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#Post#: 715--------------------------------------------------
Loss of compression
By: Stooza Date: January 15, 2013, 2:59 am
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Right, bit confused so here goes. Mk3 golf gti 16v (the other
halfs daily). Was running fine, no smoke, lots of power until
she went out to it the other morning. It fired briefly on a
couple of cylinders and then died. Tried to start it that
afternoon, nearly fires, then just cranks.
I had the plugs out to check for spark and the spark was
decidedly yelllow. Thinking that the spark may be weak and being
put out under compression I changed the coul pack and put
magnecor leads on. Spark was a nice white and firing correctly.
Still would not start.
Checked the fuel pressure, was fine. Ensured the injectors were
working and they were. So, fuel and spark is present. Did a
compression test to discover I had no more than 100 psi in each
cylinder!!!!
I then had a horrible thought that the key on the cam had broken
and was just turning the pully. Thankfully this was not the
case.
It had been cranked over a number of times, could I have bore
washed the cylinders?? If so, will cranking it over with the
fuel pump relay unplugged and my foot on the floor get the
pressure up? I am really confused and looking for guidance.
Checking the timing properly today but I did look at it
yesterday in the freezing rain and it seemd ok.
Ideas??
:)
#Post#: 716--------------------------------------------------
Re: Loss of compression
By: Stooza Date: January 15, 2013, 3:01 am
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Also, is 100 psi per cylinder low enough to stop it firing?
#Post#: 717--------------------------------------------------
Re: Loss of compression
By: JMR Date: January 15, 2013, 8:34 am
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Blimmey thats low Stu!
First off try another comp tester...or that one in another
engine to see if you get another low result...odd they're all so
low.
Crank sensor?...try another set of plugs...or a buetain torch on
the current ones.
100% sure the timing hasn't slipped?
#Post#: 720--------------------------------------------------
Re: Loss of compression
By: dumma Date: January 15, 2013, 9:48 am
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Have you checked the earths? I replaced nearly everything
electrical on mine only to find a scabby earth on the block,
which was nice.
#Post#: 721--------------------------------------------------
Re: Loss of compression
By: Stooza Date: January 15, 2013, 11:23 am
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Noticed the engine speed sensor cable was brittle and the inner
cores are touching. Low comp was down to a weak battery..
hitting about 170 now :) I will order it and see what happens.
Just sods law that the injectors fired when I tested it.. very
intermittent. Will update when i have changed the sensor. Cheers
guys
#Post#: 723--------------------------------------------------
Re: Loss of compression
By: Stooza Date: January 16, 2013, 12:04 pm
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Ok, saga continues. Crank angle sensor changed.. the old one bas
beyoned buggered! Cables bare and shorting out. Car started and
ran for about 2 seconds.. then died. I have a great spark, loads
of fuel and plenty of compression. Timing has been checked 3
times now and it is bang on the money. Cold start sensor may be
faulty, changing it on friday when one arrives but I
disconnected it and bridged out the plug back to the ecu and it
fuelled much less as to be expected. Earths were a bit dirty so
cleaned them up and they are good now (cheers dumma).
So, whats next? Fuel pressure regulator.. maybe its allowing too
much fuel in and flooding the engine? When you leave the car for
a while it starts for a few seconds and then dies.
Thoughts guys? I cant believe this is proving to be so hard. I
have had the car for 3 years and this is the first problem I
have had with it.
#Post#: 724--------------------------------------------------
Re: Loss of compression
By: Stooza Date: January 19, 2013, 8:13 pm
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Solved! Fuel pressure regulator.. changing the ecu cold start
sensor too just to be on the safe side. New coil and plugs has
gone on with the crank angle sensor. What a pain in the ass! lol
#Post#: 725--------------------------------------------------
Re: Loss of compression
By: JMR Date: January 21, 2013, 5:32 am
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Well done....Wanna sell it now Stu! ;D
#Post#: 727--------------------------------------------------
Re: Loss of compression
By: Stooza Date: January 23, 2013, 8:20 am
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lol i thought it was solved.. get this. Changed the ecu emp
sensor for one off a kr engine, doesnt fit in the hole but runs
fine from cold with it just plugged into the loom. 2 new sensors
for my car have been tried and it doesnt bloody start again...
go figure. Having another go on thursday. You looking for a mk3
valver that runs then Jason? :)
#Post#: 730--------------------------------------------------
Re: Loss of compression
By: JMR Date: January 24, 2013, 3:50 am
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Not currently...MK1 resurrection first... ;)
Your having some bizarre issues with that Stu! ::)
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