My tach started intermittenly freezing then would suddenly start working again. Now it just slowly climbs until it pegs. The longer I drive the higher it gets. It takes about 20 minutes to peg. I also now have a CEL. Any ideas?

Thanks,

John

 

pull your codes. my guess is the CKPS (REF)

 

I just looked through my FSM and the CKPS (POS) is the one that monitors engine speed. (REF) monitors engine top dead center.

REF is code 0407
POS is code 0802

 

Thanks, I'll give that a try.

john

 

lmao. pull the codes and change the tach. Mine went haywire and then died. It was the tach itself. Dont go messing with other sensors that dont usually go bad unless you know for sure they are the source of the problem. See if you can get your hands on a used tach or partial cluster and plug it in.

 

I think there is some wisdom here. The car runs fine and nothing else seems to be happening. The tach issue was off an on for awhile..now it is just the same scenario. I will deal with the CEL first, but it may very well be unrelated. The tach went weeks before the CEL came on.

Thanks,
john

 

yes check your codes first. no sense pulling your instrument cluster apart without knowing if your sensors are working. ckps failure is not uncommon, but it usually does come with other symptoms, which you don't have.

 

I checked the codes and got nothing. I checked all the fluid levels etc, and found nothing wrong. However, on the ride home the exhaust didn't sound right. When I checked it, the right side flex coupling on the Y-pipe had lost the rear retainer coupling and is leaking significantly.

Let's recap:
Tach does not work
CEL is ON
Code reader says no errors
flex coupler blown.

Does this make any sense or are these unrelated problems?

Thanks for any help,

John

 

screw the reader. check the codes yourself using the screw method.

fix the flex section by either patching the flex or replacing the whole Y pipe. (you will end up in a whole world of trouble if you let the leak continue)

If you CEL turns out to be an O2 code, the whole in your flex is most likely the cause so wait until repairing the flex before you change the O2.

I still think the tach is unrelated.

 

no code? I've never seen a CEL w/ no code. given your exhaust issue I'm inclined to go with mizzax on this one -- rear O2 readings are off. but it's probably not faulty, just wacky readings that don't jibe w/ the front ones. ECU knows something isn't right. should be a code though....

 

I don't get it either, but your explanation is the same conclusion I came to. I will patch the flex coupling in the meantime.

I just remembered that I got a CEL a few weeks ago but it reset / cleared itself in a couple of days. Maybe that is when the leak started.

John

 

alright guys, first off jjamz, im having the same problem as you. i dont know if you can relate but it started on a 50 degree day in nov. and my rpms went hay-wire and they used to every now and then work and then they would die again. my car there is nothing wrong with the engine itself and there is no exhaust leak for me so its not your exhaust. i am throwing a knock sensor code but i think yours is an o2 code if im correct ive now buddied up with you on this thread because im clueless as well i personally think its the rpm sensor itself but then again i could be wrong. if you guys could just get me up to speed on a few vocabulary words wtf is a CEL, FSM, CKPS, POS, and REF

thanks alot guys- Eric

 

I started a glossary and it got merged into the FAQ. Starts at post 7

http://forums.maxima.org/showthread.php?threadid=72447

 

Also you may want to make your sig smaller before the mods get on your ***...

John, I would either try and get the codes with teh screw method or bring it to Autozone and have them read the codes for free. There must be a code to trip the CEL light.

 

I posted earlier about possible Crank Position Sensor codes...but I want to reiterate that I too have tach problems....and while it is a major annoyance, I find no need to replace it. I have the same symptoms. Tach bounces around all over the place/ doesnt work at all/"pegs" itself...and about 2% of the time it works correctly. I've tried soldering everything on the tach circuit board, etc. Nothing works. I'd say to find out what you CEL code is using the screw method and to say screw it to the tach.

 

supposibly my crank position sensor was messed up too because i did codes at checker and it came up, but then it went away about 2 weeks later when i did another check. i dont think the cps would make our tachs not work do you?

 

Well, one of the sensors...whether it be the cam position sensor, or either of the two crank position sensors is used by the ECU to generate a signal to the tach unit. I think the signal wire is yellow with a green stripe, or vise versa. 0 to 5 volts. Also, maybe one of your sensors is just dirty or covered with steel filings? The sensors use a coil which is magnetic to generate a signal, and sometimes the tip of them becomes covered in dirt and magnetic particles. Try taking them out and cleaning them.

 

where are they located on the engine? and what exactly am i looking for other than a yellow with green striped wire?

 

the yellow and green wire is the signal wire going to the back of the instrument cluster. I used a multimeter to monitor the voltage coming from it when I played with the throttle. This told me that I was getting the right signals from the ECU, and I concluded that the tach unit itself was bad.

In your case, if your sensor is bad: one crank sensor runs off of the crankshaft pulley side. It's down underneath and kind of a bear to get to. The other crank position sensor runs off of the flywheel teeth, and can be reached from the front of the engine bay. It's way down by the oil pan, and can be removed with a 10mm socket. There's only one screw down there to the left hand side IIRC. The cam sensor is on the left hand side of the engine when you are facing the engine bay. It's up top sticking into the side of the engine about where one of the cam pulleys would be.

Go here and download the FSM:
http://phatg20.net/modules.php?name=...ownload&cid=73

More details are in the folder labeled: ECM, pages 9 and 10

 

umm.since when did the flywheel move over to the front of the engine where the oil pan is? the crankshaft position sensor by the oilpan gets it signal from the pulley, not the flywheel.

 

the sensor is located just above the oil pan on the bellhousing. I didn't say it was on the oil pan, but it's pretty close.

 

Ok guys, I was away on business for a few days so I got out of the loop. Yesterday I cut off the rusted retainer ring on the Y-pipe flex piece and put two hose clamps on it. That sealed it pretty good. Within 30 minutes of driving, the CEL went out. With that out of the way, I am back to tackle the tach issue. Nothing has changed here, it slowly climbs up and eventually pegs. Sometimes it bounces around. The car runs fine, has good performance and good gas mileage. My gut instinct is that the tach works and is just getting a bad signal. How do I isolate and check the signal?

Thanks,
John