Startup -- Finally!

[tbrown5079]

Finished the gas line last night. Already had the fluids in so I ran the pump a couple of times to get gas to the fuel rail and flush out the lines. Put Lucas injector lube and cleaner in the tank and hooked up the fuel line to run some cleaner into the injectors. Then I thought what the heck lets see if it starts. Fired right up! Sputtered a couple of times but cleared up and runs smooth. No leaks! Only one problem, no throttle response. Today I checked the butterfly and it works fine by hand and revs the engine. Took all of the plugs off and checked for bent pins or bad connections. No problem. Anybody else ever deal with this? The motor is a 4.8 out of a 2007 Sierra. I got the whole package and Wait For Me Performance did the harness.

[BR3W CITY]

I assume its DBW? Are you getting any codes? You may have a DBW component mismatch, meaning the year/type of TAC/Pedal/TB/ECU aren't compatible. Its best to verify all the components are out of the same truck (or as close as possible) in terms of year range etc.

[TwinsSpeedShop]

yeah, we need a little more info on this one. DBW or cable driven?

[tbrown5079]

Thanks to both of you for getting back to me. It is DBW. I will have to get my ODB11 port hooked up. It seems like a communication problem between the PCM and the throttle body.

[tbrown5079]

OK, got the OBD2 port. Pin 2 for data, pins 4&5 for ground, pin 16 for 12v. Is it 12 volt all the time and do I fuse the data line or power line or both?

[ls1nova71]

Originally Posted by tbrown5079

OK, got the OBD2 port. Pin 2 for data, pins 4&5 for ground, pin 16 for 12v. Is it 12 volt all the time and do I fuse the data line or power line or both?

Yes, it's 12v constant, and it's fused. No fuse on the data line.

[tbrown5079]

Thanks ls1nova71. I''ll do that when I get home from work today. Also, interesting I was going back thru old posts on here last night and found where BR3W CITY told someone that you had to have the TCC hocked up or the engine would only idle. Well when I wired up the check engine light just to see if it would fire the brake switch was hanging there so I took the power wire off there to power the check engine light. That could be my problem. I will change that today.

[ls1nova71]

You should probably have the brake switch hooked up, but it not being there won't keep the throttle from working. I've started engines on the garage floor with only the bare minimum of wires hooked up to make them run and the DBW worked on them. Did you get all the parts off the same truck, or at least the same year? Sounds like an incompatibility problem to me.

[tbrown5079]

Everything is off the same truck. Maybe I am missing a ground wire somewhere.

[ls1nova71]

Originally Posted by tbrown5079

Everything is off the same truck. Maybe I am missing a ground wire somewhere.

Or a power. The TAC ppower is often missed by people.

[tbrown5079]

what is the TAC ppower?

[BR3W CITY]

the second "p" was a misspelling. Its the power for the TAC module that controls DBW pedal input.

[ls1nova71]

Originally Posted by BR3W CITY

the second "p" was a misspelling. Its the power for the TAC module that controls DBW pedal input.

Sssorry, sometimes I stststudder. But yeah, I meant the power for the TAC module.

[tbrown5079]

I thought that was a mispelling but you know what happens when you assume. Wired up the OBD port and the only code that came up was a P 0650 that is a malfunction at the check engine light. Wired that back up, erased the code and rescanned. No faults. It will run smooth at a fast idle until you shut it down. You can rev it up by opening the throttle plate manually. If it was a wiring problem or a bad component would it run that well? I ran it with the MAF onplugged ( My regular mechanic told me that would tell if I had a problem with the redo on the PCM ) and that didn't make any difference. Is it time use a probe wire to check voltages at the TAC and throttle sensor? I saw you can check for grounds that way too.

[BR3W CITY]

IF the components are mismatched, it'll still run just fine at high-idle...the throttle plate defaults to around there, since if it were a mechanical failure they don't want the engine to die (power brakes etc) or run aways (prius)

Have you verified that all the components are from approx the same vehicle, and that the ecm is setup properly for dbw? It would usually throw a code, but that doesn't mean for sure it would. If you made any changes to the pedal assembly (like heating to bend it, or welding) it can damage the internal rheostat/pot

[tbrown5079]

All components are from the same vehicle and no welding around the throttle. I need to call Wait for me Performance and see what I can learn from them, but to be honest I haven't been too pleased when I've called them for help. They gave me the wrong wiring diagram for the vehicle and after struggling with it for hours until we realized what the trouble was they won't send me the right copy. I need to use a probe and see if I have any voltages and ground at the components.