BobMax

99 Max just hitting 60K miles.

Problem: miss at idle about every 3-5 seconds most of the time (sometimes it's not an issue). Serious miss on acceleration onto the highway. Occassional
CEL/SES light that resets itself fairly fast. Not bad just crusing.

There's been a light miss in the engine for about 5K miles. I figured it was probably a coil, but it was so infrequent I didn't think I'd be able to find it. It's gotten worse as I've crept to 60K. So, I figured it's time to find it.

I replaced the plugs today and tested the coils while I was in there. The coils all
seemed to test OK. I got infinite resistance between terminals 1 & 2. When I flipped the ohmeter polarity, I got about 90-120 ohms resistance between 1 & 2 which went infinite within a couple of seconds. All the coils tested the same. book said that I should get "something other than infinite" when testing the reverse polarity but it did not mention that it would go infinite just after you see the 100ohms - so commnets appreciated on the validity of the coil test results. FWIW, the original plugs all looked like they were firing normally although the 4 & 5 plug (rear bank, passenger side, first two cyls) were a little light/white and looked like they might be running a little hot. No indication of
poor ignition though such as a dirty plug. I have not done any other 60K service yet.

After the plug change the miss was still there. I took it out on the highway and ran it flat out off the ramp. That got me a SES/CEL which hung in there so I
checked it out. I had 3 misfire codes and one knock sensor code. Those could be old - I didn't reset it before the test drive.

I have a feeling that the miss is still a coil running intermittently. Is there a better test for the coils instead of the quick ohm meter test ? I thought of
buying a left and a right and trying replacements one at a time but then it occurred to me that I might have two lefts or two rights bad and I still would not find the problem. I really don't want to buy six coils just to be sure and then find that the problem is still there considering the price of the coils. (yikes!)

Comments, tests, suggestions... should I do the IAC clean just to be sure ? Anything else I should do or check ? Hints on the coils ?

Thanks,
Bob

Kevlo911

iTrader: (36)

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.

jguillory

When you pulled the misfire codes, which cylinders were indicated? The cylinders #'s start at the rear left (if looking at engine from front of car, rear bank of cylinders are #'s 1,3,5 from left to right; 2,4,6 are the front bank from left to right).

Most people check the coils by pulling the CEL codes then swapping the coils to another cylinder, resetting the ECU, and seeing if you get a misfire code on a different cylinder. (rear coils 1,3,5 are interchangeable, same among front - but you can't swap a front coil with a rear coil). For example, if you get a misfire on cyl #1, swap the coil with cyl 3. Reset ECU, see if code reappears for Cylinder 3. If it does, the coil is the problem. Some people say that the resistance tests for coils aren't always reliable.. Good luck.

Maximus101

Here is what the Haynes manuel say's it could be?

1) Fuel filter clogged and/or impurities in the fuel system.
2) low fuel output @ the fuel injectors
3) Faulty or incorrectly gapped spark plugs
4) Incorrect ignition timing
5) Faulty emission system components
6) Low or uneven cylinder compression pressures
7) Weak or faulty ignition system
8) Vacuum leak in fuel system, throttle body, intake manifold, IAC/AAC valve or vacuum hoses...

BobMax

Thanks gents for all the details. I will do some injector checking.

Code questions:
1. Does a misfire always throw a code ? I know for sure that the engine is still missing while running but I definately don't have a CEL yet. Does it take a certain number of misfires to get CEL to register ?

2. WHen the CEL comes on, it usually shuts off within a few miles. Shouldn't it stay on ? Or is this normal with a misfire code ?

I will check the injectors and see how they test too. Sound like that might be my problem.

Thanks.

celica

what type of plugs did u put in? if bosch theres your problem

fisher01

iTrader: (1)

1. No a misfire does not always throw a code.

2. The CEL light will blink a few times while driving, but may not stay on. Even with the light not on, a code has been stored. Pull the codes.

3. With your car being a 99, I'd bet your coils are going. Common problem with the 99. They run about 55-60 each at Courtesy Nissan. I'd suggest if its your coils, go ahead and replace them all. If not , good chance you'll have more misfires for months. IMO, misfires are hard on the engine.

izzydig

When you put it in drive or reverse at idle...does the engine constantly misfire?

I had a misfire for months...at first it was very occasional, then it gradually got worse...to the point it would constantly misfire when in drive or reverse. I tested all coils and injectors and found nothing unusual.

So I put the ebrake on, and put the car in reverse. Got out and started pulling plugs to each cyl...until I found the one that didn't make the engine misfire worse. I pulled the coilpack and extended the spring inside there. No more misfire.

BobMax

Thanks again boys. Now that it hasfinally stopped raining here in the
Northeast (for a few hours, anyway) I can go out there and test. I'll
report back.

BobMax

OK.. I think I nailed it and maybe invented a reverse detection technique.

My misfire was not consistent... about every 5th firing of the bad coil if I had to wager a guess. But, all my coils tested good under the ohm meter primary and secondary tests. I tried the "pull the coil" technique but that was not helpful since the miss was not consistent - removing any coil caused the engine to miss very badly and there was no coil that had no effect on the engine.

Then I got smart. I realized that when I removed a coil and got a constant miss from one cyl that I could still detect the "every 5th cycle" miss. That is, removing a coils gave me *two* misses: a miss every cycle and the miss every 5th cycle. Logic then told me that when I find the coil that only caused *one* miss in the engine, I would find the coil that was the culprit. That is, removing the "every 5th miss" coil would cause the engine to miss consistently (like all the others) but the *additional* miss would be gone.

That worked, I found the suspect coil. I swapped it to another cyl to see if the problem moved with it and it did. I replaced it and the idle is now smooth.

Thanks to all