on a Dyno would be a breeze compared to the trial and error on the street but yeah, no point in dynoing just for the sake of.

I agree with the sentiment of "just drive it".
Mine has no NADS, an EGR block Chip 3 inch 'zorst etc whilst I don't give it shyte 100% of the time it certainly gets metalled and taken to yellow line often enough.
If something is wrong then yes, fix it but otherwise just give it too it.

[Hodge]

Thanks for the write up evil. Good post.

@ Jamie
What sort of revs, are you getting when you're cruising at 100km/h ?

And also, what revs should the power peak at? I don't remember the last time mine went over 3k. I don't believe I never really needed to since to me sweet spot is somewhere between 2200-3000 that I'm aware of.
Maybe I don't flog it like it's meant to be . LOL

[Maxhead]

I give mine the berries all the time mate. The CRD's love it!!
Its like an Italian tune up..LOL

[the evil twin]

I give mine the berries all the time mate. The CRD's love it!!
Its like an Italian tune up..LOL

What he said... Get 'em revving and on boost and keep 'em up there until you hit cruising speed/speed limit. I am not looking for a change until 3,250 - 3,500 depending on the next gear

Mine uses heaps more fuel if I "soccer mum it".