Gen 7 troubles

[xtrmeta]

I'm setting up my new BBC with an Accel Super Ram. I'm using the Gen 7 computer and harness. I have it programmed with a basic program in the Gen 7 software. It idles and starts fine. At part throttle it's fine. But breaks up at higher RPM. When I go in and put the correct specs in the setup and fuel screens it runs worse.
The motor is a 454 with Edelbrock RPM aluminum heads and full roller cam.
This is a brand new motor. I also have the dual sync distrubutor and installed it on number one, rotated the motor back 25degrees and repointed the rotor at number one. Now the book ends there. But All At Accel told me to also set the timing at 15 manually in the computer and use a timing light to adjust the distrubutor. I have not done this part yet.
What do I need to do to clean up the upper RPM.

[camcojb]

That's a tough system to learn on in my opinion. I will say their "feed in all the engine and cam specs and I'll spit out a tune" never was close for me either. What are you using for A/F? Their wideband is known to be inaccurate, so you might double-check with a handheld one if you can get one.

Jody

[xtrmeta]

I've had the Gen 7 on this car for about a year. I had it hooked to a small block first and never really got it to run perfect. Then the motor went so I swapped in the big block. I tried to use as much of the stuff I could from the small block.
It accually ran pretty good on the small block program when I first started.
Al from Accel gave me a basic program that he said matches my motor. So I installed that and it runs better. Breaks up on the upper end. So I went in and fine tuned the setup screens sent it to the ECM and it started to run worse. So I changed it back.
I'm just running the O2 sensor the came with the harness. IT's not a wide band.
The bad part is this is my first time with fuel injection. So I don't know anything about it. I've learned alittle from playing with the program but I don't know how to tune the fuel and timing screens.
The bad part is theres no shops near me that know how to tune it.
I called Turbo People and spoke with Jobe about tuning it. But he is 3 hours away from me.
So if I can get it to run OK now I'd be happy with that. I will be installing a Procharger on it this winter. So I'd like to wait till that is done to put it on a dyno and get it really tuned.

[nitrorocket]

I found the cinnection from the harness to the crank trigger/distributer was giving me problems, played with it for a while and it ran like a champ to 7K.

[xtrmeta]

I'm using the dual sync distributor. So it is using the crank signal from there.
I believe it to be a programing issue since I don't know how to program all of it.

[Hammered]

I have the Gen7 and before you play with the VE and AF tables you need to sync the timing like the Accel tech advised. If it starts and idles then you made it through the red light/blue light procedure okay. The next step is to force timing and then using a timing light, turn the distributor until you get the exact same reading with the light. Tighten it down and don't play with it again. Unforce the timing and then work your way through the VE and spark tables.

The instructions are woefully lacking in even the most basic detail and are full of errors.

A wideband would be a good investment.

Good luck,

John

[OHCbird]

Ditto what Hammerred said. You cant play with the timing until you get the baseline established.

And another ditto on the wideband- they aren't that expensive anymore when compared to the safety buffer you can create, and the power potential of WB tuning.

[xtrmeta]

I did the timing yesterday. It helped some. But it still breaks up on the higher RPMS.

[Hammered]

I am assuming you've double checked all the setup parameters and your fuel pump pressure has been set with the vacuum plugged. It's probably safe to assume the spark table provided by Al is reasonable for your combo. I believe al heads generally require more total spark advance and there should be a lot of info on what works with the BBC E-heads, I know there is for a Pontiac (36-38 degrees).

Setup a datalog with timing, AF, VE, RPM, MAP and O2 correction as a starter. Do some runs and see where your O2 correction is. Adjust your VE table to get less than 5% correction. Some like to keep the correction on the negative side to prevent lean conditions if something fails.

Have you done any of this?

[camcojb]

One other thing, Accel in their infinite wisdom has two power keys to run the tuning; a sportsmen (I think) and the pro key. Without the pro key there are several tables you cannot adjust.

When I began tuning a friends ProCharged 406 we could not get rid of a misfire issue; also had the standard key that comes with the system. I had a friend with a pro key come in and he adjusted the dwell time (I think, it's been a while) and the miss was gone. We were also using their dual-sync and wideband O2.

Jody

[Jim Nilsen]

I was reading in super chevy about an adjustable distributor slip collar for the distributor gear that is sometimes needed to get the cam timing in line with the crank timing. I posted about this question in the ignition section but probably should have posted it here.

If anyone knows anything about what this part is and has a part number I am listening. I haven't called ACCEL yet but it sounds like this could be something you might want to look into since it would probably make it a symptom at higher rpm like you are talking about. They claim in the article that they do it all of the time but I have only heard about this when I read the article.

Jim Nilsen

[xtrmeta]

I was reading in super chevy about an adjustable distributor slip collar for the distributor gear that is sometimes needed to get the cam timing in line with the crank timing. I posted about this question in the ignition section but probably should have posted it here.

If anyone knows anything about what this part is and has a part number I am listening. I haven't called ACCEL yet but it sounds like this could be something you might want to look into since it would probably make it a symptom at higher rpm like you are talking about. They claim in the article that they do it all of the time but I have only heard about this when I read the article.

Jim Nilsen

I'm using the dual sync distributor. So the cam and crank signal get set by rotating it till they are both off. Then drop in the distibutor. Turn the motor back 25 degrees. Then point the rotor to the number one cylinder. I know all that is correct.

[xtrmeta]

I am assuming you've double checked all the setup parameters and your fuel pump pressure has been set with the vacuum plugged. It's probably safe to assume the spark table provided by Al is reasonable for your combo. I believe al heads generally require more total spark advance and there should be a lot of info on what works with the BBC E-heads, I know there is for a Pontiac (36-38 degrees).

Setup a datalog with timing, AF, VE, RPM, MAP and O2 correction as a starter. Do some runs and see where your O2 correction is. Adjust your VE table to get less than 5% correction. Some like to keep the correction on the negative side to prevent lean conditions if something fails.

Have you done any of this?

I have done the setup. First I installed the map provided by Al at Accel. IT ran pretty good as stated above.
Then I went in and fine tuned the setup specs and the Ve table. IT then ran worse. So I switched it back.
As for my fuel pressure it's 44 pounds. My regulater doesn't use a vaccum on it.
I have not done a datalog. Please keep in mine this is my first fuel injected car. So I really don't know much about adjusting things.

[xtrmeta]

One other thing, Accel in their infinite wisdom has two power keys to run the tuning; a sportsmen (I think) and the pro key. Without the pro key there are several tables you cannot adjust.

When I began tuning a friends ProCharged 406 we could not get rid of a misfire issue; also had the standard key that comes with the system. I had a friend with a pro key come in and he adjusted the dwell time (I think, it's been a while) and the miss was gone. We were also using their dual-sync and wideband O2.

Jody

I have the Pro key. My system came with the Sportsmen key but I upgraded it.

[MrForce]

What size injectors are you running? Are they adequate for the BBC? You need to watch the duty cycle. Have you forced the timing (25 degrees works well) and checked to see if the laptop matches the damper. If you are running an ignition box with rev limiting, check to see if chip is a problem ( it happens) or the rev limiter in the DFI software is set too low. If all the set up parameters in both your fuel curve and the one DFI sent you are the same, then what are the differences? Check VE values where yours ran better than theirs. Does it have more fuel or less?
Typically, when EFI setups have problems that appear as RPM increases, it is usually: a) rotor phasing. b) timing errors, and c) lack of fuel due to tuning or undersized injectors. Good luck

[Hammered]

44 psi sounds good. I think MrForce has some good suggestions. When you say you fine tuned the setup and the VE table, what did you do? I assume you're driving the car under acceleration or at sustained speed and making the adjustments while you're driving? You need to adjust the VE table for steady state conditions (i.e., sustained constant rpms). Using the log file, you can see where the O2 correction is at various steady state conditions and adjust the VE table to remove this correction or yield a less than 5% negative correction. Don't worry about being a newb, I certianly don't pretend to be an expert myself.

[xtrmeta]

I'm running 36 pound injectors. I would think they would be OK. I have forced the timing. But I did it at 15 degrees. Should I go back in and do it at 25? It's not a rev limiter problem. The one in the software is set OK.
When I setup the VE table I just entered in the info on the setup screen. I did not go into the map and change anything. I'm not sure how to do that. When I entered my cam lift and compression and the other things it asks. When I hit the calculate button it started running worse. The specs in the program from al are way off from my setup so I am surprised it runs worse.
I have not driven it and tried to tune anything.
Man I really need to learn how to do this stuff. This is getting frustrating.

[Hammered]

Okay, I think we're onto something here. I am not surprised that the calculated setup is worse than the one supplied by Accel. Their calculation algorithym is way conservative and yields a very rich map.

First, the VE table (F2) is the map. That's where you need to start tuning if you have the timing, fuel pressure, firing order, crank reference angle, etc... properly set.

Start by saving your current VE table by hitting F2 and then going to the file menu once you're in the VE table screen.

To familiarize yourself with tuning, with the engine running and the software up and connected, hit the F2 key. This takes you to the VE map. Idle the engine at 2000 rpm and watch which cells stay highlighted. Your engine will probably bounce between two cells or even three. Look at the O2 correction. For example, -10% means that it's pulling out 10% of the programmed fuel to keep the O2 sensor happy (14.7 A:F ratio). You want this to be closer to -3% or even zero so you want to decrease the numbers in the active cells by about 7%. For example, if the cell in question is 0.340, decrease it to about 0.315 and then look at the O2 correction factor to see how close you got. Make sure to hit F10 after changing the number or it won't take effect. You need to change surrounding cells so you have a gradual change across the map (i.e., no spikes or holes). The 3D graph helps you to visualize this.

To do the full range of cells you obviously need to be driving the car. Hopefully you can see why using the datalog feature is important.

I suggest you get and read Jeff Hartman's "fuel injection: Installation, Performance Tuning, Modification." I would also read the Accel instructions, as poor as they are, a couple more times. You can also go online and read the Holley Commander 950 instructions. While a completely different system, the tuning methodology is the same and Holley actually took some effort to write decent instructions.

You should be a lot less frustrated once you've taken the time to study up. I don't think any of the available systems allow you to start without knowledge of the basics.

John

[xtrmeta]

I found out last night the gauge on the fuel rail was wrong. The car was only running at 33 pounds of pressure. So I adjusted it to 40 pounds of pressure. I didn't get a chance to drive it yet. I'm going to try it out tonight to see it that helped anything.
Hammered, Thanks, that helps to understand it better. I understand the basics of how to unstall and the basic programming. But in the VE table and timing I'm not really sure.
So you think it is all fuel related and not timing?
I'll take it out for a ride tonight and see what the VE table says.
Thanks

[Hammered]

Most injectors are rated at 43.5 psi so setting it at 44 would be good, but 33 versus 40 is a big difference.

As long as your timing curve is close, which I assume it is if provided by Accell for a like application, then you need to work on the VE table.