Have a 1996 Infiniti I30, about 275k miles, manual 5spd transmission.

Last week on Friday, the engine started running rough and the CEL was flashing, so I checked the OBD and there was a code for misfire on #3 cylinder.

This happened a couple years ago, and I diagnosed that to be a bad #4 injector. Listening with a mechanics stethoscope, it was easy to hear that the injector clicking at idle was weak compared to all the others.

So this past weekend I listened to all the injectors again, and they all sound about the same, so I don't think I have a bad injector. All of the Coil-on-Plug (COP) are original, so I decided to test the #3 COP by swapping it over to #1. The misfire was still present, but it moved to #5! What is going on?

About a week before the CEL started flashing, a muffler shop repaired a hole in the flex pipe by cutting that out and welding in a new flex pipe. I think they did a pretty good job, I crawled under the car and all the welds look decent, so I don't think that they did something wrong that's plugging up the exhaust system.

Thinking that maybe I have a bad tank of gas (it was about 1/2 full and there was no problems during the first half tank of driving) I put some injector cleaner and some Heet into the tank, and filled it all the way up. At first that seemed to help, but then the CEL came back.

The problem seems to get worse and get better. Sometimes the CEL stops flashing and the engine is smoother but not as buttery smooth as normal.

 

Are you scanning for codes?

 

No, I'm using the built-in diagnostics to get the blink codes from the CEL.

 

The Flashing CEL is a Heads Up to NOT drive the car until the problem is remedied. And usually that problem is with the Catalytic Converter system.

Indicative by the muffler shop sealing the system and forcing everything through the rear Cat converter. Probably toasted and clogged from burning oil for too long and/or dumping gas from a bad/leaky injector or two for too long.

O2 sensors won't kick a code because they're working as they should, most likely causing misfires though.

Might be a good time to replace all Injectors and NOT Chinese. Use OEM rebuilts. MotorMan Injectors sells them on ebay. Go for the Coil Packs too (RockAuto) and hopefully you don't have any internal oil leaks to cause oil burning.

While you're in there that deep to replace the Injectors, you should do a refresh on everything while it's all apart. Along with IACV and Throttle Body Cleaning. MAF cleaning and so on.

Then New Cat time!

Now that you have an idea of the most likely cause, you have a place to start instead of guessing replacements.

 

A great theory, but I don't think that is my issue. The car doesn't burn any oil at all. Zero. My wife drives this car, and it has had regular oil changes since we bought it at 80k miles, about 22 years ago. I use full synthetic oil and go 10k miles between changes, and the oil is just starting to get dark at 10k miles. The muffler leak was only leaking for about a month until we got tired of the noise and we were about to depart on a long trip, and didn't want to put up with the drone for several days in the car.

However, I'm thinking that all of the injectors and all of the coils are getting pretty tired at 283k miles, so I'm going to start easy / cheap and replace the coils one at a time, and if that doesn't resolve the issue then I'll probably take the car into a shop to have them diagnose it.

If a coil was bad and there was no spark or weak spark at one cylinder, that would mean the the unburned gas was going into the converter (bad thing) and then out the tailpipe. Would that unburned gasoline be detected by smell? By an exhaust gas analyzer?

 

I guess I’m still not completely clear on the lack of use of scan tool.

 

He's doing it the old fashioned way of turning the screw on the side of the ECU, and watching and counting the number of flashes of the CEL light on the dash, which corresponds and translates to a P-code. Then he looks it up. Yields the same results, just more of a pain in the *** vs a scan tool and using the OBDII port.

Maxbumpo,
Flashing CEL is a dead giveaway that you likely have an injector issue. There is language in the Factory Service Manual (FSM) that discusses this. One or more injectors are likely bad.

 

Last time this happened (flashing CEL and misfire) it was a bad injector at #4. Listening with a mechanic's stethoscope, it was easy to hear that this injector was weak and not happily clicking away like the rest of them.

This time, all the injectors sound just fine, none sounds different than any of the others.

Is it possible to have a bad injector that sounds fine?

The next test in the FSM is to unplug each injector one at a time and see which one makes the least difference in the idle speed. I don't see how I can do that for the injectors that are buried under the intake manifold.

 

Correct, why pay for a scan tool when a simple screwdriver will yield the same result?

Perhaps I messed that. I'm looking at the procedure that starts on page EC234, and it leads through a bunch of steps like checking the exhaust system for crushed / choked off exhaust, checking the EGR, checking the injectors and checking the coils, and many more steps after that.

I guess I'll just have to try all of those diagnostic steps. The fact that this misfire moved from one cylinder to the next is a clue, I'm just not sure what it's telling me.

 

At that mileage, probably all the injectors would need servicing due to the pintle caps being gone or damaged.

Mine had partial damage when I replaced them at about 120k miles as preventative maintenance.

 

… and the DTC you’ve extrapolated is what?

 

The code is 0604, aka P0305, aka Cylinder #5 Misfire. Initially it was 0606 (misfire at #3) and so I swapped the COP between #3 and #1 to see if the problem moved with the coil. Instead, the misfire moved from #3 to #5.

 

Did you have any problems, get any codes from that? Any improvement after you replaced them?

 

My spark plugs probably have about 50k miles on them, so they are almost due for a change. I'm thinking that would be cheap insurance to put in all new plugs now and make sure that is not the problem. I used to have a 1979 BMW 528i, and one day it was really running rough with a misfire, and I gave up and took it to a shop. Lucky for me they were a very honest shop. They simply changed the spark plugs (just one had gone bad) and the car was back on the road.

 

You gave all the symptoms of a bad fuel injector.

Tge problem is a broken plastic retainer at the tip.

People tend to think it's just about anything else.
Quite often a failed injector is just fine electrically.
So often don't set codes.

Typically someone will post about issues like yours will argue that it's not an injector. Then they replace coils, plugs, other items. Once all that money has been wasted they will finally replace tge injectors.

 

Mine were in the early stages of the pintle caps breaking apart, as well as just done for maintenance purposes, so I didn't really notice any difference. I had no CEL on at any time.

 

Will this broken plastic be visible once I pull the injector? Sure sounds like my issue could be this.

 

I have some pics showing the caps in this thread. One of pics shows the injectors I pulled out with the deteriorating pintle caps...

https://maxima.org/forums/4th-genera...servicing.html

 

The injectors can be rebuilt to function like new.

I'm quite satisfied with the company I sent mine to.
excellent results.

InjectorRX in Houston charges 18 dollars per injector.
They have a fast turn around. I had mine back a week after I shipped them.

 

Most definitely. I wouldn't simply replace the pintle caps, I'd have the injectors refreshed and flow tested as well. JvG mentioned one service provider that can do everything for you.

 

Broken/missing pintle caps …

 

No waiting, no shipping back (and forth either), Original OEM JECS Rebuilt Fuel Injectors and a set of 6 matched flow injectors. This guy knows what he is doing! $125.

Get the FelPro Grommets from Rock Auto that compliment the installation under the Injectors.

https://www.ebay.com/itm/30278493569...EAAOSwRTtbMnh7

 

As long as those are truly OEM injectors, this is the way to go. Others have reported bad experiences buying so called "OEM" injectors from Ebay, only realizing that one or two of "refurbished" injectors were still garbage and were generic injectors, so a word of caution to the OP.

 

They're in my 99 and working exactly as should.My problem is a vacuum leak. Others here have bought them and never heard a complaint. He has a real store and website as well. He MOVES volumes of injectors for all cars.He delivers what he says he'll deliver. And supports it too.

Very Legit: https://www.motormanfuelinjection.com/contact.html

Tomorrow, I will pump smoke through my vacuum system and find those leaks.

I made a smoke blower that uses mineral oil, a cotton rag and soldering iron to make smoke and a fish tank air pump to push the smoke in the vacuum system. Then I'll see smoke where it leaks. No better way to find the hard to find.

 

So I'm not convinced that broken plastic pintles on the injectors will cause the misfire.

I'm going to try new plugs and new coils first, because (1) plugs are cheap and they are about due anyway, they are a wear item, and (2) coils are just as old as the injectors and in my mind just as likely to be a source of the problem, and (3) coils and plugs are much easier than injectors 1, 3 and 5.

I have ordered rebuilt injectors from the recommended eBay seller Motor Man.

The only other test I can think of would be to make up a test harness of some sort to be able to selectively disconnect the injectors one at a time. I'd need to get access to a junkyard car and harvest the connectors from it.

 

You aren't losing anything by replacing those other items first, based on the mileage you have. Just be careful with the coil plugs you go with as some do not work very well on the car. Let us know how things go.

 

Are YOU going to pull the UIM and everything in the way to access the Odd numbered Fuel Injectors or bring it to a shop? Because until you know what a JOB that is, just to test a theory is an inexperienced statement.

I have had bad individual coils gone bad and never was there a gas smell. The car stumbled and idle was slightly struggling, but nothing dramatic until two are bad. Just stumbling throughout the RPM range. with a more pronounced rough idle.

Maybe you need to read the immense amount of threads regarding Injectors and Coil packs. They all start with an OP that sounds like yours, with a constant fight throughout, until they learn the hard way. Some waste a LOT of money.

Also KNOW, if you get to the rear Injectors, and then have to reassemble everything PROPERLY with no mistakes, you will never want to do it again! So do everything right and replace everything that will be tired after 275K miles and 26 years old. And that is pretty much everything that is considered an educated consumable. Along with Rear Valve cover gaskets and cleaning the TB, IACV, MAF and EGR parts that get blocked from carbon every 75K to 150K miles. Repllace any vacuum hoses and tubes that are displaying aging and so on. PCV, Fuel Pressure Regulator, Fuel Lines and Fuel Rail lines and clamps and Filter. Maybe replace the carbon EVAP filter with the refresh as well. If you plan on keeping it to the end.

This all true and the net of your journey, so consider the truth as a gift. Unless it's too much and you would rather get rid of it!

If your wife is the driver, I can't imagine you not wanting it bulletproof reliable?

 

Ironically had this exact same issue today. First time I've ever seen the CEL flash actually.

BACKGROUND:
CEL came on a few weeks ago but the car was still running fine. I tested all the coils as well as the condenser and everything tested fine. But a few days ago the car started stumbling at idle. Re-ran the codes and it showed a misfire in cylinder 1 so I ordered a new coil pack today and will change out tomorrow. That being said this is the 3rd coil pack now I've had to change in probably 6 or 8 weeks. Curious as to if anybody else has had the same experience with all the coil packs crapping the bed around the same time?

 

I've never seen failing coils cause the CEL to flash. I hope you're right about it being coilpacks and sparkplugs, but I suspect this won't be the end of the story.
Remember, our cars are picky when it comes to coilpacks. Just don't run to Autozone or Pep Boys to get new generic coilpacks...

 

I will be doing all this work myself, and I will be replacing all the seals etc. that are required. She Who Must Be Obeyed (SWMBO, aka my wife) loves this car and would be happy to drive it until the day she dies. That is the goal, and I hate doing the same job twice, so I'm open to any and all suggestions for sources of quality parts.

Will Nissan still sell the seals / gaskets etc?

Already have: Denso double platinum spark plugs, PK16PR11 3264. They are supposed to come properly gapped, I will check that and adjust as needed.

Ordered: Hitachi coil packs for #5 and #3. I have a generic store brand on #1, easy enough to fix that in the future if needed.

Ordered: JEC rebuilt injectors from Motor Man on eBay.

 

https://www.courtesyparts.com/

For OEM stuff they are generally fairly reasonable. Not ridiculously high or ridiculously low either. Might be able to source a few things from them and others from Rockauto

 

Shop by Nissan Part numbers with and without the dash in the middle and search for lowest delivered prices.

FelPro and Victor Reinz gaskets and seals are excellent and sometimes better than OEM.

RockAuto.com is a HUGE resource for quality parts, but when they have OEM, you can usually find them cheaper elsewhere. But brands like Standard Motor, and Intermotor and a few others they carry are usually top quality. Hitachi Coil Packs are on sale at RockAuto.

NGK is the Spark Plug 4th Gens like most. NEVER use Bosch. BoredMDer on Youtube is a resource for doing this work. 4th Gen Max and I30 videos are the same process and parts.

 

New plugs in all the holes, and new coils for #1, #3, and #5. Still have the misfire at #5. That plug was fouled, as expected.

Waiting on the rebuilt injectors and the seals / gaskets now.

 

As we all suspected, plugs and coils were not the end of the story.

I hope you know how to remove and re-install injectors the proper way. Many users seems to royally screw up this part of the job (especially the re-installation part), when in actuality, it's really quit simple. Make sure you add a dab of oil or grease and smear it along the o-ring that seats the injector. It should "pop" right in very easily. Otherwise, you run the risk of tearing or improperly seating the injector which will lead to a slew of new problems.

 

I'm in the same boat but Cy2 P0302... though this happened after my injector replacement. I used the Injectors mentioned above, they work great... for me tho it's not the injectors as I swapped the injectors and my issue is still with the same cylinder. Good luck on ur injector swap, Getting to those back bolts behind the manifest sucked the first time.

 

Closing this out, problem is solved with 'new' rebuilt JECS injectors. Old injectors visibly looked fine, only #1 had pintle damage, one of the four arms was missing. Just for giggles I hooked up a harness to put power to all the injectors, and they all happily clicked away, could not tell any difference between #5 and the rest. There must have been some internal fault that caused the problem. Screens were all intact and did not appear to have any deposits or junk.

To ease the installation of the injectors, I lubed the o-rings with ATF and used a big channel lock pliers to twist and push them down into the bores.

 

Nice work man!

 

Glad to hear it! Enjoy the Max!