Hello All,

Hoping that someone out there can help with my latest fix. My 1990 Maxima (6cyl. - auto trans, factory loaded model) has suddenly become inoperable. My wife was driving the car in normal conditions, prepares to stop at a red light and all of a sudden she notices that the tone of the car's idle has dropped very low and labored. Accelerating has become sluggish and sounds as if the car is choking itself and wants die.
After hearing the car for myself, I would compare it to a car running on less than all cylinders or blockage some where in the exhaust system. Since the car was due for a tuneup anyway, I started with the usual - new plugs and plug wire set, new air filter, replaced cracked or damaged hoses, new fuel filter, and examined distributor cap and router which appear not to have alot of wear.

In a attempt to see if the car would react to a change in router position, I was surprised to find that the engine does not react to any movement of the distributor cap. This is a first for me as all previous timing issues I have dealt with, the engine has always reacted to the slightest cap movement but now doesn't.

Also noticeable is the change in the sound of the exhaust system as mentioned previously. Where the sound exiting the exhaust system usually sounded very midrange when the car was running good, now sounds a octave or 3 lower, taking on a dark, lower sound. So after a moderate inspection of the exhaust system undercarriage, I was unable to locate any cracks, holes or damage throughout the exhaust system. When the car is idling, the change of sound from midrange to the lower sounding tone seems to becoming from the catalytic converter. But before I go out and make a pricey parts change which may or may not fix the problem, I thought I'd ask and see if anyone has any suggestions that would put me on the right track.

This car is our family's daily driver and we are going on day 4 of the car not being in service, so any help would be much appreciated in helping me get the car back on the road.

Thank You in advance....

 

It would help us all a lot if you were able to post a vid. So far you mentioned everything except the injectors, which is typical to going out on these cars with mileage as high as we have.

 

Try a compression test. Then try a Lead-down test.

Also, there might be a dangerous short in the Fuel Pump Sender Unit, that you might want to check out. My 3rd gen had this problem, that took me a 1yr to figure out, and it would feel like it was going to die at stop lights and stuff. Blown fuses for the fuel pump pointed me in this direction.

Additionally, a dying fuel pump gave me similar symptoms to what you had. I replaced the fuel pump with a brand new one, and the symptoms went away, then that short in the sender unit was discovered, which was essentially corrosion ate away at the wire.

 

After reading your post in more detail. Here are additional test you should try first.

1. Test the impedance of the fuel injectors (FSM instructions) to determine if any injectors are blown. However, being that you said it is inoperable, it is not likely to be an injector, unless a bunch have blown all at the same time.

2. Timing Belt. When was it last changed. If you've gone over, its possible you've jumped a tooth on the timing belt. If you jumped a cog, you would possibly get away with 1 jumped for some time. You'll immediately notice poor performance. If 1 cog got stripped off (because of belt wear), 2 or 3 may have stripped off surrounding it, and you'll have bigger problems.

Other tests could be:
-Knock Sensor
-Items affecting Timing, other sensors

As a test you can spray a bit of fuel down the intake, and see if the engine picks up. If it doesn't, your into ignition and timing belt issues. If it does pickup your likely fuel related. Fuel related, check at the Fuel Pressure Regulator if the fuel pump is good. Also check the MAF.