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R&r.regarding Std Ecu. What Does It Mean Exacly

dori33

By dori33,
in Engines & Forced Induction

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dori33 Collaborator

dori33

Posted
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Rich and retard. Its an ecu failsafe to try and protect the motor from being overboosted.

makes sense. what sort of pressure does this normaly happen at. What are the symptoms? black smoke, lacking power, or does it cut out

SargeRX8 Grand Master

SargeRX8

Posted
Posted

Happened to me at only 10psi in my old car. As soon as I hit boost 2500, it comes on nice and hard then all power and torque vanish after about 4500rpm. Its flat shit the whole way. Don't usually see too much smoke from a stock ecu. Wait til you go aftermarket, this BMW driver was swearing his nut off after tailgaiting me then me planting it and shitting black shit all over him.

Room42 Proficient

Room42

Posted
Posted

Happened to me at only 10psi in my old car. As soon as I hit boost 2500, it comes on nice and hard then all power and torque vanish after about 4500rpm. Its flat shit the whole way. Don't usually see too much smoke from a stock ecu. Wait til you go aftermarket, this BMW driver was swearing his nut off after tailgaiting me then me planting it and shitting black shit all over him.

That is a very good reason to keep the stock ecu. Our maybe next time one of these idiot perth drivers tailgates me I'll just richen it up to 9 to one while I'm driving. And plant it. Thanks for the good idea.

Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

That is a very good reason to keep the stock ecu. Our maybe next time one of these idiot perth drivers tailgates me I'll just richen it up to 9 to one while I'm driving. And plant it. Thanks for the good idea.

hahhahahahahaaa,, I can just imagine this....

"HERE TAKE THIS DICKHEAD" then fowl your spark plugs, engine stalls, pull over on side of the road.... get your head punched in, change / clean spark plugs.... drive home.

who is the dickhead now ? LOL

and about R&R, look at the maps on the R33 to understand it more.

Room42 Proficient

Room42

Posted
Posted

hahhahahahahaaa,, I can just imagine this....

"HERE TAKE THIS DICKHEAD" then fowl your spark plugs, engine stalls, pull over on side of the road.... get your head punched in, change / clean spark plugs.... drive home.

who is the dickhead now ? LOL

and about R&R, look at the maps on the R33 to understand it more.

Hmmm...my plugs wouldn't foul for starters as when intercooler pipes have come unclamped it has run this rich and not fouled or stalled. Secondly I am a fit 6"1 92kg 31 year old man. Who was going to punch my head in again? Not many. As far as dickheads go I would say that driving so close to someones car that it is risking your rear bumper is being a dickhead. I had a f**king truck run into me in traffic a few weeks back cos he was driving like an idiot and tailgating me. I am not happy about tailgaters :rant: So imagine this...you are tailgating a white skyline, your car gets covered in soot cos you were being a dickhead and tailgating me. Then when you get out being all macho you see me get out. Then you either apologise and get back in your car or get knocked out. My patience is gone for that sort of shit. So if anyone gets any ideas then please get out of your car so I can release some frustration on you and your car.

MrStabby Grand Master

MrStabby

Posted
Posted

Ive read the term R&R being used quit often on the forum, in regards to the std ecu when too much boost is seen. think my car is suffering from this on occasions. what is it exactly

It a region on the airflow vs rpm maps in the ECU where the mixtures are very rich and the timing very low. The ECU doesn't expect the engine to ever get to those cells in normal operation, and that implies that there is some kind of fault so extremely conservative fuel/timing is used to protect the motor.

Bumping up the boost increases airflow and pushes the ECU into the R+R region of the maps.

bubba Grand Master

bubba

Posted
Posted

It a region on the airflow vs rpm maps in the ECU where the mixtures are very rich and the timing very low. The ECU doesn't expect the engine to ever get to those cells in normal operation, and that implies that there is some kind of fault so extremely conservative fuel/timing is used to protect the motor.

Bumping up the boost increases airflow and pushes the ECU into the R+R region of the maps.

No, it's a separate map of TP vs RPM that when the TP goes over that threshold timing is pulled and fuel added.

That being said, the top ends of the factory maps are so rich it's not funny, over a certain point the injectors are fully open! (saw 150% duty cycle :laugh:)

Lithium Grand Master

Lithium

Posted
Posted

Rich and retard as others have stated are just an area of the factory map which would normally be called a "hole" a poor tuner had left in a map - but argueably done intentionally when airflow gets high in parts of the rev range for reasons best known to Nissan. Possibly done to protect the engine? Not that I know of anyone having reliability issues when tuning the car properly in those zones. I think it was a stupid way to let the car leave the factory, personally.

Secondly I am a fit 6"1 92kg 31 year old man. Who was going to punch my head in again?

Short Samoan guys would be a good bunch to avoid in the first instance:

:whistling: Best policy is not testing the waters to find out, as naturally the one who does will no doubt be the one you didn't expect to be able to.
Lithium Grand Master

Lithium

Posted
Posted

No, it's a separate map of TP vs RPM that when the TP goes over that threshold timing is pulled and fuel added.

Maybe I am wrong on this - I was sure I've seen snapshots of this part of the map, so you are saying that regardless of the AFM signal etc there is a certain amount of timing pulled and fuel added? I would have thought this would have been more noticeable in a standard car, but you stand on the gas with the stock boost control etc and have no issues.... then add airflow and suddenly have the massive detuned sensation.

bubba Grand Master

bubba

Posted
Posted

Rich and retard as others have stated are just an area of the factory map which would normally be called a "hole" a poor tuner had left in a map - but argueably done intentionally when airflow gets high in parts of the rev range for reasons best known to Nissan. Possibly done to protect the engine? Not that I know of anyone having reliability issues when tuning the car properly in those zones. I think it was a stupid way to let the car leave the factory, personally.

So where does the TP Load Limit table come into it then?

bubba Grand Master

bubba

Posted
Posted

Maybe I am wrong on this - I was sure I've seen snapshots of this part of the map, so you are saying that regardless of the AFM signal etc there is a certain amount of timing pulled and fuel added? I would have thought this would have been more noticeable in a standard car, but you stand on the gas with the stock boost control etc and have no issues.... then add airflow and suddenly have the massive detuned sensation.

What I am saying is that while that top corner of the map is extremely rich (look at the required duty cycle to reach the target AFR in those cells, it's up around 150%), there is a table called TP Load Limit, which is the "afm (boost) cut" that people talk of. It tends to be maxed out in the lower RPM and decreases as the RPM increases. When your TP goes over this threshold is when "R&R" is encountered. What the ECU actually does in this instance I'm not sure (as in how much timing and fuel is altered and where it is referenced from, I do not know).

simpletool Mentor

simpletool

Posted
Posted (edited)

TP load limit is a hard limit for cutting fuel. If it hits TP load limit you WILL know about it.

R&R is a protective area on the last 2 columns (especially the last column) of the map which both increases fuel and even more drastically decreases timing. It is especially prevalent around the 4000 to 5200rpm area - you can imagine this visually by looking at the dramatic timing drop in the last cell. It is airflow based so efficiency improvements will also contribute to getting into this area as well as boost - the initial signs typically start around 9psi and getting dramatically worse towards 14psi. The onset of R&R is much more gradual than TP load limit. Kinda like developing liver disease as opposed to being shot.

Edited by simpletool
Room42 Proficient

Room42

Posted
Posted

Short Samoan guys would be a good bunch to avoid in the first instance:

:whistling: Best policy is not testing the waters to find out, as naturally the one who does will no doubt be the one you didn't expect to be able to.

Mate you'd be pissed too if your car got hit by a truck. I reckon best policy is don't tailgate and your car will stay clean. :thumbsup: Here comes the soot :ninja:

Back on topic r an r is gay. TP load limit will make you shit yourself when it happens. Had both and fixed them with a power fc :merli:

bubba Grand Master

bubba

Posted
Posted

TP load limit is a hard limit for cutting fuel. If it hits TP load limit you WILL know about it.

R&R is a protective area on the last 2 columns (especially the last column) of the map which both increases fuel and even more drastically decreases timing. It is especially prevalent around the 4000 to 5200rpm area - you can imagine this visually by looking at the dramatic timing drop in the last cell. It is airflow based so efficiency improvements will also contribute to getting into this area as well as boost - the initial signs typically start around 9psi and getting dramatically worse towards 14psi. The onset of R&R is much more gradual than TP load limit. Kinda like developing liver disease as opposed to being shot.

I'm pretty sure there is MIN and MAX TP tables, separate to the TP Load limit.

I will load up NIStune when I get home and take some screenshots.

bubba Grand Master

bubba

Posted
Posted

Ok, this is from the nissan_ecu_tuning_basics.pdf on the NIStune website..

9. TTPmax & TTPmin

TTPmin = “Total Theoretical Pulsewidth Minimum”. This value sets the absolute minimum injection

pulsewidth. This is in case a calculation (eg: unusually low reading from AFM) results in an injection

pulsewidth which would cause the engine to stall. Normally this value is only adjusted if different injectors

are fitted. Multiply all values by the ratio of old injector size vs new injector size.

Similar deal for TTPmax. It limits the maximum pulsewidth that will be used under any conditions and

values are modified in the same way. Watch out if TTPmax is set too low – it will limit the injector

pulsewidth and you won’t be able to richen the mixtures no matter what values you put in the fuel maps.

12. TP Load Limit

Commonly referred to as “Boost Cut”. Many tuners set all values to 255, effectively eliminating boost cut.

But a better strategy (assuming boost has been increased) is to adjust the values so that a boost cut still

exists but at a higher level. Values refer to TP, so work out what your max TP is and then adjust the

numbers in this table to slightly over this figure. This gives protection if boost control is lost (which can

easily happen if for example the hose to the WG actuator becomes damaged or dislodged).

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