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Rough idle

Nikki johnston

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I have a 3.8L VX commodore.
Had my car running extremely rough a couple of weeks ago. I put injection cleaner in when i put fuel in on the Wednesday, drove it thursday with no issues only to have my car running extremely rough friday. Although not completely, it gradually got better and wasn't running so rough. Replaced spark plugs, checked coil packs in which all were fine, checked leads in which again, were all fine, checked air filter in which yet again, was fine.
A couple of days later, i noticed it was making a loud ticking noise that got faster and louder as rpms went up.
Got mechanic to look at it. Taking in everything i told him and what he heard for himself, he suspected possibility of a faulty fuel injector. He also considered a possibility of a slight blockage and suggested to give a chance for injection cleaner to do its job.

Now, it has an extremely rough idle.
When in idle, the rpms are constantly going from 1 to just before stalling point instead of sitting at a certain point.
Occasionally, the ticking noise is still there.
The initial start up for the day, it sounds really sick (sounds like it wants to stall). After the initial start up for the day, no issues at all with start up.

The last few days, occassionally whilst driving, it initially feels like it has no power when i accelerate to then feeling likevit has a massive surge of power.
Mechanic now is thinking its the idle control valve.

Does anyone have any suggestions on what could be causing these issues.
Its been a good reliable car, well looked after. Serviced every 6 - 12 months without fail.
 

lout

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bad batch of fuel with water in it?
blocked fuel filter
worn fuel pump
iac wont create wot problems
 

Nikki johnston

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bad batch of fuel with water in it?
blocked fuel filter
worn fuel pump
iac wont create wot problems

Fuel pump has been replaced in last 12 months.
I bought fuel filter to the attention of mechanic (it was done about 2 years ago). Apparently, going by the kilometers, its not due to be done again (mechanics words).

Despite generally filling up at a certain service station, i considered dirty fuel. Instead of running it on 91 like i used to, i have been putting 95 in.
 

Nikki johnston

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bad batch of fuel with water in it?
blocked fuel filter
worn fuel pump
iac wont create wot problems

About 12 months ago, i had the throttle body, plenum chamber and injectors cleaned by mechanic.
One of the injectors was down (92%l. Mechanic could only get it back up to 97%.
The loud ticking noise sounds like an injector.
 

vc commodore

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Fuel pump has been replaced in last 12 months.
I bought fuel filter to the attention of mechanic (it was done about 2 years ago). Apparently, going by the kilometers, its not due to be done again (mechanics words).

Despite generally filling up at a certain service station, i considered dirty fuel. Instead of running it on 91 like i used to, i have been putting 95 in.

Seeing the fuel pump has been replaced after the fuel filter was replaced, it won't hurt replacing the filter, despite what the mechanic has said...

I had a similar problem with my ecotec running rough at idle.....My symptoms were rough idle, miss...Higher revs the miss seemed to disappear, lack of power at lower revs...

I replaced the plugs and leads making sure the leads were on the plugs properly (easy mistake to make) and voila, car fixed....

edit....Appears like you haven't replaced leads....Do that as old leads cause all sorts of issues
 

Nikki johnston

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Seeing the fuel pump has been replaced after the fuel filter was replaced, it won't hurt replacing the filter, despite what the mechanic has said...

I had a similar problem with my ecotec running rough at idle.....My symptoms were rough idle, miss...Higher revs the miss seemed to disappear, lack of power at lower revs...

I replaced the plugs and leads making sure the leads were on the plugs properly (easy mistake to make) and voila, car fixed....

edit....Appears like you haven't replaced leads....Do that as old leads cause all sorts of issues

Leads were replaced about 6 months ago.

I grew up with my dad who was a qualified mechanic, so taking in the advice he always gave, leads are always checked every 6 - 12 month service.
Leads are replaced every 12 - 18 months.

Other than now and then with the lack of power on acceleration, it drives really good, no misses....but as soon as i have to sit in idle, its rough as guts.
Absolutely hate sitting at traffic lights, especially with it getting to near stalling point.

I definitely agree with the fuel filter, and going to get that replaced.
 

Nikki johnston

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Following my dad's advice, i don't let the fuel tank get below 1\4.

Maybe getting a diagnostic done might be something to consider.

Have also considered disconnecting battery over night to reset computer.

Could be way off with this consideration, but also thought of something as simple as a relay.
Awhile ago, i had an issue with my indicators. Even though it didn't look burnt out or stuffed upon inspection, it turned out to be the relay.
Have just replaced a couple of relays (due to age). Still a couple more to replace because of same reason.
 

max101cfh

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Possible vacuum leak, I had similar issues was driving me nuts hard start bad idle sometimes when it warmed up it was ok but I had to find the problem before it got worse so i replaced plugs, leads, coils, fuel filter still had the same problem. So I thought if it's not the usual suspects then I would check vac hoses I ended up replacing the oil cap and replaced the 2 on the throttle body and the one a back of plenum found out that was really bad and reset ecu then problem gone.
 

Nikki johnston

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Possible vacuum leak, I had similar issues was driving me nuts hard start bad idle sometimes when it warmed up it was ok but I had to find the problem before it got worse so i replaced plugs, leads, coils, fuel filter still had the same problem. So I thought if it's not the usual suspects then I would check vac hoses I ended up replacing the oil cap and replaced the 2 on the throttle body and the one a back of plenum found out that was really bad and reset ecu then problem gone.

The manifold gasket was replaced a few months as had a vacuum leak due to the gasket being pretty much none existant.
Cleaned the throttle body on the weekend, its all fine.
Main air intake intake hose was replaced due to a small split about 12 months ago.

Will look at other possible vacuum leaks.

Do agree, its driving me nuts as have already looked at usual suspects as well....spark plugs, leads, coils etc

Will be getting fuel filter replaced despite it not yet due to be done
 

Red Ute

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I have a 3.8L VX commodore.
Had my car running extremely rough a couple of weeks ago. I put injection cleaner in when i put fuel in on the Wednesday, drove it thursday with no issues only to have my car running extremely rough friday. Although not completely, it gradually got better and wasn't running so rough. Replaced spark plugs, checked coil packs in which all were fine, checked leads in which again, were all fine, checked air filter in which yet again, was fine.
A couple of days later, i noticed it was making a loud ticking noise that got faster and louder as rpms went up.
Got mechanic to look at it. Taking in everything i told him and what he heard for himself, he suspected possibility of a faulty fuel injector. He also considered a possibility of a slight blockage and suggested to give a chance for injection cleaner to do its job.

Now, it has an extremely rough idle.
When in idle, the rpms are constantly going from 1 to just before stalling point instead of sitting at a certain point.
Occasionally, the ticking noise is still there.
The initial start up for the day, it sounds really sick (sounds like it wants to stall). After the initial start up for the day, no issues at all with start up.

The last few days, occassionally whilst driving, it initially feels like it has no power when i accelerate to then feeling likevit has a massive surge of power.
Mechanic now is thinking its the idle control valve.

Does anyone have any suggestions on what could be causing these issues.
Its been a good reliable car, well looked after. Serviced every 6 - 12 months without fail.
Inlet air temperature sensor?
 
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