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Dreading LS1 Misfire!

Nemesis_Dawn

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That is one very dusty engine. When was the last time the air filter was changed? An hairline crack in a spark plug can also cause a misfire.

He lives in the desert, Saudi Arabia

The air filter is as clean as it gets. The engine is dusty af cuz, yes, I'm in Saudi Arabia, and in a suburb area. I can't clean that engine properly without risking shorting the exposed wirings.
 
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Nemesis_Dawn

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How's the fuel filter.
Replaced not long ago. I'm pretty sure the problem is either with the fuel pump or the injectors with their connectors. I would do a fuel pressure test, but I don't have an access to a tester.

Although the engine did run slightly better when I removed the air intake and disconnected the MAF, but still shakes like a b**ch and sounds like it's sucking more air than usual.
 

_R_J_K_

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I replaced both the wires and plugs, didn't help one bit. Although the plugs were covered in black soot and two had a small hairline crack. These are TR6IX iridium plugs.

I'm beginning to suspect that it's either the bad wiring for the injectors are making them go haywire, or that the fuel pump is failing. I ruled out the fuel pump at first due to the fact that the car starts right up whether it's warm or cold.

That's annoying. At least they're supposed to be replaced so you won't need to worry about them for a while. Were the sooty spark plugs contained to a couple of cylinders or a bank? Was there a noticeable variation in how sooty all of them were? You had any engine lights come up?

On the loom side I would start by looking at your injector and coil plugs and make sure they're on properly and in good condition (give them a decent wiggle and pull to check if they're cracked and that they stay on correctly), then follow the loom back and start looking for cuts or where the wiring may have rubbed through.

While it's suuuuper unlikely, also take a look at the fuel pressure regulator. Generally they don't break, but make sure all the vacuum hoses are in place properly. In fact, go around the manifold and intake and make sure all vacuum hoses are accounted for.

Also found this thread while looking for idle air control sensor symptoms - https://forums.justcommodores.com.au/threads/ls1-running-rough-and-surging.226481/
 
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lowandslow

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If your plugs have cracks their shot.
 

Nemesis_Dawn

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That's annoying. At least they're supposed to be replaced so you won't need to worry about them for a while. Were the sooty spark plugs contained to a couple of cylinders or a bank? Was there a noticeable variation in how sooty all of them were? You had any engine lights come up?

On the loom side I would start by looking at your injector and coil plugs and make sure they're on properly and in good condition (give them a decent wiggle and pull to check if they're cracked and that they stay on correctly), then follow the loom back and start looking for cuts or where the wiring may have rubbed through.

While it's suuuuper unlikely, also take a look at the fuel pressure regulator. Generally they don't break, but make sure all the vacuum hoses are in place properly. In fact, go around the manifold and intake and make sure all vacuum hoses are accounted for.

Also found this thread while looking for idle air control sensor symptoms - https://forums.justcommodores.com.au/threads/ls1-running-rough-and-surging.226481/


Update. As far as the condition of the plugs, all of them seemed to look the same, while one or two looked a bit better and less sooty. And the loom and the vacuum hoses are inspected and don't seem to change anything when wiggled

I tested both the injectors and their wirings, and they're all electrically check out.

One thing I tested and did make a difference was when I disconnected the MAF sensor connector the engine did run better, albeit still shaking a bit and misfiring, and when I connected it again the engine jerks and starts to shake bad again. Does that mean that all the misfires and shaking are caused by the MAF sensor? I suspect that the engine is running rich too since the old plugs were sooty as well.
 

Trevor loves holden.

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02 sensor, tps, ica, maf all work together so one of those is your problem. Could even come down to your ecu. Remove the battery it should reset the ecu.
 

Nemesis_Dawn

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02 sensor, tps, ica, maf all work together so one of those is your problem. Could even come down to your ecu. Remove the battery it should reset the ecu.

I did replace the TPS and the ICA and their connectors, and the O2 sensors have been deleted with the cat converter long ago

I just disconnected the MAF sensor and drove the car. It still misfires a little bit but not as much, and it does feel wacky and heavy when going full throttle, but not hiccuping and not drivable like it did before.

How do I know for sure that my MAF sensor is the one that needs replacing? I do have a multimeter, but I'm not sure how or if it'll help me figure out that the maf sensor is out.
 
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