LS1 Every cylinder is misfiring WK Stato V8

[SLIfox]

Hey everyone,

WK Stato LS1 "Ghost" severe cold start misfires (NO CODES)

we replaced spark plugs and leads and noted all old spark plugs had a yellowish ash on them indicating EVERY cylinder was misfiring.

The plug and lead change was in response to a huge cold start misfire that causes the car to not want to idle and popping out the exhaust ( car is undrivable for 1-2 minutes) and we have to put "start ya bastard" down the intake to stop the misfire.

When car is warm it does shake a little but can be driven and is not noticeably down on power.

cleaned IAC and throttle plate no change.

car didnt do this 2 months ago when we bought it and has only reared its head the last few weeks.

any ideas on what to check would be great thank you. or how to check pump etc.

under the impression it's fuel filter or fuel pump due to all cylinders misfiring or a vacuum leak to the fuel pressure regulator. I'm not versed on LS's so not sure what else would be responsible for such a severe and widespread misfire problem that start ya bastard would be temporarily fixing.

 

[Phoenix21]

i'd be checking fuel pressure could be a pump on the way out or a blockage,
ive had a similar issue with my 5ltr

 

[BlackVXGTS]

If you are having the problem on all cylinders, the common part (on the electrical side) is the PIM (Powertrain Interface Module), so you could try replacing it and see if it fixes your problem.

 

[SLIfox]

It's starting to look pretty bad,

changed MAF to SS Inductions one, (original maf was going out)

verified IAC was functioning to some degree

changed engine coolant temp sensor as my partner broke it

replaced fuel pump

STILL DOING IT (BlackVXGTS I still have your info up my sleeve)

start ya bastard still makes the car run really smoothly when its wanting to cut out on a cold start

car runs VERY WELL after taking it 300KMS up the highway

just an update documenting what we're doing

 

[Skylarking]

Hey everyone,

WK Stato LS1 "Ghost" severe cold start misfires (NO CODES)

we replaced spark plugs and leads and noted all old spark plugs had a yellowish ash on them indicating EVERY cylinder was misfiring.

The plug and lead change was in response to a huge cold start misfire that causes the car to not want to idle and popping out the exhaust ( car is undrivable for 1-2 minutes) and we have to put "start ya bastard" down the intake to stop the misfire.

When car is warm it does shake a little but can be driven and is not noticeably down on power.

cleaned IAC and throttle plate no change.

car didnt do this 2 months ago when we bought it and has only reared its head the last few weeks.

any ideas on what to check would be great thank you. or how to check pump etc.

under the impression it's fuel filter or fuel pump due to all cylinders misfiring or a vacuum leak to the fuel pressure regulator. I'm not versed on LS's so not sure what else would be responsible for such a severe and widespread misfire problem that start ya bastard would be temporarily fixing.

Don’t know what’s wrong but if Start Ya Bastard makes it run well then it’d be thinking it’s a fuelling issue.

Keep in mind that these cars are now 20 years old and often are not driven much. In such instances the fuel can slowly go off and slowly clag up the tank and fuel lines.

As such, I’d start by checking the fuel tank isn’t clagged with old fuel and it’s crud, the fuel pump in tank filter is clean and the pump flow rate is to spec, the fuel line pressure is to spec and the fuel lines are clear and flow well. That way you know the fuel is getting to the injectors at the required pressure and that the pump & lines can supply fuel at the flow rate the injectors require. Then if all these checks come up good, I’d check all the injector spray patterns and that they flow correctly and consistently across all injectors.

After that, if you still have issues, maybe sanity check the compression, do a leak down test and check for vacuum leaks, etc, as you say you’re down on power. If mechanically everything seems ok, then you’d need to be looking at the electronics

PS: the fact it didn’t do this for a month or so and only reared it head in the last two weeks, don't discount you picked up some bad fuel if it’s all occurred after filling the tank… Also, if you used E10 in the last fill, don’t discount that the alcohol has loosened/dissolved years of crud in the tank and that crud has made its way to the injectors partly/fully clogging some of them up…

As to how to do things, best search for a factory workshop manual which hopefully someone has provided somewhere on the www. Such factory workshop manuals are the bees knees of good information.

PPS: ignore much of the above as I scanned the thread too quickly and now noticed fuel pump has been replaced and that the car runs well when hot So just cold start is an issue.
Maybe look again at ICS?

 

[SLIfox]

Okay I think we found our problem.

Attached photo is my mother's Adventra we were working on. That fuel rail inlet was still under a lot of pressure even after cranking it without the fuel pump fuse in. Literally throwing fuel into the engine bay.

Our V8 Stato, when we disconnected the fuel lines to replace the pulse dampener there were only a 3 drops. Pretty sure our new PAT pump is bad.

We have gotten bank 1 and 2 lean codes plus fuel rail pressure low codes previously and the car runs well on start ya bastard.

V8 did start shaking even when hot now.

I'll keep posting and hopefully we find a fix.