OK, here is my situation. I have an LS2 out of an 05 GTO swapped into a 1997 240sx I wired it in pretty much myself even though i got the "harness modification" from hinson supercars, wich consists of a few wires being tagged really. I just sent my PCM back out and they said it started up fine in their rx7 w\ls2. they previously removed the VATS and 02 related emmisions stuff to my understanding.

But here is my problem as of now: The engine cranks, fires, (sounds like it revs to idle) then dies instantly. for the brief moment that it runs, it sounds healthy

Fuel pressure rises to 58psi and holds through the process. Pump runs full time with IGN power through regulator.

Grounds: back of LH head, Front RH head, engine to chassis, gnd in the harness near the terminals, and chassis to battery all checked

PCM ground (pin71 if i remember correct) = check

PCM power: IGN power i cant name all the wires rignt now but i checked with hinson and im quite sure i have them all (theres a few in the body harness and a few in the engine harness) Some better info on these might be helpful as well as PCM B+ memory. I have no idea what most of them are for.

Alternator = Plugged in ... the homework ive done ive gathered that the computers are fussy with voltage. my DMM registers a varying 10v -11.5v, but my battery tester claims there is 12.5v tomorrow im going to try with it cabled up to another car just to rule this one out.

also, i have no throttle input... whatsoever I tripple checked the wires and the pins for the pedal and they are correct.. and as far as I know the gto wiring info is wrong from gm.


now that I think everything is on the table here, hopefully someone knows whats going on here

Thanks people

 

Am I alone on this one?

 

Do you have any fault codes?

Can you see the throttle blade move when you depress the throttle pedal?

I know if the throttle pedal and throttle body don't match up with these cars you can have problems. I just got my LS2 swapped RX7 started last weekend, I verified my TB was responding to throttle imputs before starting the engine.

 

Fault codes im not sure of... i dont have a scanner, and my car isn't going anywhere fast just yet

As far as the throttle blade .. it doesnt stay running long enough to see anything, and nothing happens when IGN is on either

 

Sounds like one of your ignition circuits is not getting +12V. It appears that it is getting power while cranking but when you release the key it shuts off.

 

I actually gave that some thought, but quickly ruled it out. I have the Nissan harness control that starting circuit all the way to the signal wire for the starter. Sort of skipped the PCM. Nothing is spliced into 12V start circuit. Unless there is somthing simple that I am missing here.

 

Sorry...I should have specified this. The engine doesn't have to be running. The ignition just has to be in the run position with power going to the ECM. If the throttle blade won't move I'd get a scanner on there and see if any faults are present.

 

Mine is at G force right now as we speak for the exact same fucken issue you described. I have an 06 Tbss motor and m6 out of an 05 Gto in my 01 SS. Did most of the work myself including the cam/knock extensions and it would fire right up but not idle. Tried everything I could think of and no dice. I guess they will figure it out, I'll let you know what they come up with I guess.

 

I didn't see it posted above, so are you running a MAF? Mine did the same thing because I tried deleting it.

 

Don't know about your application in particular, but I'd try rewiring your PCM power directly to the battery for a test, when i had electrical problems I would redo the wiring as a sort of test to narrow the options, maybe there is something wrong in your factory harness that isn't powering the PCM properly during certain circumstances, when I ran my power to my PCM I would get power when the key was on but not during cranking, had to tap into a different circuit to get constant power. Be sure to rig in a fuse in your test wiring though, you don't need a blown computer to add to your problems.
Good luck, keep us posted.

 

Let me know what happens. Maybe we have the same issue.

Yes I am. Its all hooked up and plugged in.


another update too: when i turn the key to IGN , nothing happens but if i proceed to the start position the check engine light comes on... then turns off. but when it turns off i hear a click from the pcm almost like a relay or (hopefully not) a circuit breaker??? I figured this out when i tried to turn it over without pushing the clutch pedal... nissan harness does not allow cranking

but this is interesting, because nothing else should be happening also points towards what cooks said.

 

I think you might be right check out my last post. ... somethings fishy, im gona hunt it down later tonight

 

OK turns out power indeed was supplied to the pcm in the start position. I guess I was high on something when I spliced that in. Once I fixed that problem it started up and idles now.

BUT I still have no throttle input. I had a hell of a time wiring the dbw pedal into the body harness of the pcm, but im just about positive that's done right. as far as the pcm to the throttle blade, I have no info, but it's all factory harness from the pcm out.

 

I would like to point out that I told you first LOL. Check your grounds, and you are not in REP(Reduced engine power) mode are you? You will have no throttle at all if the TAC module, pedal, and PCM don't pass all their preliminary tests. I almost junked my Silverado SS when I had the same problem, turned out to be a bad ground. Do not overlook their importance. Make sure you have body to engine, engine to frame, battery to engine. It can be tough to track these problems down without a scanner.

 

I'm gonna try and see if anyone i know has a scanner. Is there a way to tell if it is in REP mode without one? And as far as grounds go ill take them all off again and clean em up but do you know of any that are kind of hidden, other than the one on the back of the LH head?

 

On my truck it flashes across the drivers' information center on the dash. I don't know about any other hidden grounds other than there may be one on the transmission bellhousing as well.

 

No information center in my nissan cluster lol.. But as of now I think I'm stuck until I come across a scanner. I'll let you guys know if I get anywhere.

 

OK, it turns out that the pigtail I had bought from eficonnections was wired basicly upside-down. They had the same wire colors so I went with it. Lesson learned. So I rewired it according to a diagram from alldata and throttle we have. I made a little diagram to help anyone else in my situation attached. Thanks for the help guys hopefully the car will be moving once my driveshaft shows up.