Hey guys. been a few years since I've been on here so bear with me :)
Girlfriend & I share a 1993 Mazda MS-8 Efini 2.5 litre V6 with 260,000kms on it. car has proven itself over the last 13 years, has always been extremely reliable, never broken down, but now its starting to play up at idle.
Lately when the car is hot e.g. temp is sitting on 1/2, it starts to missfire & you can feel the engine thumping throughout the car, it missfires worse when I turn on the headlights. It never missfires under accelaration, just idle.
At that same time the Alternator belt was squeeling so i tightened it and the missfire stopped completely and all was normal. 3 weeks later that same belt snapped suggesting it was worn out anyway. Had a new 1 fitted and now the missfire is back with a vengance. haha. could it be something to do with the alternator charge surging causing a bad engine idle! it had been reconditioned a year ago so not sure what it could be.
Any comments appreciated. thanks
mugenb20b,
Nov 27, 6:08am
It's a bit odd that a missfire occurs at idle and not at high revs. I would start by checking HT leads and spark plugs. You might even have a worn out camshaft sprocket or lobe. Is the engine rattly at idle!
can_u_xcite_me,
Nov 27, 8:02am
have done the plugs and leads. still missfires/jolts. find it weird how when i tightened the squeeling alternator belt, the missfire went away for a while up until that belt snapped, was replaced with a new belt and now that damn missfire/jolting is back. Engine makes some tappet noise but we have owned the MS-8 since 25,000kms. its on 260,000kms 13yrs later. so to be expected i guess. will look into camshaft sprocket/lobe. :)
ginga4lyfe,
Nov 27, 8:08am
those MS-8's were notorious for idle and running problems , they commonly get intake leaks and stuff, so i would go over the intake and all the vacuum lines very carefully before clearing them of any wrong doing, then maybe look into other problems
can_u_xcite_me,
Nov 27, 8:17am
Yeh ive been reading up on google about MS-8 efini's and all ive seen is horror stories. must have got a "lucky one" to have had 230,000kms + of reasonably trouble free motoring up until now. still rememba the day i bought the thing back in 97. family and friends laughed at my $15,000 purchase because it had such a weird interior & exterior design for the time. will deffs go over the intake and vacumn systems with a fine tooth comb! thanks heaps for the advice
mugenb20b,
Nov 27, 8:19am
Also, check the air intake hose for splits between the air filter box and plenum chamber.
incar.,
Nov 27, 11:02am
Were the spark plug leads dry, not covered in oil, oil leaking from spark plug gaskets is common
mellisa2000,
Nov 27, 11:07am
Air/vacuum leak. Check also, the dipstick tube seal at the top of the stick. Notorious for vacuum leaks, check all hoses piping and vacuum lines to and from the VSV (Vac. Switching Valves) at the fire wall. Spray with Engine Start/ether along all rubber hoses etc, if it tarts to rev cleanly and idle ok as you spray, then that could be a place to start.
shane038,
6 days, 11 hours
Maybe an o2 sensor, get it checked for a fault code too!
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