EFI tuning, Need some help.

[JRouche]

Ok, Im just getting around to driving my car with an edelbrock EFI system.

Its a GM 350, rpm heads, rpm cam, nothing extreme.

It started up just fine off the base map, idles fine, good to 6500rpm.

I had some trans issues that I had to work out first. Trans didnt wanna shift at WOT till 7200rpm. Got tired of hitting 7000rpm and took ALOT of time to work that out. The engine only breaths to 5500rpm with the heads and cam, no need for such high rpms.

So anyway.. Back to the EFI. Rich!! Yup, eye burning rich, and even my wife said it smelled when she was behind me on the freeway.

So Im working on tuning it one stage at a time. This is where I need some help.

The easiest first, idle. My plan is to lean it out a percentage at a time at warm idle till I get max idle with all other conditions the same. Is that a good start? Remove fuel till I get max idle then reset my idle rpm. I dont mess with spark right? Do I just keep removing fuel at idle till what? How do I know too much fuel is removed, when the idle drops? So I take the fuel out till the idle starts to drop then dial it back a lil?

Then I was going to tune it at various load conditions. Thats gonna be a lil more involved. But I like the base line for constant throttle, might be a lil rich. Ill dial it off some for part throttle cruising.

But now how about full throttle? And I have transition throttle maps also, Im not gonna mess with that. But WOF. How can I tell what it needs.

How can I tell if it needs more spark. Yes, I can control all of the spark curves also. But Im not gonna mess with the spark yet unless I hear someone say more spark is beneficial at this or that load.

Im really having fun. But I know better than to just start tweaking this and that. Thats why Im here asking.

Id love to hear some opinions on where to increase or remove fuel for certain load conditions. And also where I might gain or lose with some spark advance or retard.

Any and ALL thoughts are welcome!! Im a blank slate at this point, ready to learn. JR

[camrat68]

Which edelbrock efi system are you using? I have their 35520 system on a 502. Start by pulling 10% idle fuel at a time until you can stand behind the car without having your eyes water. That'll be your starting point. Do you have access to a wideband o2 sensor? If not, get youself a notebook to write down settings because it'll be a whole lot of trial and error........

[JRouche]

Which edelbrock efi system are you using? I have their 35520 system on a 502. Start by pulling 10% idle fuel at a time until you can stand behind the car without having your eyes water. That'll be your starting point. Do you have access to a wideband o2 sensor? If not, get youself a notebook to write down settings because it'll be a whole lot of trial and error........

Its the 3500 unit. Thanks for the info, Ill pull some fuel out at idle till there isnt anymore nose bleeds LOL

I have an Innovate brand new in box LM-1 widband monitor. Yeah, thats how long Ive had it, the LM-2 has replaced it. But the LM-1 is still a wideband sensor. I just need to get off my lazy azz and install it. Just a matter of raising the car and drilling a hole and welding in the bung for the sensor. Then do some simple wiring. Ive had it for a year now. Im just getting tired of welding under the car. Its getting old. I really outta do that this week though. Been long enough.

Thanks for the advice, JR

[JRouche]

Oh, the engine particulars if needed.

Chevy 350, bored .030" over, Cola 4340 crank and 6" rods, splayed four bolt, Manley (full floating) forged pistons, Edelbrock RPM heads, Edelbrock Pro-Flo EFI, Edelbrock Victor water pump, Cloyes true roller timing set, ARP for just about everything, ATI Super Damper, March pulleys with serpentine belt, Flex-a-lite black magic electric fan, Griffin 31"x19"x3" aluminum radiator, Lokar dip sticks and some other stuff.........

[My427stang]

Some questions

1. What are you running for initial timing?

If you have a ton of initial, they will smell because there isn't much heat in the chamber. I limit it to 12-14 initial if I can, you can always tailor the curve to come in quick of idle.

2. How does the Pro-flow control injector timing?

If you have the injectors firing early on a SEFI system, it can pull through during overlap. By simply retarding injector timing at idle, they can clean up a bunch. Plus, its more accurate a/f mixture because the O2 sensor isnt seeing that raw fuel being pulled through

3. What thermostat are you running right now and what tep does it idle at?

EFI likes heat more than carbs at idle.

4. Does the Edelbrock have anyway to log?

If you posted what the computer was seeing, I am sure we could help more

[JRouche]

Some questions

1. What are you running for initial timing?

If you have a ton of initial, they will smell because there isn't much heat in the chamber. I limit it to 12-14 initial if I can, you can always tailor the curve to come in quick of idle.

2. How does the Pro-flow control injector timing?

If you have the injectors firing early on a SEFI system, it can pull through during overlap. By simply retarding injector timing at idle, they can clean up a bunch. Plus, its more accurate a/f mixture because the O2 sensor isnt seeing that raw fuel being pulled through

3. What thermostat are you running right now and what tep does it idle at?

EFI likes heat more than carbs at idle.

4. Does the Edelbrock have anyway to log?

If you posted what the computer was seeing, I am sure we could help more

Thanks for looking in!!

1. The pro-flo has you set "base" timing to 10*. Base timing is where you basically turn off the timing control from the computer and set the distributor. Its meant, from what I understand from phone convos with edelbrock to get a base line for the computer. Why they picked 10* I dont know. The computer will adjust for real timing. Maybe its a happy medium between physical timing and how much the computer can move the timing. So I have triple checked my base timing, its right where they want it for the computer.

2. I dont know. I do know they supply a couple of chips for various cams and intakes. The thing is, my setup is perfect for the system, for what they engineered. Its the RPM cam and RPM heads. I used the same parts that they used when they modeled the system, and the various chips are for other induction systems. But Im pretty much running the ideal setup that they marketed it for. All the way down to the spark plugs they used for the 425hp mule they used.

3. Now thats a problem Im still working through. I have a good 185* stat in place. Its great when Im stopped, engine sits right at around 185*. But Im WAY too cold even at 25mph through town. It will drop to 165* on a really hot day if Im moving. I know I need to crank the engine temps up some. Id even like to see 195* Im working on that right now.

4. Nope, its a very simple system, no data logging. Remember, this is a 1992 system, not many inexpensive data logging systems available then. Actually not many laptops around then either.

Thanks for the time to post!! Im looking for all and any help. JR

[My427stang]

Glad to try to help. Get a good stock style thermostat, the fancy modified Stewart ones have too large of bypass holes and tend to cool down. If you like to drill a hole to aid in trapped air, limit it to a single hole in a stock thermostat at the 12 O'clock point (ON EDIT - location of the hole doesn't matter on a Chevy, I forgot they sit flat, I am a Ford guy at heart LOL) and no larger than 1/8 inch.

Odds are you are getting a ton of timing at idle, so after you get the thermostat changed, if you aren't happy, pull 2 degrees out of the base timing, see if it helps a little. Timing will always be additive, so even if it adds 5 degrees at idle (its probably more like 10+, it'll still be plenty) that way It'll generate a little more heat

Finally, does it have any self diagnostics? If you get nowhere with the above two comments, I would probably start checking the sensors it has for proper function. All it takes is a bad coolant temp sensor to send it off the deep end.

[JRouche]

Ok, Im getting better at this. I pulled some fuel out at idle. Started out with 15%, then 20, then 25 then 30%. 30% was too much. I would blip the throttle and get a long (two second lean condition). So I added some fuel and set it at 28%. Idles great, no eye burning exhaust anymore. But it was prolly too lean still. From a stop going to full throttle it would go into full lean condition and stumble with a lil backfire and no go. I added a lil more fuel and put it at -25% for idle. I like it there, good for idle.

But I still have the WOT issue from a stop. So my next question is. Should I add fuel for the transition map. The transition map looks at throttle position only. I dont know if the system can react that fast so where it sees a large throttle change if it can stuff enough fuel from idle to WOT at a stop.

Or should I increase the fuel through another fuel setting such as the rpm map or the vacuum map.

And I know, sounds confusing, thats just my confused state. I really dont know anything about how to tune this EFI. But Im having a ball playing with it. As long as I dont wreck the engine.

I havent messed with the timing yet. I want to try and work on one set of variavbles at a time. Too many changes at once might produce some bad behavior.

Oh, and with the reduced fuel at idle it seems to have cured my cold running engine. She is able to get to 185-190 and run there now. More like 180 during driving (not idle), but 180 is better than the 165 I was seeing. I have a feeling the super rich condition at idle was cooling things down too much. And yeah, fuel usage has dropped also :)

So now its off idle issues. I may increase the idle rpm some, its a tad low. Ill bring that up to 800 rpm. I really dont want to add any more fuel at idle, I think its good right now.

So off idle, into full throttle? What does an engine need? As far as fuel and spark go. Id rather not mess with spark yet, unless I change the fuel.

Umm, just an indicator. Today I wanted to see if the low rpm idle I had in place was an issue. I stopped the car on the road (empty road) and held the brake to bring it up to 1000rpm. Then hammered the throttle with the brakes off. Hell man, she took off!! Posi rear end hooked up and the rear moved out a lil while the tires were looking for traction, and when they did she moved out.

Now thats what I want!! From an idle. I want to be able to throw the hammer down and NOT have the engine stumble. I know the engine has the balls. Its just a matter of figuring the efi out. The diff between 1000 rpm and idle is only 700 rpm. I wasnt spooling the engine up for a rocket launch. I think I just took it off the idle circuit and it was into a different fuel and spark map.

ANY HELP??? I do think this edelbrock efi has some possibilities. I just need to find it. Oh, and all the other modes of driving are right on. Anything above idle and she is very responsive. No problems with it once I have the Rs up past 1000rpm.

Any help at all is welcome!!! JR

[Jim Nilsen]

It sounds like you need to work with your IAC (idle air control ) or your throttle postition/acceleration part of your program to add the right amount of fuel with the appropriate throttle movement.

[JRouche]

It sounds like you need to work with your IAC (idle air control ) or your throttle postition/acceleration part of your program to add the right amount of fuel with the appropriate throttle movement.

I have the IAC set correctly. Its a basic setup. The idle is fine, it was just a lil rich by 25% , yup, that much.

The IAC valve lets more air in during idle. Kinda funny but you can actually hear it allowing more air in on extreme cases of low idle like mine. Sounds like a vacuum cleaner. The IAC valve is doing its job. I removed 25% of fuel at idle and that fixed that. Its great at idle now.

Now Im gonna play with the WOT settings a lil. Im thinking of dumping a lil more fuel in at off idle, 1000rpm and maybe a lil more spark. Just to see what happens.

I took her for a sunday drive today on a quiet stretch of road and laid the hammer down. She didnt stumble like before. First gear went fast (40mph maybe, its short, its a 700r4) then second hit hard and the rear end came loose (more than I wanted, the rear traveled about a foot and a half side ways) and I stayed on the throttle till third hit. Third gear hit too soon. It wasnt even up in the power yet and she shifted. Kinda weak. Shoulda stayed in second a lil longer.

But yeah. I think Im getting through the issues. I prolly wont change much more. The basic chip is good for my engine. It was just a lil rich on the idle circuit I think.

Shes pulling as strong as this small engine can. Shes not a power house, but good enough to get the groceries. Not even a race car. But fun even so. JR

[My427stang]

Looks like you are getting there.

I'd start looking at the timing curve closely. You may find you want to retard the timing a bit to clean up idle even more, then it may let you tweak the a/f mixture again. However, odds are you'll want to play with the curve to come in quicker. Often a good a/f mixture will look and smell rich at idle because of lack of heat in the chamber with too much advance.

Also, what are you calling too rich? 14.7 stoich is too lean for power