Lean Cruise AFR

[Blue71]

Originally Posted by 93ChevyTBI

I'm not sure at all but I bet Fast or someone else will chime in that you can convert my PCM to MPFI.

Yes, you can convert "your" PCM to PFI mode.

NOW BACK ON TOPIC !

I just happen to have the BDRW bin, took a look and compared it
to the BJYM bin the one I'm using, the EGR setting are the same.

How ever, I did forget about the flag at 400D bit 4, THANKS Fast305

[94Blazer383]

Originally Posted by 93ChevyTBI

that tuneport pic (hope that what it was...maybe LT1 intake?) was sweet. I always loved the looks of that set up in the Iroc's. I used to want to put it in my truck but like already mentioned, the swap is pricey..not to mention tuning. I consider myself very lucky...repeat VERY lucky to have a competent tuner close by. With TPI, I prolly wouldn't get that lucky again.

I'm not sure at all but I bet Fast or someone else will chime in that you can convert my PCM to MPFI. That's IIRC. Still, TPI would be nice on a truck for the torque.

Are you underestimating my abilities? The boat was pretty much the same as TPI, running in true MPFI mode on the TBI ECM.

Sorry got of topic

[94Blazer383]

Originally Posted by Blue71

Yes, you can convert "your" PCM to PFI mode.

NOW BACK ON TOPIC !

I just happen to have the BDRW bin, took a look and compared it
to the BJYM bin the one I'm using, the EGR setting are the same.

How ever, I did forget about the flag at 400D bit 4, THANKS Fast305

What about 400D bit 4?

[Blue71]

Turns EGR off at idle.

[MSlewis]

Originally Posted by Blue71

I think I have lean cruise working some what without the valve,
But it does not follow the command tables at 4BB4. its always a point leaner AFR then whats commanded. I can see (using DataMaster) it going to openloop on light loads, AF will lean out blms will change. I think it might have some thing to do with the tables at 4895.

Do you mean 4859? I do not see 4895.

[Blue71]

Originally Posted by MSlewis

Do you mean 4859? I do not see 4895.

Oops, Yes, 4859

[93V8S10]

Maybe thats why I didn't have any problems with mine. I don't use a EGR valve at all, so I had turned 400D bit 4 off a long time ago.

[MSlewis]

Originally Posted by Fast305

For a while I was running BRDW which is the Mexican Export L31 TBI .bin that works without EGR. Lean Cruise worked 100% in that calibration, WITHOUT the EGR valve. There is an idle lean limit table that is only used at idle. Once the throttle is opened enough for the idle flag to be lifted the PCM uses the main open loop air/fuel ratio table or any additional adder table.

I used that table awhile back to help cure my idle fluctuation issue due to my cams overlap. Tried everything from o2 swing points,o2 voltages, and gains, but nothing was working. The engine simply didn't want to idle at 14.7. What I finally did was use that table @ 4BA4 along with the Open Loop Idle Time @ 4BA3 to put fueling into open loop as soon as idle parameters where met, and run @ 13.5 min AFR as set by me in the min idle table.

As far as L400D bit 4 is concerned, I havn't seen a bunch of bins but suspect most do not have the EGR having the option bit being enabled @ idle due to the fact it will stall an engine at idle. Also bit 4 is irrelevant if the TPS % to enable EGR is at least stock @ above 3%. I will say that I must however be overlooking something because I've been on it for a solid week and have made 0 progress. Even tried reducing the VE table by 10% across the board to see if the AFR would follow the change, but all that did was bring INT up. BLM still stayed stagnant @ 126 and WB stayed right around 14.7-15 even though commanded was 16. Uncheck bit 0 and everything is back to normal. What am I missing????
On a side note, after swapping this 350 back in my fuel mileage even without lean cruise working is SOOOO much better and tuning is SOOOO much easier than that 383. This thing purrs like a kitten and appears to be getting around 14 in town, still, the goal of 21ish Hwy would be better.

[MSlewis]

Well I tried something different today to no avail other than another way to keep the CEL off. I thought maybe the EGR test was failing and even though I had the diag bit unchecked on 5B02 bit 6 that it was somehow connected to not enabling lean cruise. So what I did was insert the constant for 4E4D and not allow it to even run the test until 255 MPH. DIDN'T WORK...still not enabling lean cruise, o2 still switching, BLM's still locked, but no CEL either.

[Blue71]

Originally Posted by 90C350

Just wondering if you guys know how to set up lean cruise settings with the 7747 ecm. I can always use a little more MPG.

Here is the patch for the 7747 to add lean cruise to your bin.