Niggling issue
 

Morning guys,

After a thousand google searches and scouring of numerous forums I still can't seem to find relevant info on a problem that has just surfaced. The info provided in the countless threads read would have me busy for the next week problem solving as the answers were so broad.

The problem began Saturday morning... Filled up at a different BP service station in town with 98 the evening before. The other station I normally use which is quiet new had no fuel :(

The issue is when under load (3500rpm) i can feel the car hesitating/misfiring/jerking..Passengers can't notice it but I can certainly feel it. It will hesitate? for a second or two then continue boosting as per usual.

Has anyone experienced anything along these lines? Happy to spend some time to try and diagnose the issue but am looking for a good place to start.

Will try the following tonight:

- Clean MAF
- Check for any obvious vac/boost leaks

Could it be a bad batch of fuel? Off boost it drives absolutely fine its just the initiation between going from vac to boost.

Cheers,


Shaun

I have never heard of any issues with bad batches of fuel from BP, but have read quite a few coming from Caltex. It's always a possibility however. I'm not sure who does it, and I think it could be expensive, but you could get the fuel tested. If I had a feeling it was fuel I'd park it up and get it tested. Drive too far, cause damage to the engine, then it'll be a shit-fight trying to get BP to cover a rebuild. Fingers crossed it's something simple and just coincidental!

Thanks mate. Will look into it. Forgot to mention no codes were thrown.

Your afr's may need looking at, I had a similar problem with my betty a few months ago. Car had to go back on the dyno for a retune.

Afr's were completely out of spec and running lean in a few places, car was down on power too, about 30kw.

Have you made changes at all to the car recently?

Hey Nick, no changes mate. Nothing other than an oil and filter change.

I just did this. (Thanks for the pointer Gordon)
[url=http://www.iwsti.com/forums/diy-mods-and-installations/254372-fuel-line-extension-stumble-fix-mod.html]Fuel Line Extension / Stumble Fix Mod - Subaru Impreza WRX STI Forums: IWSTI.com[/url]

Common symptom is a hesitation anywhere between 2400 and 3500 apparently. It does recommend you have the map adjusted accordingly as it will now run a bit rich. My 08 STI is due back for a remap soon anyway but initial test drive says it fixed it.

It's already been done mate. Was tuned to suit as well. Thanks though.

Has already been done to this car by the previous owner.

Check your spark plugs

Is the car still running on a big red pod filter (aem filter)? Tom did have the similar issue, it was the maf. Maybe u live in dusty area, and maf and filter needs a refresh? Next time u come to perth, I can give u some aem filter cleaner, or u can use the k&n one.

Also check ur spark plug as Jezza said.

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