Tachometer help please

[coty]

Hey guys I have swapped a 1jzgte into my 87 mk3. The thing runs and drives awesome until today. For some reason my tachomter shows no rpms when the car is running but as soon as I tap the gas it comes up without any issues. I also noticed that the car doesn't rev past 2000 rpms either. Am I in some kind of weird limp mode or something? This car ran great all the way to redline up till today. I didn't mess with anything that could cause this either.

 

[dslocal]

codes?

 

[coty]

I just tried checking those and I get nothing...... I even backprobed the check engine wire on the computer. Correct if I'm wrong if I connect a test light to that wire on the back of the ecu will it flash the codes? I have everything wired right for the conversion stand point. Also do your guys check engine light blink when you turn your key because mine never lights up at all.

 

[coty]

Ok guys just answered my own question. Ecu grounds out for the test light to flash. I also found out that my check engine light on dash is burn out.... You have to supply 12 volts to the test light and the ground is the check engine light to get it to light. So I get code 13 which is rpm signal. I am going to dig deeper next but if anyone has any ideas please post.

 

[dslocal]

start by checking the plugs and camshaft position sensors, iirc while running they should be producing about 1.5v AC. You might need a graphing meter to see it.

 

[coty]

start by checking the plugs and camshaft position sensors, iirc while running they should be producing about 1.5v AC. You might need a graphing meter to see it.

Ok i'll check that next.

 

[coty]

Update I graphed both camshaft sensors and the crankshaft sensor at the ecu. All the sensor graphed perfect. The crankshaft sensor looked awesome and both the camshaft sensors were above 1.5v ac as stated above. Is my ecu bad? Have any of you guys/gals had a bad ecu in one of these cars?

 

[ihiryu]

yes, i've had a bad ecu on a 2jz. It wouldn't run at all, on the coils only the number 1 cylinder fired, the rest would have power, signal, and ground but wouldn't fire. I put my aem on with a base map, and bam started right up

 

[coty]

Another update. I double checked my cam sensor 1 and its very flaky. I thought it was my oscilliscope but it isn't. The reading for cam sensor one keeps falling off and dying but cam sensor 2 is very solid. Where can I get a cam sensor for my 1jzgte?

 

[coty]

Another update. I double checked my cam sensor 1 and its very flaky. I thought it was my oscilliscope but it isn't. The reading for cam sensor one keeps falling off and dying but cam sensor 2 is very solid. Where can I get a cam sensor for my 1jzgte?

Well I replaced that cam sensor and no luck...... I'm gonna stick a camera in the cam hole and see if that trigger on the cam is ok yet.

 

[coty]

camshaft looks great trigger is intact. Any ideas?

 

[dslocal]

Is the signal still falling off after you replaced the cam sensor?
Bad Ecu's are really common on the 1j's in fact I bought my car not running and the first thing I did was swap out the ecu with a AEM and it fired right up. I wouldn't jump to that yet but it sounds like its a possibility. If you can get your hands on a friends to try that would be good.

Or you could pull yours apart to look for leaking capacitors...
I was thinking about this more and it could also possibly be your igniter. I was thinking this because the tach gets a signal through it don't go buy new ones either unless they test bad too. The last thing you should do is just throw parts at it.