Idles Rough

You need to decide whether it is due to something not working right in the engine which should cause decreased performance or if it's due to a bad mount for the engine or trans.

If you think it's an injector issue, the engine would run REALLY rough if one of them was not working. Best way to test for a failed injector is to track it down to the cylinder by pulling off the ignition wires until you hit one that causes no change. If one of the injectors was bad the car would run very bad. You should try to pull the code to see what set off the check engine light, (free at autozone).

"Roger" wrote in news:VrWrc.24936$zw.11885@attbi_s01:

Thanks for the reply. I hadn't thought of a bad engine mount. We don't have Autozones here, but I will definitely track down the check engine code.

Thanks again, Bruce

There are several good injector cleaners... many people (myself included) have had very good results using Techron. It also works well with combustion chamber and valve deposits, and is recommended by BMW.

While it's most effectively used periodically to remove light deposits and varnish build-up, before it becomes a problem, you could try this: add two bottles to a full tank and burn off that tank, then run one bottle in the next tank. I had good luck doing this on my Rodeo when I had rough idle and weak low end at about 80K miles, and I've read where several others have too. Even if it doesn't solve the problem, it does no harm and is not very expensive before going on to other, more expensive remedies.

There are some shops that use special equipment to run cleaning solvents through the fuel rail and injectors while still on the car. That can be effective, but serious contamination means you'll need a true injector cleaning. This means removing the ejectors from the engine and cleaning them in fairly strong solvent, using pressure and ultrasonic baths, then checking the spray pattern and flow. I'd try to get a shop to do this before I'd consider the expense of replacement.

These aren't just snake-oil... they really are effective within each remedy's abilities. But if the problem is mechanical or electrical then any kind of cleaning will do nothing.

BuddyWh

Hi,

I really appreciate your thorough response about fuel injectors. I'm from the (really) old school of carburetors, and am not familiar with fuel injectors. I did some reading on them yesterday, though, so I'm learning more, a little at a time. I should educate myself on them, as all my cars now have fuel injectors.

I took the car out this morning, and except for the rough idle, it ran just fine. Sometimes the idle stays above 1000 rpm, and sometimes it drops to about 750 rpm. If the idle stays above 1000 rpm it's fine, but when it drops below that, it's rough, hot or cold. I'm going to look at the specs. and see what idle should be. Perhaps it's supposed to be 1000 rpm, and is dropping for some reason. The problem is that I never drive the car, so I don't know what's 'normal'. My daughter drives it primarily on very short trips to school and it never warms up. I tend to feel and hear developing problems before anyone else, but with the girls in my family, I'm usually informed about a problem after it's been around for a while. Not complaining, just stating the dynamics at my house.

Thanks to Roger's advice, I did locate an Autozone in my area, where they USED to test diagnostic trouble codes for free. Now, the state of California, and only the state of California, forbids them to do this for free. So, they don't even do it for a charge, but they will loan you the equipment for a deposit of $180 (it's $90 to buy it outright). I borrowed it, and asked for some advice on it's use, but they said they weren't even allowed to give advice. However, the fellow was nice enough to break that law for me.

Hope the California legislature doesn't find out that I got some free advice. Sorry, but I feel a rant coming on about our lawmakers.

I'm going to check the diagnostics codes and go from there.

Thanks again, Bruce

BuddyWh wrote in news: snipped-for-privacy@4ax.com:

Bruce wrote in news:Xns94F1BA27EC3D1parcxmannetscapenet@63.240.76.16:

OK, I borrowed an Actron ODB II Auto Scanner, model CP9135, to see what made the check engine light come on. I get code P0304, with the description Cylinder 4 Misfire Detected. All other systems, fuel, O2, etc, tested fine.

Hoping that this would be a simple ignition wire problem, I bench tested the number 4 wire, and it is fine. I tested all other wires to be sure my testing method was ok, and they also tested fine.

I put the wires back on, and then pulled number 4 from the plug head, and held it close to the valve cover. A very consistent and steady spark jumped to the valve cover, and there was no noticeable difference as to engine idle. In other words, the car did not idle any rougher with the number 4 disconnected.

I am now stumped. With a number 4 cylinder misfire detected, I expected the plug wire to be bad, yet a steady spark jumped from the wire's end to the ground (valve cover). I can't swap wires between plugs to test, because the numbe 4 wire is the shortest wire, and won't reach any other plug.

Also, why is it that with a steady spark observed, there's no difference whether the plug wire is or is not connected to the plug? If I'm getting a steady spark, what else could be causing a misfire? Not timing, since the other 3 plugs are firing fine. Not a fuel problem, because the scanner detected none, and the plug would fire anyway, fuel problem or not.

I'm really at a loss at this point, and I hate to turn the thing over to a shop at this time. I'll have to think about this some more, and hope that someone may have an idea.

Sincerely, Bruce

Bruce wrote in news:Xns94F2A0D57A51Cparcxmannetscapenet@204.127.204.17:

I did some googling. See this:

If there's no difference with the plug connected or not, and there is spark, then the only other two choices are no fuel or no air for combustion. It sounds like a stuck injector on that cylinder (no fuel getting in).

Yes, it sure does sound like either no air or fuel, since there is spark. What's got me is there is a check on the scanner for fuel system, and it checks out ok.

I'm now checking this:

Thanks for the reply, Bruce

"E. Meyer" wrote in news:BCD6A7BD.7ADB3% snipped-for-privacy@ieee.org:

Awww C'mon guy's .

Y'all are better that this.

This is guy has provided everything you need to diagnose his problem.

Stay tuned kiddies.

Will the mighty Bruce get the assistance he needs........ maybe ?

Will BuddyWh be able to figure it out, so far he is as cold as ice with his dirty injector theory....maybe not

Tune in next time...

Same Bat time... Same Bat channel

A scanner can't tell if there is a mechanical problem with an injector. I've seen many cars that run like crap but the computer says everything is OK. Have you pulled the plugs yet? Does it have NGK plugs or something else?

What?

There can't be anything wrong with the car, the computer/scan tool says it's all OK! :-)

Steve T wrote in news: snipped-for-privacy@uni-berlin.de:

Hi, Steve...I like your sense of humor.

Yes, I have pulled the plugs and they were worn normally. The gaps were huge since the electrodes were worn. I did replace them, with the proper NGKs and gapped per the owner's manual.

I did check all spark plug holes for water, and there is none. I could also see all the piston heads, and they all looked the same. I also pulled all plugs, one at a time, and turned the engine over and then smelled for gas to see if there was any difference in smell. I was smelling to see if gas was getting to number 4, but not being burned. All smelled the same. I'm not sure what this told me, though. I exptected to smell gas in number 4.

Here's something I did try:

Remember that number 4 is misfiring. The scanner indicates this (yeah, I know the scanner can't diagnose a mechanical problem like a sticky injector, as you say) and when I pull the number 4 ignition wire off while the car is idling, there's no difference in idle. Also let it be known that since the number 4 wire is the shortest of the bunch, I can't just swap it with another, so I pulled number 3 off and put it on the number 4. Yes, I did connect the wires correctly, observing firing order. I started the car. Now I've got no number 3, so it's idling rough, but I've got a wire going to number 4. This may be the hint...when I pulled off the good number 3 wire that was connected to the number 4 plug, the idle got worse. This indicates, at least to me, that the number 4 wire is bad, even though it tests good for continuity and resistance.

The next step is to install a new set of ingition wires. They're $50 at Autozone. This seems like the next cheapest step in the elimination process. I'll do this tomorrow, unless someone has another idea.

By the way, I kind of like that scanner. I looked at some other, more expensive ones. Neat little toy. While I still have it, I may check my other cars, all of which are running fine. But, it may be like going in for a check up when you feel good...the doctor finds some little thing and wants you back for more tests. Hmmm...maybe I won't test the other cars.

I'll keep you posted.

Sincerely, Bruce

You probably missed where it's burned through the side..

It may not be your biggest problem, but if you haven't replaced the PCV valve, do so. It can result in a bad idle.

JM

Ok Gang.

Here is your hint , It is 3 words long .

Lean Cylinder Missfire.

Hmmmm, Now you have to ask yourself .... Self, What causes a lean cylinder missfire?

Homework Assignment, due May 25 . 7p.m EST

What can cause a lean cylinder missfire ?

Steve T , sorry dude you are exempt from this test but feel free to answer it anyway.

Will all the brainiacks on alt.autos.maxima be able to figure out this runability condition?

Will Commissioner Gordon be able to find the Bat signal in time.

Tune in tomorrow..... Same Bat Time...... Same Bat Channel

Steve T wrote in news: snipped-for-privacy@uni-berlin.de:

Crap. I replaced the ignition wires and problem persists. Hmmm...

Time for the Techron? I bought two bottles and I'm ready to pour it in. Yes? No?

Bruce

"NissTech" wrote in news:Swusc.16380$ snipped-for-privacy@twister.tampabay.rr.com:

BIFF! BAM! SPLAT! ZOWIE!

Now you're just guessing, just like I am but you're looking at the car! Have you checked for vaccum leaks? I doubt pour in the tank FI cleaner will fix it if it is an injector. Is that injector even clicking etc etc.