If any of the coil packs are bad, can they cause the engine to misfire ? My car when its warm outside, after being driven for a while starts to shake and blow off smoke. I had the car diagonised before and they found one of the ignition coils to be bad (before i had a multiple cylinder misfire code). The problem improved a great deal until recently when the weather got warm out. I am going to take the car to the dealer again (like the 3rd time) to see if they can see what the root of the problem is. What I think is happening is that one of more of the cylinders are not getting a proper spark which causes the fuel in that cylinder to flood and somehow that unburn fuel comes out of the exhaust.

Many of you know that I have posted in the past about this problem but still havent been able to solve it. Ill describe it again.

Symptoms: Car vibrates like crazy,a lot of thick smoke comes out of the exhaust when it does this, almost shuts off, REALLY REALLY ANNOYING AND EMBARRASSING !

What have been replaced so far: Spark plugs, fuel filter, one of the ignition coils.

Problem: Usually after driving for a while, if you shut the car off for about 10 mins or so and restart it then the car starts acting up like described above. After 2 mins of driving, the car returns back to normal. But, since the weather has gotten warm out, after getting off of the highways, the car starts acting up regardless of restarting it and does NOT improve at all (no matter how fast or how long you drive). I usually let it sit for hours when it gets cool out and then the car drives like nothing is wrong.

And no its not a blown head gasket as the coolant doesnt leak at all and the car does not overheat at all.

Anyone with a bad fuel injector experience any of this?

Thanks again for listening.

 

What kind of spark plugs did you use? What code is the ECU throwing?

 

It's probably another coil pack. Bad injectors are not near as common as bad coil packs are.

You can either pull all the coil packs and check their resistance with an ohm reader, or when the car starts acting up again try disconnecting each coil pack one at a time. If you disconnect a coil pack and the car runs the same then that is the bad one. If you disconnect a coil pack and the car runs worse then it's not the bad one.

Getting the "multiple cylinder" misfire is very frustrating, hopefully your ECU will throw a specific cylinder misfire code. It will make it easier to find the problem.

 

Spark plugs are NGK's and the ECU is not throwing any codes. I waited 15 mins to see if it would throw one while it was acting crazy but it didnt.

 

I have had misfire problems in the past. My car had a bad misfire for a week before it finally threw a code, and other times it never would. My problem some how went away, but I expect to have to pay for new coil packs in the future.

 

Since the car sometimes doesnt act crazy, I am going to by an ohm reader and test the coil packs that way. How much would an ohm reader run?

 

or swap them wiht a friends for a few minutes to see if it correct anything

 

I saw a digital multimeter with OHM reading at autozone for like $15.

Andrew

 

0603 0604 0605 0606 0607 0608
If one cylinder is misfiring the problem is spark or fuel. A misfire due to a spark problem usually results in a Service Engine Soon light and one of these Diagnostic Trouble Codes:
0608 - Cylinder 1 misfire
0607 - Cylinder 2 misfire
0606 - Cylinder 3 misfire
0605 - Cylinder 4 misfire
0604 - Cylinder 5 misfire
0603 - Cylinder 6 misfire

There are two tests the home mechanic can make, the sound test and the resistance test.

Sound test...
This test is performed with the engine idling. Use a mechanic's
stethoscope or a length of rubber vacuum hose, and listen to each injector.
All injectors should sound alike. If you find one which makes a different
sound (or no sound at all) you have found a problem.

Resistance test...
This test is performed with the engine off. Use an ohmmeter to measure the
resistance of each injector. This does not require removing the injectors.
I don't know the correct resistance value for the injectors on your model,
but they are typically a low number such as 16 ohms. The important thing
is they should all be equal. If you find one injector with substantially
higher resistance than the others, it is bad. If you find one with zero
ohms (short circuit) that is truly unfortunate, because the injector is bad
and it may also have damaged the Engine Control Module (the computer)
because of excessive current drain.

Measuring the resistance of the front bank of cylinders is easy because the
injectors are in plain view. Disconnect the injector electrical connector
for cylinder #2, measure the resistance, reconnect the connector. Repeat
for the cylinders #4 and #6.

Measuring the resistance of the rear bank of cylinders is almost as easy,
but it is difficult to reach the injectors. The resistance may be measured
at a conveniently located electrical connector. Notice the largest,
thickest electrical harness at the top of the engine. This is the Engine
Control Harness and it is shaped like a U, with the open top of the U at the
driver's side of the car. The U has two corners. Look at the corner
nearest the passenger seat. Just inside that corner you will find an 8-pin
electrical connector. This is connector F131. Disconnect this
connector. Now look at the male part, the connector half with the pins
exposed. They are arranged in two rows of four pins.
The pins are numbered 1 - 4 (top row) and 5 - 8 (bottom row).
Measure the resistance of:
- injector #1 between pins 1 and 2.
- injector #3 between pins 1 and 6.
- injector #5 between pins 1 and 5.
Be sure to measure the PINS, not the female receptacles.

The dealer's shop is equipped with high-tech diagnostic instruments. These are wonderful devices but they are expensive and the dealer has to recover his cost by charging you for diagnostic time. Sometimes the home mechanic can do legitimate diagnostic work with nothing more than a ohmmeter and a rubber tube.

To Test Ignition Coils:
With the ignition off, disconnect the electrical connector from the ignition coil. Connect the positive (+) probe of an ohmmeter to terminal no. 1 and the negative (-) probe to terminal no. 2 of the coil connector - the meter should indicate infinite resistance. Reverse the meter leads ( negative probe to terminal no. 1 and positive probe to terminal no.2) - the continuity should be indicated, but not zero ohms. If the results are not as specified, replace the coil.
Connect an ohmmeter between the secondary terminal ( the one that the spark plug connects to) and terminal no. 1 - the meter should indicate infinite resistance. If not, replace the coil.
Note - Ohm meter to test coils is not the most reliable way. Some peoples’ coils tested perfectly, but they still misfired.

 

My max has 146k milesw on it with the original coil packs.

I have had the same problem you describe and it was a BAD injector.
I got white smoke on one bad injector that stuck open. When another one was on its way out the engine would shake like crazy then run ok after I let it sit for a while. I think what was happening is the injector would get to a certain temp and the resistance would go way out of spec and cause it to shut down or misfire.

I've replaced all 6 injectors in the past 42k miles and haven't had anything but smooth sailing since!

I would hazard a guess that many people replace their coil packs on this assumption that these are at fault when they are actually having flaky injector problems. But that's just a guess.

 

Today I went to autozone and bought that multimeter along with some tools. I checked all 6 of the coils and they showed a reading of 4 ohms to 2 ohms consistently. None of them showed 0 (three pins, so mixing and matching the pins is how I achieved the readings). They all showed the same behavior so I am ruling the coil packs out unless of cource the multimeter test either failed or I did something wrong. So I am going to test the fuel injectors tomorrow, I saw the front three which seem each to check but the other three look like a PIA (couldnt even find them).

Hey maximomo, you may be right but I hope I dont have to replace all 6 fuel injectors. Did you buy them used or new and how much did they run you?

Can I buy fuel injector cleaners and keep flushing the fuel system or that wont work?

Thanks guys.

 

The back 3 are under the intake plenum. If you have a manual you can find the pinout on that gray connector near cyl 1 and check the rear 3 that way.
You can also pull the plugs and check them to see if there is any sign of irregular firing or soot. Next time you get the cloud of smoke pull the plugs and see which one is dirtiest.

Oh, You won't have to replace all 6 injectors. I had one go out in the rear so I replaced all 3. Didn't want to have to do that job again.
Then I used the two "spares" from the rear set as replacements for the front. But none of them lasted all that long. They all started failing within about 15k miles.
I bought them new. There are several sites online where you can get them for pretty cheap. I've used speedycarparts.com and drivewire.com.
I wouldn't buy used injectors.

 

Quotes from those sites are 91 shipped for a new fuel injector. Anybody have any other sites which beats that?

The car must have bad fuel injectors because before I bought the car, it was sitting garaged for 5 to 6 months. Will check them today.

 

Another update:

I dont know if I tested the fuel injectors correctly but with an multimeter all of the injectors showed continuity and all of them showed almost the same ohm reading (for some reason the multimeter always shows 0 for all of the readings, I tested a coin and it even showed 0) Important thing is that they all showed the same readings.

If this is the case then what else can cause my problem?

On a side note, my idiot mechanic disconnected one of the O2 sensors thinking that it might solve my problem which it obviously did NOT. So I have to get that O2 sensor reconnected and figure out where the root of the problem really is.

Any one have any input?

 

First, make sure you have the ohm meter set on the lowest setting of X1 ohms.
You should get a reading around 10ohms on each injector.
Funny thing, I just had an injector die on mine. It would miss out when I started the car for the first few minutes and then run fine. I tested it and sure enough 12ohms. I replaced it and NO MORE misfires.

In fact, all of my injectors failed in a similar way. They start out misfiring once in a while then get worse to the point they don't fire at all. That was the only way I could figure out which on was bad. It doesn't take long once they start going.

One question I have is did you get any error codes from your ECU? I would expect with an O2 sensor unhooked you would. Did you get any other codes?
Even a code showing a bad coil might point you to the cylinder that has the funky injector. When my #4 injector was going I got erroneous #4 coil misfires.
After moving the coils around and still getting the error I replaced the injector and no more problem.

 

I got a Check Engine Light on once, 0701 which indicated a multiple cylinder misfire. After that I got a full tuneup and my mechanic replaced one of the coil packs. The problem never went away except that the car drove a lot better.

I never got any more codes, if I did it would have probably solved my problems. Sometimes I let it sit huffing and puffing for 15 mins and it still doesnt show any codes. Even with the oxygen sensor disconnected it hasnt triggered a CEL.

Today it drove fine except when I restarted it, it did its usual thing for a min or two until I drove away from a parking spot. But thats nothing out of the ordinary, it always did that.

I am going to retest the injectors, maybe the ohmeter I have is screwed up or something. I did have it on the x1 ohm setting. I dont wanna take it to the dealer right now incase they find that disconnected o2 sensor and tell me that, that was the problem and its all fixed now. Would be a waste of 100 bucks. Jeez.

 

Mine was doing the same thing! I'd restart it and it would run funky until I drove away.
Next time it does that pop the hood and start unhooking the injectors one at a time. Well, at least the front 3. If the engine changes, like shakes more, after you diconnect one then that means it's working. If you disconnect one and the engine doesn't seem to notice.... that's the bad one.
Hopefully it is one of the front 3.... though the rear 3 seem to go out first.

Did you ever clean the grounds on the intake manifold?
That probably isn't it.... but it doesn't hurt to do everything you can that's free!

 

Ill try that the next time it does it but the ones in back could be the ones which are out. The gas goes like nothin cuz of the excess fuel being let out through the exhaust. I got 177 miles on 14 gallon because the car was at its worst this week. If I cant figure it out then I think I will tell the nissan dealer to check my fuel injectors and such.

 

At the price of gas it would be cheaper in the long run to replace the rear bank!
If you are comfortable with removing the intake plenum the injector part is easy. It'll cost you $300 in injectors. Then you KNOW the rear set is good.
And the 3 you pull out can be swapped in and out of the front.

Taking the plenum off isn't hard except the stupid bracket between the firewall and the manifold and the EGR port. They are both held on by 12mm bolts.
I did mine and cleaned up the Throttle body, EGR stuff, and IACV all at the same time. It's a Saturday job if you do it.

I have no idea what the dealer would charge to replace the rear bank. Probably $700 +!

I'll bet you can find some willing maxima.org enthusiast in your local area to help if you need it. Some of these guys really know their stuff!