as the days are heating up I am having issues starting the car, never in the morning or evening only after the car has been sitting in the heat for at least an hour, at this point takes about 10 seconds of turning over (at the most) before it starts at which point I also have the smell of "oh crap i just poured a litre of fuel down my exhaust". when it fires it catchs strgiht away and is sweet as. Oh and a hot day means anything over 35 deg normally, under this it seems to be fine. Any suggestions people, as an aside there is also an intermittent idle issue on very hot days as well where the idle drops to around 400rpm then suddenly back to normal 5 minutes later, I think its a loose connection somewhere on the idle valves as its not missing just very low idle speed anyone think this is maybe connected.
prvr valve is specificly designed to aid in hot day re starting, check to see if your's is still there, if it is it might have died.
Update, found one of the major causes if not the main one. first a little history - Wife drives a Mk3 Supra with a 7MGE, we have just had a HG failure which if anyone knows these engines they wont be surprised. have an ACL kit on its way now from the states but wife has been driving my Z. Wife shops at the local Woolworths and gets her fuel discount for Caltex, un beknown to me she is filling my car with caltex vortex 95 octane (which I have never used) I however went down to BP and refilled t=wtih Ultimate nthe other day andf wife comes back to me saying "Hey you fixed the car what was wrong?" I said ??????WHAT????? havent had a chance to get ner it yet. Story unfolds problem started the day she filled with vortex continued for the week and a half of vortex fuel and stopped the day I refilled with BP ultimate. Wife now has strict refueling guidelines for my Z
While the vortex fuel is thinner than BP ultimate and V-Power, 35 degree ambiant temps aren't enough to turn the fuel to vapour in the lines. More likely is that you have an intermittent electrical issue that conveniently dissapeared with the fuel change. Look at the AAC solonoid, and look for any vac leaks. On startup, the ecu uses coolant temp to determine the % increase in fuel delivery for startup, a vac leak post throttle will cause that fuel increase to even out and you MAY have difficulty starting it. The thicker BP fuel will mitigate this a little.
I would agree however it started the day she filled with caltex and ended the day we refilled -from quite empty to boot- the moment we put BP back in, never run it on vortex before and never had this issue in nearly 8000 kms and done nearly 600 since we refilled and not had had a single episode, this by the way coincides with an erratic problem of very slow idle when stopping at lights etc again only during the day that has also dissapeared. nopw I dont believe the fuel is the actual cause but I do believe that its properties may have mad a faulty module (most likely fuel related) play up worse than before. Also this problem with the start was only happening after the car has been running but within a 1/2 hr to 2 hr time frame from shutting the car off, my guess was more likely heat soak from the engine causing the problem (if it was vapor lock) if the engine was left half a day or had not been run at all that day then started no issues.
hi Andy ... your observation on variable fuel "thinness" intrigues me as i had never heard of this before and was completely unaware of this variable property of fuels .... appreciate any more that you can add e.g. how this comes to be, is it an element of the refinery process, additives ... whatever ... thanks .. baz.
Yes I'm also intrigued as I worked in the oil industry for over 35years. All australian fuels have to meet a standard and believe it or not no refiner gives anything away. therefore if the standard states that it has to have a minimum vapor pressure (RVP) of "X" thats exactly what they blend to, same with octane or 50%, 70%, or 95% boiling pt
Sorry BAZ and Martian As we all know any JDM car should run on a 98+ octane fuel rating, As one off the few in NSW , BP 98 is still a true 98 unleaded arround,RON, As for a fuel using ethonol to boost it's RON it might be a negitive position for may a Z The changing fuel, (RON) between states and the ethonol content should be consided ross
ross .. my intrigue is with, seemingly, that one fuel Brand can be "thinner" than another ... i do not know whether Andy is in fact referring to ethanol infused fuels but he did not refer in any way to ethanol... by the way, not all JDM vehicles require 98+ RON .... i use only 95 RON in both my Zeds, one for over 6 years, without any issues ... and i know one very spirited TT zed driver who is tuned to 95, again without issues ... .. and i do not touch ethanol based fuels ...
I'm no chemist, and the comment was based arround when Shell Optimax first came out, it was refined to have a higher density of gasoline, with the idea that with working O2 sensors you would see a viable drop in fuel consumption. BP also followed this route, but from my knowledge caltex never did. I remember having a 98 mondeo at the time, it hated optimax, response was down, felt sluggish, yet it loved vortex. O2 sensors were shagged. After thinking about it more, it's likely you just got a shit batch of fuel, as I run whatever 98 octane fuel happens to be close by when the light comes on and have never had an issue.
In reference to the comments about density of fuel I had never heard it before either but I have heard it 3 times in the last week from unconnected people (one being Andy), one of the informers was saying its to do with the additives being a lot less dense than other fuel brands. This theory I can understand as I am un able to find any real info about it I am not going to make any defining statements but a couple of basic searches have found a few different forums having similar threads some have even mentioned vaporlock and starting issues (one fishing forum was also complaining about caltex australia as the cause). All I know is that is the last lot of calrex fuel going into my car from here
I only use vortex 95 in my zed and have Never had an issue. Car starts instantly every time. Last time I used bp Ultimate I had a catastrophic engine failure in my Mk4 supra while cruising down the hway!!
