Eternal Shine of a Check Engine Light

[yuriklan]

Every time I'm truckin down the road and that amber light is not shining, I feel like something is wrong. It feels like when it's dark that I have an engine problem, and not the opposite.

I replaced the EGR sensor, the light went down, no P0401 for 250km. One heavy step on gas, and it came up again. I replaced the hoses, light went down. 350km later, going uphill, it was back. Always P0401. Opened the exhaust manifold, cleaned all of it. Out. And now it's back.

Any suggestions on how to permanently find and fix this issue?

 

[Curious Hound]

Oh, great. Now we have to go look up a code.

until then, my answer is; “ I know what’s wrong. Ain’t got no gas in it.”

 

[Uncle Gump]

I'm gonna guess this is for your 95 4.0L?

Moving this to the 4.0L forum...

 

[yuriklan]

Oh, great. Now we have to go look up a code.

until then, my answer is; “ I know what’s wrong. Ain’t got no gas in it.”

Sorry, the code means "insufficient flow to EGR".

 

[yuriklan]

I'm gonna guess this is for your 95 4.0L?

Moving this to the 4.0L forum...

Sorry, it is indeed for my 95 4.0. Thanks for moving.

 

[Curious Hound]

Thank you.
So, the EGR valve is controlled based on a difference in pressure measured across an origice on the EGR tube. This is measured by the dome sensor. So, need to check that and make sure it’s properly connected. Also check vacuum hose to EGR valve and the hoses from the dpfe sensor to/from the EGR tube. Do not reverse those hoses.

 

[yuriklan]

Thanks. Do you know where I can find an schematic for these connections? The Haynes Manual was not helpful, and I need something idiot-proof to do it myself, as the local shops are refusing do to any work on it.

 

[Curious Hound]

I’ll try to remember to post some diagram pictures after work tonight.

but, what you want is called the EVTM - electrical and vacuum troubleshooting manual and you want it specifically for the year of your truck. These can usually be found on eBay either paper copies or digital on dvds. I have the one for 93, which should be close enough to use for this instance.

 

[yuriklan]

Please share if you have these connections. 70 dollars plus shipping to Brazil is a very expensive proposition.

 

[yuriklan]

Thanks. Do you know where I can find an schematic for these connections? The Haynes Manual was not helpful, and I need something idiot-proof to do it myself, as the local shops are refusing do to any work on it.

 

[rumblecloud]

@curious : If it would help any, I have a 94. I'm just not sure what pages to post Vacuum? Dome Sensor??

 

[Curious Hound]

@curious : If it would help any, I have a 94. I'm just not sure what pages to post Vacuum? Dome Sensor??

Vacuum diagram, and electrical pages that show circuitry for EGR and dpfe. They’re probably in the engine controls section. If so, that’s only a few pages. So I would probably post that whole section for his engine.

I’ll be getting off work in a few minutes. Drive home, make a sandwich and photograph the pages, I should have them up by around 8:00pm. But copies from the 94 manual would be better.

 

[Curious Hound]

Here are the pages for the engine controls section. Pages 27-3 and 27-4 show the dpfe sensor and egr solenoid. After that, is the vacuum diagram, which does NOT show the vacuum to the egr solenoid, unfortunately. Finally, is the blurb that describes how the dpfe sensor and egr solenoid work.

 

[SenorNoob]

I feel you've probably posted that entire set of manuals now...

 

[rumblecloud]

I'll put the corresponding pages from the 94 up later this morning...