7 posts
1994 Nissan Maxima GXE
Murfreesboro Tennessee
7-27-2008
Timing issue or something else...CODE-51
3:28 PM 8/4/2008
94 Maxima GXE with a S.O.H.C. engine with 221,000 miles. This thing started going through fuel injectors like candy. First the ecm showed a code 51 - fuel injector signal circuit fault. Found the # 5 injector was bad so I replaced it. Drove the car for about 2 weeks and the # 1 injector went out-replaced it. Drove the car again for 2 days & the # 6 injector went out so I replaced all of them. After that the car still ran rough as if it were missing or still had a bad injector but did not throw a code for a day or so. Then the # 3 injector went out again !!! I have checked several different things & replaced the TPS, Coolant TEMP. Switch, Ignition Module & Coil. The car has new plugs, wires, cap, rotor, button, & .PCV. The timing belt has not been replaced but I did inspect it about 20,000 miles / 1 year ago & it looked fine. Is it possible this thing jumped time even though it has cog style pulleys on the cam gears ?? I have started searching to see what makes the injectors pulse to dispense fuel but have found nothing. Could it be the timing belt or my ecm is fried sending incorrect voltage/signals to the injectors. There are no codes at this time and car still runs very rough !!!
You may first check to see if there is any corrosion on the wiring for the injectors. That's the only thing I can think of right now that could be causing that many problems with the injectors.
As for valve timing, while the cover is off one way to check the valve timing would be to line up the dimples on the cams with the dimples on the valve covers and the dimple on the main sprocket to the notch on the oil pump housing. If all of them line up then the timing is on.
Next thing you could do is check the ignition timing.
On the way the injectors are fired, the cam angle sensor is actually in the distributor and that is basically what tells the ECU when to fire.
If you need any large items shipped like engines or even front clips, I can help you out. Just go to AssociatedShippers.com and get a quote.
7 posts
1994 Nissan Maxima GXE
Murfreesboro Tennessee
7-27-2008
« Re: Timing issue or something else...CODE-51 (Torque)
10:37 AM 9/1/2008
O.K. guys I am an old school mechanic but this one has got me so I need some help from someone that may be more knowledgable on this car than I am. I removed the timing covers to see if this thing had jumped time. The belt, tensioner, water pump, & cam seals, valves, springs, etc.. all looked perfect. I rotated the engine to TDC on the # 1 cylinder & the dimples on the sprockets aligned perfect with the dimples on the covers. I reassembled everything and then changed the cam position sensor & distributor. Started the engine & set the timing to 15 degrees advance. The car still runs rough. I started pulling the plug wires while the engine was running. When I got to the # 4 & # 6 cylinder & pulled these wires the cars running condition did not change. I left the plug in the head & installed another plug in the # 4 & # 6 wire. Both plugs are firing. All the injectors are new so I placed a screwdriver to each injector & the injectors are pulsing. I have even installed another ECM but this did not help. Before you post please read all the items on the previous post that have been changed & yes the MAF sensor tested good so I do not think that is the culprit.
Just for the heck of it... check the alternator voltage while the car is running, see if its putting out more than its supposed to be.
Were the spark plugs themselves in 4 and 6 ok?
That's definitely a very strange issue... the only other thing I could think of, if those cylinders have both fuel and spark, would be an air issue... blockage, valve(s) not opening, etc... which I would think would be pretty unlikely.
The most reliable way to check injectors is to use a hand-held voltmeter to verify that their coil resistance is within the spec range (close to 11.5 ohms) and you can also connect a Noid lamp to the injector harness connection points in order to determine if they are getting a signal.
Other than that I suppose a couple of them could be clogged, but then again something as mechanical as that would not generate an electrically driven/registered Code 51. The problem has to be electrical; start at the injectors and work back up the harness/connections to the ECM.
1972 Datsun 240Z - non op since 1986 1987 Toyota MR2 - 199K+ and counting 1993 Infiniti J30t - 174K+ and counting 1997 Ford 150 - 87K and counting 2003 Saturn VUE - 112K and counting
