1994 Nissan Maxima, v6 automatic. It misses until it's warm, then starts running smoothly until you drive it and approaching a stop, it drops the idle down to +/-500 rpm and dies, I start it up and its runs good until you try to accelerate fast and it starts to miss again with a loss of power. I have replaced the timing cam sensor with a new one, checked the TPS, check the MAP, check the cam oiling solenoids, replaced the O2 oxygen sensor and the plugs. As I was replacing the plugs, I noticed that all three of the front ignition coils were cracked. I think that might have something to cause the missing and dead idle. Once it was cold, I removed the coil wire and noticed the same skip on the same cylinder until it warmed up and then it would run OK (smooth). I have also replace the fuel pump with a new one, checked the pressure regulator and its OK. When it has acted up on me before, I pulled over to the side of the road while it was in this mode and manually opened the throttle and it acted like it was starving for fuel. I have a good solid fuel pressure and I closed off the return line to the tank, it made no difference. The three rear cylinders fire perfect. Its the three front that's driving me crazy. Decelerating fast triggers the missing, if I push it to neutral and coast to a stop, most of the time, its OK, but not always. I have checked the PCM several times and it only shows a "knock sensor" code 34. I reset it over and over and still the same results. I'm thinking that since the front coils are cracked that it setting the code 34 since it misfires or pre-ignites. I have also tried to adjust the cam sensor extremely slightly in different direction with no results. Please does anyone have any clue. I am ready to start looking for a wrecked 1994 Maxima and start subbing. My wife is passionate about keeping the car. Thanks
If you have a code 34 you need to address the problem. The knock sensor helps control timing. When the engine detonates the knock sensor detects this and retards the timing. You need to repair this problem before you go on. A sudden drop in ignition timing on deceleration could cause a stalling problem. Resetting the code does not make it go away.
Having three cracked coils can cause a miss. When the engine starts missing do see any arcing around any of the coils? Common sense is if they are cracked you need to replace them. If the miss continues then diagnosis further.
Install a vacuum gauge on a vacuum port that is manifold vacuum (below the throttle plate) and when the engine misses watch the gauge. If the needle starts bouncing with the miss then you are looking at a valve problem, possibly a weak spring, lifter leaking down or maybe a worn camshaft. Look at these parts if the needle bounces when a cylinder starts missing.
Did you ever change the fuel filter? You didn't mention it. As you probably know a clogged fuel filter can cause fuel starvation.
Did you do a compression test? If you did what are the readings for each cylinder?
Did you ever clean the throttle plate and Idle air control motor? When they clog up with carbon it can cause stalling.
Look into these suggestions and get back to me with more detailed information. The information you sent is very good, but with a problem that comes and goes you need to be more detailed with your information. The better information you send the better I can help you. You seem to be doing a good job so far, keep it up.
Thanks, I need all the help I can get at this point. Driving to work today, it was worse, had to pull over finally after it kept continually stalling. I got frustrated and disconnected the vacuum line from the fuel pressure regulator on the fuel rail, why not, stuck on the road every 5 miles and nothing else worked. Amazingly, It started right up, had more power and could drive faster easier. I didn't plug off the vacuum port at the plenum and it continued to run better until I was arriving at my destination and had to slow down to about 20 mph and when I went to turn into the subdivision, it died. I started it again and was driving up a small incline and it started to miss real bad. Got to where I was going and shut it off for couple of hours, got back in started it up drove it 35 miles back home almost and It died as I was turning into the apartment complex. I do have a new fuel filter as you mentioned, I have changed the setting on the cam sensor with no difference. So, the next is the Knock sensor which I'm told is under the Intake plenum. I have worked on mechanics practically all my life, have extensive electronics training and all kinds of testers and gauges. But nothing to obd a Nissan. I guess they made it personal. I did have it scanned by a Nissan Dealer Mechanic and he told me that the Knock sensor was all that was coded. OK, first the knock sensor and then the three coils. Keep up with me guys, Thanks, Stan
Let us know how you make out after the repairs. We can go on from there.
Well, I'm back to square one, Replaced three front coils, runs better, no misses. Replace the Idle control Solenoid although the one I took out worked just as good, no change. Replaced the TPS, Idled better and didn't flutter like the old one but that was after I had also cleaned the throttle body where the butterfly was sticking. Replaced the Knock Sensor and no change. Even rechecked the map again, its as good as knew. Replace the new Fuel filter with another New fuel filter. removed the fuel return regular and it was perfect. I keep saying all this and repeating no change except faster acceleration temporarily starting off, but when it warms up to normal operating temp, it feels like its starving for fuel. Stop, turn it off, start up again and starts off fine up to about 20-35mph and it starts cutting out again. Never misfires or backfires, just starts starving for fuel seems like. That's why I put another fuel pump filter on it. Setting still, I can rev it up to about 4k and then after a few seconds it starts to die down. Let go of the throttle and it idles OK with the new TPS. The new TPS also keeps the deceleration rpm to .9-1K. If I sit long at a stop sign/light, it'll quiver down to 5-600 rpm and die unless I pad the gas pedal momentarily. That makes it worse starting off again though because now its starving for fuel now.
So, what do you think about an in-line fuel pressure tester to see what the pressure is when its starting to act like its going to die. When I put the new fuel pump in the tank, the old one was completely rust (not corroded) up. The new pump came with a new filter. Next option is to run a voltmeter gauge wire to the pump hot wire to see if there is a constant voltage source for the pump. After I put in a new fuel pump fuse relay, I'll stay with the 20amp I believe that's the one currently in it now. The engine doesn't rattle knock chatter or grind, it actually runs pretty good when its running for 149k+++. I know, I still haven't done a compression test on the cylinders yet, but I'm not seeing a reason to do that at this point. But I won't not rule out the possibility. What do you think now. Thanks, Gizmo
Hey, its me again, Gizmo. It does have a new cat/converter on it, noticed that when I put the o2 sensor on it. I also noticed that when I took out the old plugs, they all looked practically new. I still replaced them with NGK Platinum and it did make a significant difference in this engine particular. Also, the car had been setting for a week since I worked on it last. When I replace the in-line fuel filter, there was no pressure or gas in the line when I disconnected it from the fuel rail, I thought there should at least be some gas running out of it, don't you think, even if it has been a week since it was last started. Thanks, Gizmo
Take the fuel pressure test. The fuel pump pressure should be 36 PSI, and then take off the vacuum line to the pressure regulator and the fuel pressure should jump up to 43 PSI.
A volume test should also be done. You need to disconnect the fuel line and put the fuel line in a bottle then jump the fuel pump so it will run. The safest way is to jump the fuel pump at the relay.
With the pump running for about 30 seconds you should get about a liter of fuel in the bottle.
Always work safely. If you can do the volume test with someone else. You don't want to spill fuel and have a fire hazard. Safety is always first.
Check all the fuel lines and make sure there are no kinks or collapsed fuel lines.
Get back to me when you can with your results.
TS ME AGAIN, GIZMO
NOW AT WITS END AGAIN. I INSTALLED A PRESSURE GUAGE INLINE AFTER THE FILTER AND BEFORE THE FUEL RAIL INLET. AT YOU SAID, 35 RUNNING ALL THE TIME, DISCONNECTED THE FUEL REGULATOR VACUUM HOSE, IMMEDIATEDLY JUMPED TO 45, RECONNECTED AND THE STANDARD 35. MONITORING THE GUAGE WHILE IDLEING AND REVING THE THROTTLE, BOUNCE BETWEEN 20-22 AND 35 ACCORDING TO THE THROTTLE POSITION, MAINTAINED 2K RMP AND THE PRESSURE MAINTAINED 30-35. VACUUM TEST ON THE INTAKE PORT WAS A STEAD 15 PERIOD, NO FLUX'S, NO QUIVERINGS, OR UP AND DOWN. WHAT GETS ME IS, NOW ITS COOLER, 50-F, OUTSIDE, IT RUNS FINE UNTIL IT REACHES NORMAL OPERATING TEMPERATURE, JUST BELOW HALF ON THE TEMP GUAGE ( THIS TAKES ABOUT 1-2 MILES CITY STREET DRIVING AND THEN ITS STARTS AGAIN. I CAN SLOWLY ACCELERATE TO NORMAL 45 MPH SPEED LIMIT WITH NO STRAIN ON THE GAS FEED, BUT IF I PUSH HARDER OR TRY TO GO FASTER/QUICKER IT PULLS DOWN AND TRY'S TO BACKFIRE THROUGH THE BREATHER ( HADN'T HEARD IT BEFORE BECAUSE I WASN'T LISTENING CLOSE ENOUGH). LET UP ON THE ACCELERATOR AND IT STOPS SPUTTERING BUT STARTS TO DIE. ON THIS ENGINE, THE OIL FILTER SCREW UP FROM THE BOTTOM. ON OTHER V-6'S IT SCREWS IN FROM THE SIDE AND THERE IS A POS AND REF CRANK SENSOR. SOME PARTS DISTRIBUTORS CALL THE "CAMSHAFT SENSOR" I INSTALLED ON THE REAR OF THE LEFT BANK A "CRANK POSITION SENSOR". IT HAS A COIL PACK FOR EACH PLUG AS I HAVE REPLACED THE FRONT THREE AND WITH SOME IMPROVEMENT IN CRANKING. NOW, I JUST STILL FEEL LIKE SOMETHING IS WRONG WITH THE TIMING NOT ADVANCING OR RETARDING LIKE IT SHOULD. WHAT IF I REPLACED THE PCM INSIDE ON THE CENTER CONSOL, THINK THAT WOULD HELP.
OR NOW WHERE DO WE GO. THERE IS ABSOLUTELY NO WIRES COMING FROM OR AROUND THE DAMPER PULLEY THAT I SEE AND NOTHING RESEMBLING A CRANK SENSOR ANYWHERE UNDER THE ENGINE. PLEASE, LORD, WHAT CAN I DO NOW. THANKS GIZMO
Do you have the single over head cam or the double over head cam engine?
Did you ever check the fuel volume, you know the amount of fuel that is delivered for 30 seconds? You would need to disconnect the ignition system and hot wire the fuel pump to do this. You could just pull the ignition fuse to do this.
Have you ever checked the base idle on the engine? That is the idle speed with out the use of the idle air control motor. I'm sure there is a special service procedure on this. The base idle can be too low and even with the help of the idle air control motor it can still stall.
Have you ever checked the engine timing.
Have you ever checked the charging system; it should be between 14.1 V to 14.7V. I had a vehicle once that I thought was a fuel problem. It would load up with fuel blowing black smoke. After doing all the tests and they all passed, I just happened to notice that the charging was just 13.0 volts. After replacing the voltage regulator and charging was restored to 14.7 V the apparent fuel problem went away.
Won't hurt to check you have done it all so far, why not this.
You are at the time that the system should be checked with a scanner, not for codes but for the information that is given by the PCM. The scanner checks for all of the electrical functions done by the PCM. We need this information while the engine is running and the car is driving. The will show important information that you just can't see with regular meters.