Boo-ya! First extensive car repair I've done since I swapped a 455 into a '77 Cutlass

Scottwax

New member
...and that was 25 years ago.



'74 Z/28 I had after that only needed a starter change in the 2 years I had it, did an intake swap but no biggie on a 350. Sunbird, both Celicas, my Accord, 626 and other Maxima, really didn't do anything very involved.



Anyhoo...



Last night, I went from 6th to 4th to get around a slow moving left lane moron on the freeway and as I am accelerating, I feel a distinct loss of power and a hard misfire. SES light started flashing so I got off at the next exit, pulled over and checked the codes. P0303. Of course, the rear bank under the intake. I babied my car home, if I gave it too much gas it would flash the SES light, which is bad. Anyway, pull up at home, very rough idle and a bad miss with any throttle.



Pulled up my Maxima FSM and checked for the P0303 code, plus typed it into search at maxima.org (never underestimate how much a forum dedicated to your car can help you out) and seems the predominate cause is either bad plugs or a bad coil. The search here led me to this link: Spark Plug / Ignition Coil Replacement which was very helpful and made me realize it wasn't too complicated.



Started on my car at 9 AM this morning, got it all apart by around 10 AM (the driver's side upper elbow bolt is a PITA!) and pulled the coil and plug on #3. My guess is the plugs had never been changed, the gap was HUGE. Nominal plug gap for us is .043 I believe, looked to be more than double. The plug in #3 had what looked like melted metal at the base of the side electrode. Since I had purchased a set of coils from a fellow .org member a while back, I knew I had 6 good ones so I could replace coils as needed. My son drove me down to Pep Boys to get some NGK platinum plugs, then down to the Nissan dealer (a good 15 minutes each way) to get the manifold gasket-better safe than sorry, right? Got back home just before 11 AM and by 12:20 I was done. I had changed all 6 plugs (all had huge gaps), two coils, #3 (just to be sure!) and #5 since that tube was filled with oil. Took a few minutes with towels to get as much oil out of #5 as possible before removing the plug. All other tubes were pristine. Wish I had picked up a 6th gen rear valve cover too, but I'll do that in a few weeks when I have more time.



Car started right up, a little blue smoke from the oil in #5 that got into the combustion chamber. No idle issues, car feels very smooth now. So far, the hesitation I was having when I went from light to heavier throttle appears to be gone.



Pro tip: If you separate the elbow from the manifold, you don't have to remove any coolant lines. Nissan didn't have that gasket but the old one seems to be working fine. However, in the future, like when I replace that leaky rear valve cover or do the intake spacers, I'll replace the elbow gasket too.



Starting out, note my GAB airbox. I think I picked up a good 90-100 hp at the wheels with this mod! If there had been a sticker involved would have been even more POWER! ;)



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Airbox removed:



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Manifold off, now I can get to the back plugs:



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Got gap?



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Holy gap batman... I would say it was needing new plugs. How cramped is the engine bay on you're maxima?



Sent from my SCH-I500 using Tapatalk
 
Not much room between the firewall and the elbow on the intake manifold but I was able to get in there enough to get all bolts started by hand.



Car has 155k miles on it, my guess is those plugs were installed on the assembly line.
 
Scottwax- Hey, that seemed like a good quick job. You weren't kidding about those plugs!



And I got a good :chuckle: out of the gains from your drilled airbox.
 
Accumulator said:
Scottwax- Hey, that seemed like a good quick job. You weren't kidding about those plugs!



And I got a good :chuckle: out of the gains from your drilled airbox.



Airbox modding is serious bidness. ;)



One of the guys has a dyno sheet showing a 9 hp gain for the ghetto air box mod with a K&N drop in filter. About the same as most aftermarket short ram intakes show.
 
Scottwax said:
One of the guys has a dyno sheet showing a 9 hp gain for the ghetto air box mod with a K&N drop in filter. About the same as most aftermarket short ram intakes show.



Hey, all joking aside, that's mighty impressive (if it's legit). Must be awfully restrictive.



But then, I'm not a big fan of K&N/oiled air filters myself (gee, not to open a contentious can of worms or anything :o ).
 
The problem with K&N filters, at least when it comes to MAF problems, is that when people clean and re-oil them, they use way too much oil and it coats the MAF and takes it out.
 
Scottwax said:
The problem with K&N filters, at least when it comes to MAF problems, is that when people clean and re-oil them, they use way too much oil and it coats the MAF and takes it out.



Yeah, that's what I'd figured, but I just don't like having the variable in there at all. Eh, that's just me making sure things are Accumulator-proof ;)
 
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