i999Maximagirl

iTrader: (2)

Hmmm...ok I'm at a lose. My max is about to have a heart attach. For about 2 weeks the car hasn't been working correctly. When I press on the accelerator the car at first does not respond. It hesitates and seams to "choke" before it finally moves. I already replaced the fuel filter, the spark plugs, and had the ignition coil replaced in February. What else can possibly be causing this? Any ideas will be greatly appreciated.

Christine

thebigsadler

iTrader: (4)

I had the same problem this summer and took my car to Nissan for the 30K check up.. i just had them flush the oil and put in synthetic and do a throttle body flush.. havent had the problem since.. i know what you are talking about, with the hesitation when you press gas.

NickStam

iTrader: (3)

what is a throttle body flush ? and why would changing oil solve the problem?

Daniel B. Martin

What is the model year of your Maxima?
Which transmission?
What is the odometer reading?
Has all scheduled maintenance been performed?
Has the Check Engine Light ever been on? Is it on now?
Is this symptom more pronounced with a cold engine, warm engine, or both?
Your 4Gen Maxima has six ignition coils. Did you have one replaced, or all six?
Does the engine start readily? Idle smoothly?
The engine "chokes" before moving. Once underway, does the engine have normal power?

i999Maximagirl

iTrader: (2)

-1999 Maxima SE
-Manual
-62k
-All maintenance performed on sched
-Check engine light was one in January thats why i had the ignition coil replaced by Nissan. Went on again last Thursday around 12 noon when I was out during lunch. But then it reset itself on the way home from work and the car ran fine up until Sunday night. Then the problems started all over again.
-Happens with cold and warm engine
-Engine starts and idles with no problems
-Chokes right before moving, as I am under way it will sometimes choke also chokes when I shift gears.

I put fuel injector cleaner in the car during my lunch break lets see if that helps it at all.

Daniel B. Martin

Thank you for the additional detail. It helps.

The fuel injector cleaner may produce a benefit. Let's be optimistic about that... and also patient, because it will be several days before the treated fuel has all run through the injectors.

Your air cleaner filter was supposed to be replaced at 60K. You did not mention that. Was it replaced?

Does your engine have any mods?

Has the car ever been in a crash?

The fact that this problem is observed with cold and warm engine suggests the Oxygen Sensors are not at fault. The Engine Control Module shifts into Closed Loop Mode only when the engine is warm. When the engine is cold it operates in Open Loop Mode, and in this mode the signals from the Oxygen Sensors are ignored.

The fact that the engine idles smoothly suggest the Exhaust Gas Recirculation valve and the Positive Crankcase Ventilation valve are working properly.

You did not answer the question about normal engine power after the "choke" symptom.

Does the coolant temperature gauge show normal operating temperature (about midway between Cold and Hot)?

When the Check Engine Light turned on, the ECM stored one or more Diagnostic Trouble Codes for subsequent retrieval. Those codes are valuable clues. Even though the CEL reset itself, those codes may still be available for readout. You can do this yourself. Please read the Sticky Thread Important: ECU Diagnostic Trouble Codes. The first post in that thread points you to a Web site which gives detailed instructions for doing the readout. Please do the DTC readout and post your findings on this thread.

i999Maximagirl

iTrader: (2)

-For the most part after it chokes it does pick up and works "normally" until I try to push the car again.

-Temp guages register normally.

-Max has never been in an accident thankfully.

Only "engine mod" is a K&N filter, which I also cleaned on Saturday and a UDP. Also have a short shifter but that does not come into play here in any way that I can see. If by some miracle I get out of work early or even on time for that matter I will try to run the codes tonight.

Does any of this make sense, or am I just babbling?

Daniel B. Martin

This all makes sense.

Plain Jane (my '99 GXE 5-speed) has no engine mods. I have scant knowledge of the aftermarket air filters. Some require the owner to wash and re-oil the media from time to time. There is some risk of over-oiling, with the consequence of oil being swept downstream with the filtered air and contaminating the Mass Air Flow Sensor. The MAFS is one of the vital sensors in the Maxima's electronic engine management system. Is your K&N the oil-type?

Let's do three things, in this order...

1) Do the DTC readout and see what gave the ECM "heartburn".

2) Drive the car normally until the treated fuel has been consumed.

3) If the DTC readout does not provide useful information, perform a fuel pressure test.

Daniel B. Martin

A fuel pressure test is a standard diagnostic test. You will find instructions and a diagram or picture in the Chilton repair manual (page 5-3) and the Haynes repair manual (page 4-3,4).

Bleed the fuel rail pressure by pulling the fuel pump fuse (#32, 15 amps) and making several attempts to start the engine (it won't start). Install a T-fitting with a pressure gauge in the flexible rubber fuel line just downstream of the fuel filter. Install the fuel pump fuse. Start the engine. With the engine idling you should see the pressure maintain a stable 34 psi. Temporarily remove the vacuum signal hose from the fuel pressure regulator. The fuel pressure should increase to 43 psi. Reconnect the vacuum signal hose and operate the throttle to vary the engine speed between idle and 3000 rpm. The fuel pressure should vary between 34 and 43 psi.

Readings less than 34 psi could be caused by an obstructed fuel filter, a weak fuel pump, or a bad fuel pressure regulator. Readings greater than 43 psi could be caused by a bad fuel pressure regulator or an obstructed fuel return line.

After turning the engine off the fuel system should hold pressure for many hours. If the residual pressure bleeds off in only one hour that is a sign of a problem... bad fuel pump check valve, injectors with an internal leak, bad fuel pressure regulator, or an external fuel leak.

i999Maximagirl

iTrader: (2)

GULP!!! Yes it is, but I had problems with the car before I cleaned and oiled the air filter. I also put the stock one back on for a while to see if it was the air filter that was causing this headache. Unfortunetly this did not correct it.

Daniel B. Martin

Perhaps the Mass Air Flow Sensor is gooped up with K&N oil. Re-installing the stock filter did nothing to clean the MAFS.

MAFS stands for Mass Air Flow Sensor. The MAFS is located just downstream of the air cleaner. It measures the amount of air drawn into the engine. For more information about the function of the MAFS and a test procedure, please refer to the Chilton repair manual (page 4-16) or the Haynes repair manual (page 6-9). The MAFS is a vital engine control sensor. It is also sensitive, easily damaged, and expensive.

The Maxima factory service manual makes no mention of cleaning the MAFS. The dealer probably won't even consider it; he wants to sell new parts rather than rejuvenate used ones. One "motorhead" magazine described rehabilitating a dirty MAFS by cleaning it with carburetor cleaner. If the DTC implicates the MAFS, you could try this. However, this should be reserved as a last resort measure.

When you step down on the accelerator and feel that "choke" symptom, does the pedal stick momentarily and then suddenly move? Or does it move freely but the engine fails to respond?

i999Maximagirl

iTrader: (2)

Moves freely...

Tai Mai Shu

which Y-pipe would you get? Thanks for the input.

breaux124

iTrader: (1)

You don't know Daniel very well.

Daniel B. Martin

I'm happy with the power made by the stock VQ30DE engine so I don't plan to install any engine mods. I'm also put off engine mods because so many Maxima.Org members post messages on this forum describing problems which arose as a consequence of installing mods. Sometimes it is a bad mod, sometimes it was a botched installation, but either way they would be better off without the mod.

Daniel B. Martin

Having given your symptom report more thought, there is some reason to suspect the TPS.

The Throttle Position Sensor detects the throttle valve position and sends a signal to the Engine Control Module.

The Throttle Position Switch consists of a Wide Open Throttle position switch and a Closed Throttle position switch. The WOT switch sends a signal when the throttle is open at least 1/2 of the WOT position. The CT switch sends a signal when the throttle is fully closed.

The Sensor and Switch are integrated into one unit designated TPS. It is mounted on the rear face of the Throttle Body, in a reasonably accessible location. Procedures for testing, adjusting, and replacing the TPS appear in the Chilton repair manual (page 4-18) and the Haynes repair manual (page 6-8). These procedures require only an ohmmeter and a screwdriver.

Tai Mai Shu

I would of firgured with someone with your know-how would know how to do some mods , plus, if anything goes wrong, im sure someone in this fourms would know what to do. oh well, personal opion. thanks anyway!

i999Maximagirl

iTrader: (2)

OK I ran the ECU codes (thanks to geomax for your help). When I counted the pulses I got 6 and 4. I just entered the numbers into the Decoder and the diagnosis I received was CYLINDER 5 MISFIRE. I changed my spark plugs on Sat so I doubt that is the reason. What else could be causing this, and is this something I can repair on my own with out having to go to Nissan?

Daniel B. Martin

Diagnostic Trouble Code 0604 points to a misfire in cylinder #5. If you know how to read the DTCs, you also know how to reset the Engine Control Module. Please do this reset and then drive normally until the Service Engine Soon light turns on again. Then do another DTC readout and see if the Code is the same. If it is, there is some diagnostic work you can do on your own.

Daniel B. Martin

DTC 0604 points to a misfire on cylinder #5. A variety of problems could spawn this code...
- Improper spark plug
- Insufficient compression
- Incorrect fuel pressure
- Exhaust Gas Recirculation volume control valve
- Open or shorted fuel injector circuit
- Faulty fuel injector
- Air leaks in the intake manifold
- Open or shorted secondary ignition circuit
- Lack of fuel
- Magnetized signal plate (flywheel or A/T drive plate)
- Front oxygen sensors

The rear bank of cylinders is #1, #3, #5. If you care to do some diagnosis before going to the dealer, consider the following steps.

1) Exchange the #1 and #5 ignition coils.
2) Exchange the #3 and #5 spark plugs.
3) Reset the ECM.
4) Drive the car normally and wait for the Service Engine Soon light to go on.
5) Do a DTC readout.

If the misfire DTC points to #1, you probably have a bad coil assembly.
If the DTC points to #3, you probably have a bad spark plug.
If the DTC still points at #5 you have at least narrowed the scope of investigation and should proceed to examine some of the other "check items" on the list above.

chris j vurnis

Maybe its the fuel pump??

Does it happen under wider open throttle or light throttle?