EZ EFI New Tune every time engine is started.

av8 · #1 (**permalink**) 07-30-2010, 07:41 PM

Hi, I have had the EZ EFI running fine on a SBC for about 6 months now but have recently had problems.
Pertronix ignition module died and this was followed with poor battery performance and difficult starting.
New Pertronix and new battery fitted.
Starts great but ran rough so set the handheld to start a 'new tune' and it ran great.
I then park up and later restart and it runs rough so I 'new tune' again and it's fine.
I seem to have to 'new tune' it after every time I start,.... what could be happening here?

Thanks, Martin.

FAST Tech Maxwell · #2 (**permalink**) 07-30-2010, 08:03 PM

Can you give us a better description of "ran rough"?

What is your IAC value in Live Data at a warm idle?

What are your AF Targets and Acc Fuel set at?

av8 · #3 (**permalink**) 07-30-2010, 08:36 PM

I realise now that 'ran rough' is a bit vague.
I'll checkout the above over the weekend.

Martin.

Webby · #4 (**permalink**) 08-06-2010, 10:31 AM

I also seem to have similar symptoms. engine has been running the same tune for a bit now and although great at decent revs, when I blip the throttle for a downchange at lower revs the engine just dies (stickshift). I thought this was due to air leak upstream of 02 sensor but now that is cured problem still occurs but goes away when I start a new tune. Have tried richening idle and mid range but makes no difference. idle and mid range set at 14.0 now. Accel fuel makes no difference either. TPS and IAC set as per handbook.

Webby · #5 (**permalink**) 08-09-2010, 05:52 PM

OK so I started a new tune at weekend. Left everything a per the book even left mixtures as they come with new tune. iac @21 Engine started and idled great drove great good response to throttle blip at all rpm. covered 400 odd miles. by the end idle hunting from 800-1000 (set at 900) blipping throttle at low revs stalled engine completely. ran great above 2500 rpm.

Webby · #6 (**permalink**) 08-10-2010, 07:44 PM

Hey Matt or any of you tech guys. Do you have any comment to make on this problem? I am happy to give you any more info you require on my system to get me over the problem.
I would assume that the ecu is homing in on the targets etc over time and that maybe the targets are wrong. However some help in deciding which way to try moving them would be great. The engine just seems to get rougher under 1500rpm over time. ie hunting idle and inability to free rev from low revs only.

FAST Tech Maxwell · #7 (**permalink**) 08-10-2010, 07:53 PM

Surging usually happens when the engine is not happy with timing or air/fuel ratio. How much timing do you have at idle and at about 1500rpms?

What does the engine idle at if you tape or plug the IAC hole on the throttle body? It should maintain pretty close to your target of 900rpm.

Have you done any other work on the car? I thought you had this thing running pretty good. What is the MAP reading at idle?

Webby · #8 (**permalink**) 08-11-2010, 05:45 AM

Hi Matt thanks for the response.
Car does run good straight after new tune. I have done quite a bit including changing to 8 injector manifold and sorting exhaust manifold leaks. I have only noticed this having done some decent milage in between mods. Map reading 44 at idle. Timing is difficult to read because of surging I can see it advancing and retarding with revs. There is no vac advance never has been. advance curve has not been changed from what was set by engine builder (american speed) 17 at 900 and 38 at 3000. Timing possibly a little retarded. Could retarded timing cause this? Dizzy was obviously out to change inlet manifold but dropped straight back in to the marks I made.

FAST Tech Maxwell · #9 (**permalink**) 08-11-2010, 08:41 PM

Shoot a timing light on it and see what you get before we try and go much further.

Let me know what happens.

lim34 · #10 (**permalink**) 08-12-2010, 07:38 AM

Hi Matt,
Following on from av8 thread who was looking into the problem we are having with "Rough Idle" , i seem to have similar problems to Webby.

The initial data before starting the engine was :

AF Idle : 13.5.......changed to...... 13.3
AF WOT : 12.8.....changed to.......12.5
AF Cruise : 14.0....changed to.......15.0

Engine starts right on the button, but will not Idle and will stall until revs are kept up till warmed up.
Once warmed up to normal running temp, it will idle fine and wont stall if throttle is blipped.

Ignition timing when warmed up and idleing at 850rpm is 19.

Was wondering if plugs ( Champion Platium ) are fouling up when cold, making it run rich till warmed up.