maxz32

I remember some page around that showed how to do the self test to find out what the error code is? And where is there a listing of all the error codes?

Thanks in advance.

Daniel B. Martin

You will find instructions to do a DTC readout and reset
the Check Engine light at:
http://vbxmaxima.8m.com/ecu.html

The DTC "translations" are found at:
http://vbxmaxima.8m.com/ecudecoder.html

maxz32

The errors don't look good:

Knock sensor
and
Cylinder1 missfire.

Great... So now what to do from here? Any suggestions?

Thanks

Daniel B. Martin

Here is some information about the Knock Sensor, taken from the '99 Maxima factory service manual.

1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve
cover of the forward cylinder bank, as viewed from the
front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.

The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.

Daniel B. Martin

You may have a bad spark plug or bad ignition coil in cylinder #1.

Two ideas ... You could use both...

Idea 1) Follow the ignition coil test procedure found in the Haynes repair manual on page 5-8. This requires an ohmmeter.

Idea 2) Exchange the suspect coil in cylinder #1 with the presumed good coil in cylinder #3. Erase all stored Diagnostic Trouble Codes. Drive the car normally, expecting the Malfunction Indicator Lamp to turn on again. When it does, do a DTC readout. If the DTC now points at cylinder #3, the ignition coil or power transistor is bad. If the DTC still points at cylinder #1, suspect a bad spark plug.

Do you by any chance have a Front Strut Tower Brace installed on your Maxima? I recall one case where the FSTB rubbed against the low-voltage ignition coil signal wires and causing a misfire.

maxz32

Nope, no front strut brace yet. Thanks for the tips. Its raining pretty hard right now though so I can't go digging around in the engine bay.

Do you think the car is okay to drive with the Knock sensor and cylinder misfire errors, or should I leave it parked? What kind of damage could happen if driven?

Thanks Daniel.

dch95

I,m not Dan B. Max but I would think it,s OK to drive and shouldn,t do any harm that would hurt your engine. BTW if the tests that Dan gave you show everything is OK perhaps changing your plugs and using injector cleaner may take care of some (or all) of your problems. Hopefully the plug is bad, caused a missfire and then the knock sensor picked this up and then gave the computer these codes. Sometimes mechanical maintenance (as opposed to electrical) solves problems.

Daniel B. Martin

The Diagnostic Trouble Code tells us that cylinder #1 is misfiring or has misfired at some time in the past. It does not tell us if the misfire is solid (all the time) or intermittent. This is an important distinction.

Does your engine idle smoothly? Does the car pull away from a stop sign smoothly and with reasonable power? If so, the misfire is intermittent. If the engine "chugs" as you pull away from a stop sign, the misfire is solid.

If the misfire is intermittent, it is safe to drive the car normally and work on the engine when the weather improves.

If the misfire is solid, minimize driving. Don't drive at all if you have alternate means of transportation. The reason is that the fuel injector is still delivering fuel but the spark plug is not igniting the mixture. Raw fuel is being sent downstream into the Catalytic Converter. This increases the burden on the Cat, causing it to run hot and shortening its life. In the extreme case the Cat can catch fire.

As for the Knock Sensor, you may ignore that problem as long as you fuel with 91 AKI gasoline. I expect that you won't have to replace the KS. When you fix the misfire the KS problem will also be resolved.