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-   -   8V92 Intermittent surge at idle (https://www.wanderlodgeownersgroup.com/forums/showthread.php?t=34224)

Debugjaws 06-26-2019 04:04 PM

8V92 Intermittent surge at idle
 
91 WB, 8V92, 60K miles. I have an intermittent engine rev / surge at idle. Typical idle sits at 600 RPM. Twice now I've had this surging occur, where it will either modulate back and forth between 600 and 700 RPM's, or it will raise to 700 RPM's and stay there. Each time this has occurred, I shut off the engine and re-started, and the issue stopped.


Sounds to me like a throttle position issue (if these have such a sensor), fuel flow, or other.


Any thoughts would be greatly appreciated.

Debugjaws 09-09-2019 09:09 AM

Still having this issue. Idle surges higher towards 800 - 900 RPM's. Pretty consistent if I've run the cruise. Could there be an issue in the high idle circuit? Something tied to the cruise circuit? Maybe air throttle? Getting ready for a 800 mile round trip. Doesn't effect while driving, only at idle. Any thoughts are appreciated.


Quote:

Originally Posted by Debugjaws (Post 456145)
91 WB, 8V92, 60K miles. I have an intermittent engine rev / surge at idle. Typical idle sits at 600 RPM. Twice now I've had this surging occur, where it will either modulate back and forth between 600 and 700 RPM's, or it will raise to 700 RPM's and stay there. Each time this has occurred, I shut off the engine and re-started, and the issue stopped.


Sounds to me like a throttle position issue (if these have such a sensor), fuel flow, or other.


Any thoughts would be greatly appreciated.


brhodes 09-09-2019 10:59 AM

Have you checked your engine for any error codes?


It sounds like an issue with a dirty ground, or a dirty pin connection in the engine interface plugs in the front lower main electrical panel. Open the front panel and check the Amphenol connections on the road side.
Another possible thing to check is a dirty throttle psosition sensor on the foot pedal or loose connection.

Also, clean the ECM plugs of the engines computer as fine dirt can get into these.


One more thing to check is the MAPP sensor on the side of the blower behind the ECM.

captainbb 09-09-2019 01:32 PM

Gerry did you ever get silver leaf? I ask because it will tell you what percentage the throttle is at, thought it might help with troubleshooting.

Big Fro 09-10-2019 07:16 AM

Do you experience surging while going down the highway without cruise? But, with cruise there's no surging? If so, it's your TPS.

Debugjaws 09-10-2019 09:03 AM

Quote:

Originally Posted by Big Fro (Post 463983)
Do you experience surging while going down the highway without cruise? But, with cruise there's no surging? If so, it's your TPS.

No, it's only at idle. However, I experience it at idle if I've been using cruise. The other day I experienced it right at ignition.

Randy Dupree 09-10-2019 10:08 AM

The old mechanical Detroits would sometimes get a "roll" at idle.
It was common and the buffer screw would take the roll out.
I'm not sure at all if a D deck engine has a buffer screw.
Barry?

brhodes 09-10-2019 02:50 PM

No, all DDEC engines are electronic controlled so there is something his computer is seeing to tell the injectors to add additional fuel at idle which is why he needs to see if there are any codes registered, clean all the plugs as suggested or even may need to upgrade his EPROM Stabilizer kit in the computer to the last version #154 if it hasn't been done.


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rwoody 09-10-2019 08:13 PM

and make sure MAP and TPS sensors are correct

no loss of voltage when this is going on or having bad spots with DOMV during testing

Debugjaws 09-12-2019 12:38 AM

Quote:

Originally Posted by captainbb (Post 463916)
Gerry did you ever get silver leaf? I ask because it will tell you what percentage the throttle is at, thought it might help with troubleshooting.

Hi Brian,

Yes I did. Thanks for the tip. I'll check it out on this next trip!


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