doggydowg

Hiya guys

at what boost does the boost ecu retard the timing?
And how much does the ignition get retarded by?

addiction

the overboost will cut the ignition at 10.5psi(thats if it's not chipped) and will retard it when the act hits 70 degrees

doggydowg

does the igntion curve not get retarded when you coem on boost thoe?
does the boost pipe that go to ecu also tell the fuel ecu to richen fuel on boost?

JesseT

Sure it retards but it's difficult to answer your question witha value. The ignition advance is taken from a 2D map with RPM and MAP as variables.
No it doesn't. The fuel ecu doesn't have a clue of the amount of boost, only the amount of air flow. Surely these are a bit linked, but anyhow boost info is not delivered to the fuel "ecu".

doggydowg

cool so in thery if i was to blank the pipe from the boost ecu it would never relise it was on boost so it wouldnt retard the timing when on boost another way of getting a bit more power used to do this on my r5 turbo;_)

i reckon the igntion is probably retarded around 6 oC on boost?
So rather then running say 18psi which is what it fuels for i could get away with no retard on boost and just run less boost say 12psi but be at the same power with maybe a bit less torque?

Thanks in advance for replys sum good info didnt relise fuel ecu puts in more fuel for more air thats clever

GrimmeRS2K

the fuel ecu just tells the pressure actuator on the metering unit to supply fuel after calcualating info sent by all the sensors on the back of your inlet, its was quite clever in its day, but it has it limits nowadays

i wouldnt run it with that pipe disconnected if it was me.

Tony Turbo

It's not a self mapping system...

Sounds to me like if you carry on it will end in tears

doggydowg

when you say its not a self mapping system does this mean the boost ecu cant tell the difference between 2 or 10psi i know unchippd ones can tell after 10.5psi, what boost does the boost ecu retard the timing by roughly or is it as soon as your on booost the ignition get retarded regardless of how much boost u run?

Tony Turbo

I think you are confused, or you have confused me, that's for sure


It's not a "boost ecu", it is an Ignition ECU, it has nothing to do with boost. When you chip an RST, the chip is replaced with usually an unlimited boost chip and a different ignition map. This map is fixed. Each chip manufactuer has a slightly different map. It doesn't matter if your boost is 11psi or 31psi this ignition is the same.

The fueling for the boost level is all set on the metering unit. There are 3 points of adjustment, idle, cruise and full throttle.

I'm not 100% sure what you are trying to achieve...

doggydowg

ok basicly at the moment my car seems to stutter above 10psi when i have a boost pipe conected to the ecu, however when i disconect the pipe it runs fine above 10psi say 12.

it never had this problem before i have ran 18psi as my max boost in the past as this is what my metering unit is set up for, i have an unlimited boost chip and what i think may be happedning is i have a split ina boost pipe that is opening up above 10psi and causing a leak then the ecu detects this and then stutters.

I want to try and bypass this till i put new samcos on, if the ecu has nothign to do with boost why run a boost pipe to it surely it needs a boost reding to do something or is it purely there for when ppl are running ecus with a 10.5 boost limiter?

In which case it wont matter if i run a boost pipe to it or not as i already have an unlimted boost ecu?

Thanks Paul.

doggydowg

ive just bled about 1 psi from the boost ecu ie fitted a bleedvalve just before the ecu and it now drives fine on boost, im going to borrow sum1s ecu 2n as i think maybe this is the problem?

doggydowg

i have found sumthing in haynes which is calld a fuel trap which is suppoesd to go inbetween the ecu and vac pipe i have not got one of these fitted at the mo maybe that is the problem?

GrimmeRS2K

never heard of a fuel trap before, nothing on my ecu vac pipe?

why would there be a fuel trap on a pipe that carries air?

Tony is right on what he says about the fuel ecu it hasnt a clue on what boost the car is running, it just have, lets say programs on it to evaulate what the sensors are telling it i.e Cold Start enrichment, Throttle opening, Full load, overrun and also a fuel cut

GrimmeRS2K

and the reason why u cant run it without the pipe on is, with any chip in a rst ingition ecu it just tricks the ecu into thinking, thats say its running 8psi, when really ur running 20 psi etc.

doggydowg

hiya sorry to drag this out

you said

"and the reason why u cant run it without the pipe on is, with any chip in a rst ingition ecu it just tricks the ecu into thinking, thats say its running 8psi, when really ur running 20 psi etc"

The only way i can run my car properly seem to be with the pipe removed i am a bit confused are you lot saying that with removing that boost pipe i am not going to effect anything then ie i can run 12psi with pipe removed and everything will remain as it was before just like having a chipd ecu with unlimited boost as the igntion ecu will not see any boost and the metering unit will take care of fueling and the igntion ecu doesnt actualy retard the ingion on boost so the pipe being removed wont matter?

Thanks again

GrimmeRS2K

as said above, that vacuum pipe what carries air, senses the air, for a boost cut, and engine load to select a pre programmed ingition curve from the memory of the ecu, but as said a modified ecu can have a altered map to suit setup

hope this helps, put it this way, if it was just a case of removing the pipe, there wouldnt be such things as chipped ESC 11 ecu as all johnny boys would just remove it and we would have alot more blown up rst's around

doggydowg

chears so it has a purpuse after all it selects a different map on boost
thanks guys got there in the end, ive found the one way valve thing it all thoe it is on the pipe from crankcase breather to top of manifold mine was bit bklockd so have fitted a new one will try tomorow

GrimmeRS2K

doggydowg

tis a fucking weird one i cant see how bleeding off sum off the boost to the ecu means i can then go back to runing unlimited boost again i have thought of a shady way round this run my bleedvalve on max value all the time ie blledoff 6psi and then run a boost pipe from bottom of bleedvalve to boost ecu this way it still gets enuff boost tp change it to 2nd map when on boost and i can run 12 or 18psi or i could just get a new ecu if that turns out to be the problem.

What is it inside the ecu that the boost pipe goes to maybe this has developd a fault and i could replace this bit?

Rick

Not true at all.

Rick

Map sensor - and they are commonly faulty.

davidreader5

HI,

All sounds suspect, if you remove the vacuum hose from the ignition ECU,
the car will not function 100%, as from this and other sensors works out the ignition advance and retard, ie distributor for speed reference, engine load,
(vacuum) and temperature signals, dertermines the correct spark ignition (advance) also controls boost limit from amal valve with input from air charge temp
sensor, checks for too high boost etc, and also retards the ignition if air temp to high,, just get it chipped and setup correctly, before you have major problems
R5, totally different as on carb,

DAVE R