multi cylinder misfire remedy

[renkema]

Found serveral references to this in both current and archive, but none went to the heart of my issue.

I have a '97 q45t that's been nothing but sweetness and light for 92k miles. Today, while walking to the car, I inadvertently setoff the alarm via the keyfob. I cancelled it, started the car and began to get the symtoms of a misfire while going up a hill. This continued to the dealership where they tested and said I had codes indicating a multi cyliner misfire. They suggested I fix the problem by replacing ALL of the coils and the 2 knock sensors (only $3,500). They said that should fix the problem as they had NO way of ascertaining which coil was bad. I had it there for service 2 weeks ago. All they noted was that there was at some point (not currently), knock sensor codes gerenated.

I have 3 basic questions. 1) Are they even on the right track as I've seen references here that suggest other problems and,2) is it really impossible to discern which coil is bad 3) are the knock sensors the potential culprit.

I called an out of state infiniti dealer's parts dept that I've ordered from before and they said that the all 8 approach didn't ring true. The parts guy looked up coil orders from his own shop and 95% of the orders for coils were singles (no 8 at once). On top of that, my local dealer shop only had 3 instock and was pressureing me to go ahead and order the 5 more so they could do the work the next day.

All of this may be legitimate, but at 200+ a pop, I would think there would be a way to determine which coil was bad. I'm thinking worst case, I 'll put the coils on myself and save the $1000 in plugs and labor they want to install all 8. I don't think I can install the knock sensors. I installed a transmission in an '89 honda, but I think these newer cars require more skill and tools than I have.

I'm not looking to pan my dealer, but I would like some help on determining if their advice is helpful or self-serving.

I'm new to the forum. Hopefully, I'm following protocol in all respects. Let me know if I'm not. Thanks

[maxnix]

I think you need to peruse Q_ship's thread on this subject.

[renkema]

I reviewed that post first. Note my errant post in that thread (I'm a newbie). I was trying to reply to texasoil's comment that touched on the multi cylinder code issue. I then searched the archives as suggested. I still couldn't find an answer as to testing which coil is bad and the need to replace all eight to takle the multi cylinder misfire code problem.

[Q45tech]

If you own the 97 long enough you probably will need to replace all 8 coils.

Why many techs want you to replace all 8, to save you the time and trouble of return trips over the next 100,000 miles.

The act of pulling coils on off may contribute to accelerated problems depending upon care exercised so makes sense to change plugs whenever you do coil work even if the plugs only have 20,000 miles on them.

As sparkplugs wear the gap widens and the voltage required gets higher and higher and higher to bridge the gap.

You could order all 8 and save 20-25% and replace them ourself.

[Skibane]

I had it there for service 2 weeks ago.

What kind of work did they do on it back then?

[maxnix]

I still couldn't find an answer as to testing which coil is bad and the need to replace all eight to takle the multi cylinder misfire code problem.

Exactly what is the code number for the "multi cylinder misfire code"?

[renkema]

the multi cylinder was PO300 and the knock sensor was both PO325 and PO330. I got the codes from the invoice from the dealer, not from my ability to get the codes myself.

I see the PO300 and PO325 on the 4th gen list, but not the 330(maybe the 25 and 30 mean the both sensors).

I reconfirmed with the service dept. that if these were replaced, the problem would be fixed (pretty much is actually what they said).

My sense form responses to my problem and other posts is that I could handle installing the coils/plugs myself, but not the knock sensors, but again I may be getting ahead of myself in truly diagnosing the problem (and the fix)

By the way, I drove it home from the dealer with no issues, but the SES light is still on (not blinking), which makes me think even if they cleared it while testing, the problem(s) are still there.

Thanks for the help. Hopefully, I giving enough info.

[maxnix]

AS you can see from EC260 and EC261 attached, there are a lot of things to verify and correct if deficient.

[renkema]

I had orginally taken it in 2 weeks ago as the SES light was on. Embarrassingly , it was from not rehooking the air intake sensor when I replaced the airfilter. This meant that the sensor sensor had been disconnected for 2 days. They also mention that at some point, the knock sensor codes had been tripped, but they were not currently concerned as no code was currently being transmitted. Other than rehooking the sensor, they did rotor service.

They also changed the trans fluid and cleaned the intake. By that I mean the service that is performed on the throttle body to remove deposits that make the throttle stick and jerk when the excellerator pedal is depressed.

[maxnix]

I had orginally taken it in 2 weeks ago as the SES light was on. Embarrassingly , it was from not rehooking the air intake sensor when I replaced the airfilter. This meant that the sensor sensor had been disconnected for 2 days. They also mention that at some point, the knock sensor codes had been tripped, but they were not currently concerned as no code was currently being transmitted. Other than rehooking the sensor, they did rotor service.

They also changed the trans fluid and cleaned the intake. By that I mean the service that is performed on the throttle body to remove deposits that make the throttle stick and jerk when the excellerator pedal is depressed.

Um..."Change transmission fluid" meaning fill and drain? Better do some research on that one. Search on flush and posts by Q45tech.

TB cleaning is nice, but not sufficient if you have over 75K. Got to do the plenum, IAC and EGR valves also.

"Rotor service" would be retruing the rotors? But no new pads?

"Air intake sensor" is the temperature probe in the intake ducting? Or the MAF sensor connector?

[renkema]

not the MAF (I know where that is thanks to other posts), it must be the temp sensor as you say (it's right in front of the filter in regards to airflow)

The rotors were turned but they said no new pads were necessary.

They said the trans fluid looked burned so I'm assuming they flushed and refilled.

Regarding the multi misfire code culprits in the PDF, is the ignition secondary circuit the same as the coils? If not, I dont see the coils even on the list.

RE: the IAC and EGR, the idling seems fine, bu t I'm not oppose to changing those.

The plugs have about 35k on them. Per the PDF list, I should start there.

I'm still not getting the indication from the PDF list or posts here that confirm that the primary cause of the error codes are the 8 coils as my dealer says. It may be a good idea at 100k to change these, but may do nothing to fix the problem.

[maxnix]

1.) The rotors were turned but they said no new pads were necessary.

2.) They said the trans fluid looked burned so I'm assuming they flushed and refilled.

1.) Most strange! Might as well put in new pads and postpone future labor charges. Replacing old pads with new pads is minimal labor when the rotors are pulled.

2.) Assume at your own peril! Ask and verify! Obviously, you need an auxiliary ATF cooler and more frequent white papertowel tests of the ATF.

The list of items is to verify before the coilpacks are assessed. That is the items on the list must be verified as functioning correctly or replaced before diagnosing the coilpacks if the OBD II codes are still present.

[renkema]

I'm going the route of replacing the knock sensors myself and install a new set of plugs. Looks pretty straight-forward from the step by step post I found here. I don't think that will cure the problem, but I think it should be done anyway given the error codes on both (325&330)

Can you recommend a ODB II scan tool. I saw an auto enginuity on ebay for $200. I've got a PC laptop. I think I'll need this to reset the SES light if I go the one by one replacement route on the coils which I've been tracking on Q_ship's post. I'm not sure this trial and error will work as I have no idea whether it's just one coil or not. I also try the resistance test, but as you've posted, it may be in the secondary winding or elsewhere. This was a diagnostic bust by Infiniti.

This is a great resource, I just wish I understood the technical a little better but I'm getting there. thanks for the help

[maxnix]

I'm going the route of replacing the knock sensors myself and install a new set of plugs.

If you are due, then fine. But realize almost any malfunction in the engine will throw a knock sensor code in OBD II. I would tackle the other stuff first, starting with the easiest and least expensive.

Nissan guys tell me KS codes are so ubiquitous in OBD II, they ignore them until everything else has been eliminated. I mean bad fuel will result in a code.

[renkema]

you may be right on the KS. Others here seem to have had improvement with replacement at around 100k. Hopefully, I will too, but not counting on it.

As the car appears to run completely fine on the open road, I feel like the problem is an intermittent electrical problem (spark as opposed to flow). The other items on the list (injectors , EGR, gas) would seem to manifest with a repeated symptom which I don't see.

Of the other items on the list: plugs( I'm replacing), the front heated Ox sensor and the EGR I can replace. I'm not sure how to rule out injector problems other than having them cleaned. I would think the dealer would have noted that, but I would'nt be here writing if I had 100% confidence in their diagnosis.

[bullittandy]

Search for my posts on K/S replacement on a 97+ Q. You don't have to remove the plenum as opposed to earlier cars.

Also search for O2 sensor replacement, the front driver is much easier if the brake booster is removed.

Sorry I don't have links maybe some other clever member will post each.

Good luck, by the way, plugs, K/S and O2 sensors are all worthwhile replacement items even if they are not causing current problems so feel confident that even if all of your problems don't go away you've made a good investment.

[renkema]

The KS and the plugs are on the way and I will install them this weekend.

I saw a detailed post of KS replacement with pics on q45.org but that had the plenum involved so it must be on a pre97.

Strangely enough, the car is running perfectly at the present time, but the SES light is still on. How do I reset it to see if the codes are still registering? Also, I saw the laptop based OBDII readers on ebay ($200). Are they adequate to pull/reset codes for my '97?

thanks for the help.

[maxnix]

OBD II readers are usually capable of resetting.

Are you replacing all 4 O2? Guess you can replace the sensors and the harness without pulling the plenum, but I guarantee the plenum needs cleaning, along with EGR valve, manifold tube, and IAC valve.

Get all the gaskets and do it.

[bullittandy]

The KS and the plugs are on the way and I will install them this weekend.

I saw a detailed post of KS replacement with pics on q45.org but that had the plenum involved so it must be on a pre97.

Strangely enough, the car is running perfectly at the present time, but the SES light is still on. How do I reset it to see if the codes are still registering? Also, I saw the laptop based OBDII readers on ebay ($200). Are they adequate to pull/reset codes for my '97?

thanks for the help.

OBD II is a consistent set of codes across different manufacturers so any code reader will read any OBD-II code that you have. Code readers can be had for as little as $75.

[texasoil]

Sorry to see you planning to throw costly parts and lots of time chasing a ghost. LOTS of things can cause transient misfires--like a slug of water in the fuel!!. If the engine is runnig normal, clear the SES light and check for NEW error codes get a cheap OBD-II reader that can reset the codes and save LOTS of time and $$$ chasing faint shadows in the mist.

[bullittandy]

Sorry to see you planning to throw costly parts and lots of time chasing a ghost. LOTS of things can cause transient misfires--like a slug of water in the fuel!!. If the engine is runnig normal, clear the SES light and check for NEW error codes get a cheap OBD-II reader that can reset the codes and save LOTS of time and $$$ chasing faint shadows in the mist.

Spark plugs, O2 sensors and K/S are all costly but are also due for replacement at this time-no?

[renkema]

I think both of you are right on this one. Texasoil's reference to "water in fuel" was profound as I had initially suspected this or something similar when I felt the engine miss initially causing the SES to light. I ignored my self-diagnosis when the dealer said that the coils and k/s had to be replaced. The car has run as usual since Friday. As of yesterday, the SES light went dark. The dealer did clean the throttle body 3 weeks ago. Could some artifact have been left that worked it's way out? Who knows?

At this point, I feel like I have time to think about what to do next from an upkeep, performance, and maintenance point of view instead of a troubleshoot. At 100k; the k/s, plugs, egr, iac, and O2s, as well as cleaning the plenum probably need to be addressed. What I do and when I do it is going to be completely dependant on the feedback I get on this forum as given this incident, I have no confidence in the skill (and maybe veracity) of my local dealer service department.

[Q_SHIP]

Good luck. I'm actually going to be checking my injectors soon. I ohm teste all the coils ant they came out clear. Injectors are pretty easy to determine if they are bad or not.

[goody90q45]

Check out this link to ohm your injectors and KS.

http://www.q45.org/ohminjectors.html

This link is for a 90-96 but I don't think the 97+ are any different once you get the plastic cover off and can see the engine. KS code can be set off by a number of things that have nothing to do with KS. No sense putting new ones in if you don't need them. Good luck.

[Q_SHIP]

Oh and just for the hell of it, I threw in a can of BG44 to see if it could (maybe) clean out the injectors.

[Q_SHIP]

Well, I ran the BG product in my car. After 100 miles the car runs flwlessly. Im a firm believer in the BG product. It's saved me twice now. Must have been a dirty injector.

[Qproject]

renkema,

so did you resolve the problem with your routine mantenance ? is your CES light still on ?

did u ever replace the coil packs ? knock sensor ?

I think both of you are right on this one. Texasoil's reference to "water in fuel" was profound as I had initially suspected this or something similar when I felt the engine miss initially causing the SES to light. I ignored my self-diagnosis when the dealer said that the coils and k/s had to be replaced. The car has run as usual since Friday. As of yesterday, the SES light went dark. The dealer did clean the throttle body 3 weeks ago. Could some artifact have been left that worked it's way out? Who knows?

At this point, I feel like I have time to think about what to do next from an upkeep, performance, and maintenance point of view instead of a troubleshoot. At 100k; the k/s, plugs, egr, iac, and O2s, as well as cleaning the plenum probably need to be addressed. What I do and when I do it is going to be completely dependant on the feedback I get on this forum as given this incident, I have no confidence in the skill (and maybe veracity) of my local dealer service department.

[Q_SHIP]

KS is very common on the Q. I replaced mine right away when I got the car.

[renkema]

I will do the maintenance this weekend (which will begin with new plugs). I may try the BG44 as Q ship suggests.

The SES light is out and the car is running as before.

I will post the effects of the above once I have completed, but I urge all who have the coil and KS code issue to pause and read all of these posts as they could potentially be chasing ghosts.

[maxnix]

I will do the maintenance this weekend (which will begin with new plugs). I may try the BG44 as Q ship suggests.

If you suspect water in the fuel, or even if you don't, run a can or two of ISOHEET (not HEET) through it.