r1_pete
|
| posted on 30/11/17 at 02:18 PM |
|
|
EFI injector size / tickover help / advice needed
I have the E Type running qite nicely on my home brewed inlet setup, but, I cannot get a stable slow tickover, currently ticking over at just under
1000rpm, I should be able to get the 6 cylinder motor ticking over at 700.
The ngine is mildly tuned, balanced, tidied ports in an xj6 efi head, plenum injection, very close to xj6 volume and the xj6 throttle body.
I’m thinking injectors with a lesser flow rate, hence needing a longer open duration might help, it is currently running 440cc, I have a set of 220,
and 250cc injectors, the stock xj6 ran 210cc.
Theory Being that the injectors cannot deliver a small enough volume at low revs....
Can anyone offer a view as to whether this is worth persuing?
|
|
|
|
|
rusty nuts
|
| posted on 30/11/17 at 07:03 PM |
|
|
Do you mean it will not idle below 1000 RPM.or does it stall? If it's because it will not idle below 1000 RPM is it possible to retard the
ignition timing at the problem speed ?
which should drop the idle speed . An air leak may cause a high idle speed.
|
|
|
40inches
|
| posted on 30/11/17 at 07:37 PM |
|
|
I had a similar problem Pete. I solved it by dropping the RPM threshold in Autotune to 500rpm
then left it ticking over with Autotune enabled until the idle stabilised. Rock solid at 800rpm 
I have a new set of XJ6 injectors you can try if that doesn't work.
|
|
|
SPYDER
|
| posted on 30/11/17 at 08:13 PM |
|
|
Hi Pete. Firstly, check for air leaks as suggested. Are you running an Idle control valve? Is it closing?
What AFR is it at idle? My engine is happiest at 12.5
What is ignition advance?
Is the fuel pressure regulator referenced to vacuum? That would help.
I had similar problems, ie. low pulsewidth idle, on MS1. I fixed it with High Res code.
Its now on MS2.
Why the need for 440 injectors? Whats the duty cycle like when flat out?
Have you tried running closed loop at idle?
|
|
|
r1_pete
|
| posted on 30/11/17 at 10:56 PM |
|
|
Thanks for the pointers, a few things to check out....
Main problem is cutting out when dropping back to idle.
I’m pretty sure 5here are no air leaks, there arent many joints and all seals are new, and gasket joints assembled with a smear of wellseal.
I don’t presently have an idle valve, but I did include the wiring.
I’ll check duty cycle, reason for 440s they were denso, cheap and many values available in the same body.
Iirc, idle advance is 10 degrees before
I’ll try closed loop and autotune...
[Edited on 30/11/17 by r1_pete]
|
|
|
theduck
|
| posted on 1/12/17 at 07:49 AM |
|
|
I assume you don’t have an idle control valve? If so the.ln you want a column in the ignition table below your ideal speed, say 500/600 where you
increase timing above idle speed by 2-5 degrees. This will have the effect of bringing the regs back up if it doesn’t quite catch at idle.
[Edited on 1/12/17 by theduck]
|
|
|
SPYDER
|
| posted on 1/12/17 at 11:35 AM |
|
|
More questions Pete...
Are you using Overrun Fuel Cut? Try switching it off or raise the revs at which it disengages.
The overrun area of your VE table may need looking at. Some people run weak in the overrun area ( for pops and bangs) or to act as a kind of fuel
cutting measure. This can make it difficult for the engine to "catch on " again when dropping to idle. Just tune for 13-14 AFR on overrun.
Autotune will do this for you if you give it authority to do so.
You are almost certainly running in the "non-linear" area of your injectors at idle. I suspect that this will be problematic no matter
what else you do to work around the idle issue.
If your pressure regulator isn't referenced to vacuum then I would try making it so. This will reduce fuel pressure at idle and need a bigger
pulsewidth.
You would need to redo your VE table though.
|
|
|
coyoteboy
|
| posted on 1/12/17 at 01:40 PM |
|
|
Are you running an aftermarket ECU? They're [engines in general] very sensitive to injector dynamics at low opening durations. I couldn't
get my stock engine/injector setup idling properly for ages until I got the injector opening/dead time nailed and the battery voltage compensation too
(which right around idle starts fluctuating a lot and affects injector opening time. Eventually I could only get it if tuned to 14:1 AFR (any leaner
and it was a mess) and by isolating the IAT because the slightest heatsoak would knock the inlet density off and send it into misfires.
[Edited on 1/12/17 by coyoteboy]
|
|
|
r1_pete
|
| posted on 1/12/17 at 05:57 PM |
|
|
Wow, Thanks all, I’m going to print this lot off and soend a few hours going through the setup tomorrow.
Yep, its an aftermarket ecu, MS2, I do have fuel cut, but Im sure it drops out at 1500 rpm, might be best switched off, the fpr is adjustable and vac
ref.
|
|
|
.jpg)
