Cleaned MAF contacts Dialectic grease and removed MAF cleaned sealed and reinstalled, Checked battery 12.9v, soldered battery terminal connectors and cleaned,
Removed and cleaned Idle air Control valve plunger (did not test it).
Ran bottle of Sea Foam though brake booster,
sprayed TB cleaner into TB,
Sprayed out Cam pos sensor plug,
Cleaned off Ambient Air temp sens,
Reassembled all with attention to detail.
The Intermittent Stumble at idle with AC on or off Saga continues, Still No Repeating/No Codes.
Replaced Air Tube Insulator part#16523-31U00.
Replaced Fuel Filter with OEM it was bad bad bad all sorts of black crap came out, I ran it for 15miles and still the idle stumble continues.
Replaced Air Filter OEM.
Replaced all the spark plugs later in the day with OEM NGK PFR6B-11 sent via (Joe infinitipartsusa.com), this did not fix the problem but I noticed at first the idle was high 1000rpms then settled to 750 then to around 625-650rpm. The plugs needed replacement.
Reassembled and cleaned plus dialectic greased all contacts.
Ran OHM test on all ignition coils (they are OEM Nissan) not sure the whole ohm range thing but I followed the book page 404 EC and got ohm reading through pin 2 and 3 on all coils, all OHM in same range that would lead me to believe they are all good(FSM IS MISLEADING SEE OHM TEST BELOW)
Removed EGR valve cleaned and tested,
plenum EGR tube ok could not remove but cleaned out.
New main fan.
Valve covers are OK no oil in plug holes.
Had battery tested OK.
Had Alt tested OK.
Replaced PCV valves.
Ran 80mph 10 miles noticed that when it stumbles at idle it also dims the interior lights dash etc but beams look ok.
Ok so I just replaced my ignition coils and compared old with new.
I am using a commercial electric M1015B NON digital ohm meter.
Making contact with the correct polarity i.e. red black wire on the ohm meter makes a difference! i.e. make sure you set up ohm meter as diagrammed!
, I did not believe it until I triple checked when switching leads. I have the Ohm meter set to X10 and I have done the calculation for actual ohm's not K or M. Black lead to volt meter in the green com port and Red lead is in the VmA ohm port. See diagram for explanation.
I tested all old coils and all new coils and all new coils were same range +/- 10 ohms! and all new and old were Hitachi OEM.
I got new coils from Joe at infinitipartsusa.com.
I had four bad coils as per my comparison test.
Looking at the ohm difference between bad and good coils should be enough if your numbers are not an exact match.
The range difference is substantial and consistent 3850 ohm.
(**Note the FSM said that if "no OHMs then bad if has continuity its good"; as per page EC 404 FSM, i think that "no ohm bad vs cont good" statement is incorrect
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Went For a long drive and put it into every situation that I have had the stumble become problematic i.e. at idle with AC on and AC OFF, stop and go traffic 25 miles, plus sat in driveway 20min plus. NO LOW IDLE STUMBLE, STUMBLE FIXED!!!.
I would Like to thank Maxnix as he called it as far as Coils; but still it was a bunch of money to drop so I had to try everything else first. I hope the Ohm test helps others as now i have four backup coils even though I wont need them for 100K..I hope. (2000 q45 Y33 107K)UPDATE 800 miles no stumble
