This used to be a true statement. Not so much anymore.
I said "usually", no company is perfect, Edelbrock and Holley still both produce some of the best options there are for EFI. I typically run Holley EFI with Edelbrock manifolds on my personal stuff even though Edelbrock makes one of the best sequential MPFI systems on the market, especially for the price.
Did you miss or forget where he found the MAP sensor readings being erratic?
He suggested that I try swapping the on on my Jimmy to see what results I found.
I found a MAP sensor with ABSOLUTELY no part number on it! I bought this system myself, new, so it was the original to the system. But they couldn't even use a sensor good enough to have a part number on it??!!! That's crap quality BS there!
I grabbed a used one from one of the LS engines that we had around and it made a big difference!
It runs much better now! I put up with it since late in 2018, (7 years) assuming that I was missing something in the programming. I was seriously considering swapping to an LS because of how crappy it ran.
Please don't take things personally, I'm just giving out info for people to learn, all I said was that a lean misfire from the ECU cutting fuel is not going to be caused by false O2 readings from overlap, that would cause the opposite, it would be pig rich if it was getting false O2 readings from overlap as it would see the oxygen from the intake on overlap, think it's lean, and keep adding fuel, I've seen it happen in person but it's usually cams bigger than that. That has nothing to do with the MAP sensor, that's a separate issue.
If you have a bad MAP sensor you can usually see that when you can view the MAP reading live and you generally know if it's a reasonable reading for the application, and if needed compare it to a vacuum gauge. For this I have a conversion chart I made nearly 2 decades ago that converts between kPa and inHg, and it's also in my app.
I agree with shutting the learning off if it's cutting fuel where he doesn't want it to and its running fine mostly elsewhere, it's just that the overlap is not the reason for it cutting fuel. Now on the other hand with the Holley I just program that stuff out but I have also ran cams slightly bigger than his in a SBC and the Holley learns fine with the self learning even at idle and I have built customer engines with cams similar to his that ran fine with the Edelbrock as well, so I don't think the overlap is his problem, it's something else. And a person could spend time trying to figure out why it's cutting fuel when it doesn't like it, but if shutting the learning off while it's good keeps it from going bad I would just do that.
Also it sounds to me like he needs to turn the accel fuel up if it's going lean on tip in but he knows that. Waiting to turn up the accel fuel makes sense if its cutting out fuel when he doesn't want it to, but most self learning turns off unless throttle is steady state. That's a limit of the Edelbrock is it's just pump shot and duration, so if turning the pump shot up causes it to be too much somewhere else in the throttle nothing you can do about that but try to compromise. The Holley has multiple charts you can tune the accel fuel different for different throttle positions, temps, MAP, etc.
In the Holley you can also actually change the self learning in different RPM windows, and limit which way it can go. For example, below is the learning I have used in the Holley to stop it from adding fuel from overlap. It can only take it out, this fixes the overlap false reading issue. For his application where it is taking out fuel when you don't want it to you could restrict the negative side instead. Of course I always turn learning off once the engine is running as good as it can anyway, otherwise eventually it will learn some bad data from an exhaust leak or something down the road. I manually tune from there, if needed. I do usually leave closed loop on for most applications, unless bracket racing, but I do limit the closed loop down to 10% or less.
In the car I am tuning now with a lot of overlap (278/292@ .050, 311/
[email protected] duration)
and open collectors, I basically have to turn off self learning below about 4000 RPM and 30% throttle and tune it manually as the O2 reading is pretty much worthless below that, being a lot of overlap and open to atmosphere, it requires a lot of airflow before you can trust it, even then spark plug checks are your friend. You have to go by feel, does the engine like it, MAP reading, exhaust, plugs etc, because the O2 reading is absolutely worthless in that scenario even for manual tuning.
Bent saved me from scrapping several thousand dollars in parts and labor because I didn't know how to check and verify the data was making sense. I told him thank you multiple times!
I will be following his advice that he detailed in his post, #1181 and on the phone, to look for some more improvement in a few areas.
I get along with bent just fine so I have no problem with you taking his advice.
He chucks crap I chuck it back, for example he hates CDI boxes and he likes heavy crossmembers. I like CDI boxes and light crossmembers!
As for the EFI, I typically recommend the PF4 for someone who wants simplicity and doesn't have power adders, need trans control, or want data logging or full programmability. For most people that is more than enough. For someone like bent that likes to tinker, he would be better off with the Holley, I would of recommended that to him if he got it from me, not sure where he got it.
I do have a Holley Terminator X Max universal system in stock that would control the Edelbrock hard parts. Edelbrock just uses the Ford TFI targets in their distributor and some connectors would have to be changed or adaptors made but it would do it no problem. Though he could use the regular Terminator X with his manual trans.
I have had other customers inquire about that too.
