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backfire issue
joscorstjens - 10/5/09 at 11:38 PM

Hi, I just used MLV-analyser to calculate new VE - values. I use MS1 on a Ford Sierra 2.0 injected engine.
1.
When I do a test drive, I get more back firing than on the first run. I wonder wether the ignition is too advanced or whether the PW goes too low? Any other parameter I should play with (e.g decel)?

2. When I start the engine, it runs well until I push the accelerator, then the engine dies. Which parameter do I need to change?

tia!


blakep82 - 10/5/09 at 11:57 PM

is it back firing out the exhaust or intake?


coozer - 11/5/09 at 07:58 AM

Mine was running rich and backfired at idle during the emissions test at SVA Should have seen his face!

If its the exhaust bang them I would suggest richness in the low to midrange area's??


flak monkey - 11/5/09 at 09:25 AM

Its its popping and banging form the exhaust its too rich, if it from the carbs then its too lean or not enough advance.

For a stock pinto your advance wants to start around 8deg at idle and linearly increase to 36deg at 3500rpm at WOT. Once you get to 36 deg it shouldnt go any higher.

If you wanted to just get it running you could map it in 2 dimensions for advance exactly the same as a dizzy gives you. Ie just increase the advance with revs and ignore the throttle position. Then once you have it running nicely you could add in some more advance for the overrun areas etc.

David


joscorstjens - 20/5/09 at 11:46 PM

it is backfiring in the exhaust when I get my foot off the accelerator


paulf - 21/5/09 at 01:00 PM

I had this and to cure it I richened up the lowest row of the table ,the ones that it ony runs in during overrun.Megalog viewer weakens them excessively if you have a lean mixture set for the over run and then it cant ignite in the engine so ends up in the exhaust and builds up until it back fires.
Paul

quote:
Originally posted by joscorstjens
it is backfiring in the exhaust when I get my foot off the accelerator


joscorstjens - 22/5/09 at 12:22 AM

I used auto-tune in megatune and this got rid of most of the backfiring. A pitty that this feature is not yet into tuner studio ms.
Still some weak backfire every now and then but my spark table goes up to 46 which is a bit over the edge, I assume. Does anyone have a good spark table for a stock injected pinto 2.0 ohc?


wilkingj - 27/5/09 at 11:38 AM

Backfiring in the exhaust on the overrun (foot off throttle and slowing down) can also be an air leak in the exhaust. Check the manifold gaskets, and pipe joins.

I had a pinhole in a weld that caused this.
took ages to spot!