I just installed the ZZX cam in my car. Before the install my BLM were 128 and the IAC was at 7. Now the BLM is 160 and the IAC is 88. Which should I tune first?
If I get my IAC down to where it needs to be will the BLM drop also? That cam is sucking so much more air.
The other problem is I can't remember the formula to get your BLM correction. I think you divide the actual BLM by 128 then multiply that by the (RPM map KPA cell)?
Next, should I just add fuel by using the + -. Or should I tune each cell. I would figure the whole VE map would be lean.
Any help would be greatly appreciated.

 

At first I was going to say that something is wrong ... then I saw that you swapped from a 236/242 to the ZZX? The ZZX has LOWER duration numbers which will increase your volumetric efficiency in the lower RPMs and decrease it in the higher RPMs (comparatively speaking of course).

If it were me I would open up the throttle blades some using the throttle stop screw. When the car is fully warm you want the IAC counts to be as low as possible. I shoot for around 10 counts. Once you get that set then you'll want to tune the VE table. Read my VE tuning article for how to tune the table.

Tim

 

TRAXION: I use to open the throttle blades but they would have to be opend so far that I would only get 3.70v TPS at WOT. What I had to do was drill a hole in the throttle blades to get the desired IAC. This also brought my BLM back to where they needed to be. With the blades open the car ran rich. Now I get 4.46v TPS at WOT.
The ZZX I have was speced with a cam doctor to 240/240 with a 1.5. I am using a 1.6 so the cam is now a 242/242 .596/.598. From what you are saying WOT should still be about the same?
Should I use the percent method to the lowers? Or pick individual cells? I know that in your VE tuning sticky you stated that you pick cells and create a curve accordingly. I am not as good as you by a long shot. I think I will have to stay with the +/-scale.
Thanks for your reply. I now have some where to start from. What do you think my final VE will be at WOT? Do you think it is possible to reach 100% VE on a N/A motor?

Brett

 

I forgot that the MAP volts went from 2.70-80 in park and 3.10-30 in drive to 3.20-30 in park and 3.40-50 in drive. I don't know if that helps at all. Do you think this will make it harder to tune?

 

Brett,

Wow - For some reason I was thinking that the ZZX cam was 228/228 ... I think I got it confused with the ZZ409. It's definitely weird that your BLMs shot up to 160. NORMALLY, when you go to a cam with bigger duration you expect to lose volumetric efficiency in the lower RPMs. This results in LESS fuel being needed. Thus, BLMs will drop (which indicates that the ECM is pulling fuel out). The fact that your BLMs went UP indicates that your VE with the new cam is actually better (unless something is wrong - bad O2 sensor, etc). Hmmmmmm.

For the VE just pick several points and tune those VE cells. This will give you an idea to how the curve is going to look (in graphing mode).

As far as 100% VE ... it really depends. If you are using small injectors, low fuel pressure, or an injector constant that is too high then you could hit 100% VE on an NA motor. It really just depends on how the fueling of the entire system is setup. I think that I have my peak torque point on my VE curve setup for close to 100% VE. I do this from a safety perspective. Also keep in mind that in the upper RPMs you will most likely be in WOT Power Enrichment anyhow. Thus, the VE curve will have other adders with regard to fueling such as the WOT PE vs. RPM table and the WOT vs. Coolant table.

Tim

 

I hogged out the throttle blades. The IAC is now at 0-1 which is low I know. I need to add a little Devcon and that will be taken care of. The BLM's came down to 145ish. The car runs like butt though. I think the distributor is messed up. When I disconnect the EST the car dies. I changed modules to no avail. I will change to the stock distrubutor in a couple of minutes. The problem is with the EST connected I can put the timing light on the balancer and read 6*. It should read like 42* or there abouts. I think this is alot of my problem. I did drive the car and it was about normal at cruise and rich under accel. Your theory was dead on correct.

 

Hey Tim. I found out what was causing all of my problems. Operator is a dumb azz syndrome. When I put the distributor in I rolled the motor around to 6* BTDC. I then ligned the rotor up with the #1 terminal. Well it needed to be advanced another 12-14* to be correct. Hence the dieing when I would disconnect the EST.
You were right on all accounts. The car does run a little richer now. 124-5 on the BLM's. Sorry I wasted your time earlier. I also hogged out the throttle blades for no reason. Like I said, nothing a little Devcon didn't cure. Thanks for your time and explinations.

Brett