running dta, have lowered the tickover injector time to 2.50ms which is the lowest i can go before it cuts out , but i am still rich with a lambda of 9 is it cus the size of the inj is opening with such a small amount of time but still letting loads of petrol through ?

 

u need to check it with a CO meter, as lambda at v low engine speeds wont always regsister the same CO

 

A "lambda of 9" means nothing ?????????

do you mean AFR or lambda ???

If you mean 0.9 lambda then that is not that rich !!



If it is truly rich, you have at least one or more of the following problems...

1) fuel pressure too high

2) Injectors are not fit for purpose

3) cam overlap causing low manifold pressure

4) sequential injection - injectors in wrong firing order

 

yeah AFR , target is 13.5 ish , as i lower inj time the afr rises from about 9 to 10 , but as i go lower on inj time ,the car cuts out ?

 

Confused !!

You say AFR 13.5 - I understand this.

But what does 9 to 10 mean ?

I reckon your injectors are not suitable for what you want them to do.
They may be good for power but idle will be a problem !

In this situation, you must either ...

1) accept a rich lumpy idle

2) lower the fuel pressure (which will reduce top end fuelling too !)

3) use a higher idle speed to keep injectors in usable working range.


Are you using grey injectors by any chance ?

 

afr of 9 rising to 10 when i lower inj time from 3ms to 2.50ms inj are msd 500 or 525cc's , tried 2bar fp , i can live with a luppy rich idle if its not detrimental to the engine, i.e flooding the cylinder with so much fuel it reduces the lubrication on the bores of the cylinder ? if that makes sense !

 

is it because the steps on the map are to big,

from 3ms to 2.5ms is a huge step for idle

 

fuel map

idle settings, but changing the target i.e 840rpm
it doesn't seem to control to that rpm?

 

Are you gonna rev the engine to 9000rpm??

If not, then you want to re-set some of the break points for down at the bottom end of the map perhaps?

Be interesting to see how this turns out as im about to start mapping my DTA on 437cc injectors in the next day or two

 

I'm not supprised at 2.5m/s at idle with an injector that size is this an 8 litre engine

 

at Tony

 

well it won't run with a lower inj time, and i need this size injector to make the power i want

 

Your options are:

1) Fit smaller injectors

2) live with it as it is!

3) find better injectors


Alex

 

4) Fit better ecu that will do less than 2.5ms. Thats shonky.

 

I thought he ment the engine would cut out with a pulse width less than 2.5 ms....


Alex

 

map it properly

 

Up the idle to 1100rpm.

 

Are you using one or two squirts per two engine revolutions? Is the management sequential or batch injecting? Also, surely the tuning resolution must be more accurate than 100 us?

Upto a point you could play with the ignition timing at idle to retard it a bit so you can idle with a higher map value. You can also try to lean it a bit at your idle speed and richen a bit just below your idle rpm, so if it tries to stall or run bad, then it will pick up again. Same with timing too. A rising rate fuel regulator will also improve the situation a little.

 

it will go lower , its a dta p8pro , you can map it stu if you can fit me in ? if ya fancy it serious request btw

 

Lee, are you sure its not the ignition timing causing it to cut on lower fuelling, and like miker says, try a slightly higher idle at this stage, then work back to a lower idle later on once you have cracked it.

 

no not sure , i didn't mind having a play with a bit of fuel ratio's but timing if i fook it up could be Bad for the engine aye