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So, After all of the work and parts replacement, cleaning, diagnosing it turns out that my catalytic converter is bad! It was blocking the exhaust which was the cause of all the symptoms . Having it replaced. The up side of all of this is that I really have learned a lot about my Pathfinder and had the opportunity to interact with and receive help from all of you folks. It certainly won't be the last time you hear me chime in here. Thank you

So I have tried everything that you all have been nice enough to take the time to suggest. Dropping at the mechanic on Monday. I will let you all know what he finds. Thank you again

Does The IAC operate only during the idle cycle or both idle and higher speed? I suppose if it were stuck in the open or closed position from carbon build up it would effect it during either cycle.

Thank you very much

Any help out there?

No codes

I see this has been read a little. If you can please post whatever you have. Thank you

MmI have a 93' Pathfinder V6 automatic. It has a rough idle and engine surge. It usually starts right up, idles up to 900 rpm, then drops to 4-600 and idles rough. It also has a slight stumble in park during acceleration. Check engine light on. Here is what I have done so far. REPLACED- Burned out ECU (no codes) Air filter Plugs Distributor cap Rotor EGR and hose PCV valve Coolant temp sensor Battery CLEANED- MAF Throttle body(front and back) Entire engine bay CHECKED- O2 sensor by unplugging while running All vacuum hoses And replaced any worn, cracked. Did the carb cleaner vac hose spray test on all visible (including the slightly hidden FPR) vacuum hoses. The only thing I can think of is the IAC? Please help! Thanks

Starts, idles a little rough and stumbles a bit when accelerating. I have not actually driven it as my tags have lapsed as I can't pass smog so I can't get it registered. I don't know if a good freeway run wouldn't help as it has been sitting for 1-1/2 years. If so , I can have someone follow me so the CHP doesn't see my tag.

I tried the 02 sensor. No change. Just sprayed all of the vacuum hoses....nothing. As of right now. It starts , idles and most of the time it doesn't die. I have not tested/replaced the IAC which, unless I am missing something (certainly possible) is about the only thing left except the coil? Just so I can rule these out for sure, how do I test the TBS and MAF?

Will do , Thanks

Cancel my last about the plug heat range

OH, I thought the lower the number (5 vs. 6 ) was a hotter plug? I just used the same ones on the last mechanic tune up 11 years ago. Both sensors are krusty and have worn wires . I DID check the fuel pressure regulator vacuum hose and it's solid. I will use the spray trick to see if/where their may be a leak. Thanks a bunch.

Ok, So I changed the plugs, cap, rotor.......no change. When changing the plugs on the left side where the the are clearly visible I pulled out a piece of vacuum hose . It was and end that was cracked all around whatever it plugged onto and the other end was rotted off . It might be nothing or a clue about a vacuum hose that is disconnected? I am getting closer to that point of frustration of dropping it with my mechanic but I don't want give up. I have the two new sensors for the coolant/engine temp that both screw into piece connected to the upper rad hose. I read that these can effect idle?

No smoke at all!

So, I thoroughly cleaned the engine bay.....WOW! Now I can actually see what I am working on. I checked the cap and rotor,,...........horrible! Rotor heavily pitted , black. Cap contacts look like someone poured acid on them as they are super pitted, malformed, etc. I ordered both from Nissan and they are actually only a few bucks more than the off brands. Putting all in on Friday. Will post the results

Thanks for the input. So, It starts up, idles to 900 a little rough, stays there for a minute then drops to 400-500 and is very rough. After replacing the EGR ,PCV It will now keep running and not die when in park (auto) but is a bit rough. I have replaced three VAC hoses as well . I am hosing it down with non solvent engine bay cleaner to give it a good bath. I pulled three plugs and one was fine, one black, dry and one black oily. I have ordered new plugs as my locals don't stock the NGK BRK5EGP's (7090) that are in it. Checking the cap and rotary as well.

WOW! Thanks for all the feedback. I have since discovered that I was not operating the ECM correctly. Since learning how to read codes correctly all I get is a 55....no codes. I have since replaced the PC and it's hose since it broke in half as I pulled it off. I tested the MAF and the TBS which were both good. The vehicle has sat for over a year and the engine bay is pretty caked . I have also since noticed three vacuum lines on the EGR and air intake hose so I will replace those. The EGR is the factory original so I can't imagine it still working well. I believe I will address all those, then the spark plugs.

Hey there everyone, Just dropped in here and need help.m My 93 Pathfinder has a low, rough idle and dies when I give it gas to drive it. I pulled three codes that are- Mass air flow sensor Leaky injector Knock sensor. So far I have cleaned the MAF, replaced the air filter while I discovered a rodents nest resulting in a chewed filter and that felt like liner material. The MAF is the original 32 year factory unit so? Any direction as to next steps is appreciated. Thanks