Hi,
I have an 1989 F250 with 302, automatic 4x4.

I'm getting a code 84 EGR circuit failure. I replaced the EGR vacuum solenoid, and that didn't help. also getting the 33 code, egr valve not detected opening.

My milage really sucks right now. Engine is running a little rough

Any ideas on what the problem might be. The EGR valve was replavced a little over a year ago when I was having some other problems, so I'm pretty sure its not the EGR valve itself. I check the voltage to the ERG vac solenoid, Key on Engine off, it was reading just under 12vdc, and I also checked the egr valve position sensor. and that checks out ok.

Any ideas on what is causing the EGR circuit failure?

Thanks in advance.

 

84=EGR vacuum solenoid circuit failure=EGR vacuum selenoid bad or circuit is bad

33=EVP sensor indicates EGR is not opening properly=EGRis bad, EVPis bad, and/or there is a vacuum leak

 

I replaced the egr vac solenoid, checked the voltage to it with the key on , engine not running, and got just under 12vdc. is that the correct voltage?

I usually get a "33" every so often, and all I do is take the EVP sensor off, and press the rod on it a few times, and the code goes away... I guess it gets dirty.

 

I have a similiar issue with my 93' 460, check for vacuum to the egr valve while driving, if there is no vacuum when driving, make a jumper wire for the vacuum solenoid and run it to ground and see if there is vacuum at idle with the egr vacuum hose off. If that works the ground wire is broken some were(test wire to ecm) or the ecm is not ground the solenoid as is the case with my truck. Hoping a new or good ecm will fix this as I need to smog truck 8 months ago.

 

Blu,
I'll check it out 1st thing in the morning. Hopefully that is a simple fix. At idle, I feel a small amount of vacuum at the egr valve, nothing very strong. As for grounding the solenoid, how would i go about doing that?

Thanks,
Bill

 

Same situation with the vacuum signal at the egr valve for me too. Take a Digital volt meter and probe the back terminals of the vacuum solenoid if the volt number is negative the red probe is on the ground. Just take a piece of wire and strip the ends off and jam the one end into the back of the terminal and with the engine running and feeling for vacuum take the other end of the wire and touch the valve cover or master cylinder and see if the vacuum gets stronger. Sounds hoky to use the wire that way but it works as long as you get contact with the terminal in the back and a good ground. Make sure first thou that the vacuum coming to the solenoid is good. The solenoid may be working and you have a leak somewhere else.

 

sorry to add to the above if grounding the solenoid works, check the ground wire to the ecm with an ohm meter, if the wire is broken then repair or run a bypass wire, if the wire is good then either the ecm is bad or something is not telling the ecm to open the egr. Resistance on the wire should be no more than 0.3 ohms.