# 98 Frontier EGR problem



## jdix (Oct 9, 2008)

I know this problem has been hashed and rehashed but I can't seem to find the info I'm looking for. I've got a 98 Frontier w/ 193K 2.4 4 cyl. I was getting a missfire on I believe #4, a cat converter error, and a EGR error. I changed the plugs to uridium and ran 2 bottles of Sea Foam through the gas tank and I'm down to the EGR code. I did the test with the diaphram and when I push it up it runs really bad stalling if I push hard enough. Its got some resistance to it. I'm not sure how freely it should move. What I've found is that its most likely plugged passeges that I need to clean out or atleast thats where I should start. My question is what passages do I need to clean out? There's a short rubber hose that goes to the part next to it.( EGR backpressure transducer maybe) Then there the metal pipe maybe 1/2' that looks like it goes to the exhaust manifold, then there's a maybe 1/4' pipe that goes into the bottom of the EGR backpressure transducer. I'm assuming the exhust manifold pipe is the one that needs to be removed and cleaned. The fittings look really rusted and should be a huge pain so thats got to be it. What should I use to clean it? A metal pipe cleaner and some type of solovent? Does anyone know of a step by step right up with the proper wrench sizes. Maybe I'll just be better of ordering a new pipe and fittings since these look so bad. 

Thanks for the help.


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## azrocketman (Oct 5, 2005)

I would bet that the EGR orifices in the intake manifold are the culprit. If you look at the top of the intake manifold you will see 4 screwed in plugs that have provisions for a hex wrench. You will need to remove the throttle body (or at least disconnect it enough to move it) and loosen the EGR valve to access the all of the plugs. I used gun cleaning brushes (.22 and .38 caliber worked well in the ports) and Hoppes #9 (a gun cleaning solvent that loosens carbon)to clean the ports on my engine. The job is not extremely difficult but it is time consuming (took me about 3 hours but I'm not a fast worker). Look at Nissan service bulletin TSB NTB04-044 (available if you register at the All About Nissan Cars site).

Steve


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## Cusser (Apr 16, 2004)

I had EGR error code on my 1998 4 cylinder. First use a hand vacuum pump and rubber hose to pull a vacuum on the EGR valve while the engine is running (plug the unattached hose); if the engine stumbles or stalls, then your EGR valve itself is working. If so, you most likely aren't pulling a vacuum on it when it's supposed to. On my 1998, all my vacuum hoses appeared to be in real good shape; however, UNDER the EGR transducer was a short (2 inch) piece of vacuum tubing that had corroded and broken in two, impossible to see without removing that transducer. Replacing that 2 cent piece of tubing took care of my issue. So I'd check ALL the vacuum hoses very well.


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## jdix (Oct 9, 2008)

Thanks I'm going to do the ports on Tuesday. Any chance you remember what the size of those hex's were? I checked all the hoses and they look good.


Thanx


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## azrocketman (Oct 5, 2005)

Sorry, I do not remember the hex size.

Steve


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