HedgehogSandwich adi Posted January 20, 2002 Share Posted January 20, 2002 This is actually a problem on my mkiii 2.5tt, but the engine is a similar design to your mkiv's (mines a 1JZGTE) so here goes. Filled up with optimax today, ran fine for a while but im now getting spluttering, and also its missing badly on high boost. someone suggested i may have burnt my plugs out due to the higher octane. Has anyone else had similar symptoms? Would the plugs problem cause the missing? The plugs were the standard replacement toyota ones, fitted about a month ago. I've now diluted it and its running with half and half but the problem is still there. adi 92 2.5tt Quote Link to comment Share on other sites More sharing options...
Soop Dogg Posted January 20, 2002 Share Posted January 20, 2002 Don't know if this is related, but some others in the group had a discussion about Optimax recently. Go to page 5 of the Technical thread and you'll find on 7th December an item entitled "Running hot on Optimax". Some people have experienced problems with temperatures and idle speeds etc. when changing to Optimax. Have a read.....may or may not be related.:smile: Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted January 20, 2002 Share Posted January 20, 2002 I had the idle speed problem, but don't have a EGT gauge so can't tell that. Resetting the ECU seemed to sort everyones problem out. Quote Link to comment Share on other sites More sharing options...
AJI Posted January 20, 2002 Share Posted January 20, 2002 I thought that running on Optimax allows a 'cleaner burn' of fuel entering the engine. If anything I would have thought that running optimax would sort out more problems than it would cause. The MK-iv engines are designed for RON95 fuel or higher, thats what is says in the manual anyway, but I'm unsure about the MK-iii engines. Have a read of your car manual and in the back it should specify which fuel is prefereable, but if your car is modified then everything changes anyway. Try Steve's idea and re-set your ECU, apart from that I'm not much help, sorry. AJI Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted January 20, 2002 Author Share Posted January 20, 2002 Optimax i've heard *can* be good, but can also cause severe engine damage. It ran fine in my old 3.0t with improved economy and smoother power, so i thought id try it in my 2.5tt (identical in many ways to the mkiv engine). I tried it half and half first which ran fine so tried it with 100% optimax, which is when the problem started. My best theory is that i've burnt the plugs out (only been in four weeks) im slowly trying to get the tank empty of optimax and refill with normal UL. I've reset the ECU but no joy. The ironic thing is i've ran it on SUL with no problems before this. adi Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 20, 2002 Share Posted January 20, 2002 Quote: from HedgehogSandwich adi on 1:09 pm on Jan. 20, 2002[br]Optimax i've heard *can* be good, but can also cause severe engine damage. adi Where did you here this ? Was it a reliable source or rumour ? Quote Link to comment Share on other sites More sharing options...
Flipfinger Posted January 20, 2002 Share Posted January 20, 2002 Yeah...getting a bit worried now Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted January 20, 2002 Author Share Posted January 20, 2002 It's been a subject of the scooby owners club for some time i think. A member on the UK supras list also told similar horror stories of the older 'improved' fuel some years back (cant remember what it was called) which was brought out by shell, and promptly wrecked various engines. AFAIK the problem occurs due to the excess heat caused by the higher octane, which can burn valves out or in worst case scenarios do some damage to piston tops. It could all be scaremongering though . Basically i reckon if youre engines running fine on it then theres no problem, you can continue to use it. Im not an engine expert and could easily have got this wrong. My theory is i've either burnt out the plugs, or an exhaust valve. Either way theres no way i'll be using optimax again. adi (Edited by HedgehogSandwich adi at 3:57 pm on Jan. 20, 2002) Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 20, 2002 Share Posted January 20, 2002 http://www.stopstart.fsnet.co.uk/smilie/monkes.gif Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted January 20, 2002 Author Share Posted January 20, 2002 As an additional, just been checking the net to see other problems caused by optimax, and on the TVR site it states that TVR themsleves says not ot use optimax in their engines , because it isnt safe to do so. Yet many TVR members give good results from using it. I think its down to using the correct plugs with it, colder plugs are fine but the standard ones dont like it. Ps how do i type an emoticon?? Quote Link to comment Share on other sites More sharing options...
Phil Wall Posted January 20, 2002 Share Posted January 20, 2002 You must hug you mouse to get emotions. Check the enable emotions box below the post writing area then click on emotions to the left of the post writing box. High RON should not be a problem in JAP cars as they are mapped to 102 RON. Sounds like ECU reset, and or plugs. Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 21, 2002 Share Posted January 21, 2002 This is interesting... When did Optimax become available? I ask because I have suffered from huge engine damage and I still don't know why. It's another lead to follow... -Ian Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted January 21, 2002 Author Share Posted January 21, 2002 I think it was around september. Optimax itself isnt the problem, its the high octane it provides. Damage mainly consists of burnt plugs, high EGT, and occasionally burnt valves (expensive). I've also been told that extreme cases can cause piston damage, but i'm not sure about that one. Chris Wilson is probably the man to ask. adi Quote Link to comment Share on other sites More sharing options...
Alex Posted January 21, 2002 Share Posted January 21, 2002 Quote: from HedgehogSandwich adi on 1:25 pm on Jan. 21, 2002[br]I think it was around september. Optimax itself isnt the problem, its the high octane it provides. Damage mainly consists of burnt plugs, high EGT, and occasionally burnt valves (expensive). I've also been told that extreme cases can cause piston damage, but i'm not sure about that one. Chris Wilson is probably the man to ask. adi Might have caused more than that, hey Ian! Hmm I'm tempted to try a couple of tanks of BP SUL (personal pref for BP SUL over all others) and see if I get the hesitation at WOT at 1.1-1.2 bar. Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted January 21, 2002 Author Share Posted January 21, 2002 What happened to Ian? Quote Link to comment Share on other sites More sharing options...
Alex Posted January 21, 2002 Share Posted January 21, 2002 His MKIV has just had an untimely heart transplant op....it detonated/blew up at high boost. (Edited by Alex Holdroyd at 3:24 pm on Jan. 21, 2002) Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted January 21, 2002 Author Share Posted January 21, 2002 Thats bad news, was this anything to do with petrol then? Quote Link to comment Share on other sites More sharing options...
Adam W Posted January 21, 2002 Share Posted January 21, 2002 Yeah - there wasn't enough off it! I don't think it was the type of petrol which was the problem, just a case of running lean at high boost, possibly caused over time by a faulty fuel pressure regulator. Quote Link to comment Share on other sites More sharing options...
Alex Posted January 21, 2002 Share Posted January 21, 2002 Truth is we don't know why Ian's car failed. But lack of fuel is the prime suspect. Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 21, 2002 Share Posted January 21, 2002 Of course, I shall update you all if I ever get to the bottom of it I'm not pointing any fingers yet, it could still have been anything. I don't think I ran into an overboosting situation, though. I'm going to get the fuelling checked out by Mr. C. Wilson esq., and see what he thinks... -Ian Quote Link to comment Share on other sites More sharing options...
Lee Hockley Posted January 25, 2002 Share Posted January 25, 2002 Quote: from Ian C on 6:59 pm on Jan. 21, 2002[br]Of course, I shall update you all if I ever get to the bottom of it I'm not pointing any fingers yet, it could still have been anything. I don't think I ran into an overboosting situation, though. I'm going to get the fuelling checked out by Mr. C. Wilson esq., and see what he thinks... -Ian Did you get engine stalls before you had this engine damage ? Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 25, 2002 Share Posted January 25, 2002 Quote: from Lee Hockley on 8:13 am on Jan. 25, 2002[br] Did you get engine stalls before you had this engine damage ? Tried but he burn't his hands on the exhaust. Oh you said stalls..........:biggrin: Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 25, 2002 Share Posted January 25, 2002 How rude No, there was absolutely no indication of any problem before failure. It seemed a bit slower than it used to, but I put that down to getting used to the power - Of course, there may have been a lean condition causing power loss going unnoticed because we always put that sort of thing down to getting used to the power -Ian Quote Link to comment Share on other sites More sharing options...
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