Brian --

Good discussion!

So.... if the A/F ratio is set for 14:1 and the actual, and set, match - what possible difference does it make? I.E., you set the idle A/F and the ECU with the help of the O2 sensor makes sure that's where you're at.... I would ASSume then that the PW is properly set/adequate etc for the situation?

I too appreciate this discussion. You said exactly what I was thinking Greg. I ASSumed that this is what made the EZ-EFI easy! You set the A/F ratio you want and based on the spent gasses tested by the wide band O2 sensor the computer changes the settings necessary to maintain that AFR. I understand Brian's explanation and don't disagree with it. My thing is, I went with the EZ-EFI so I didn't have to know all that. We didn't want to spend 5k on the induction and another 5k in tuning and dyno time. And yes I think we all know there are people doing that. I also wanted to do as Jody said and use a rear mounted regulator. As he said this is a whole different discussion. For me I will go back to my previous comment. "Must" implies no other option. I think you Greg have proven that the EZ-EFI system works well when applied to the correct application and without vac. ref. to boot. Jody has also found an application that did not suit it with Charlie's Cammer. In Jody's case, I don't think it had anything to do with the lack of a vac. ref. regulator. To me this concludes it is not a "Must". I'm not trying to maintain a pissing match here either, but as we have discussed in the past, there are many people that read these posts who do not participate in the discussion. For them to read this and feel they "must" do this I think is not right. Anyway, I am comfortable with what he have done so far. When the truck is on the road, I will know whether I just stuck my size 14 in my mouth! :cheers:

I gotta say this, these type of threads can contain the best information. And Brian, I'm not trying to be a Jackwagon. :lol: A debate over this stuff is better than a lot of other things! :thumbsup:

I did move the regulator up to the engine and ran a vacuum reference and it made no difference in how it ran or the issues I was having. The issue with Charley's car is that the EZ EFI is not the right system for that combo, he's going to an XFI.

Agreed, that the EZ EFI is good for what it was intended for... not something as radical as that car maybe.

I do totally disagree that the vac line does not have to be connected to the regulator in the EZ especially.. it will run rich in most cases if you do not do this. If you switch it from not hooked up to hooked up then it will take time to learn out the areas where it was trying tune around the perssure differential. The more vac the engine makes the more this will be a problem.

I am saying this for the exact reason you are saying it "does not matter" so other people on the board that read this do it the right way and don't try to over think it... like you said if you wanted to know this then you would buy a tuning EFI system. In this case just follow the directions and don't think about it.

When I do things... especially EFI.. there is only one way to do things.. the right way. This is a clear cut right way to do things, so why would you do it any other way?

PW proper... no.... works yes... here is why. Without the regulator hooked up and lowering the fuel pressure to maintain the same flow, the ecu has to trim out the extra fuel and really lower the numbers to get there. It sometimes can do this and sometimes cannot. There are several guys complaining about having engines that run too rich and the EZ will not tune it out. Most have found this when there was no vac line connected. If you read the CPG Nation board.. this is one of the basic settings people mess up.

I had a shop in your neck of the woods calling and calling me, since I was up there... had a EZ... one of Bobs... 10 different people whith o scopes looked at it and no one could get it to run... I went and reset the wizard.. went through the screens... hooked up the vac line and wow it runs without any black smoke. They were also told there was no need to hook up the line.. not true.

You understand what the regulator is actually doing? Correct?

The rear mounted regulators... yeah.. another problem there.. I had two burned up offroad cars because of that last year.

I wasn't speaking of the EZ. I've only done one of those, and it doesn't work for the combo (750 HP 494 Cammer Nascar twin throttle body engine). I made several changes to get the vacuum up, but being rich is not the issue...............

Again, we're just discussing your claim that the reference line must be used. I was speaking of all EFI, but even with the EZ Efi I'm not sure I agree. It's obvious many people have them running fine without it. Is it a good idea to help it self tune, apparently so. A "must"......... no. I have tuned too many EFI systems without it to agree.

It's all semantics. When you speak in absolutes you'll invite people to give examples that contradict what you're saying. If you said that the system is designed to have the reference line attached, and it helps the computer learn the tune much faster, I don't think that anyone would disagree with you. It's the absolutely "must have" wording that doesn't fly, because we have examples of that not being true.

I've done countless rear regulators without burning any of them up. GM does it on the late model Vettes and other cars. Of course they bump the fuel pressure in those, which I also do. There are several cars on this site that are tracked and street driven with the rear mounted regulators, either as a separate regulator (still bypassing, just doing it at the rear of the car) or using the GM Vette filters that regulate/bypass right from the filter.

Why won't this work? Well, it will, but curious why you think it's wrong. One of the main benefits is eliminating all that hot bypassed fuel from heating the tank and leaving you stuck on the side of the road (ask the dozens of Power Tour cars that experienced that from year to year how much fun it was).

Put an engine on the dyno sometime with 8 O2 sensors and play around with regulator placement and you will see why.

Even with running the regulator in the front and looping the rails can show as much as 1 AFR point from side to side.

What stops the fuel from just bypassing the fuel to the tank insead of going to the engine? It will follow the easiest path.

There are other ways to dealing with hot fuel than bypassing it in the back.

bypassing in the rear works for a low performance engine but when you start to get something that really needs fuel flow it will not work. You will end up with burned valves and or broken pistons.

So you agree how it works... but since I explained why it is the right way to do it... and since you can make it work the wrong way then... it's not necessary? Come on. I can make an engine run with the .008 piston to wall clearance... does that make it right? No.

Look at all the OEM pump engines that don't use PWM pumps and they all have vac referenced regulators... OEM changed to that in the early 90s.

It is an absolute. Must have and the right way. If you don't agree then you are saying the injectors should flow more fuel at part throttle.... and you already said that isn't the case. Besides how hard is it to hook up a vac line?

still don't get the bolded part. There's more than fuel pressure that affects how much fuel the injector sprays. Of course idle needs less fuel than wot or load areas. But you don't HAVE to lower the fuel pressure to accomplish that, you can change the pulse width. I'm not arguing which is "more correct" I'm simply saying it is not a "must" to run the reference line. If it was a "must" then eliminating would not allow the engine to function. That's how absolute a "must" is. Do you get what I'm trying to say? I can take a car you've tuned with the reference line and disconnect the line, re-tune the VE or fuel tables, and make it still run fine. I'm speaking of an end-user tunable system, though I ran Charleys car with EZ EFI both ways and it ran, started, and drove perfectly. The problem with that combo is learning harder throttle areas.