Happy New Year y'all...

Well, I am into my 14th month or so with my project car and getting oh so close to getting it completed! The build has gone rather smoothly since I haven't been in any rush to hit a specific completion date -- I just want to get it RIGHT and not cut any corners along the way. (Link to build thread below).

My problem is explained in this note below to my stand-alone harness builder & PCM tuner. Haven't gotten a response as of yet, but he could be on vacation or something... Email to excellent wiring guy:

I have actually heard my 2005 GTO LS2 engine start up in my Miata this past week. Thanks to you - this was possible. I've attached a link to my latest page on my build thread to sort of show where and how I mounted everything. And yes, my PCM and fuse box will have a carpeted, steel sheet ( thicker than sheet metal) cover to keep shoes and feet out - but still have plenty of air circulation by keeping it open on top and RH side.

Okay, I'm a little stumped. The engine fired up on first twist of the key on 12/30. Didn't idle very well though. I quickly learned that the pedal is not working. With the key in the ON position, it does not move the throttle body blade at all. The engine will only idle rough and then it can often just choke off. The throttle body is closed at all times.

I do know that with air intake system off and watching the throttle body when you turn the key to ON, the large blade jumps from 90% closed to about 100% closed. The TB has not been ported or taken apart by me. It looks stock and doesn't appear to be in a bind.

The codes it left me that first night were P0122, P0123, P0223, P1516, P2102, and P2127.

It may also be worth mentioning that this system uses a Hitachi blade-type MAF. (It uses a short jumper/ conversion harness [purchased originally from ZIP's Corvettes] since I am using a Z06 Corvette plastic, cold-air intake & filter assembly).

With the MAF unplugged, it still idles very, very rough.

Has my 2005 GTO pedal gone bad? I found a How-To article on this pedal for opening it up and bending the "fingers" about 1/16" up for better contact. Apparently, I've learned that the 2005 GTO pedal was not a great production item!!

What would you do next if you were me?

http://www.v8miata.net/build-threads...na-794/page15/






Thanks for your help or suggestions.
Patrick

 

Have you checked your fuel pressure at the rails? You said that the throttle blade does move on initial key on and after that it's unresponsive? Did you check for voltages while cranking or running?

 

I have a 2005 GTO LS2 as well. My first start was also super rough. When I would hit the pedal it would barely recognize it. In my case, it was a bad ground somewhere in the dash harness (I am using the stock GTO dash harness to run everything in the car). When I went over all the wiring, I tightened everything up and that's literally all it took. Next start was perfect.

You might also try taking the battery cable off for 30 seconds and then putting it back on. Sometimes that will sort out such things.

 

Thanks guys - Fuel, she has plenty of. New 300 liter/hr in-tank pump seems to be doing great. And yes, the throttle blade quickly moves in about 1/2 a second from mostly closed to 99.9% closed . But the blade doesn't move via pedal.

Super Dave, Always enjoy reading your comments. And from what I have been reading and searching this week, it looks like a lot of folks have had LS2 DBW start-up issues...

My wiring vendor did email me back this evening. He asked that I give him a call tomorrow. Glad to! He may have some insight on this issue.

Will update this as I head down the path to a smooth running, open-header LS2!

 

I would clean the connection terminals at the pedal, jumper harness to pedal (if used) and at the throttle body. As well as check the pins at the ecm to make sure they are properly seated/locked into place and haven't been pushed back. Next I would get a long section of wire and go from the ECM to the Pedal and TB connectors verifying continuity.

What year is the ecm calibration and color of the TB blade? Could be a mismatch with those as well.

I had some issues with my 07 E67 start up with an LS2 throttle body and had some connector contact issues and needed to swap 2 wires at the TB connector to get it to work right.

 

this and , try starting it disconnecting the pedal and reconnecting while running , see if pedal works , if not try disconnecting and reconnecting the throttle body while running

 

Yeah, i agree with the last post give it a try?

 

At this point in time, we are confirming the wiring at the connector for the throttle. There's a possibility that a few of the wires may be "flipped" or reversed from what is required. I hope that will be the answer as depinning the plug should be somewhat easy to do.

Keep you posted. Maybe she'll fire up before I leave town later in the week.

 

Well, might as well share my frustrations... I'm out of town 5 days a week and get the weekends to squeeze in some LS2 swap funtime here and there.

Did confirm that the wiring is correct on the pedal! I was looking at someone's nicely drawn diagram from the wrong perspective!! All is good there.
Since I suspected the GTO pedal was bad, my friend had a new one dropped off for the car. We plugged it in, twisted the key ON, throttle body blade "zero's out" like it should, but the TB won't listen to the NEW exact-replacement pedal.

Now need to figure out if the PCM maybe doesn't send enough voltage to the stepper motor or if the TB itself is bad..?

REALLY need to have an experienced GM LS engine guy diagnose this thing with the GM scanner tool - but the car isn't drivable. Bums me out

 

Drive by cable mod & re-flash PCM...problem solved.

 

^ This

 

Wanted to wrap up this LS2 throttle concern that I've been experiencing the past month or so... It has been solved. Took it to Carolina Auto Masters for Jeff and his team to tackle with their GM Tech2 tool and their excellent trouble-shooting analysis. Within just a few hours, my LS2 was running smooth, LOUD, and responding to a donor LS2 GTO DBW pedal. I had 2 issues: 1 was a loose pin connection at the PCM coming from one of the reference voltage wires at the pedal. The other was a bad pedal. The intermittent loose pin connection made diagnosing the pedal properly a little tough until that was resolved.

More of the story here:
http://www.v8miata.net/build-threads...na-794/page18/

The guys jumped right in! Excellent GM High Tech engine team at C.A.M. in Durham, NC!