Help plz need rough idle advice

[Crocodile]

Have taken my car to 3 Holden specialist mechanics on the Gold Coast and none of them can solve this rough idle problem. Plz someone help, I’ve done spark plugs, tested injectors, tested coils, cleaned every hole, checked every connector and plug, checked vacuum leaks etc. Changed air filter unit. Throttle body full clean. You name it it’s been done. Is it possible for a timing chain to be off ever so slightly without being picked up? And thus causing a horrible idle?

 

[Fu Manchu]

One of those things needs checking again.

 

[Crocodile]

One of those things needs checking again.

It’s been looked over all those things, by three different places ? Surely there must be something I’m missing

 

[Fu Manchu]

Have you sorted the PCV? There’s a walkthrough in the how to section?

Smoke test the intake system. Smoke test the exhaust system. Buy a machine or make one. They will find the slightest of leaks. Spraying solvents or other methods just don’t find the hard stuff.

Fuel pressure test checked out ok?

Start digging into live data from some of the sensors.

Is the purge valve functioning correctly? Remove and test. Is the ECM operating it ok?

MAF, o2’s and fuel trims, etc. Throttle position % at idle. Vacuum leaks can be diagnosed from those as well.

Next from there require an oscilloscope to start looking at data wave forms on the various sensors.

 

[Fu Manchu]

It’s been looked over all those things, by three different places ? Surely there must be something I’m missing

But did they do those things? There is a lot of things not being done if the problem has t been diagnosed yet.

 

[Fu Manchu]

Is the fuel cap working correctly?

Have all the harness earths been checked and cleaned? There are a few and I don’t mean the battery earth. Mild corrosion in threads and contacting surfaces will easily cause gremlins you’ll chase for years.

Has the battery health been tested?

 

[Fu Manchu]

Have cheap or counterfeit (many sold as legit plugs) been bought off eBay and used?

Have cheap coils been used? Bosch. NGK are solid brands to use.

 

[Fu Manchu]

It’s been looked over all those things, by three different places ? Surely there must be something I’m missing

Unfortunately you have been missing the decent workshops.

 

[Crocodile]

Unfortunately you have been missing the decent workshops.

well these work shops are top rated on the gold coast. if you have any recommendations id be open to taking it to them

 

[Fu Manchu]

Look. To illustrate what I mean by a good workshop can diagnose it. The data will absolutely do the talking.

Now I get what’s going on sort of. I’ve only got self taught (through necessity). Much of the automotive industry should be across this stuff and it’s not. The people with these skills are around in Australia. There are a lot in fact. The best source I have found is via the TAT network (The Automotive Technician Network). They do this stuff everyday and then share it among their members. What they don’t do is make finding members workshops easily. I can only suggest contacting them via their website and see if they can find a member near you.

Bernie Thompson is next level but very clearly walks people through the process and explains the whys. An excellent teacher. Even if you don’t keep up, watch it so you understand just what’s involved with finding your solution. Also what is clearly not being done so far.