MicroSquirt.com read only forum (Jan.15,2018)

MsNS-E 029q2 V3 fuel only oddfire V6 LC-1 wideband


Hi all I am having a bit of a problem and need some insite.My jeep wants to backfire when I get it in the upper rpm kpa range on a hill the wideband is telling me I am running pleanty rich 12-11.5-1 (to rich?)so I dont belive it lean but the bacfkire sounds like it is coming from the intake.I have run it richer before I got the wideband with no difference so before I go and lean out would you guys please take a look at what I have and give a bit of advice.
I checked the plugs and the only thing I could see was it is just a touch ver slightly on the lean side but nothing that would concern me.
The motor is very strong everywheres else and if I lug slowly up the hill it does not do it.
Thankyou to any one who helps

Thankyou! 71jeep

71jeep wrote:MsNS-E 029q2 V3 fuel only oddfire V6 LC-1 wideband


Hi all I am having a bit of a problem and need some insite.My jeep wants to backfire when I get it in the upper rpm kpa range on a hill the wideband is telling me I am running pleanty rich 12-11.5-1 (to rich?)so I dont belive it lean but the bacfkire sounds like it is coming from the intake.I have run it richer before I got the wideband with no difference so before I go and lean out would you guys please take a look at what I have and give a bit of advice.
I checked the plugs and the only thing I could see was it is just a touch ver slightly on the lean side but nothing that would concern me.
The motor is very strong everywheres else and if I lug slowly up the hill it does not do it.
Thankyou to any one who helps

Thankyou! 71jeep

What kind of timing are you logging when it does this?

Under load........... could be
- timing not advance enough
- intake valves not seating properly
- bad plugs (ignition)
- bad fuel pump (not maintaining fuel pressure)

Did it just start doing this?

I am running fuel only.

The heads are brand new.

Will install some new plugs just to get that out of the way.

I will check the pump it is new but that means nothing.

The motor has an HEI 4pin in it I just remembered that the vacumn advance is disabled right know it was causing the motor to ping at one time when I first started tunning.I seen no ill affects but I was never pushing the motor till now maybe I should hook it back up?Could this cause this type of problem?

It has been doing it since I have been pushing it in the upper KPA with MS it did not do it when I had the carb on.

Thankyou for you input it is greatly appreciated.


Thankyou 71jeep

cant say that it is due to the vacuum advance. i also have that problem where my engine wants to backfire but the ego says I am in a rich state. I have the vacuum advance inserted but same thing happens. Right now I am suspecting that there might be problems on the distributor

Could someone please look at my datalog and to see if maybe there is something else I maybe missing.PLEASE!


thankyou 71jeep

the wideband is telling me I am running pleanty rich 12-11.5-1 (to rich?)so I dont belive it lean but the bacfkire sounds like it is coming from the intake.

71 Jeep,

Always believe what the engine tells you over what the wideband tells you. In this case, backfires in the intake usually mean too lean - so richen it up by 15-20% If the backfires go away, you've found the problem (keep an eye on the duty cycle too).

Wideband sensors are a helpful tool, but they shouldn't be relied upon until their accuracy and set-up is known to be good, and correlates with what you see from the engine.

Lance.