I recently completed a VQ swap in my 240sx and I'm here because it seems like this is the best place on the net in regards to VQ swap talk in general...

Anyways, the other day I tried to hook up my tachometer by splicing into the negative side of a coil. Not only did my tach show nothing, but that particular coil completely shorted out and now I have discovered that others have shorted as well. The ECM throws a P0300, or misfiring code. After removing the splice and replacing all of the fried coils, the engine continues to blow coils. I thought I might of fried the ECM, but I sent that out and it is fine...

I'm kind of lost on what to do next? Replacing coils is expensive and I'm not quite sure what could be the problem?

 

Who did you send the ecu out to? They probably just opened it up & looked for anything obvious, which when I've fried an injector driver it was obvious, but doesn't mean you don't have a problem.

VQ swap- 3.0, 3.5? What year/model is the harness & ecu from? You'll want to hook your tach up to the rpm signal from the ecu, and measure the pinouts per the fsm, and make sure you have no harness shorts- once you do all that you can fix the problem or condemn the ecu.

 

VQ 3.5 with 350z harness and ECM... Zfever out of tampa that does the Osiris flash to remove NATS is who I sent it to, they said they actually hooked it up to a 350z and had no problems. And ya, no 'RPM signal' from this ecu, the tach signal is through CAN lines, so it's a digital signal. I've done some harness/multimeter tinkering but I'm not too experienced in electrical diagnosis, just basic automotive electrical, ie fuses, relays, wiring diagrams, etc. There is continuity between all of the grounds on the coils and common. The positive side of the coils shows some resistance with ground, but not a dead short, so I think this is the source of my problem... I just don't know where to go from here... I disconnected all of the sensors and that resistance is still there. However, when I disconnect the ECU that continuity disappears, which gave me the impression of an ECU problem. However, I have since bought another ECU and it acts the same way. I haven't run this ECU just plugged it in... So this resistance only exists when the comp is plugged in...

 

not much help on the coil problem,


but you can swap the gauge cluster and this will make the tach work. I was using a 2005 spec v cluster. Im actually going to sell all of my ecu swap stuff soon.


You should look into swaping the 05 spec v cluster, the things youd need to see about would be fuel lvl, and speedometer , and the warning lights etc etc




Your cruise control on the swap dont work does it?

Do you have a manual cooling fan? (not electric) lol

Working AC?


sorry for all the questions

 

Don't mind the questions... as long as someone can give me some answers

No AC, Cruise, and I have an electric fan... it's a street/track car, no doesn't have anything but the necessary...

It's done here, just have the intake/maf off...

 

oh ok thanks for the info!!!

check out my ecu swap

http://forums.maxima.org/all-motor/6...-ecu-swap.html

 

did you mess with the wiring harness at all?

 

Did you read my post dude, lol? Ya, you must be a gator... lol just messing, I'm a student at FSU right now

But ya, I did all of the wiring myself to make the engine run by modifying the stock harness. Ran fine until I tried to hook up the tach. I think next I'm going to replace all 6 of the coils and go from there... I haven't been able to find any shorts on the harness...

 

i meant the ignition part of the harness. there is an "ignition conditioner" in there and i wanted to make sure you didnt remove it/break it

 

Ignition... Condenser... you mean? Ya, checked it... and based on the value in the fsm, it's fine.