Engine noise rough at start up
Thread Starter
Teching In
Joined: May 2023
Posts: 7
Likes: 1
Engine noise rough at start up HOLDEN STATESMAN WM SERIES 1 6.0L Gen4 L76 OHV 16v MPFI V8 260kW 6sp Auto 4dr Sedan
Hello Fellas,
First time LS owner and First time poster. Any additional information you need please ask.
I've owned the car for 3 years and no problems. This problem is getting worse.
When I start the car, the engine is noisey and when I rev the engine to 1500 - 2000rpm it runs rough. Feel the car rock.
I drive off slowly to normal speed after a few minutes the car is driving fine. Whether I drive car for 10 30 or 60 minutes no problem. I stop at destination
I restart car 1/2 1 or 2 hours later no problem. Runs great.
If I start car 8 - 10 hours later after work the rough start happens again.
No fault codes
I've changed spark plugs
Tested coils ok
Can hear individual injectors working.
Fuel type 98
Changed oil 1000 miles ago 5w30 full synthetic.
Any help will be greatly appreciated.
Hello Fellas,
First time LS owner and First time poster. Any additional information you need please ask.
I've owned the car for 3 years and no problems. This problem is getting worse.
When I start the car, the engine is noisey and when I rev the engine to 1500 - 2000rpm it runs rough. Feel the car rock.
I drive off slowly to normal speed after a few minutes the car is driving fine. Whether I drive car for 10 30 or 60 minutes no problem. I stop at destination
I restart car 1/2 1 or 2 hours later no problem. Runs great.
If I start car 8 - 10 hours later after work the rough start happens again.
No fault codes
I've changed spark plugs
Tested coils ok
Can hear individual injectors working.
Fuel type 98
Changed oil 1000 miles ago 5w30 full synthetic.
Any help will be greatly appreciated.
Teching In
Joined: Feb 2023
Posts: 6
Likes: 0
Take all you spark plugs out and either a mirror and flash light or a wooden dowel rod and stick down in the cylinders to see if you can pick up anything wet or you could have someone spin it over a few seconds to see if it pushes any liquid out of the spark plug holes. Maybe injectors leaking down also?? You would want to do this on one of your off days in the morning after it's been sitting over night. Are you having to add some coolant to your reservoir? Any ck engine lights?
Last edited by Mike Gerace; May 18, 2023 at 09:22 AM.
I’d start with looking at the tune during cold start. Sounds like a fuel trim issue at startup to me. You’ll want a tuner to do this with the needed software such as HPTuners.
Thread Starter
Teching In
Joined: May 2023
Posts: 7
Likes: 1
Could be a coolant problem.
I have had to fill the radiator with 1-1/2 litre of water every few weeks.
Over the last 6 months, I've had coolant leaking from the radiator cap and hoses. I just thought it was a faulty radiator cap. But still leaks with new cap. I've also noticed when the coolant level is low in the radiator where you can see the cooling fins the radiator doesn't leak. But when I fill the radiator up, I notice the cap and hoses start to leak again.
So could be a coolant leak.
Should I use a head gasket fix like Rislone in the radiator to see if this fixes the problem?
I have had to fill the radiator with 1-1/2 litre of water every few weeks.
Over the last 6 months, I've had coolant leaking from the radiator cap and hoses. I just thought it was a faulty radiator cap. But still leaks with new cap. I've also noticed when the coolant level is low in the radiator where you can see the cooling fins the radiator doesn't leak. But when I fill the radiator up, I notice the cap and hoses start to leak again.
So could be a coolant leak.
Should I use a head gasket fix like Rislone in the radiator to see if this fixes the problem?
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Verdad Gallardo Could be a coolant problem.
I have had to fill the radiator with 1-1/2 litre of water every few weeks.
Over the last 6 months, I've had coolant leaking from the radiator cap and hoses. I just thought it was a faulty radiator cap. But still leaks with new cap. I've also noticed when the coolant level is low in the radiator where you can see the cooling fins the radiator doesn't leak. But when I fill the radiator up, I notice the cap and hoses start to leak again.
So could be a coolant leak.
Should I use a head gasket fix like Rislone in the radiator to see if this fixes the problem?
I have had to fill the radiator with 1-1/2 litre of water every few weeks.
Over the last 6 months, I've had coolant leaking from the radiator cap and hoses. I just thought it was a faulty radiator cap. But still leaks with new cap. I've also noticed when the coolant level is low in the radiator where you can see the cooling fins the radiator doesn't leak. But when I fill the radiator up, I notice the cap and hoses start to leak again.
So could be a coolant leak.
Should I use a head gasket fix like Rislone in the radiator to see if this fixes the problem?
Thread Starter
Teching In
Joined: May 2023
Posts: 7
Likes: 1
OK, thanks che70vell I will not use the rislone fix.
I'll take the spark plugs out in the next couple of days and see if there is any water in the cylinders over night.
Also I'll book the car in at a mechanic and get him to check the tune also.
I'll post again after I've seen the mechanic, hopefully with what the problem was.
Thanks for your help
I'll take the spark plugs out in the next couple of days and see if there is any water in the cylinders over night.
Also I'll book the car in at a mechanic and get him to check the tune also.
I'll post again after I've seen the mechanic, hopefully with what the problem was.
Thanks for your help
Thread Starter
Teching In
Joined: May 2023
Posts: 7
Likes: 1
#update#
This is the strangest problem.
I removed the spark plugs and got a mate to turn the engine over while I watched for water or anything coming out of spark plug holes. Nothing came out.
After I replaced spark plugs, I started the car in my garage. Same rough start. I reversed the car up the driveway (the driveway is steep) and had to stop for a few cars. Applied handbrake and placed in park. As I was stopped I rev'd the engine. The engine sounds great.
So I drove back down into the garage and rev'd the engine, rough again. I did this 6 times.
When the car is on a steep slope the engine runs great.
Engine oil level is full.
The local mechanic has no idea what the problem could be. He thought I was joking with him, lucky my mate was there to back my story up.
This is the strangest problem.
I removed the spark plugs and got a mate to turn the engine over while I watched for water or anything coming out of spark plug holes. Nothing came out.
After I replaced spark plugs, I started the car in my garage. Same rough start. I reversed the car up the driveway (the driveway is steep) and had to stop for a few cars. Applied handbrake and placed in park. As I was stopped I rev'd the engine. The engine sounds great.
So I drove back down into the garage and rev'd the engine, rough again. I did this 6 times.
When the car is on a steep slope the engine runs great.
Engine oil level is full.
The local mechanic has no idea what the problem could be. He thought I was joking with him, lucky my mate was there to back my story up.
TECH Resident
Joined: Sep 2019
Posts: 825
Likes: 262
From: Melbourne, Australia
So you reverse up a steep incline and the car runs better? On the flat its running rough?
Would it be fair to say the fuel could be getting to the engine easier , im sayin weak fuel pump
Would it be fair to say the fuel could be getting to the engine easier , im sayin weak fuel pump
Thread Starter
Teching In
Joined: May 2023
Posts: 7
Likes: 1
Hi guy,
I finally got my hands on a fuel injection test kit.
I turn key to the on position before start.
The gauge reads 58psi after 3-4 seconds the fuel pump stops then the pressure drops to 53psi.
I start the car pressure on 57-58psi
Rev the car constant 58psi
Car idles 58psi
When I turn car off pressure drops to 53
30 minutes later pressure still at 53psi.
I was hoping to see a lower psi pressure to be able to say it's a pump or regulator problem.
Do these pressures seem correct?
I finally got my hands on a fuel injection test kit.
I turn key to the on position before start.
The gauge reads 58psi after 3-4 seconds the fuel pump stops then the pressure drops to 53psi.
I start the car pressure on 57-58psi
Rev the car constant 58psi
Car idles 58psi
When I turn car off pressure drops to 53
30 minutes later pressure still at 53psi.
I was hoping to see a lower psi pressure to be able to say it's a pump or regulator problem.
Do these pressures seem correct?
Hi guy,
I finally got my hands on a fuel injection test kit.
I turn key to the on position before start.
The gauge reads 58psi after 3-4 seconds the fuel pump stops then the pressure drops to 53psi.
I start the car pressure on 57-58psi
Rev the car constant 58psi
Car idles 58psi
When I turn car off pressure drops to 53
30 minutes later pressure still at 53psi.
I was hoping to see a lower psi pressure to be able to say it's a pump or regulator problem.
Do these pressures seem correct?
I finally got my hands on a fuel injection test kit.
I turn key to the on position before start.
The gauge reads 58psi after 3-4 seconds the fuel pump stops then the pressure drops to 53psi.
I start the car pressure on 57-58psi
Rev the car constant 58psi
Car idles 58psi
When I turn car off pressure drops to 53
30 minutes later pressure still at 53psi.
I was hoping to see a lower psi pressure to be able to say it's a pump or regulator problem.
Do these pressures seem correct?