hoping to find some EFI troubleshooting advice aND recommend

Hi I should probably start by saying that this is my first EFI car and I have zero tuning experience ( with EFI I mean....) This setup was on my car already when I bought it. 383 sbc Holley Stealth ram , Holley rails and injectors, BBK tbody, ACCEL gen7dfi
I work on my own stuff, but have always been a carbs and points guy until this car.
Here's where the circus music should start up-
I don't have the ability to tune Accel gen 7. The Cal map cable that I have is damaged and is no longer recognized by the system. I knew that when I bought it . I didn't know at the time how hard it would be to find it replacement Accel gen 7 cable.
It hasn't been an issue it's been running4 a little over a year now that I've been driving the car i
as my daily driver. In the last month it has for whatever reason gone Rogue I'm prepared to replace the Accel gen 7 but before I do, I want to make sure it is 100% necessary. I was hoping to be able to run the symptoms by you and see if it sounds familiar? From a cold start it will run fine and I can drive about a mile and then at the same spot it will start surging violently and then cough and die. I pull over and park and wait 10 minutes the car will start ,run fine for about a mile and then do it again. I can smell it just dumping fuel but then it will starve itself lean 30 seconds later and then do it again you can also hear a ticking coming from the Gen 7 box when it starts screwing up . the other thing I noticed is that my air-fuel digital gauge keep resetting itself like I had shut the car off and on when the surgIng starts. Does this sound like a bad controller ?

It does sound like the controller has a failure. It's been quite a while since I messed with a gen 7 or 6 so I can't remember if the 7 is potted. I would take it apart and look for some bad components. The wideband going out at the same time as the failure starts is troubling too. I'll contact a tuner bud of mine that has tons of experience with the Accel stuff and post back when I can.

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Originally Posted by In-Tech

It does sound like the controller has a failure. It's been quite a while since I messed with a gen 7 or 6 so I can't remember if the 7 is potted. I would take it apart and look for some bad components. The wideband going out at the same time as the failure starts is troubling too. I'll contact a tuner bud of mine that has tons of experience with the Accel stuff and post back when I can.

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Hey thank you so much. It was a long shit that maybe there would be a simple fix it answer. I know you recommend using GM controllers over aftermarket stuff(im pretty sure you do , right?). If i were to go looking for one , which would i have the most success with?
Thanks-
AJD

Based on what I am hearing from you, I would use a '7730 ecm(or the waterproof '7727 version) since it sounds like this is a TPI variant project. Maybe repairing the accel won't be bad, I will know more tomorrow.

Does that controller use an o2 or wideband for closed loop feedback?

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Originally Posted by brian617

Does that controller use an o2 or wideband for closed loop feedback?

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Both of those are stock GM ECMs. They use narrowband O2 sensors for closed loop feedback.

pretty sure he was referring to the accel.......

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Originally Posted by tayto

pretty sure he was referring to the accel.......

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Correct

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Originally Posted by brian617

Does that controller use an o2 or wideband for closed loop feedback?

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Wideband

The way you describe the problem it sounds to me like when it switches from open loop to closed loop fueling the problem starts, which would indicate a problem with the feedback from the wideband. Watch your data stream and look for that switch from open to closed loop.

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Originally Posted by brian617

The way you describe the problem it sounds to me like when it switches from open loop to closed loop fueling the problem starts, which would indicate a problem with the feedback from the wideband. Watch your data stream and look for that switch from open to closed loop.

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He stated in the first post he does not have a working cable for the ACCEL 7, thus monitoring the data stream would more then likely be impossible as well.

Have you thoroughly checked all your electrical connections for loose, corroded or broken anything.
- bad grounds
- hairline crack in a fuse
- broken wire or bad crimp
- corrosion on a positive or ground connections
- corrosion in a plug (even weathertight plugs fail)
etc!

Just had a intermittent issue on a Ram 2500, had been to 2 other shops that could not fix it.
Had it in 5 minutes, a hairline crack in a fuse that would test good with a probe. Wiggle the fuse with the truck running and it would die.

Electrical issues can be a pain, but the basics need to be followed to trouble shoot them.

Louis

Well then have to do it the hard way and monitor AF sensor voltage input with scope or dvom. Or possibly unplug the AF sensor keeping it in open loop.

thanks for the help. What tells it when to switch from open to closed? What triggers that?

thanks
Gonna do a thorough run thru

In an OEM ECM there will be closed loop timers and also it watches for changes/switching of the oxygen sensor. However I'm not familiar with the Accel, so this may or may not be true with it.

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Originally Posted by brian617

In an OEM ECM there will be closed loop timers and also it watches for changes/switching of the oxygen sensor. However I'm not familiar with the Accel, so this may or may not be true with it.

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It runs good until the exact same distance from my driveway, and then starts surging everywhere. I was thinking maybe a temp controlled fynction or something? Like the iac valve but something for fuel regulation/delivery? I am a totall newbie to EFI so pardon my layman speak please....

A very common failure is the coolant temp sensor feeding the ecu, it's a cheap part to throw at it since you can't watch anything. Next would be a new wideband sensor since it sounds like it fails once it enters closed loop.