So I am finally getting somewhere with my engine build. Had lots of issues with Vac leaks on manifold gaskets etc. Car is starting to run right after playing around with PW. However from day one with my Dynamic EBL flash II it has shown in closed loop that it is running perfect 128/128. When I give it gas the BLM will move around a bit. However based on my burning eyes and nose, I can tell it is still really rich. Anyone have any ideas on this one. I have checked the exhaust manifolds for leaks, replaced my o2 sensor (heated) triple checked o2 wiring, new HEI ignition system, new plugs (old were carbon fouled). Also lowered PW vs voltage, MAP PW, TPS PW. Still getting a rich condition... Any help would be appriciated. Not sure where to go from here. Thanks!

 

I'm not the most savvy at ecm and electronic tuning but it does seem odd to show 128 in closed loop and still be rich. Are you sure it's in closed loop?
Fuel pressure?
Have you tried tuning with a wb o2?

 

I do know that with one O2 sensor on one side of the engine, the non-O2 sensor side can be going totally haywire and the ECM will think everything is hunky-dory and report a 128 BLM while the non-O2 sensor side is running pig-rich or super lean.

On the flip side, the O2 sensor side could be having a malfunction causing a lean condition.... and if you somehow tuned around that, then the ECM is trimming fuel richer on the O2 side which can make the otherwise normally-operating non-O2 side run extremely rich even though the ECM is reporting 128 BLM.

I know the short runner manifolds often times suffer from the "split BLM" issue due to poor idle air/fuel distribution (i.e., one side at low BLM and the other at high BLM), but your setup says "TPI" in it, so I'm assuming you still have the factory long tube runner TPI manifold.

Other things to check would be that you have 14.7 is the stoich constant in the calibration and not accidentally something lower.

As was stated, a WB O2 sensor would definitely be of help (esepcially if it's installed on the side opposite the NB side).

 

Thanks for the replies! My FP is right at 50 (vacuum removed). Unfortunately I dont have a WB yet. I have dumped a lot of money in my build and cant spend any more at the moment. A regular o2 should get me close enough. Although it would be good to have one on each side.
I do have TPI long tubes. I pulled all the spark plugs and they all had exactly the same amount of carbon on them. So I dont think there is an issue one side to the other so they are all rich... All cylinders are within 5psi of each other. The car has yet to be driven on the new engine. I think I may just drive it, maybe that will work out some bugs??

 

Are you sure its in closed loop? Is it 128/128 at idle and thats where you smell rich? Sounds like when you hit throttle it exits open loop and goes into closed and thus the numbers move. How far do they move?

possible its so rich its either causing the o2’s to be to cold and drop out of closed loop, or incomplete burn introducing air in system and making it seem its ok afr but its not

i always recommend a wideband o2 to confirm. And Check plugs


easy thing to do is yank fuel til engine doesnt run smooth, see if you ever get the blm values to move

 

100% agree with this.

 

Why 50 psi? Are your injectors small?

 

Sounds like a plan. Build some heat in the engine, seat the rings. Don't beat on it, just run it up a bit.

If there is a lot of cam, overlap will fool the O2 sensor into thinking the engine is lean. Running open loop idle helps with this.

RBob.

 

I agree. If it is not idling smooth you have misfires which can cause the rich smell. The o2 sensor reads oxygen not fuel. A misfire doesn't burn the oxygen so the sensor thinks it's lean and adds more fuel. I fought my idle for years with a mild cam and headers. I almost got kicked out of a parking garage because the exhaust was so stinky. I was in closed loop and the wide band was reading 14.7. I finally went open loop idle with the AFR at 13.8 according to the wide band and now have a smooth idle and no more smell. Reading the spark plugs shows my motor is happy now.

 

Yeah, Im in closed loop and still rich. Im going to tune out some fuel. then just drive it.. Hopefully this weekend. Car hasnt seen pavement in almost a year, lots of crap has accumulated in front of that that needs to be moved

 

Was this ever solved?

 

Just curious. Changing the AFR should not affect closed loop operation right? I mean it would affect BLM/INT as they compensate for more or less AFR but it would not make the car run rich... right?

 

How do you "tune out some fuel" in closed loop? Would BLM/INT correct anything you "tune out" and you would be back to square one....too rich?

 

True. You would have to adjust the non-idle O2 thresholds.