I just installed a LT4 Hot Cam in my 89 L98 TPI and I am working on the idle tuning.

With a MAF system, can you make any adjustments to the idle enrichment? I am working with a Wide-Band 02 and I would like to setup/change my AFR at Idle.

Any ideas on what table or parameter that can be changed in the PROM to do this? I have been looking.....

Thanks!

 

Do you want to make changes with closed loop on?
- change the "closed loop rich/lean threshold vs airflow (table starts at 046B, 9 rows), at the lower airflow values for idle. 450 mV would be "stoichiometric" I think, but most of the stock chips have more than 530 mV, so maybe it's saying that's the upper threshold. 700 would make it a little richer, 200 would be lean.

Do you want to make it richer/leaner during warm up?
- use Open Loop % Change vs LV8 (table starts at 03DC, 17 rowas), at the lower LV8 values for idle.
- also can use Open Loop % Change vs Coolant Temp table (041A, 17 rows). That will change a/f at all loads.

Do you just want to make the BLMs get closer to 128?
- MAF Table #1.

 

Thanks so much for the info . I will make some changes in the specified tables in real time emulation until I get what I need (best idle with that CAM).

 

You shouldn't need to make many adjustments for that cam at idle. It's a pretty lame/weak cam. That's not intended to be a an insult. It's just that the HOT cam isn't really agressive by any means and I wanted to get that point across. It doesn't have a lot of overlap or duration.

BTW, don't you tune for money? Definitely interesting to use this board as your tech support for things that you will get paid for. JMHO though.

Tim

 

Now it that's true, that just doesn't seem right somehow...

 

The car idles OK with the stock tune, just trying to make it better. I do agree the cam is not huge, but for a stock 350 on the street it works for the application.

I do own a tuning shop, but this tune is for my car, so unless I pay myself, no money here. I also have offered free dyno time to members of this board, so I think some advise is not out of line.

Thanks for the feedback and input on this topic.

 

Well, that sounds a bit better. To bad yoiu're not in the Dallas, TX area with a free offer like that one.....

 

curious what do you consider "huge" aggresive" and if you were tuning for 'that" cam (duration)....would you still change those same things?

 

Adjusting the "closed loop rich/lean threshold vs airflow" seemed to do the trick. It did not take much of an adjustment, about 20mV more lean. Seems to have a much better idle now with no "hunting".

Thanks again for your input.
Nate