hoping to find some EFI troubleshooting advice aND recommend

[brian617]

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

[NomakeWan]

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

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

[tayto]

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

[brian617]

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

Correct

[johnatthebox]

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

Wideband

[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.

[trlrider]

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.

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.

[brian617]

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.

[trlrider]

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

[johnatthebox]

thanks
Gonna do a thorough run thru

[johnatthebox]

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

[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.

[johnatthebox]

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.

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....

[In-Tech]

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.