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93 Ford E350 5.8 rough idle only when hot

  • guafa
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11 Jul 2019 22:23 #31713 by guafa
Hi guys,

Is it an electrical issue?

A guy have posted a video in which says this engines are prone to CMP failure, which is inside distributor.

I have checked for vacuum leaks sprying water, i have cleaned throttle body and i have changed throttle body gaskets.

KOEO says it has evap and egr issues (which were cancelled who knows when and why).

Any advice in this big engines (which are not my working area), would be very apreciated)

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12 Jul 2019 06:42 #31718 by PDM
A coil or injector can start acting up when they get warm.

Do you know what codes it had? Evap and egr issues can cause rough idle.
Do you have scan data or just reading codes off the cluster?

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12 Jul 2019 07:19 #31719 by guafa
Replied by guafa on topic 93 Ford E350 5.8 rough idle only when hot
Thank PMD for your advice.

I'm pulling codes from cluster (i'd love to find the way to pull datastream with my obd2 launch scanner).

Codes are 327 (evp or dpfe) and 565 (canister purge circuit). Please bear in mind purge line and egr were cancelled, so i think they are not related with rough idle. Are you agree?

Customer told me that when rough idle began, he heard a "tick" sound, like a solenoid. I can't still relate the sound with the issue, since it doesn't have purge valve, neither egr valve.

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12 Jul 2019 07:25 #31720 by guafa
Replied by guafa on topic 93 Ford E350 5.8 rough idle only when hot
When rough idle is on, if you shift drive or reverse, the engine dies, so i think it wouldn't be a single injector, am i right?

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12 Jul 2019 08:28 #31723 by PDM
That sounds normal. If the engine is struggling to run, adding load will make it worse.

You really need to get direction on the problem. Is it not enough fuel, too much air, missing spark, etc.

Here's an easy one. Do a cylinder drop test by pulling plug wires one at a time (off the distributor cap so you don't get zapped). See which ones do or don't cause a change in the idle speed.

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12 Jul 2019 12:55 #31733 by Matts Auto
Replied by Matts Auto on topic 93 Ford E350 5.8 rough idle only when hot
possibly EGR valve partially sticking open at idle?

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