Stock EVO 9 skips a beat/slight misfire
Sep 18, 2018, 04:03 PM
#1
Newbie
Thread Starter
Stock EVO 9 skips a beat/slight misfire
Hello there, looking for some help with my Evo 9! I got the car last December, bone stock 2006 RS.. did all the necessary maintenance with only OEM parts, timining belt, puleys, tensioners, spark plugs, filters etc,running amsoil 10w30 signature. Car has NO mods, at least known to me..no exhaust no re-map..bone stock. It was running absolutely fine, until maybe begining of summer, when temperature started to raise. Car is running fine upon starting and until it warms up after that though it starts skipping a beat every 5-10seconds if i do a few hard runs and let it idle, the idle itself stays absolutely calm and steady, you can notice the skip at the exhaust, it changes its note for a second, whats weird is that it doesnt do it all the time..pulled out the spark plugs and looked fine to me / i DID NOT gap them btw, they have the stock factory gap/, dont think there is a vacum leak, its boosting all right, was sluggish during the hot days but that is normal. Now that the weather cooled down a little bit, it does not do it that often! I dont know what to check at this point..i was thinking maybe lifters or valvles? Car has 88,000 miles. I would appreciate any advice/opinion ! Thanks
Last edited by DilyanM; Sep 18, 2018 at 04:30 PM.
Sep 19, 2018, 08:38 AM
#6
Newbie
Thread Starter
Yeah i am pretty sure they are stock, car was running just fine when i got it,i should ve noticed if the cams werent stock. Coincidence or not it started doing it with the beginning of summer. I will gap the spark plugs, gap could have gotten even bigger ever since put them, 5k miles on them now,.
Sep 20, 2018, 01:01 AM
#7
Evolving Member
Man this is funny. I was having the exact same problem with my car for the first month or so I had it. Drove me crazy. It felt like it would skip a beat all the time! I can tell you one thing, that once I quit putting crappy CA 91 gas in it and strictly run e85, it idles great. My tuner is running like 10 degrees of timing at idle which may be what fixed it.
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Sep 20, 2018, 07:27 PM
#8
Evolving Member
My car has a slight miss at idle sometimes. I figured it was the MAF but have cleaned it many times and the miss always comes back. I want to do new spark plugs again and gap them as well. My car will miss most if I run it hard while hot temps outside. When I get off the gas to let it idle it will have a miss, pulling a away from a stop it will miss slightly for a moment then be normal. Driving under acceleration it pulls like it should no issues. I have never figured this out.
Sep 21, 2018, 10:34 AM
#9
I had the same issue when my car was on stock cams, it would sound like a misfire but engine would never stumble and idle wouldnt drop so i never worried about it. Plus it drove just fine so i figured it was "normal". If anything you could replace the spark plug cables with new OE ones.
Sep 22, 2018, 05:45 PM
#11
EvoM Community Team Leader
follow all the hoses around the throttle body and make sure nothing popped off. Then do a boost leak test.
Sep 25, 2018, 03:08 PM
#13
Newbie
Thread Starter
Believe it or not a had a bad/disconnected negative, the one right behind the intake and under the strut tower bar! Replaced it last night with a aftermarket one, a bit larger...so i cross my fingers and see how that goes! Cleaned the +/- of the battery as well ! Thanks for the responses,will keep you posted.
