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1993 Pathfinder - What now? Very low idle all of a sudden.


MrEviLDeD
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Hello everyone,

 

Not sure what happened. The pathfinder was running well before starting the repairs. This morning I was driving it and the idle is very very low. Barely enough to keep running. When Driving there seems to be no problems. Soon as I come to a stop and take my foot off the gas it takes this nose dive. First thing this morning when I turned her over she was running. But then I noticed that the rpm was going up to 1000, down to 750, up to 1000, back down to 500. Eventually it was dropping down to 250... And almost stalling as I slowed down enough to turn a corner or stopping at a light or sign,

 

I have no idea really what to do. Notable things that have happened is that the battery has died (while I ran the radio working on the truck). Since it has been charged and the pathfinder seems to turn over ok. It was cold out yesterday morning and I tried to turn the pathfinder over and the battery died so I put the charger on it. After a number of hours she turned over just fine. Plugged her in last night and this morning she turned over fine.

 

What things would cause this kind of behavior? I have searched through the forums and the only thing that connects to my problem in any way is poor fuel pressure. I have no proper way to test this. It has been snowing, then melting, snowing then melting.. Could water have gotten into something?

 

What are some suggestions for my next move? One step forward, two back with this one... :/

 

 

Edited by MrEviLDeD
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This hiccup that you're experiencing is very common. I don't know if this will help you but when this very thing happened to me I finally got it fixed by having a two step fuel injection service performed at a local oil and lube center. They also cleaned the throttle body. Part of that service is a drip thing that they hook up to one of your vacuum lines while the engine is running, it takes about 20 minutes. That really did fix mine. I think it has something to do with the Idle air valve, which is on the back drivers side of the engine under neath the intake plenum.

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The factory service manual has a diagnostic table in the EC &EF section giving lists of items to verify for their correct operation. I think it's in the garage section of the these forums. I don't have a fuel pressure gage but the regulator seems to be a suspect part often. I'm sure a gage/kit is available at CT or UAP-NAPA.

 

sent from under Ernest the Pathfinder

 

 

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Thanks for the section heads up. I have a fsm for the 93. Just wasn't sure where to look in the thing it is huge.

 

I am going to go and check the MAF connector. I should replace the valve cover gasket anyhow which means being able to replace the IAC valve.

 

After all the work so far I just didn't feel like having to pull my passenger seat and go code hunting. :/ Patience is growing thin on this project but have sunk so much into it so far I cannot properly walk away. I will be honest I have spent everything I can on this pathfinder so I simply cannot afford any more tools or parts in good conscience to get it going. To add I still need valve and intake gaskets. :/

 

 

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With the age of your truck if you have not yet changed the vacuum hose lines that is the first place I would start. I'm guessing but I wouldn't be surprised if the line behind the block isn't connected by the way you describe your situation.

 

Like gv280z said...a good injector cleaner etc is a smart thing to do. You can't light a candle with a wet wick. After I did my cleaning the engine's compression came back to life. I went with TerraClean to do my cleaning and was happy with the results.

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try putting some gas line antifreeze in your gas, you may have gotten bad gas. I would also check the throttle body and if their are any deposits where the butterfly closes clean it as best you can with carb or TB cleaner and a tooth brush. If you haven't done it already ( which you should on a vehicle 20 plus years old), replace ALL the vacuum lines, one at a time, even if they look good, the ends tend to crack.

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Have you run the ECM for codes yet? I am just learning about these rigs too but that always seems like a great place to start.

 

No I have not. I was going to do that tomorrow if I can find the time. However there was no further problem today. She idled at 750 like she should be and ran like a top. However I did go in and fiddle with the IAC sensor connector as well as the MAFS connector before heading out the second time. Maybe that was part of the sudden cure.

 

I figure soon as it happens again I will pull the passenger seat and do some LED counting.

 

 

With the age of your truck if you have not yet changed the vacuum hose lines that is the first place I would start. I'm guessing but I wouldn't be surprised if the line behind the block isn't connected by the way you describe your situation.

 

Like gv280z said...a good injector cleaner etc is a smart thing to do. You can't light a candle with a wet wick. After I did my cleaning the engine's compression came back to life. I went with TerraClean to do my cleaning and was happy with the results.

 

I will locate and go over the rubber as suggested.

 

Just to be clear about the injector cleaner. This is just a simple fuel treatment I add to the fuel or do I need to take the Pathfinder in to have someone do this? Someone outside of the forum suggested that I clean my mafs. What would I used to clean it? Is this the kind of thing break cleaner is ok for or do I need more finess ?

 

I am pretty certain I have a drivers side valve cover oil leak so I have to pull the intake and can have a better look at those rubber and replace the IAC valve and sensor, clean the intake if it is cruddy.

 

Let's just hope it was an isolated incident.

 

Thanks for the suggestions everyone.

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These snuck in while I was replying :)

 

yep check the fuel pressure regulator vac line on the back end of the plenum mine rotted off and caused the same miss behavior

 

 

I will do that first thing tomorrow. Seems to be the popular consensus regarding the rubber.

 

try putting some gas line antifreeze in your gas, you may have gotten bad gas. I would also check the throttle body and if their are any deposits where the butterfly closes clean it as best you can with carb or TB cleaner and a tooth brush. If you haven't done it already ( which you should on a vehicle 20 plus years old), replace ALL the vacuum lines, one at a time, even if they look good, the ends tend to crack.

 

I will pick up a couple bottles tomorrow as well.

 

I know dumb question but will the FSM tell me what size of hoses I will need? I doubt they would all be the same diameter. Guess I just go buy some spools and make a morning of pulling and replacing.

 

 

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No most of the vacuum lines are the same size, just take one off and match it up, remember to replace one at a time so you don't mess up where each goes.

 

I think the fuel injector treatment like GV280Z suggested is a shop only one. A bottle of Techron or similar in the fuel once in a while won't hurt either.

 

To clean the MAF sensor they sell a spray that is made just for that, be careful with the thin wire inside the MAF it's very tiny, just spray it with the cleaner and let it dry.

 

When I cleaned my throttle body I removed it from the intake plenum so I could clean both sides but the most important area to clean is the inside where the butterfly sits against when it is closed.

 

 

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I noticed you mentioned the battery was put on charge. Usually after a charge, batteries have a tendency to not last for much longer. How old is the battery? The average life of most batteries is 3-4 years and that's it. I'd start by replacing the battery instead of wasting money going and getting professional cleaning etc. It might just be the battery that is responsible for the unusual power loss re low rpms

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Sounds idle air control related to me. Basically it's the thing that bumps up your idle speed when the engine is cold. I suspect it kicks in with the power steering and air conditioner as well so that those can't stall it out. Yours might need cleaning, or the connector might be a little corroded. Good to hear it's back to normal now though.

 

I used denatured alcohol and a q-tip to very carefully clean my MAF. Be sure that whatever you use won't leave a residue, and be gentle with the sensor filaments.

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If you are OCD like me :D ...

 

Clean throttle body with CRC Throttle Body & Air-Intake Cleaner

Clean MAF with CRC Mass Air Flow Sensor Cleaner

Clean any electrical connectors with CRC Electronic Cleaner

Put Permatex 22058 Dielectric Tune-Up Grease around electrical connectors to prevent future corrosion & moisture/oil/dirty entry

 

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  • 3 weeks later...

Low idle and stalling issue started back up again today. I believe it is as suggested the ground wire to the MAF. I went out with a loonie and tapped the connecter a couple of times and the idle jumped right back up to normal.

 

Thanks!

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