Seeking Opinions

The other day my "Service Engine Soon" light popped on while running at a highway speed although there was nothing different in the way the car felt. It still had plenty of power...plenty of acceleration and did not overheat. I got it home, popped the hood and started looking for signs of touble. I found nothing out of the ordinary...no electrical diconnections, no cracked hoses....no stray oil, nothing appeared to be wrong. The next morning I fired it up and immediately noticed it was running rough, as if one cylinder was'nt firing. The rough idle did not improve, even after the motor warmmed up.

I've never worked on one of these Nissan motors before so I'm a little lost as to where to start. Normally, I'd start pulling plug wires and spark plugs for closer eximaniation. So what do I do?

Thanks
SmL

check engine lights sometimes run on a timer, "like it's time for a checkup", even if there's nothing wrong, you probably loosened some sensor wire or something...

check the Mass airflow sensor. does the idle fluctuate from like 700-1100rpm?

I suspected the "Check Engine Soon" light was simply part of an automated maintaince process i.e. at "X" miles the light just goes on and the owner takes it in for servicing. However, the noticably rough idle indicates something is wrong. My local dealer will cover the repair under warranty provided it's a powertrain related issue. If it's wiring or injectors or something of the like then I'm liable for the repair. To me the problem suggests a fouled plug. But how do you get the pulgs out to inspect them? Looks like I have to take off the top of the manifold to get to some of them. Is that right?

SmL

The Check Engine Light is not a service reminder indicator. It indicates something is wrong with your car.

You can perform diagnostics on the car yourself and get the codes from your cars computer very easily.

Go here for a quick write up with pics on how to obtain the error code from your car's ECU.
http://vbxmaxima.8m.com/ecu.html

Once you get the code, you can go here to have it decoded which will tell you what device has failed.
http://vbxmaxima.8m.com/ecudecoder.html

If you go to your local book store pick up a Haynes Shop maunal for your car for about 12 bucks. It explains how to read your cars ECU, and it lists all the error codes and details how to troubleshoot and fix just about everything on your car.

It can save you a lot of $$$$ in repairs!

Hey NJMAXSELTD,

Thank you for passing that onto me! That is exactly what I needed to hear. I will purchase the shop manule, identify the code and then decide whether or not I can fix it or have to take it to a dealer.

SmL

When I bought my G20 it was "missing" a cylinder at low RPMs, and it was a clogged injector. No big deal. One time I was test-driving a Pontiac 6000LE and it suddenly went rough, and one of the spark plugs had literally popped out of the block, the dealer re-drilled the threading (leaving the shavings IN the engine) and needless to say I didn't buy the car.
There are a few things that could cause your missing cylinder.
And for future info, the "check engine" light isn't for decoration like on my dad's Chrysler, but indicates an actual problem, usually with the fuel/emissions system. Your car has OBD II diagnostics, which means the car periodically checks itself to make sure all sensors and emissions parts are functioning properly. If the same part/sensor returns a "fail" code twice, the light comes on to let you know that the car is in need of service. Usually these are problems you wouldn't notice otherwise, such as o2 sensor out - that's why the car lets you know since there are usually only slightly noticable symptoms such as slight loss of power and reduced gas mileage.

Another note - the main reason why you'd experience loss of power and reduced mileage when an o2 sensor is out, is that the car operates in "fail-safe" mode, where the computer assumes a "safe" reading, and runs the mixture really rich, to account for different altitudes. Because of this the car is using more gasoline in the mix, and some of it doesn't get burned, causing the reduced mileage and power.

I think you'll find Nissans to be very reliable in the general sense - esp. in terms of engine durability, after all the Max has Ward's 10-time engine-of-the-year winner VQ - but periodically with any car lilttle sensors and such will fail and need to be replaced. You can diagnose yourself with the method above, or take it to the dealer, they will charge $40 to diagnose for you. Hope this helps.

Hey NJMAXSELTD,


I've ordered the Haynes manual but it will take a few days to reach me. Last night I followed the procedure on your web site for extrapolating the ECU error codes. I performed the test four times and got the same consistant results each time. There were two error codes that showed up: 02 01 (Ignition Signal Circuit) and 14 05 (?). The ECU Decoded didn't have the number fourteen as an option for the first code number (it only went as high as thirteen). Had the second code been 13 05 it would have equaled Fuel Pump Control Module.

Just looking for personal opinions here, so what are your thoughts on the following:
(1) What is a 14 05? Is it just an errant code that I shouldn't be concerned with?
(2) When the Check Engine Light originally came on the motor was running somewhat rough (as if one cylinder had not been firing). After sitting over the weekend I started the motor and appeared to run flawlessly (although the Check Engine Light was still on). After diagnosing the error codes AND resetting the Check engine light the motor still seems to operate normally (all cylinders appear to be firing). I put about forty miles on the car this morning and the Check Enging Light has not come back on. Could the motor have experienced some kind of electrical "hic-up" that caused the Check Engine Light to first come on?
(3) I'm a shade-tree mechanic only. I can take things off and put them back on and change fluids but beyond that and I'm out of my element. GIven that, should I just take this in for the dealer to fix or am I simply looking at replacing a sensor or two ?

Any and all advice is appreciated.
Thanks
SmL

i had (have) a problem with my service engine soon light. i ran a computer on it and found out it was something with the evap in my fuel lines/tank. there was a whole load of things to try to fix it but i never bothered. cleared the codes and the light went away, but came back a few days later. it stayed on for awhile but went off for like a week, now its back. i dont think its anything serious because the car runs fine, ill prob take the bulb out.

sml -

The ignition signal fault is probably a coil pack that is failing. It may happen again. My suggestion is to keep resetting the light until the ECU figures out which cylinder it is. You will eventually get a misfire code tied to a specific cylinder. At that point you will need to get a new coil pack for that cylinder.

How many miles are on the car? Also have the plugs ever been changed and if so what brand are in there???

I'll try to check out the 14-05 code in my manual for you and post it up. I think it may be the evap system but I'm not sure. The evap system is located behind the drivers side rear wheel. There is a canister and a valve back there. The valve gets full of crud from being in a not so nice location on the car. Usually just a removal, clean up with WD-40 gets it working again.

Your errors are very easy for a "shade tree mechanic" to fix! The ignition signal fault might not even come back again... ya never know...

Tom

I searched for 1405 in the Haynes book and came up blank. So I went to MAxima.org and searched the forums for 1405 and discovered a few guy who have had that code come up. Nobody was able to identify it. :confused:

I suggest you keep you eye on the CEL and see what codes it thorws you as time goes on. Hopefully this was a fluke and you'll be ok for a while.

Keep us posted!

Tom,

The car has 48k on the clock and I'm running the recommended plugs (NGK PFG5-11's). The car is pre-owned and in very good condition. However, the plugs may be from the factory. BTW the plugs looked good: grey-white in color with no carbon build-up or evidence of excessive heat. With 48K miles on the motor and plugs in (seemingly) good condition would you recommend I leave them in or replace them?

I didn't want to wait on my manual to arrive via mail so I hunted one down at a library (almost forgot what the hell a library was). Just my luck...there's no 1405 code in the Haynes 1993 thru 1999 manual (hand slapping forehead "Damn!!!").

The ECU was re-set and the Service Engine Soon light went off....at least for a few miles then it came back on again ("Double damn"). However, THIS time the ECU only gave one code (perviously it gave two: 0201 and 1405). And the code it gave was 0201-primary ignition circuit fault.

So I pulled the plugs/coils just to inspect everything....and everything looked fine. The manual identified the plugs/coils as "secondary ignition". But the given error code identified "primary ignition". What the hell is primary ignition? Tracing the car's electrical path (mentally) it occured to me "...the battery begins the engine's ability to produce electricty/saprk" and I replaced the battery just a few weeks ago. But I did it in the pouring rain and didn't take time to properly remove all the corrosion from the existing cables. I just yanke out one battery and threw in another.

I disassembled-cleaned-petrolum jelly'd all the battery connections (including the red plastic female connector off of the positive cable), reset the ECU and ran the motor for a few minutes. Then I checked the the codes again and got an 0505 (the everything is fine code). I'll wait and see what happens.

Sorry about the long message and thanks for the Evap suggestion. I'll pull that and get it cleaned up tonight

Regards,
SmL

sml - Looks like your onto something with the corrosion on the battery terminals. It may be a bad ground thats throwing the codes. Clean it up and see what happens.

Your at 48K and Nisssan calles for plugs at 60K. Let me just tell you I tuned up my 99 at 60K just a few weeks ago and the difference in performance was amazing. I think 60K is actually to far to go on a tune up in our cars. If I were you, I'd do a complete tune up. Plugs, Fuel Filter, Air filter, PCV valve, Oil change (if needed) and also the Tranny fluid and coolant change.

My car felt like new again with a smoother pull in the mid RPM range. I was suprised at how much crud was in my fuel filter too. My plugs looked OK for 60K miles. But like I said, the difference in performance was big time! I'm moving my major service interval back to 40K miles. So my next tune up per say will be at 100K.

Keep me posted on your error codes.

Tom,
Again thanks for the insight. Although my motor seems smooth and strong already a tune up certainly couldn't hurt. Not to mention I'm loosing my job today (sucks...lay-off that I saw coming). So having some extra time to dedicate to tuning up this motor won't be a problem.

I purchased the car last August (a $14k Ebay deal if you can believe that) with 38k miles on the clock. Since owning it I replaced the air and oil filters and switched out the oil and thus far it's had "ZERO" issues.

What are your thoughts on using a teflon-oil-additive such as Slick50? I've had good results with it in past cars and motorcycles. This Nissan motor didn't seem to mind the quart of Slick50 that I dumped into it during my last oil change. Are you aware of any reasons why someone should or shouldn't use this type of product in these Nissan Maxima motors?

SmL

About 5-6 years back the FTC charged and banned Slick 50 from making certain claims in it's advertising in America. The FTC found the company's claims of increased performance and reduced wear were unsubstantiated.

Here is a link to the FTC search engine and you can see what they have to say about Slick 50, Prolong, etc.

FTC Search (http://www.ftc.gov/search)

I would stick to a good top quality motor oil, preferably synthetic. Just choose which one. I personally have used Mobil 1 for over 25 years now. Just my two cents.

Pedro

SmL

There are reports that additives which add coatings to the inside of your engine can actually harm it.

For example: The Teflon in Slick 50 will stick to the internals of your engine. But think about that for a second. Coating the walls of your oil channels will make them smaller. It will also cause tollerances to get smaller in certain key areas. That can lead to starvation of oil in extreme cases due to restricted oil passages. Things that can and will get effected are your bearings and top end.

I don't think one quart is going to hurt anything so don't be alarmed. On the other hand, don't use oil additives. Just stick to good old oil. The best oils on the market today are:

Castrol GTX 10W-30 conventional motor oil
Mobil 1 Tri Synthetic Blend
Amsoil Synthetic

These have been proven over and over again to perform the best in protecting your VQ motor. If you log onto Maxima.org, in the 4th gen forums there is a spread sheet you can download into Excel. It contains oil analysis results from Blackstone Labs from various Nissan owners using quite a few different oils. Those 3 oils always produce the best results. I'm using Castrol GTX 10W-30, and actually have been using Castrol motor oil since the day I got my first car back in 1981. The internals of every car I've owned remained very clean. My old Honda Prelude had 170,000 miles on it. The guy I sold it to was amazed how clean the valve trane was when I pulled the valve cover off to adjust the valves for him just before he took ownership. (I loved that car!) And I've never had a vehicle consume any oil between oil changes ever!

Sorry to hear your losing your job. :( When you get a few bucks, change your plugs (use the NGK Platinums only!) your fuel filter and PCV valve. Believe me, you will FEEL the difference in performance!

Best of luck to you!
Tom

P.S. Check engine light still off?

Tom,

Hey thanks for the support. It's about time I stopped working at jobs that I don't like. Now I just gotta find the one I DO like.

Anyway here's the latest on the error codes. Just as you predicted I eventually reveived a 06 code (cylinder misfire detected). This particular one happened to be on cylinder no.6. So I switched coils no.6 and no.2 (both happen to be up front and on opposite ends of the motor. Then I put a few miles on it and guess what...Check Engine Light comes on. However, this time it's an error code for (you guessed it) cylinder no.2. Lookes like I've got a bad coil.

So having never purchased parts for this motor I don't know where I can go to get a good price. Local dealer, import parts shop or other? I don't mind mail/online ordering. Any suggestions?

SmL

I think the dealer might be your only choice here. Try Courtesy Nissan on the web. http://www.courtesy-nissan.com/ Tell them you found them throught Maxima.org and you'll get a small discount. There down in TX but will ship the parts up to you. Call around and shop price, you might save a few bucks!

Glad you've found the problem.

Good luck!
Tom