VZ V8 Safety Mode Issues

[VZ5.7]

My 2005 VZ SS manual has a problem where the dash alarm sounds then "Reduced Power" "Safety Mode" is displayed and the engine drops back to near-idle. As my car is a manual this leaves me with not even enough power to keep the car moving or move off from stationery (perhaps an auto trans would slip enough to allow the car to creep along?) I've had this car for about six months now since trading my 2004 VZ SS manual ute for it in Melbourne (a car which ran perfectly every day of the over six years I had her). The first time the "Safety Mode" activated was on the drive back to Adelaide at about 20km from home. I had initially blamed water getting in somewhere it shouldn't have as it was in torrential rain. The second time was about three months later while towing on a fine day when it happened twice, and recently the problem is happening more and more frequently to the point where it has failed at least every second drive (over 10km) for about the past week, three times now at traffic lights where I sat there waiting to be able to restart without fault while cars behind got rather pissed-off, and today three times in the one trip of about 25km. The problem is totally random, sometimes in cold weather sometimes hot and any temp in between, there is no warning as everything operates fine right up to the point the alarm sounds and power is lost simultaneously.
The owners handbook says this mode is due to a fault with the throttle actuator system. I've connected my dads Tech-2 scan tool but the model he has only shows active faults, not those stored in the ECUs memory, and of course the system was not in "Safety Mode" at the time.
I'm a motorcycle mechanic myself so am familiar with similar "fly-by-wire" throttle systems on bikes, however we do not use the Tech-2 code readers as the Japanese manufacturers all have their own diagnostic systems. Money is tight so having a workshop look at it and possible not find the issue, or taking a gamble and replacing parts hoping they've assumed right is out of the question at present. This seems to be a somewhat common issue on these models so I'd love to hear other owners experiences, especially what the cause and fix is for such issues.
Any help would be great, Thanks.

 

[Reaper]

Plug in a full feature scan tool which should point you in the right direction. TPS on the TB is a reasonably common fault (had it on my E3 Senator) which will throw it into limp home mode every time. The sensor on the pedal could also do the same but you need to find the code before chucking parts in a hope of fixing the problem which as you know can get very expensive.

 

[VZ5.7]

Thanks Reaper
I've spoken to a customer of mine who works for a local Ultratune who says he has seen the TB TPS issue a few times but mainly on the V6 (unfortunately a complete assembly as they dont sell the TPS as a spare part...) He said he can connect their scan tool and check the stored codes, and hopefully point me to the actual component at fault. I was worried that the code may just indicate a system or circuit malfunction and not point to an individual component, so I am hoping it is a specific code. I don't mind spending the money where it's needed but throwing expensive parts at it which may not be the culprit just because of poor diagnosing really frustrates me. I'll keep you posted on my progress.

 

[VZ5.7]

Thanks Reaper
I've spoken to a customer of mine who works for a local Ultratune who says he has seen the TB TPS issue a few times but mainly on the V6 (unfortunately a complete assembly as they dont sell the TPS as a spare part...) He said he can connect their scan tool and check the stored codes, and hopefully point me to the actual component at fault. I was worried that the code may just indicate a system or circuit malfunction and not point to an individual component, so I am hoping it is a specific code. I don't mind spending the money where it's needed but throwing expensive parts at it which may not be the culprit just because of poor diagnosing really frustrates me. I'll keep you posted on my progress.

Ok had the car checked by Ultratune with their Diagnostic equipment last Sat, only fault in history was a low battery voltage (probably while the car sat idle in the car yard before I bought her) so without any fault codes relating to the "Safety Mode" issue I am having I am none the wiser... They cleared that code and I left, and it wasn't until tonight five days later that the problem re-occured, four times in about 20km!! I had stupidly thought it may have rectified itself somehow after being hooked up to their equipment... Since Sat I had been carrying my dads basic scan tool so that I could connect it while the Safety Mode was active and try to read any codes as the fault was active, however even while the engine was running in the "Reduced Power Safety Mode" there were no codes at all??? Really don't know what to do next??? I can't trust my car and don't know anyone who might be able to sus such a problem with no apparent clues???

 

[Benboy]

Ok had the car checked by Ultratune with their Diagnostic equipment last Sat, only fault in history was a low battery voltage (probably while the car sat idle in the car yard before I bought her)
so without any fault codes relating to the "Safety Mode" issue I am having I am none the wiser... They cleared that code and I left, and it wasn't until tonight five days later that the problem re-occured, four times in about 20km!! I had stupidly thought it may have rectified itself somehow after being hooked up to their equipment... Since Sat I had been carrying my dads basic scan tool so that I could connect it while the Safety Mode was active and try to read any codes as the fault was active, however even while the engine was running in the "Reduced Power Safety Mode" there were no codes at all??? Really don't know what to do next??? I can't trust my car and don't know anyone who might be able to sus such a problem with no apparent clues???

If purchased from a car yard (Dealer) then surely you will have a Warranty to cover any breakdowns etc. get in touch with them.

 

[VZ5.7]

I contacted them numerous times with details of this and many other smaller problems but even after threatening consumer affairs, Fair Trade Vic. and the Motor Trade Association they still washed their hands of me. I guess they knew that driving the car back to Melbourne from Adelaide probably wasn't going to happen, and I'm sure they would have already sold my VZ SS ute on so getting her back wouldn't happen... If there had been any VY-VZ SS manuals for sale here in Adelaide for reasonable prices I wouldn't have had to travel interstate in the first place, unfortunately manual SS sedans are $4k to $6K more here in SA (where they were all built) than on the East Coast. Sad that trading my perfect ute for a sedan was forced upon me post divorce as I have two children and needed the extra seats...
I'd love to Name and Shame the Dealer, and tell everyone ALL the things that they did wrong by misrepresenting this car and in the handling of the deal!!! but need to be sure they wouldn't have grounds for a defamation case against me as I don't have the funds to fight them in court.

 

[VZ5.7]

Update on the actual "Safety Mode" problem with my car;
Had a weekend away last week, a four hour round trip, the car activated Safety Mode 9 times on the run there requiring me to pull over, turn the key off, wait 30 seconds or so then re-start and carry on until it next happened, which was about every 4km for one stretch of the journey...
On the return run it only happened once... go figure (same rout same temp, same load, same fuel...
During this week two days have been trouble free and two have been full of break downs. Anyway finally spat the dummy before burning the car and have bought a New Genuine Holden Throttle body and Gasket from ebay $380 all up when my Holden Dealer wanted $550 for the TB and a further $55 for the oring. The seller I bought the o-ring from specialises in LS1 parts and confirmed that the sealed TBS was a common issue on the VZs.
I figured paying a dealer or workshop a few hours labor to perhaps find nothing as there were no codes, and the problem is so random and can sometimes hide for days is the same cost as just buying the new parts and fitting them myself. Even if a mechanic found the part at fault I'd still have to buy the new bit and pay them for their time.
I'll fit my new parts and let forum followers know the outcome.

 

[XUV]

wasn't just dirty and in need of a clean

 

[VZ5.7]

Ok, so I fitted the new throttle body a couple of weeks ago and the problem hasn't reoccurred since. The car also runs smoother at low rpm light throttle when before it would have an intermittent momentary hesitation. I haven't yet cut open the old throttle body to see if I can see anything wrong with the motor / gears / tps, but there was a clunking sound from inside when rocked from side to side which the new unit didn't do...

 

[PaRaDoX]

Ok, so I fitted the new throttle body a couple of weeks ago and the problem hasn't reoccurred since. The car also runs smoother at low rpm light throttle when before it would have an intermittent momentary hesitation. I haven't yet cut open the old throttle body to see if I can see anything wrong with the motor / gears / tps, but there was a clunking sound from inside when rocked from side to side which the new unit didn't do...

As its drive by wire, the TPS is built in. I can explain why this causes such a huge issue.

The TPS is used to calculate engine load and thus ignition timing, without a correct reading the engine can detonate so as a safety feature it restricts all timing advance