hesitation and flat spots possible bad tank of fuel ?

[psquire45]

Hi All

just want to mention the symptoms and the history over the last week or two and see what solutions or things to check i get back.

up until last week car was running fine. a little rich on cold mornings with a faint hint of black smoke from fuel when cold only.

the other morning ( thursday ish ) i was running around left right and sent a little bit late for everything all morning so neglected to fill up and ran the tank right down. as i was hurried i put $20 of the 98octane in at a liberty just to tide me over until i could get to a bp or a shell.

car was running fine when i pulled in, after driving out no more than 30 meters down the road i started to notice flat spots, hesitation, and the occasional backfire (intake and exhaust depending on what mood its in.)

drove straight to shell and filled rest of tank with optimax to try and "thin" what im assuming is a tank of bad fuel however didnt seem to make a whole lot of difference

after 3 days hesitation backfiring etc very repeatable and consistent.
pulling away from a standstill up until 2500-3000rpm lots of flat spots,coughing etc
driving under light load / cruising is fine accelerate with out change down in gear = coughing and hesitations
idle seems fine not rough
cruise seems fine
anything over 3000rpm drive perfectly normal

so sudgestions, any one had anything similar? where to start? i pulled the plugs they all seem normal. no oil, not too clean, but did confirm my expectation of running rich

[NitroDann]

If it was the fuel it sounds like water in it. Fill it with E10 and it will be fixed.

Dann

[Guran]

Liberty 98 has 10% ethanol and pre-2005 MX-5s are not recommended to use E10. Normally, any water in the tank will happily sit in the bottom. But if you suddenly add fuel that has ethanol in it, the water will dissolve in the ethanol and you'll start burning it. Car will run rough until the water-contaminated fuel is totally gone. (more advice in this thread)

The fuel thing could be a coincidence. Could be dodgy plug leads. I recommend you find someone in your area with same MX-5 as you (NB8A right?), and try their leads. If that fixes the problem, then you've found your solution. Or if you've got a multi-meter, check the resistance on your leads. (more info in this thread)

[psquire45]

Liberty 98 has 10% ethanol [/url])

you filthy little mother F#$%#$^$%^ they warn about e10 on there budget blend containing upto 5% but no warning on the 98

so a little conflicting on the info that you guys have come back with.

so ive added fuel that has ethanol which has mixed with the water etc in either my fuel tank or the servos tank which is now going through my fuel system.

to solve this i can add either more ethanol fuel ?
or just run it dry and start filling up with normal premium again.

any adverse effects from running this ethanol/fuel/water mix through the car other than coughs splutters and farts ?

edit... thanks for the responses to guys ive been worried sick about this the last few days

[NitroDann]

their 98 wouldnt have ethanol.

Add ethanol.

Dann

[hks_kansei]

http://www.libertyoil.com.au/products/w2/i1004825/

Liberty's MSDS says it's 98ron ingredients are:

Petroleum Hydrocarbon 90%-100%
Benzene 0%-1%


I couldn't see a listing for what the other potential 10% is made up of.
I would presume ethanol, but there's no way of knowing if what they've got in the pump at that time is 0%, 10%, or anywhere in between.

[psquire45]

actually the link to their website for liberty fuels does say down the bottom that the 98 contains 10% ethanol.... shame the pump doesnt display it that clearly

[hks_kansei]

actually the link to their website for liberty fuels does say down the bottom that the 98 contains 10% ethanol.... shame the pump doesnt display it that clearly

Guran's link?

That's United petroleum.

Did you fill with United or Liberty?

[Guran]

Apologies but Google gave me a bum steer . I searched for "Liberty 98" and got directed to the United website.

For the record, United's Premium 98 does contain 10% ethanol.
http://www.unitedpetroleum.com.au/fuels/premium-98

Not so sure about Liberty PremiuMax 98, but it does not come with very good recommendations, and plenty of adverse comments.
http://www.7perth.com.au/view/today-ton ... uel-tests/
http://www.rexnet.com.au/forum/index.ph ... ge__st__30

[psquire45]

small update.

added another 1/4 tank of optimax last night and its running a little bit better with slightly less hesitations and flat spots.

i think my plan of action atm is to run it as is down to 3/4 again top up with another 1/4 optimax. and repeat until my mechanical sympathy level allows me to go for a long enough drive to empty the tank.

after which a complete refill with optimax, change of fuel filter, oil change (its due anyway) then plugs, leads, injectors etc etc slowly increasing in cost until its fixed and running smoothly again

[project.r.racing]

or drain the tank? start completely fresh?

[zero00]

I run all mine on Shell V-Power 98

Just filled one of my Corollas with V-Super priced at 155.9cpl

Liberty, United, 7-11, won't touch them

No problems to date, you pay a little [little?] more but worth it - BP only if I can't get Shell and NOTHING else!

A mower, outboard, and small engine repairer on Bribie Island claims BP Ultimate 98 octane has ethanol in it, but that could be heresay

Hope you get it sorted out but seeing it started almost as you drove out the driveway of the service station, I'd be eliminating leads or that's one hell of a coincidence

[Basho]

or drain the tank? start completely fresh?

X 2

[psquire45]

well another 1/4 tank of optimax and a bottle of octane booster hasnt seemed to help ( if anything it may be a little worse now.)

time to start throwing money at it. will get new leads and plugs and fuel filter tonight

[vrmmmpshhh]

I'd suggest fuel filter too.