Hi,

Last Saturday I had Genie extractors, a high flow cat and Lukey 2.5" cat back exhaust fitted to the EF I6 5 speed.

A couple of days afterwards I started noticing some slight flat spotting and misfiring under light acceleration and some slight misfiring during idle. It seems worse on a cold start and seems to go away after driving for a while. It is fine under heavy acceleration. It's most noticeable between 1500 - 3000rpm.

After exhaust was fitted I noticed Cruise control was not working and after getting some help on the forums I found the cruise switch on the brake booster had been left disconnected by the bloke that fitted the exhaust.

Could there be some other sensors or hoses etc. he may have disconnected to fit the extractors or exhaust and then forgotten to connect back up like he did with the cruise switch?

So far I've replaced:

- Plugs
- Leads
- O2 sensor
- Fuel filter

Any suggestions or help is much appreciated!
Cheers

Why dont you simply take the car back to the fitter of the system and explain to him then Problem solved instead of us guessing and he should do it for free

Because if they check over it and find nothing wrong with their work I'll have to pay them for the labour. Also it was fine the first couple of days after the exhaust was fitted so it may just be a coincidence.

Not sure if it will rectify the problem, but resetting the ECU might help a little. Usually helps when some mods are done to the car.

When I installed my extractors, the O2 sensor was removed (in my case replaced as well), leads for clearance and the belt shroud (also for clearance). So not much needs to be removed.

sounds llike problem i had an was coil pack brackng down .

Thanks for the replies all.

I found the problem!

I bought this car about 2 weeks ago. Straight after buying it I filled up with 98 octane Caltex Vortex fuel. Everything was running sweet and dandy.

Last weekend I got the extractors and exhaust fitted, and at that time I had about 1/4 of a tank of the premium fuel left. So for a few days after getting the exhaust I was still running on 98 octane and didn't have any issues.

Then I wanted to fill up with standard 91 octane (my car is stock except for the extractors and exhaust) to see if I got less kms to the tank. I realise now that this is when the misfiring and flat spotting started. I did think it could be it so a few days ago I bought a bottle of nulon octane booster and dumped it in the tank but it didn't make any difference. That's when I decided to spend the weekend replacing stuff trying to fix it, because I thought if the fuel was the problem the octane booster would have fixed it. Replaced plugs, leads, O2 sensor, fuel filter. No difference.

Yesterday I was running low on fuel so filled up with 98 octane Caltex Vortex again. Instantly it was like a new car. Smooth as!! Even starting it up on a cold Canberra morning today it was smooth as.

Isn't it a bit strange that a completely stock EF (except for exhaust and extractors) doesn't like 91 octane?

Im a lot Sus about the not liking 91 octane. My gut feeling is that the fuel companies are deliberately downgrading 91octane. My Wifes Car also runs like s**t with most 91octane... where a year ago it ran fine.

Nigel

No Idea what 91 goes like in my car, would rather push it to another servo selling proper fuel than put that crud anywhere near my car or the wifes little astra. Nasty Nasty stuff. Good for generating work for mechanics and helping repco sell parts people don't always need.

Ethanol is rubbish unless properly set up for it.

We get non-E10 91octane. Same about no ethanol. Wont use it.

Reminds me of that old saying "Petrol is for washing parts, Alcohol is for drinking, Nitro is for racing"

When I first put my exhaust on it ran s**t.
An my mate reminded me about advancing timing cos of different back pressure or somthing.

I currently have it at approx 14 BTDC

the ultimate is running nicer cos it burns a little better and your car isn't tuned right maybe?

I've run opal fuel (low aromatic 91 RON), regular unleaded (91 RON), Premium (95 RON), and Ultimate (98 RON)

and honestly? NO DIFFERENCE!!!! In running quality, performance, consumption.

If anything, I can feel Ultimate working on a nice cold morning.

Fair comment, however the EF is a different beast. The EEC V it uses uses more advanced Timing, knock sensor, and the engine was built to make slightly higher power.

On an EB/EA style car the difference shouldnt be a lot - there isnt a sensor that will be able to take real advantage of the higher octane, but on later cars it makes a difference

And I stand by my comment - 91RON has gone to s**t in the past couple of weeks/months. I dont use E10, and wont.

Nigel

Sorry to continue going off topic here a bit but i use E10 in my BF (granted it does say e10 suitable on the petrol flap) but havnt had any issues with it, prolly been using it for 3.5 years or so. I put the odd normal unleaded in every now and then but usually dont worry about it. Once i have done modding the engine i might look at making the switch to ron 98 and tuned accordingly on it but the stuff is soo much more expensive its hard to justify the extra cost.

ive noticed my car runs like crap on 91octane, 95/98 runs fine. i dont know if its cause my ecu is used to the higher octane or if the petrol company's are getting even more stingy.

Nigel: hey man. Yeah your probably right, maybe the EF/ELs had a more "refined" tune to get the better performance whereas the earlier EA-EDs had a "broader" stock tune.

Might be an interesting discovery when I put a EL motor in my car...

Phil: Ive had no issues with E10 too, although I haven't run it in my car, I went on a family holiday and drive from Sydney to Coffs Harbor in a rental Territory, on the way up I just filled up with unleaded, but when in Coffs spotted a Mobil with E10, so all the way back I used E10. And the consumption was pretty much the same.

I reckon the last comment was fair, maybe it comes in "batches",
I remember there was a thing in street fords mag, they did dyno runs on a car...only swapping the oil, to see if you can get a gain (extra few ponies using Mobil 1 from memory) anyhow I do t think this would be a useful for fuel..too many variables