Accel Gen7 tuning issues

[thedugan]

While I try to figure out who to bring the car to for help with tuning issues looking to still figure it out if I can.

Been messing with it on and off for 3 months and not making much progress

Running a SBC with superram intake, gen7, wideband, 55pound injectors.

Car starts fine and runs but has very low vacuum. 8-10 pounds. I have checked for vac leaks and cannot find any.

Fuel pressure at the rail shows 45 pounds, which is what I have the ECm programmed for. Running a walbro pump in a rock valley efi tank, with a single line to the front thru an aeromotive bypass regulator referenced to vacuum. The one issue I might see is I dead headed the rails.

AFR is fine when it starts up but once it warms up it goes full lean. I am not sure where else to look to fix this. No exhaust leaks ahead of the sensor to throw it off.

Any ideas guys. And anybody know a good tuner in Northern NJ or eastern PA

Doug

[68 SuperRam]

Jobe at Turbo People in NY - did mine

[Hammered]

Have you adjusted the VE table?

[thedugan]

I have adjusted the ve table to a point. It's okay on startup and when cold. Once it makes heat I have the issue It's once the wideband kicks in it goes lean.

[MrForce]

What is the target AFR for the wideband at the point where it goes lean? Has it been configured? What happens if you disable it?

[thedugan]

I'm rethinking having the rails deadhead and putting a loop on the end. Its a space issue on why I did not do it but for the time being I could loop it to see if its an issue at the rails. Was deadheading the rails a bad idea?

[camcojb]

I'm rethinking having the rails deadhead and putting a loop on the end. Its a space issue on why I did not do it but for the time being I could loop it to see if its an issue at the rails. Was deadheading the rails a bad idea?
I've run with and without a loop on deadheaded rails, no issues either way.

When it goes lean, have you ever highlighted the cells it's operating in on your VE/fuel table and increased them? If so, how far? Did it change the a/f at all?

I'm thinking it could easily be as simple as your VE table is off and a simple increase will fix this. I have no idea what tune you're using at this point, but I've never had one that didn't need to be tuned a fair amount from the default setting, even when running the software some of the EFI systems has that builds you a tune off of your engine specs................

Jody

[John McIntire]

I've talked to the guys at Cartek in Garwood about eventually tuning mine when I get it running, they said that they are familiar with the Gen 7 and it wouldn't be a problem.

[thedugan]

Ah cartek in garwood. Good idea. I pass it everyday on the train never thought of them.
Going to look at the tune a bit. I've been working on a file Frank and I have edited. I'll look at the ve table some more and see if it gets any better.
When I get home I gotta look to see what the afr actually is on startup befor the wideband kicks in. I would have thought the wideband would tak care of this all....

[thedugan]

Jody from what I remember when frank was on the phone with me when we tuned it we added and added but could not get it to go rich. We figured there was a vac leak when it got hot. I did find a vac leak at the plenum which is now fixed

[thedugan]

Started it up this morning. Also ran the data log so I have info when cold and when HEGO on.

So AFR at startup and when cold is around 12.00

When the HEGO goes active it goes up to high 14's . This is when the Wideband starts creeping up and goes full lean (25).

Vac is hovering at 7 pounds when at idle. Around 20 when at 3k RPM's.

[Hammered]

Check your AFR table. I believe it defaults to 14.72. Your car may want it richer at idle so check those cells. If the AFR is where you want it and it's still pulling 25% fuel out, then you need to adjust your VE table.

[thedugan]

Got an appointment with Cartek for next Thur. So ill get the tune as close as I can then let them go thru it. I'm a bit nervous I hope there are no issues or problems, ill be really relieved if they get it running and find nothing wrong.
Nice guys too.
Interesting they are not a fan of the meth kits. Would rather I run an intercooler setup. Water to Air

[John McIntire]

Awesome, can't wait to hear about your experience with them!

[Jim Nilsen]

Good to hear your getting some help.

It sounds like once it is warmed up and the idle air control goes down it goes lean and needs to be adjusted in the ve table .

Learn as much as you can from the tuner. Also let them know eactly what you are going to do with the car and what is expected of the engine.

Good luck !

[Mike Norris]

I am curious how much cam you have in there based on this issue as well as the low vacuum as well as what the base idle is set at.

With the larger cams, you can get reversion in the collector at idle, especially a low idle. This allows for unburnt fuel to be in the collector area due to the lope (misfire) which has a lot of oxygen in it and can show lean. The WB picks it up as lean and adds fuel when it is not needed.

If this is the case and the AF is controllable via the WB and VE adjustments everywhere but idle, you may have to not allow closed loop function till off idle.

Hope this helps.

Mike Norris

[thedugan]

Hey Mike, thanks for the help so far. The tune is much better with help from you and Frank. This is the cam im running that I got from Frank .
Comp Cam Cl-12-468 242/248 548/579 113 lobe

[Mike Norris]

That explains the low vacuum and in the Comp description is says "Best at wide-open throttle". I would say an idle of 950-1000 would be needed to get the EFI closer to happy, but may still need to be in open loop at idle.