# Please help a newbie out. :)



## lmills (Jun 14, 2008)

Hey guys, 

Been having some problems with a truck I recently purchased. After doing a search on the forum for the problem I have, it pointed to the MAF sensor. Well, I tried pulling the sensor today and cleaned it with no luck. Afterward, I did some more searching and figured out how to read the codes. 

Upon checking the codes I pulled up a 

13
23
24



The truck will only rev to 3K rpms and acts like it is hitting a rev limiter. I want to go ahead and replace the MAF sensor since the symptoms are pointing in that direction, but at $250 I would prefer to know for sure that it is the problem. 

Thanks in advance for any help


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## zanegrey (Dec 5, 2005)

you must not have read all the way thru it..read it all again..

so forget the 23 and 24 for the moment and replace the coolant sensor.

and restart engine check for performance and reread the codes.

leave the maf alone..

report back when finished..

end line..


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## Nissanpickup (Nov 16, 2005)

13 Engine Coolant Temperature Sensor.
23 Idle Switch.
24 Throttle Valve Switch.


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## 88pathoffroad (Jun 6, 2004)

Yeah, sometimes the CTS will trigger several codes due to it running wrong because the temp switch is faulty. I'd try that first.


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## lmills (Jun 14, 2008)

zanegrey said:


> you must not have read all the way thru it..read it all again..
> 
> so forget the 23 and 24 for the moment and replace the coolant sensor.
> 
> ...


Well, the problem I am having is that the instructions state that I should be able to turn the key to the on position then switch the ECU switch to the diagnostics position, wait till the LED's blink 3 times, then turn the switch off and that will put it into the 3rd mode which is self diagnosis. The problem is, as soon as I switch the diagnostics switch to the on position, the LED's start blinking the codes immediately. 

The other thin is I have consulted the manual and also read the instructions on the board here for reading codes and it says I should have a ECU with a dial for the diagnostics switch, but I do not. I have just a normal on/off switch. I am not sure if that was something they did earlier on or not.


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## zanegrey (Dec 5, 2005)

if you got those first codes then you did it right..

replace the sensor aand read the codes


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## lmills (Jun 14, 2008)

OK, will do.


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## jkretzer (Mar 1, 2008)

hurry up and get that jewel on the road!


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## 88pathoffroad (Jun 6, 2004)

Sorry...when I wrote that I should have modified it a little...



> How to pull ECU error codes for 87-95 Pathfinders and hardbody pickups:
> 
> The ECU is under your passenger's side seat. You can gain access to it by simply sliding the seat all the way forward and removing the plastic cover from the ECU. You can also remove the seat if you want, it makes access a little easier.
> 
> *The VG30i ECU's have a tiny toggle switch on the side of the ECU with a small snap-in switch cover that must be utilized to select the diagnostic mode of the ECU. The 4-cylinder ECU and the VG30E ECU has a slotted switch that turns 1/4 or 1/2 turn clockwise and counterclockwise to do the same task.*


I should have stated: some early 4-cyl HB ECU's have the switch as well. In any case it will have one or the other. I've added the info to the thread now.


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## lmills (Jun 14, 2008)

OK, I tried replacing the coolant sensor. It got rid of the 13 code. Now I still have the codes 23, 24 and a code 43 has popped up. The 43 was there once before, but seemed to be intermittent. Now, it is totally back. LOL


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## zanegrey (Dec 5, 2005)

does the problem remain??

take a look at the tps .
is it loose? check it's connection and clean the connection .
the reread the codes..

do not worry yet about the 23 and 24..


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## Nissanpickup (Nov 16, 2005)

code 43 is the tps (throttle position sensor) it is located on the throttle body on the opposite side of the butterfly valve i believe


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## OchnofConcrete (Jan 7, 2008)

might need another throttle body. sensors can be replaced but.. yeah.. anyone got that?

you said you cleaned the MAF... how? you clean the TPS?


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## lmills (Jun 14, 2008)

zanegrey said:


> does the problem remain??
> 
> take a look at the tps .
> is it loose? check it's connection and clean the connection .
> ...


yeh, the problem is still there. It appears to go into limp mode or something and will not rev over about 2700 RPM and the exhaust smells very rich. 

as for the MAF sensor, I cleaned it with a cotton swab and alcohol like I read here in the forums


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## zanegrey (Dec 5, 2005)

b4 you do n e thing else check the secondary coil for cracks and spark...

if the coil is good then concentrate on the tps..


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## 88pathoffroad (Jun 6, 2004)

The ECU will prevent the engine from revving higher than 2750 RPM's if either the MAF or the TPS is not functioning properly.

Have you reset the ECU by disconnecting the battery and then rechecked the codes?


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## lmills (Jun 14, 2008)

I had it disconnected when I installed the battery, but have not disconnected it since replacing the water temp sensor.


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## OchnofConcrete (Jan 7, 2008)

88pathoffroad said:


> The ECU will prevent the engine from revving higher than 2750 RPM's if either the MAF or the TPS is not functioning properly.
> 
> Have you reset the ECU by disconnecting the battery and then rechecked the codes?


your car's in Safe Mode...
your Nissan has a Safe Mode just like any computer.

it needs to be reset, with like Rogo said.. a funtioning TPS or MAF.... or CPS.

sure there's some other sensors that can cause a car to do this too. but basically since there's no tuning in the part of the engine via the *detached or broken* sensor.. the computer does not allow you to go above 2700rpms mainly so you don't destroy the engine.

i get that right? ecu just needs to be reset after you replace the part... right?


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## lmills (Jun 14, 2008)

OK, I have tried disconnecting the battery. I left it like that for 2-3 days. Upon reconnecting it, I fired the truck up and It ran OK for a couple minutes then went back to the rough idle and not revving over 2700 RPM. Checked codes again and pulled the 43 code, TPS and the 23 and 24 code. The Engine Coolant Temp sensor code is gone for now.


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## zanegrey (Dec 5, 2005)

concentrate on the tps..fix it then re read codes..

what do you


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## lmills (Jun 14, 2008)

OK, I will look in that direction. What do you mean in the last sentence?


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## zanegrey (Dec 5, 2005)

i do not know what that is ??


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## OchnofConcrete (Jan 7, 2008)

OchnofConcrete said:


> your car's in Safe Mode...
> your Nissan has a Safe Mode just like any computer.
> 
> it needs to be reset, with like Rogo said.. a funtioning TPS or MAF.... or CPS.


if you just reset the computer with a still bad sensor, then the computer will automatically go back to the Safe Mode. and not allow you to over-rev a disabled engine.

fix the sensor (and adjacent components) and you'll be fine.


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## lmills (Jun 14, 2008)

OK, just for an update....I replaced the TPS with a new unit. The 43 code for the TPS is now gone and the truck does not go into limp mode any more. Now I still have the 23 and 24 codes. 

The truck still burns very rich at idle and the idle is slightly rough. I have checked for vacuum leaks and also measured vacuum at idle. Vacuum was right around 15 at idle, but very shaky. Also, I did verify that both coils are firing and appear to be very strong.

Last but not least, does anyone have a schematic for the vacuum lines? I am not 100% sure all of them are on correct. 

TIA

Lloyd


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## zanegrey (Dec 5, 2005)

read the codes one more time ..
but right after you read the codes hit the gas pedal once and the re read the codes

record what you get .

then put you foot on the clutch and move the shifter thru 1 and second and the reread the codes again ..

record what you get..

i think that will get rid of at least one of those codes..

find the vacumn line that goes to the fuel pressure regualtor and verify that it gets it vacumn source straight from the manifold..

it is also time to verfy your timing..


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## lmills (Jun 14, 2008)

OK, Thanks Zanegrey! I will give that a try. I plan to work on it some tomorrow and checking the timing was one of the things on the list along with checking the brakes to see what is seized up and not working. LOL. Now that I almost have it roadworthy enough to take it for a test drive, I would like to be able to stop it


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## OchnofConcrete (Jan 7, 2008)

lol, i've done that before..

spent a good week straight puttin a car together and didn't bother to check the brake before i ran it.. 

was a helluva ride. 

had to pull a 90* stop! lol.


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