Vz sv6 problems

[Freddy1333]

It runs perfectly when hot. I haven't tried restarting it when hot, just an hour or 3 later. I might do a Kodak on it and see what develops.

 

[Fu Manchu]

Vacuum leak. When heat expansion happens the leak seals up.
I’d be looking at doing a smoke test in the intake system. Anywhere the smoke leaks out is where the vacuum leak is. Laser pointer or torch does the job of helping locate the leak.

 

[Freddy1333]

Haven't got the equipment yet to do a smoke test but here's an update on the issue in which the eng would intermittently cut out a couple of seconds after firing up as normal when warm; a few days ago after it did that, I turned key to off, waited a couple of seconds and tried to re-start but it cranked for about 10 seconds without firing - first time ever. I switched off, waited perhaps 20 sec and it started ok. Thinking that it may be the crank angle sensor on the way out I fitted a new one. Then the next day after it cut out after starting I turned key off, waited a sec or 3 and tried to start but it didn't crank so key off again, pause, retry but no crank again, wait a few more seconds, retry and it started and ran as normal. No codes, runs perfectly otherwise. Today its cut out twice immediately when starting warm. Starts and runs perfectly first thing in the morning.

Somehow I don't think it's a vacuum leak - and its intermittent. As stated earlier, it's a 2005 VZ V6 auto wagon, new fuel pump was fitted a few weeks ago but did 2000km towing since - all ok.

Thoughts & ideas?

 

[krusing]

Get it scanned professionally
You did mention no codes, how was it diagnosed?
Not every DTC activates the MIL,
And some scan tools won’t display some DTC’s,
If it cuts out without any DTC’s logged,
It’s either a power issue,
Or Vac leak,
Fuel blockage,
Fuel filter
Fiel pump connections
Ground connections, especially the ones on the engine,
Starter motor connections,

When did this start happening?
Has any work been done on the motor

Side note: (I recently replaced the start motor on my Adventra, as it had seized, being it was the original one at 265,000 k/s, and found the battery cable was loose,)



?

 

[Freddy1333]

Thanks Kruzing - I'll do some more checking of connections. I did the PCV valve mod before Xmas and fitted a new fuel pump a few weeks ago but the issue started after I'd recently since done 2000km towing a camper trailer. The car runs perfectly otherwise and the fuel filter was replaced about a year ago - say 15,000km. I tried 3 scanners, the cheapest one came up with a code related to the alternator but the Kingchrome and OBD2 Oz scanners my son got for a Colorado both show no codes. The battery's probly 4-5 year old. The alt is charging 13.9v. No work has been done on the car other than above.

Would low voltage immediately after cranking cause it? But the 10 sec cranking a few days ago and no start would indicate to me that the battery is ok. How sensitive is the system to low cranking volts? The eng cranks over real good.

I'll check more thoroughly for vac leaks in the next coupla days.

 

[Freddy1333]

I did some more thorough checking of vac connections today and found this:

One of the 2 PCV lines into the manifold. If replacement has solved the problem I'll take back all the tasty stuff I thought about you blokes who said vacuum leak.

I'll let youz know in a week.

 

[Freddy1333]

Well, that didn't fix it. It cut out immediately after starting on the second start of the day after sitting for an hour.

I checked battery while starting; about 9.2v - switched off and restarted ok showed about 8.8v but it started and kept running.

Checked again 30min later - 10.2 v while cranking. It started then cut out. Second go started and ran ok.

I can understand readings around 9v being a problem but above 10.0v should be good - but it ain't always.

I'll hafta do some more checking.

 

[Fu Manchu]

You need to understand that finding what’s wrong isn’t going to be a single defined answer. There has to be a starting point and methodical elimination of causes by checking and testing.

What if you have gone down rabbit holes, have half the motor apart and someone finds the battery voltage is low or there’s a plug not connected correctly as you re disassembling. That’s the stuff you want to avoid.

You’ve found a vacuum leak.

Check all the plugs. Clean them with CO Contact cleaner. Do the maintenance on the earths. Inspect them. Clean them. It’s all basic stuff that costs almost nothing that doesn’t require someone to be getting paid by the hour to sort.

Without higher end interfaces, finding your problem will be like finding a needle in a haystack.

 

[Fu Manchu]

I’d not be happy with those voltages.

 

[rambunctious]

I’d not be happy with those voltages.

Have to agree with you, these cars seem very susceptible to voltage problems

e.g My VZ Wagon was slow starting (turning over) even though I kept the battery charged up but when it gave ma an O2 sensor code, I cancelled it a couple of times, but when it decided to run rough I decided to do something about it.

First up I changed the batteries in both key remotes, did not seem to help, so finally I changed the starter for a new starter (new high torque) and it's been great ever since.

Also the OP's battery is at 4-5 years old so may be time to renew it.