kornchief
New Member
First time post and have found much help with my VP V8 on these forums....so in advance, thank you for everyone sharing their knowledge on here!
I have a 1992 VP V8 SS Commodore with a 304 stock engine and 4 speed automatic gearbox.
The issue that I have is when I started my car after work the other day it started as normal on the first turn but then immediately started behaving abnormal with the revs fluctuating up and down.
I gave it a rev and noted that it seemed like it was running on less cylinders as it sounded like a Harley and was very rough. This did not subside no matter how much I revved it. It sounded and felt like a box of crap!
If I let it idle it would surge again ranging from 100rpm to 1000rpm and after a bit would stall out.
Nevertheless I threw it into gear and kept the revs up to make sure it didn't stall out. Out of frustration gave it a boot full of mean stuff around a few corners to see if it would clear. I noticed at high revs it performed like it would normally, screaming its head off, loosing traction, with no issues. After a few corners and the engine was completely warmed up, I noticed that it was back to normal behaviour when idling and taking off normally. I thought, beauty, it has fixed itself somehow!
Thought maybe a small fuel blockage and it cleared but next morning it was the same after initial start up. Nothing wrong with the ignition as it started on first turn again as normal. I let it warm up and it seemed to correct itself. Went out at lunch with it still misbehaving and drove it 30 mins after stopping for a bite to eat so the engine was still warmish but the symptoms returned when driving back to work, although it did clear about 1 - 2kms later.
I am happy to start diagnosing on the weekend but have come up with these theories.
1) Fuel pump dying and struggling to pump fuel as it makes the pump noise when turning to ignition but once started it keeps whining for a minute or two which I think is unusual compared to a mates VP. Perhaps changing the fuel pump is a good start.
2) Check spark plug leads while car is running 1 by 1, taking 1 off and looking for a engine performance change/decrease and then reconnecting, going through each plug and if 1 or more produces no change in performance when the lead is off then I have a crook spark plug and/or lead.
3) Check spark plug leads while car is running 1 by 1 with a screwdriver that has a rubber handle. Stick the screwdriver down the spark plug lead opening while making sure I don't touch the shaft of the screwdriver so i don't get zapped :clap: and arching it against the engine block to see if there is sufficient spark from the lead.
4) Replace fuel filter: but I did this a year ago and will be disconnecting it to check if it has good pass through
5) Check fuel lines
6) Check distributor cap for cracks etc.
7) Replace Coil
8) Replace O2 sensor
Step 4 - 8, I would like to avoid if possible so I though I would see if anyone else has any thoughts on what could be causing this issue.
Hoping its a fuel issue and not engine related.....dropped cylinder :/
Thanks
JJ
I have a 1992 VP V8 SS Commodore with a 304 stock engine and 4 speed automatic gearbox.
The issue that I have is when I started my car after work the other day it started as normal on the first turn but then immediately started behaving abnormal with the revs fluctuating up and down.
I gave it a rev and noted that it seemed like it was running on less cylinders as it sounded like a Harley and was very rough. This did not subside no matter how much I revved it. It sounded and felt like a box of crap!
If I let it idle it would surge again ranging from 100rpm to 1000rpm and after a bit would stall out.
Nevertheless I threw it into gear and kept the revs up to make sure it didn't stall out. Out of frustration gave it a boot full of mean stuff around a few corners to see if it would clear. I noticed at high revs it performed like it would normally, screaming its head off, loosing traction, with no issues. After a few corners and the engine was completely warmed up, I noticed that it was back to normal behaviour when idling and taking off normally. I thought, beauty, it has fixed itself somehow!
Thought maybe a small fuel blockage and it cleared but next morning it was the same after initial start up. Nothing wrong with the ignition as it started on first turn again as normal. I let it warm up and it seemed to correct itself. Went out at lunch with it still misbehaving and drove it 30 mins after stopping for a bite to eat so the engine was still warmish but the symptoms returned when driving back to work, although it did clear about 1 - 2kms later.
I am happy to start diagnosing on the weekend but have come up with these theories.
1) Fuel pump dying and struggling to pump fuel as it makes the pump noise when turning to ignition but once started it keeps whining for a minute or two which I think is unusual compared to a mates VP. Perhaps changing the fuel pump is a good start.
2) Check spark plug leads while car is running 1 by 1, taking 1 off and looking for a engine performance change/decrease and then reconnecting, going through each plug and if 1 or more produces no change in performance when the lead is off then I have a crook spark plug and/or lead.
3) Check spark plug leads while car is running 1 by 1 with a screwdriver that has a rubber handle. Stick the screwdriver down the spark plug lead opening while making sure I don't touch the shaft of the screwdriver so i don't get zapped :clap: and arching it against the engine block to see if there is sufficient spark from the lead.
4) Replace fuel filter: but I did this a year ago and will be disconnecting it to check if it has good pass through
5) Check fuel lines
6) Check distributor cap for cracks etc.
7) Replace Coil
8) Replace O2 sensor
Step 4 - 8, I would like to avoid if possible so I though I would see if anyone else has any thoughts on what could be causing this issue.
Hoping its a fuel issue and not engine related.....dropped cylinder :/
Thanks
JJ
