1998 I30 code 0608 cyl # 1 misfire problem needing help

[zul8tr]

car has 91koil and filter at 4k - 4 mos

I have a code 0608 misfire for cyl #1 and been having this issue over past 6+ months. Have used fuel system cleaner (Gumout Regain) and that clears it up but then it returns in the the next fillup so I have done this a few times but still misses. Here is what I have done but still no luck exactly locating the problem. I am beginning to suspect the injector but before replacing that I want to make sure.

First it only happens after warmed up. Engine then has an intermittent miss at idle very noticable in drive. You can see the tach drop a 100 +/- when it misses. Has good power under acceleration.

1 Plugs were replaced at 60k car has 91k. Used same NGK's platinum per Nissan. Pulled plugs yesterday checked gap and at 0.041" No usual carbon buildup and all center insulators looked all the same with good color

2 Yesterday checked injectors at idle all click the same even # 1 when there is a miss in engine.

3 Yesterday pulled the IACV control and cleaned all the orifices and holes . No serious carbon. All ohms in spec

4 When I replaced the valve cover gaskets back in 4/09 I cleaned the EGR tube at the back of the plenum it was blocked with carbon. Also cleaned the plenum and as much black soot in the lower manifold as possible at this time. At this time I ohm'd the injectors and all were about 12 ohms.

5 Yesterday checked the EGR function no leaks at idle and valve opens with engine rpm increase when warmed up. diaphram holds vacuum.

6 Yesterday checked all the coils per Haynes manual . Ohm'd across pins 1 and 2 and got about 1100 ohms on the 2000k scale. When ohm probes were reversed got infinite resistance thus OK per this test

7 About a week ago replaced fuel filter since it was overdue at 30K

I plan on using Techron Concentrate Plus today and see if that cleans out any carbon gremlins?.

I would like to ohm the injectors again but can only do the front injectors, need to pull plenum to do the rear or can those be done thru the ECU harness? Do not know how to do this. If done what increase in resistance do the harness wires add?

What to do next? All help is appreciated.Thanks

[turbocat]

i would try switching 1 of the other coils to cylinder 1 and see if the misfire continues on cylinder 1, if misfire continues i would suspect the injector, I would also do a compression test on cyl 1, I would also check the vacuum, if i remember right my 98 max at idle is around 20 hg of vacuum with a steady vacuum needle, if vacuum gauge needle is not steady, could be other problems involved.

[zul8tr]

I forgot the vacuum reading in my post. Did that yesterday is was 21" Hg at idle when warmed up with a steady needle except a slight drop when a missfire occurs.

I will reverse the coils as suggested.

What are your thoughts on why miss cleared up with the Gumout Regain?

I will do the Techron then continue.

I will do a compression test. I know to pull all plugs but what is disconnected to stop the fuel flow? Is there a fuse for the fuel pump under the dash at drivers side fuse box that if pulled will stop the fuel or something else?

How do you ohm the rear injectors without pulling the plenum?

I want to exhaust all before replacing an injector.

Thanks

[maxhopper]

All of the testing procedures should be in section EC. http://www.nicoclub.com/FSM/i30/1998_I30/

[zul8tr]

Been there and done the procedures that are direct to do. Some are not direct like pulling the injectors (esp the rear under the plenum) to check the spray pattern. I do not have Nissan shop computer that some of the test procedures require so I am doing the obvious direct ones.

The question still remains if the injectors ohm in spec and click the same while running how do you figure out if there is a problem with the injector?

[MinisterofDOOM]

You can try moving injectors around to see if the misfire "follows" one.

[zul8tr]

The location of the rear injectors under the plenum would make this not a practical procedure as they are not accessable without pulling the plenum. This would certainly be worthwhile test for the coils and already doing that. BTW pulling the injectors usually means some damage to them (even with PB Blaster soak) based on my experience with my 92 300zx.

[maxhopper]

Remove the plenum, pull the injectors, have them sent out to be tested and re-ringed. It usually costs about $6 per injector.

[NutriaforBreakfast]

I believe fuse #32 stops the fuel pump

[NutriaforBreakfast]

I think you can also check the "duty cycle" of the injector.That shows the time of opening and closing of the injector. MyFluke multimeter has that capability but I have never used it.

[99MAXNYC]

Hi, I own a 99 Maxima and when I hit 100k I had the same intermittent problem. I went to the Nissan Dealer and they told me the same code. They suggested I change knock sensor & all coils. I just changed cylinder #1 coil & spark plugs and have never had another problem since. I presently have 151k on the clock. Hope I was some help. Happy New Year to all.

[zul8tr]

Well I

Hi, I own a 99 Maxima and when I hit 100k I had the same intermittent problem. I went to the Nissan Dealer and they told me the same code. They suggested I change knock sensor & all coils. I just changed cylinder #1 coil & spark plugs and have never had another problem since. I presently have 151k on the clock. Hope I was some help. Happy New Year to all.

---------------------------------------------------------------------Well I switched coils from cylindere 1 to 3 and the miss followed the coil. It took a pedal to the floor to hit the passing gear to get an ECU code. But it verified the coil as the problem because the miss went to cylindere 3. Note that miss at idle would not throw a code. I bought a coil at Advance Auto ($80) since they were the only ones that offered a 90 day cash back and 9 month exchange or store credit, not bad for an electric part. I thought this prudent since uf I had to return it Nissan ($130 for coil) offers no warranty and other after market jobbers (Pep Boys and Auto Zone) offer 90 day exchange.

Thanks for the replies