Curly One for you EFI Specialists :)

[HSV 671]

Hi all.
Can anyone help me in diagnosing a possible tps problem on my LS1 clubby. It has been ongoing and I've put up with it for 12 month's +. The issue is that it throws a "Trac Off" light and starts at 2000 rpm then decreases to hold idle @ 1500 rpm. Mech has replaced the iac and still has same problem. He has reset the iac and still same problem. I have replaced the tps which fixed the "TRAC OFF" issue for now but still will high idle but with no Trac problem. Today I have disconnected the tps and all issues are gone ( pcm throws Trac off light cause of no sensor connected, but idle is @ 850-normal with it disconnected). It starts at 1000 rpm and idles back and holds @ 850 rpm and car is fine, still disconnected, however, with it disconnected again, when under hard acceleration it will ping on Ron98 whereas it never before with it connected. So has this new eBay sensor gone bad within 2 month's? Or can it be a wiring issue in the tps loom, or even pcm which could be loosing memory. Mech seems to think there is a bad earth somewhere. Also I have followed the workshop manual in resetting the iac, and to reset the pcm which is to pull the fuse, turn ignition on (but not start.... 3 beeps), turn off, Relpace fuse, start car.......did not do anything to fix issue with sensor connected. T Y for your time.

 

[MRNICK]

Simple question for starters. Does the car have a throttle cable setup on the Throttle Body or is it Fly-By Wire (no cables from the firewall area running into the Throttle Body)?

 

[HSV 671]

Has 1 cable to throttle body butterfly spring.

 

[MRNICK]

Awesome. So the common mistake people make when replacing a TPS is not setting it all together.

The TPS uses a switched signal at both idle and 76% throttle (which the ECU safeguards as 100% throttle). I have seen these cause all sorts of weird issues when they've been replaced without performing the adjustment side of things.

Ill post up the process when I get a few moments as I need to take a look at the factory service manual for the specs of what it should be adjusted to. Hope you have a multimeter!!!

 

[richardpalinkas]

Ls1 tps are non adjustable.

Sent from my SM-N9005 using Tapatalk

 

[Kdouble]

Give this a go mate, https://forums.justcommodores.com.au/threads/vy-how-set-pcm-properly-after-reset.102967

 

[HSV 671]

Thanks Kdouble, MRNICK & richardpalinkas.
We did that as well. Also with scan tool(s). Its good after all that up until I start driving it for a bit.... then goes back to playing up. Its been disconnected for days now. No issues with start up idle or running idle, COLD OR HOT. Does use more fuel I've noticed with less power. But, at least it's not racing atm when clutch goes down, which is annoying. Yes my workshop service manual says tps not adjustable tooz although it does give reference to a 1.25 V, only iac and computer will relearn the pintle steps. I'm thinking its the tps. Looks like I might have to go real deal genuine and fork out $300...... reason I come to that..... computer looks like it holds memory for iac (tps disconnected) but will go bonkers with it reconnected......? I'm Over it!
Thanks for all of your help much appreciated

 

[HSV 671]

60k to 1/4 tank of V POWER. tps not connected. around town. Trip computer says 20.9l/100k

 

[richardpalinkas]

Look for any vac leaks. Idle will rise if there is a vac leak. Or check your coolant temp sensor.

Sent from my SM-N9005 using Tapatalk

 

[HSV 671]

yeah mate, checked all those and they're in specs. no vacc leaks st manifold.