94 pathfinder VG30E knock sensor and FSM EF & EC 137

[khawks]

The FSM states to check knock sensor by checking for continuity between pin e of the harness and ground. page 137 of EF & EC continuity should exist.

Well it does not, pin e is the signal wire, there is no wire at all for the ground side of the sensor in the harness, even though the Hitachi/Asimo or whatever new name is has two pins on the knock sensor. (my old KS was definitely bad/cracked)

Did prior years use a 2 wire harness? Just wondering why the FSM is in error unless I am missing something?

I have read various opinions on whether the ECM adjusts timing based on KS signal/voltage. I would think that is the entire point of having a KS and I know from experience in subaru EJ25s that they run just like my pathy does right now if the KS is bad. First time on a VG30E for me.

 

I am chasing down intermittent stumble and lag like so many have posted before me. Failed emissions high HC and 
CO, all plugs black, and you can see it in the tailpipe and smell it.

The solenoid for my AAC is bad as well, ordered a sentra AACV in the hopes the solenoid might fit.

temp sensor is nominal, temp gauge nominal, MAF clean and nominal, swapped distributors no change.

I have reman injectors from rock auto but am waiting on the sentra AACV part before installing.

If it doesnt fit I plan on plugging up the vacuum lines and manually adjusting idle.

 

Kirk.

 

 

 

 

 

Edited 8 hours ago by khawks
additional info

[Slartibartfast]

The knock sensor in my '93 is wired the same as yours. Two terminals, only one pinned in the plug. The circuit diagram on EF&EC-99 agrees. The sensor must ground to the block. When I checked mine, chasing a knock sensor code, I did the same test on EF&EC-137, and like you I found no continuity. Annoyingly there isn't a spec for the sensor itself, but I noted that my old (bad) sensor read about 2 megohms across the terminals, and the new one read 558k ohms. The '97 manual specs 500-620k ohms, so the replacement was within that spec, for whatever that may be worth. 

 

If the knock sensor hears something that the computer doesn't like, the computer pulls timing (EF&EC-19). If the sensor circuit reads out of range, it'll set a code. EF&EC-23 says that if the code is set, it'll pull timing "according to operating conditions," which it does not elaborate on, so, . Mine seemed to get a little power back after I replaced the sensor, but that's just the butt dyno talking. 

 

I do not see anything in the manual suggesting that a knock condition (or a bad knock sensor) would change the fuel mixture. This means your rich condition is likely unrelated. I would suspect injectors (would be weird for all six to be bad, unless someone's previously swapped them for the cheap crappy ones that a few people on here have had trouble with), oxygen sensor (gets stuck reading "lean"), or coolant temp sensor. A bad temp sensor or corroded connector can tell the computer that the engine is much colder than it is, so it assumes higher air density than exists, and dumps too much fuel. 

 

I had a stumble just off idle and an intermittent failure to idle when warm on mine, which turned out to be the plug for the MAF. The sensor itself was OK, but the pins on the plug side were hogged out. Messing with the plug would clear it up for a while. I finally got sick of it and spliced in a new plug, and it hasn't done it since. I didn't notice any signs of a rich condition, though, and it ran fine so long as I didn't expect it to idle.

 

8 hours ago, khawks said:

I know from experience in subaru EJ25s that they run just like my pathy does right now if the KS is bad.

 

Funny, I recently started my first rodeo with an EJ25. Timing belt/water pump/etc. Those valve covers look like fun.