smason

It was not logging. Engine builder says it melted a piston and the motor had signs of major detonation. Apparently both the shop that sold me the motor, and the tuning shop are both sketchy people.

Well its been a sad week. After getting my car tuned (1JZGTE), some of my first high gear high boost pulls blew the motor. I was wondering if there was any way to see the data of the final moments of my beloved JZ. Whether oil pressure tanked or it over boosted etc...

Yeah mine is upwards of 4.034 or something on a Nissan S13

Well I have an update! I've been working almost non stop so I've been very busy. But this will be the finale - I think. I have just been driving with the tachometer which is less twitchy, and no speedometer. Well as legend has it, last night I was driving to work, and the speedometer came to life! I changed nothing. I did nothing. The RC circuit works and it is kind of accurate. The multiplier works but the speedo is just 'out' at higher speeds. No fault of the G4. This is a classic representation of a USDM 240sx and it's troubles.

The VSS did not fix the speedometer. I built that RC circuit fine. Trying to find a friend with an oscilloscope.

I have a new tach, and it sort of works. Is accurate with a .93ish multiplier, but it randomly pegs. Looks like it's just an issue with the cluster. Now to find a good tachometer. Note for future USDM 240SX S13 cars. : YOU MUST USE A DOHC TACH. Speedometer is the same between the two. Waiting on the vss, should be here today. Then we'll see if that's working or not. Common issue with s13 clusters.

I took the tacho right out of the cluster, gave it +12v , GND, and Aux 1 as tach/ pwm. No luck on either. Trying to find a 3rd gauge cluster.

I've shut them all off, noticed 4-6 had some sort of limitation. I've pulled the tacho right out to eliminate harness issues. Fed direct power and Aux 1 set to tacho. Still not working. I'm going to try and borrow an additional tach from a friend but who knows.

So after lots of research, I hardwired the output of the ECU directly to the tach. It still doesn't work. I am seeing a DC voltage (6v) on this wire. Does that make sense?

Im just compiling all the info i can find online here. Sorry for the spam. The DOHC tach gets a 0-5V signal from the ECU and the SOHC tach gets a 0-12V signal off the coil.

Found this: "The dohc tach and sohc tach work completely different. The sohc works on a pulse single just like an autometer tach. the dohc tach works on a voltage scale."

I was checking run time values and i see this. Does this have something to do with it?

Spoke too soon. Something is still wrong. Speedo does not work and tach is stuck at 7k. Im using aux 5 and 6. Is there any issues with that?

So after lots of research, it appears that there is a difference internally from the SOHC to DOHC versions of the car, mine is an 89 with single slammer, I swapped the dash over to a DOHC, and it seems to be functional. Whether that was my specific unit or a actual incompatibility I am not sure. Now to tune the multiplier. And the tach jumps around alot. Not very smooth. Any advice?

Hm. Ill test that shortly. Neither speedo or tacho are working. I think my VSS might be bad, is there a way to simulate an output to check my speedometer? The cap/resistor circuit makes a sin wave across 0v, so if i send a DC voltage it should work, no? Found this: He was trying to get his cruise working.