1999 Q45 Miss at idle

[poweroptions]

Somethings got to give. My 99 Q has 47,000 pampered miles. A miss developed at idle occassionally at 37,000. It then thru codes 138 and 139 at 40,000. We replaced both o2 sensors. Was fine for a couple days MIL came on dash. Again code 138. Went back to shop another new o2 sensor and new premium plugs. Didn't help. Went back to Infiniti (Oct.07) for a ECU reprogram at 41,000. Was fine for months, now at 47,000 same damn thing. Miss is back and more pronounced at idle, MIL is on dash, consultII prints code 138/139. This is starting to irritate me and is adding up to be $$$, with no sure fix. WHAT the hell???????? Do any of you NICO guys have a suggestion???? PS it has always had Premium gas.

[maxnix]

Pleae define "Premium Plugs."

Tire 1 Premium?

Ever thought about going to T-3?

Have you read the stumble at idle and the let's fix this threads?

[poweroptions]

Replacement plugs are NGK PFR 5G11, likewise replaced O2 sensors are NGK too.

[maxnix]

Good. Helps if the intake path, EGR and IAC valves and EGR tube are clean.

Read the posts, erase the codes, switch two coil packs.

OBD II scanner of any competence should give you a cylinder fault code.

[poweroptions]

aarrrrgggh, well thats all clean, it was clean. lord everything looks like it is still brand new on my car. switch 2 coil paks, reset and bam 5 miles down the road MIL flashed on the minute I gave the car gas to pull onto the highway, only this time the car shifted weird on it's first shift. didn't do thats anymore thank god. grrrrrr. i ordered some bg44k today. my mechanic told me to go buy a FORD, I luv my Q. Saved the darn thing as our good car never driving it much and I hate it acts weird at idle, to the point passenger/clients notice it. GRRRRRR.

[Q45tech]

"my mechanic told me to go buy a FORD,"

That is his way of telling you he is a MECHANIC not a properly and fully trained TECHNICAN qualified to actually work on your Q.

The major problem is even fully trained and competant techs who DON'T see many of your make and model and year. It would be the same if you drove a V8 audi, BMW, Ferrari, Masterati, Mercedes , or an LS460.

Ignition coils in the 97 and later Q are more fragile than the bullet proof 90-96 models.

47k pampered miles is 9 years of ABUSE is much like Japanese driving only 5k per year...............the car is beautiful but worn [unseen] and ready for export because of age factor of many components.

We have 97 customer with 300k + miles from continuous interstate travel who are just now startimg to have problems.

AGE alone can be a factor with electronics [connections/solder/capacitors, etc]

Extreme care must be exercised in replacing spark plugs or the coils may be damaged in the process

You probably have 1 or more defective coils that are just on ragged edge or working.

[maxnix]

So did the OBD II fault code follow the coil or stay at the original cyllinder?

[poweroptions]

It is showing 138 & 139 again.

[elwesso]

dont always assume that the CODE is the PROBLEM, it could be showing the underlying cause of something else..

If you replaced your o2s and the connections looked good its probably not that...

I would personally look into a coil pack..

[poweroptions]

Cars been to Infiniti Sewell Dallas, mechanic /technician your choice. ECM reset, no codes, car at factory specs. Drove it 200 miles SES back on and stumbling idle came back with the light. Infiniti service rep called and sending driver to retreive Q. Service rep called and has little idea why this is recurring. Began at 40,000 miles in Oct. of 2007. Now at 47,000 miles and April 2008. Still a problem and unsolved. It has been to Infiniti 3 times now and I'm losing interest in this car fast, 8 other cars in my garage that don't have problems.

[bullittandy]

Cars been to Infiniti Sewell Dallas, mechanic /technician your choice. ECM reset, no codes, car at factory specs. Drove it 200 miles SES back on and stumbling idle came back with the light. Infiniti service rep called and sending driver to retreive Q. Service rep called and has little idea why this is recurring. Began at 40,000 miles in Oct. of 2007. Now at 47,000 miles and April 2008. Still a problem and unsolved. It has been to Infiniti 3 times now and I'm losing interest in this car fast, 8 other cars in my garage that don't have problems.

You have a bad coil. Repeat, you have a bad coil.

Now, which one? I have no idea! If you can discover which one it is you will love your car again. How to discover the bad coil? I have no idea!

Seriously, this is a common problem that has been present on the board for several years and the consensus is that the coils on 97+ fail.

Now, can anybody come up with a creative way to determine which coil is bad if there is NO code for a cylinder misfire? (Q45Tech, please don't offer the idea about measuring exhaust pulses and timing them to the cylinder yada yada yada-no one has the equipment except for you and SuperUber).

I have 8 spare coils from a parts car and plan on changing them one at a time until the misfire on my 99Q45T goes away. Another idea would be to buy 4 new coils and replace one bank and see if that fixes it, if it doesn't then take the four used ones (that are good since the problem isn't fixed) and put them on the opposite side. Ebay also has a set of 8 coils brand new for about $575 which is isn't terrible.

[96Qowner]

What Andy said. We went through a lot trying to narrow this problem down. It's a marginal coil. Tell the techs.

Unfortunately, it won't code unless it misses several times in a short period. If you have Consult hooked up when it misses, you should be able to spot the cylinder. The trouble is getting it to miss when you want it to.

A lot of Infiniti shops want to just replace all the coils. When one goes, others are reaching the end of their useful life, too. But it's spendy. Your call.

[poweroptions]

Q's back from Sewell Infiniti Dallas. The service dept. reset the ECM. Kept it a couple days and test drove it 100 miles. No codes, and the miss is less frequent but still there once in a while at idle. GREAT service at Sewell. Gave us a new 08 G37 for a loaner , no charge, frickin fasssst agile tight car. To small for me at 6'3" but was fun for the couple of days. Sewell waived all fees, no charges. NICE ! Again WOW what service for a 9 year old car. I have one new coil coming and will start interchanging it one by one till I find this gremlin. It sure is nice not seeing the damn SES light on. thanks to all for your help and guidance !!
Modified by poweroptions at 7:28 PM 4/8/2008

[poweroptions]

Well 4 or 5 weeks later the SES is back on code 138 O2 sensor. Back to Sewell Infiniti in Dallas. They are now telling me that both O2 sensors need to be replaced with Infinti O2s. They are saying that the NGK replacement I installed is not the same as the Infiniti parts. Is this true?? Now they are saying $600 to replace both O2 seems HIGH to me. I ordered my replacement Os from Sparkplugs.com

[Q45tech]

14 years of independent Infiniti experience has told us to always use OEM parts and not buy discount coils, O2 sparkplugs, electronic sensors, or non Nissan remans.

Too many low quality look alikes with dubious quality control.

[miata007]

BTW, getting OEM coils from Joes is only $500. I've orded mine two weeks go and still waiting since 2 of them are on back order.

If your car is over 100,000 mi and getting this engine mis-fire, I don't think is a bad idea to replace all 8 coils. Once I installed mine, I wlll let you guys know how it goes.

Last week, I was able to replace the valve cover gasket on the driver side.

007

[bullittandy]

$500 ain't that bad.

I've been thinking about buying 4 new and doing an entire bank and then if it isn't fixed moving the 4 used coils to the opposite bank.

But like its always said here, if you plan on keeping the car for awhile then might as well bite the bullet and spend the moneyand buy 8 coils at once.