2002 Maxima 3.5. Changed rear bank plugs and coil packs 1, 3, and 5. Got code P0300 (multiple plug misfire) when engine started. Very rough running. Is it possible to connect ignition wires 1 and 3 to the wrong coil pack? Plug 5 was done prior to working on 1 and 3.

 

The wires were correct. They are numbered so 1 and 3 were properly connected. Still running slightly rough but no codes.

 

Let's back up here. Tell us, why did you replace these specific 3 coilpacks in the first place? And it sounds like you only replaced 3 out of 6 spark plugs too. Why is that? Did you install OEM coilpacks? NGK plugs?

 

I had already replaced the “easy” front ones. Had to wait for better outside weather to finish the job. Used NGK plugs and SPECTRA coil packs. Code P300 has returned.

 

Take back those Spectra coil packs and grab some Hitachi ones off Rock Auto. Ir used oem. They don't go bad enough to be to afraid of used.

 

Also check for air leaks.

 

Ok, makes sense now. Well, it's either the SPECTRA coilpacks or possibly one or more fuel injectors causing the misfire. I'd start by returning the SPECTRA coilpacks and going with OEM.

Is the car drivable? With any luck, you'll get a specific code like 0302 pinpointing which cylinder is causing the issue rather than the generic 0300 code.

And since you had the UIM off, check for air leaks as the other guy pointed out.

 

Man the same crap OVER & OVER AGAIN! USE HITACHI or OEM (HANSIN) COIL PACKS ONLY! STAY AWAY FROM CHEAP ALTERNATIVES! I will be testing the NGK coil packs just to see where they standup in the real world and test them out as an alternative to let you fellow Orgers know! E3 plugs worked well on my 4th Gen and actually increased my mpg.....

 

Thanks. I did have a vacuum hose not attached. Attached the hose and engine runs smoothly up to 5,000 rpm but as soon as there is a load it runs really rough with almost no acceleration. Code P0300 returned. Will replace coil packs and check plugs for cylinders 1 and 3. New NGK plugs should be good but will check gap.

When I changed the rear bank plugs and coil packs on 18 April, the old plugs were all loose and had carbon deposits on the sides of the plug. The car was running OK but had below normal acceleration. No codes but a slight miss. I suspect the slight miss was the loose plugs. Previously when I changed the front bank, the plugs were loose also but there were specific cylinder codes so I replaced both plugs and packs since it was an easy fix. That was a few months back.

When I replaced the rear bank plugs and packs on 4/18, I was shocked when the car didn’t run as expected.

I have limited abilities for any further repairs and no access to a scan tool. Would a scan identify the specific problem?

On a happier note for me, I recently purchased an all-electric Volvo XC40 recharge. First maintenance is at 40,000 miles where they rotate the tires!! The Maxima is my “dog” car and has been great for 18+ years.

 

Runs rough/poor acceleration when there is a load is a symptom of one or more failing/underperforming coilpacks.

 

I hope you are right. Will change the coil packs on 1 and 3 next. Those are the coil packs that I recently replaced.

Thanks for your help.

 

Deleted.

 

Progress. Replaced coil packs on 1 and 3 and now down to code P0303. Car running better with only one cylinder not firing. Will replace
coil pack 3 with a good one. Throttle and accelerating procedures when finished.

Getting this procedure down to only an hour.

 

Sounds like you are on the right track! Please be sure to follow up at the end so other users can benefit from your symptoms/solution(s).

 

SUCCESS!!! Changed out the #3 coil pack in only 30 minutes. Should be easy after performing the same procedure five times in less than a week. Car runs great now with no codes.

My saga started in the fall sometime when I decided to replace the valve covers to fix a small oil leak. Nothing major just a few drops of oil each night. Decided to replace all plugs and coil packs since it wouldn't be much extra work. Got the parts from Rockauto as usual. NGK plugs and Spectra coil packs. Did all the work and everything was fine for several months. Got code P0304 and thought it was a bad coil pack. Replaced that coil pack but the code continued. When I checked the plug for that coil pack, the plug was loose and the plug had carbon deposits on the side. Decided to check the other two plugs on the front bank. Both plugs were also loose and had deposits. Decided that loose plugs could exist for the rear bank plugs. so I ordered both coil packs and plugs hoping to remove the manifold one last time. I did the front "easy" packs in late fall but deceded to wait until spring to tackle the rear since the car was running great.

Last Sunday--4/18/2021--I decided to finish the job. As I suspected, all rear plugs were loose. Completed the job and started the car and to my surprise it ran like a truck. Appeared to be two cylinders misfiring. Got code P0300 which is multiple cylinder misfire. I suspected cylinder 1 and 3 coil packs but the code P0300 isn't specific. Turns out that both new coil packs for 1 and 3 were defective. Did I use a defective torque wrench? I don't know but torqued the latest plugs by hand.

Lesson learned. Code P030x can be several things but coil packs and loose plugs are two possibilities. Always check the plugs when replacing a coil pack. Loose plugs don't appear to give a code until they become very loose. All of my six loose plugs had carbon residue on the sides due to excaping gases.

And NO you can’t cross the plug wires.

 

Thanks for the update and conclusion to your issue. So now that the car is running properly, what coilpacks are in the car? OEM or Spectra?

 

Four Spectra and two others from a previous change. May get two more Spectra. If I have more problems I will switch. Any inexpensive suggestions?

Update: Decided to replace all of the coil packs. Ordered 6 Hitachi from Rockauto.

 

Good call. Hopefully you took advantage of the 5% off using the discount code in the Group Deal Forum.

 

Took your advice. Ordered six Hitachi coil packs from Rockauto.

 

Always go with OEM..... anything else, the car hates it

 

HAPPINESS: When your 2002 Maxima 3.5 runs correctly--finally!

Had additional problems this week while waiting on the Hitachi coil packs to arrive. Four days in a row the car was missing when I started it up in the morning. It was obvious that one cylinder was missing. Threw a code shortly after starting to drive. Each time I drove about 2 miles and pulled over to check the codes. Was code P0303 each time. However, after getting the code and erasing it the car was not missing--only a very minor miss with no code. One day I drove 70 miles with no additional codes. Figured it had a bad connection when the engine was cold? Decided to change the connector while waiting on the Hitachi coil packs. Must have done something wrong since the engine was now missing on two cylinders and was basically undriveable. Got the dreaded code P0300--multiple cylinder misfire.

Got the Hitachi coil packs from Rockauto and decided to install them and redo the coil pack connector this morning. Took my time on the coil pack connector to make sure I had a good connection. Buttoned up the engine and SUCCESS!

Took car for a 12 mile test drive at 45 - 70mph. Car was getting 27.8 mpg when I got back.

During the installation found out that there is a mini wiring harness for the rear bank that plugs into the green connector on the back of the engine. Includes the green connector and three coil pack connectors. Called local Nissan dealer and got a possible price of $246 if one is even available.

Was my problem the Spectra coil packs? Most likely. That and the fact that all 6 plugs had loosened over time. The loosened plugs gave a small miss but without codes, but a code will eventually show up. I cranked the new ones down pretty tightly by hand.

Hope this is my last time to post on this problem.

 

Glad your issue is resolved! OEM coilpacks FTW