Problems on one tank of Optimax

[trinitycall]

Recently i've been running B1RBL (chimaera 400HC) on BP ultimate.... everything going nicely. I put in a tank of optimax as i couldn't find a BP garage and B1RBL starts popping and banging more than before and is a little hesitant on acceleration, also engine note changed.

I guess the question is - can a different type of petrol make this sort of difference or is it just coincidence?

also, is the v8 that sensitive to petrol types?

If it is down to the petrol, has anyone else had a bad experience in similar circumstances?

Regards,

N

[Podie]

Mine doesn't like 95... at all

Mine lives on Ultimate most of the time, but I do put in Optimax if I get the chance, or any other 97/98 at a push... seems to pop and crackle a little more on the Shell, but nowt else... could even be the placebo effect..?

Go back to Ultimate for a few tanks and see if it goes away...

[blujay10]

I've only had my 4.0 Chim for 4 weeks and have used 2 tanks of Optimax. Also use it in my "other car" with no problems.

[chassis 33]

I'm starting to wonder if there are additives in the different fuels to make the the engines addicted to them. Far fectched i know, but my Chimaera will only run happily on Optimax; BP Ultimate makes it run like yours seems to on Optimax.

Like i said, it's far fetched and very conspiracy theory-esque, but there is a precident, sort of. In a past life (job) I designed military gensets, cabable of starting at -50oC ambient. There are two ways to start a diesel engine at very low temperatures, either a heated air intake, or injecting ether into the engine. The problem with ether is that the engine becomes addicted to starting on it and even at mild ambient temperatures you start needing to inject ether to make the engine run.

Just my 2p!

Alternatively is the Chimaera ECU adaptive, with say a knock sensor to advance the ignition to combat detonation, or to correct for an altered lamba reading and it needs a couple of tanks to get used to the new settings? Do the running problems happen above 3100rpm?

Regards
Iain

[damnfinechim]

My 400HC also started playing silly buggers after I put a little Ultimate in - only a tenner - as I usually always use Optimax
(see thread [url] Wont rev much past 3500| www.pistonheads.co.uk/gassing/topic.asp?t=198785&f=8&h=0) [/url] )

Would these symptoms be relevant for this problem? Hmmmm

Just so im clear -
Ultimate is ??RON
Optimax is 98RON

Thanks
Kempy

[Podie]

damnfinechim said:

Just so im clear - Ultimate is ??RON Optimax is 98RON

Ultimate WAS 98, is now 97.

[trinitycall]

chassis 33 said:

I'm starting to wonder if there are additives in the different fuels to make the the engines addicted to them. Far fectched i know, but my Chimaera will only run happily on Optimax; BP Ultimate makes it run like yours seems to on Optimax. Like i said, it's far fetched and very conspiracy theory-esque, but there is a precident, sort of. In a past life (job) I designed military gensets, cabable of starting at -50oC ambient. There are two ways to start a diesel engine at very low temperatures, either a heated air intake, or injecting ether into the engine. The problem with ether is that the engine becomes addicted to starting on it and even at mild ambient temperatures you start needing to inject ether to make the engine run. Just my 2p! Alternatively is the Chimaera ECU adaptive, with say a knock sensor to advance the ignition to combat detonation, or to correct for an altered lamba reading and it needs a couple of tanks to get used to the new settings? Do the running problems happen above 3100rpm? Regards Iain

now that is a top post... i'm loving the conspiracy theory idea. Fact is stranger than fiction.

the problems occur throughout the entire range.

Could be abit of adjusting going on. tempted to stuff aload of bp ultimate back in.

[chassis 33]

Next they'll be putting stuff in our coffee to make us addicted to that and not able to start, indeed function without it...

Regards
Iain

[jimothy]

chassis 33 said:

Next they'll be putting stuff in our coffee to make us addicted to that and not able to start, indeed function without it... Regards Iain

I somehow think they already have...

[225]

Optimax degrades quite a bit over time so the longer its been sitting in the garage pump the worse it gets. I always try and use it if I can. Tesco are doing 99ron stuff I heard the other day.

[Paul (93 Chim)]

I filled my 4.0ltr up the other day with optimax, and she started missing aswell, was running sweet as a nut before hand. I'll burn this tank up and fill up with the usual 95ron before I start stripping bits off.
Have just fitted plugs, extensions, dizzy cap and rotor arm last week and all was fine then. Leads are about 6 months old.
Not sure about the coil.
Seems OK when I boot it, it's only when the revs are below 2000.
She idles OK aswell.
?

[dparpotta]

Been using optimax and ultimate with no problems.

The other day i put in 95ron and its been the same to be honest.Im wondering whether to stick with 98ron or just go for the cheaper alternative.

[stegefal]

I've religiously used Optimax since day one, but had to put in normal 95 RON due to an emergency low fuel problem. Mine didnt like that at all, was in a right huff till I refilled her with Optimax yesterday.

Running really nice now. Typical woman.

[just_william]

Try to put in at least a 97 RON but have often had to put old 95 stuff in but must confess that she sems happy with all. Although the cheaper petrol does make for less miles per tank.

[Andrew Noakes]

chassis 33 said:

The problem with ether is that the engine becomes addicted to starting on it

How?

[nztrev]

Never read so much toss!
Put in 95 to over 100 race gas,car never missed a beat.

[chassis 33]

Good question, and not one i've ever had to explore since the heated inlet air was the companies prefered route because its all the the engine manufacturers would give warrenty on! I think it could be to do with carbon build up. I can ask the questions if you like?

Regards
Iain

[trinitycall]

UPDATE:- drove chimaera to the office today... symptoms:- running 10 degrees hotter than normal; mis-firing, very lumpy.

The switch in petrol could just be coincidence. To be on the safe side i'm going to have the laptop plugged into the black box lunch time to see if there is anything going tits up on the ecu side.

[scared but happy]

Seems to be an ongoing debate: www.pistonheads.co.uk/gassing/topic.asp?f=23&h=&t=199271

(I found mine PREFERS Optimax)

[edward1]

I've read with interest a number of posts relating to Optimax, I hvae used this and BP ultimate for track days etc due to the higher octane rating, but normally the chim drinks std 95RON. (Partly because I don't pass anywhere that sells the other stuff without going out of my way, the nearest I normally get is Sainsbury's Super (97RON I think))

To be honest I don't notice any difference on the road, no pinking at any point in the rev range, pulls smoothly. Either my ignition has been adjusted at some point to allow it to run happily on 95RON or maybe I'm just lucky.

I do object to paying the excessive amount they charge for Optimax etc so I'm glad it runs OK on 95.

Maybe she's become addicted to the std cheap cr*p!