what problems could be caused by the heat

my misfire problem is definitely due to heat!!! i never have any problems in the mornin.

normally(?) my problems only start after the engines been running for 50+miles, today it started after 10.
when should my fan kick in? it seems to be hardly ever workin which isnt right as we're in a heatwave.
what could be causing a misfire only in the afternoon when the whole car is hot, despite not havin been driven!!!!!!!

this is really startin to get to me
 

not

I have an idea but its not well supported by searching the forum on terms like "Rough running", or something. I can't remember where I heard it (might have been here under an indirectly related topic)…..

It could be that the hall sender in the distributor, or dodgy wiring to/from, is on the way out and when it gets hot, intermittently works, causing rough running/misfiring etc.

thank you mate wkd!

could that explain a bit of carbon on one of the dizzy caps terminals?

Fuel evaporation??? :dontknow:

Whats the rad cap like ? if waters evaporating out as steam through the cap then the level will drop below the water temp sensor. It will turn its self onto warm up mode .... very rich fuelling . this happend to mine a while ago .

i did hear a hiss from the expansion tank cap yesterday, but the levels are well within min max indicators

thats what mine was doing , got a new cap and i havnt heard it since !! the cap is designed to vent off excess pressure when temps get very high but its governd by a pooey little spring thats week and feeble . try it it cant do any halm .

just got her back from the garage and fuel pressures at 85psi so its not fuel, amd gonna try and sort the dizzy this weekend, and header cap

nice 1 guys

cabriaulait said

thank you mate wkd!

could that explain a bit of carbon on one of the dizzy caps terminals?

As hairyarse suggested evaopration, but probaly due to fuel getting warmer caasing the octane level to reduce and the reduced spark causing the fuel not to ignite so easily.

Rob  

so i do need to improve my cooling system , ie my mk2 rad thread

No, fuel tempeture is not part of the cooling system, It just a problem with the weather. Cheaper fuels will do it more, it just as they get warmer the octane can escape and if your car is setup for 98 ron unleaded (Standard for golf) and you are using 95 ron (General unleaded at pumps) then it won't take allot for things to run a little rough.

My car runs on 95 ron perfectly (Super Market) but if i put in standard shell it runs allot better, not tried optimax yet, too expensive!!!!

Rob  

Try the optimax. I think it has noticable results.

not that then, im running esso supreme 97 ron with an octane booster to raise it to 98+

gonna go down the dizzy route methinks

Sounds like the dizzy is a very good starting pont.

Rob  

am i better sorting out the one on there or just replacing with a new one

You can also have a coil that is almost dead.  As internal insulation in th coil starts to die, you can have temperature related problems.  Check to make sure that all of your electrical connections are tight (wires to the coil, etc.) when it is hot.  

Matthew

cabriaulait said

am i better sorting out the one on there or just replacing with a new one

By a new cap, and leads, then maybe a hall sender, if its not any better, but check the coil out as well, It's always a bit of trial and error.

Rob

thanks guys,  mill autos here i come

quick update,
changed dizzy cap, rotor arm and coil
and it was a bit better but still there

then i put my mk2s rad, fan and thermoswitch and

BINGO

chq this terminal out

it hasnt happened since and ive really tested it, pulled away in 5th from 20mph and not one misfire before, that would have been impossible.

my oil temp is now 98 max, the temp gauge stays well below the halfway
mark, i think my fan wasnt being controlled properly and it was all just too hot in there for the wiring and coil

lookin back i probably just needed the coil and a new thermoswitch but it would of needed it all anyhow so what the heck.

cheers for the pointers

now i can get it tuned :wink: