General SAFC II & H8 ECU

[kiddsm95]

Here's an interesting question. Yesterday I was running the H8 ECU with Ceddy Mod's and my SAFC II was all zero'd out. The car ran perfectly fine, but when I pulled the SAFC II off (Sold to DSMT member), the car now runs extremely lean. My WBO2 pegs lean!

This is just at idle, so at 750 rpm my AFR's should be 14.7, with timing at 7° advanced (compensated for big cams). Any ideas why this would happen?

 

[steve]

Did you remember to reattach the MAF signal wires since they are cut and the SAFC inserted in between them when you took it out?

 

[kiddsm95]

Yep, the pink and orange MAF wires on the SAFC II. I re-attached that blue/yellow ECU wire and soldered it back together.

The car will idle at 14.7 on the WBO2 for 10-15 seconds, then it just nose dives lean. The rpm's drop alittle bit and the exhaust starts popping indicating lean AFR's.

 

[clockworktoy]

Double check your soldering job, other than that there should be no reason why any change should occur if the afc was zero'd out.

 

[knochgoon24]

Check your MAF wires again.

 

[kiddsm95]

I'll check when I get home. Just so I understand correctly, if the MAF wires came apart this would disrupt the MAF signal and make the car lean out? It does go rich when I give it some throttle, but the instant I let off it goes lean again.

I'll let you guys know what the culprit was.

Checked the MAF wires and they were still intact, but I guess I didn't put a sufficient amount of solder on. Cleaned it all up, re-soldered the wires and now the car runs great.

Thanks.

 

[kiddsm95]

After a couple days of driving, I've got some other interesting things going on.

1. Everyonce in a while when the car idles it'll go lean (18 afr's) again, but when I shut the car off and turn it back on it will run ok. Why does turning it off and on correct this issue?

2. As the car runs, it's fairly rich (11.4 afr) at idle & cruise. My high & low octane maps are set to 14.7 at idle and for low load cruising conditions. The only spots on my fuel maps that hit 11's is at 260 load (wot). My WBO2 is installed in the factory rear O2 bung, and my factory O2 sensor is wrapped in foil stowed away (old DSM trick). Since I've got the rear O2 shut off via CeddyMods periphery bits it shouldn't be relaying any info to the ECU correct? Thus it shouldn't be the reason for the rich condition.