Engine is a 383 with AI 200cc top end kit and 232/244 110+4 cam. BBK 58mm TB with the idle hole drilled. Spark plugs are TR6's gaped to 0.050. Car is an M6.

I'm having a few issues at idle and I'm just not sure what to tackle first. I'm thinking they are interconnected. The issues are as follows:

Split and inconsistent BLM's. Sometimes they look good and other times they don't. About the only thing consistent is the LTFT stays split and sometimes is nearly at the limits even when the BLM's look great. I had this exhaust system on the stock engine and didn't have these issues at all.

Knock retard of up to 3* with a commanded 25* while sitting in the mid 60s for MAP and 800-850 rpms. Sometimes it's there other times it's not. Coolant temp is 160-170 during this time. I started higher with the spark in the upper 20s low 30s and have slowly been bringing it down. It's to the WTF point. I'm not convinced it's truly knocking but I'm not ignoring it.

Idles rich to my nose. Wish I had a wide band O2 sensor. Car smells rich. I've been playing with the injector offsets at idle and that has helped tremendously. Spark plugs look good. Can't get consistent temp readings on the header tubes to really use that as a guide though. During this time of changing the offsets, BLM's didn't change.

So suggestions on what to tackle first? I'm considering pressing a tube into the TB to ensure the idle air passes into the intake properly. That just simply bothers me with the lazy design of an expensive part. I'd hope it would help the split BLM's but I'm not sure.

I'm reasonably sure I have no exhaust leaks but am open to suggestions on how to best check. I hear nothing out of place. O2s are new.

Anything else? Using Scan 94/95 for logging and have TunerPro and CATS

Thanks

 

are the 02 readings consistently high on one or both sides (600-800)?

that would indicate a rich condition.

aftermarket TB's present issues on split/inconsistent BLM

If you have your stock TB, put it on and see if the BLM thing settles

what is IAC counts at idle with engine at operating temp?

 

No, I get decent voltage fluctuations from the O2s while idling. Once moving and while cruising at steady RPMs I get normal, rapid voltage fluctuations.

IAC counts are in the 40s or so at idle and warmed up. I do have the blades cracked just a small amount. I didn't want to drill too big of a hole before I maybe tried making the idle passage better. I reset TPS back to ~ 0.60 volts

I didn't even think about putting the factory TB on and trying it. Great idea. I'll give it a shot.

Thanks

 

Well, I tried out the factory tb. Really the only difference is the split BLMs seem to recover more quickly and not go to the extremes. Still split though and occasionally does wonder out of whack, high or low.

I did notice the LTFT values always split and do so quickly when off the throttle. Press the throttle a little ~1200 rpms and they come back closer together immediately. The direction they move when split always stays the same.

Any ideas? I'm thinking about putting the 58mm TB back on to keep working on the tune.

Thanks