CEL is flashing

1997 NISSAN HARDBODY
109,000 MILES
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CEL came on and was flashing, shop says it is the 4th cylinder misfiring, new plugs, new wires, new cap and rotor, good compression and the injectors are fine. The shop said that the manifold possibly had too much carbon and that the EGR valve was pushing all of the unused fuel through cylinder 4, causing it to shut down. They bypassed the EGR valve and the CEL went off, but the truck is running rough and has a whooing sound coming from the engine compartment. Do you know what could be wrong with my truck??
Dec 12, 2012 at 7:17 PM
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KASEKENNY
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More than likely this is still related to the EGR valve. I would not bypass the EGR as the PCM is expecting a certain amount of exhaust gas to be introduced back into the intake.

I would suggest testing the EGR to find out if it has failed. If it has then replace it.

Here is a video that shows how to test the valve:

https://youtu.be/DqUCbbKdWf4

As for the rough idle that is more than likely a vacuum leak that we need to find. Here is a guide that will show you how to do this:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Below you will find the process from the manual on how to test and replace the EGR valve as well. I highly suspect that once the EGR is operating that most issues will be resolved.

Please run through this information and let us know what you find.
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Jul 20, 2021 at 2:09 PM