Idle bouncing

[Formula218]

Hello all, I need help diagnosing a idle issue with my shitbird. I was cruising down the highway the other day and out of nowhere my tach started jumping. While cruising at about 1800rpms it was jumping up to about 3500rpms. The actual RPMs were not changing at all, and it responded to throttle like normal. I did pulls through 4th-5th and not didn't feel any misfires at all. Voltage seemed normal on the dummy gauge.



Here is a video of it at idle, it moves much less but still does it. I've checked all the battery (DEKA ETX18L) and they were tight, same on the alt. The alt had some power steering fluid on it so I cleaned that up but maybe the alt is hit?? Maybe the cluster is sad?

For those that don't know, the car is a 94 with a 5.3 swapped in. Up until Saturday is was completely normal, and I had been driving it about three hours without issue when it started.

[SSlowBoat]

Hello all, I need help diagnosing a idle issue with my shitbird. I was cruising down the highway the other day and out of nowhere my tach started jumping. While cruising at about 1800rpms it was jumping up to about 3500rpms. The actual RPMs were not changing at all, and it responded to throttle like normal. I did pulls through 4th-5th and not didn't feel any misfires at all. Voltage seemed normal on the dummy gauge.



Here is a video of it at idle, it moves much less but still does it. I've checked all the battery (DEKA ETX18L) and they were tight, same on the alt. The alt had some power steering fluid on it so I cleaned that up but maybe the alt is hit?? Maybe the cluster is sad?

For this that don't know, the car is a 94 with a 5.3 swapped in. Up until Saturday is was completely normal, and I had been driving it about three hours without issue when it started.

scan it and see if the pcm is doing it too, if not, check wiring, or gauge is shot

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