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Strange mis-fire problem
Car is a 92 plymouth laser AWD
I hope this is where i post this... Anyways i just got my motor put back togather and i have about 80 miles on everything. First off, the car idles great when its cold(900rpm) BUT unless im giving the car barely any gas the car misfires, but only when im driving. Once it gets warm it idles low(varies from 350 to 500) The bottom end is a modern stage 1 block followed by a rebuilt head by modern, mostly everything is new. When i unplug the MAF i get a CEL and the car dies, so that cant be the issue. i Just put in an coil pack, so thats not it.. Car also seems to be running really rich right now Just kinda lost right now, not sure where i need to be looking or if anyone has any idea what could be wrong, your knowledge would be appreciated :) If you need any more info just let me know, i think i covered the basics -Tim |
Re: Strange mis-fire problem
Your car is probably in desperate need of a tune. Have you done a boost leak test since getting everything back together?
Stock coil pack? New or used? If used, is it known to be good? What spark plugs? What gap on those plugs? New spark plug wires? What kind of wires? |
Re: Strange mis-fire problem
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No boost leak test yet, right now im not even running boost, i have the MBC turned all the way down. Also i know for a fact that one of the couplers on the intercooler(aftermarket front mount) is loose. just went out and noticed Coil pack is a stock newish one(barely used) It is good. NGK V power plugs(i think NGK made the v powers, cant remember) Gap is currently .30 Spark plug wires are an unknown brand(came with the car) They are 8.5mm wires |
Re: Strange mis-fire problem
Replace those wires with some quality NGK or Taylor wires. Get that coupler tightened and do a boost leak test.
What turbo do you have and how much boost do you plan on running? A gap of .030" is generally fine for a mild setup, but may be too much depending on your plans. What heat-range are your plugs? |
Re: Strange mis-fire problem
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I have a small 16g, i havent really thought about how much boost i should be running on this, probably just a safe set amount, 15psi or so. This is suppose to be a daily(haha) but we'll see. |
Re: Strange mis-fire problem
.030" gap on a 16G @ 15psi is about perfect. Stock heat-range is 6 (NGK) which would probably be fine with your setup, but a 7 wouldn't hurt.
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Re: Strange mis-fire problem
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FYI, i did take the plugs out the other day and the ends of them are pretty much black, forgot to mention that. it really seems like its getting a mass amount of fuel, however, the fuel pressure is at 40psi. stock i believe was 38 or 39? |
Re: Strange mis-fire problem
I think stock on the 1G was 38, but someone correct me if I'm wrong. Get some new plugs (NGK BPR7ES would be the ones to go with) and wires in your car and get that thing tuned.
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Re: Strange mis-fire problem
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Re: Strange mis-fire problem
Your problem awfully sounds like what my car was doing. What me and a friend did to solve most of the problem's was.
-Swap a different maf in (Reason why stock 1g maf was not compatible when i put in the 3g original maf it stopped burning rich and hit boost nicely) Actually driving it allowing the computer to straighten its self out worked miracles to. -I adjusted my Fast idle control motor screw (Con idle lobe.Mine is close to all the way open) -Fixed every single boost leak (No matter how small it makes a difference) -New Filter with the maf -PCV valve was stuck as well A Proper Tune Would Definetly help.Yet im sure where ever you take it they will check for all those problems. So i suggest look into those potential problems first. Try and fix all the small things and take it in. It will help you safe money, as well as make things faster. Hope This helps |
Re: Strange mis-fire problem
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Yeah pretty much the car will start to buck and just won't want to go anywhere unless i feather the throttle. if i give it barely in gas it will SLOWLY get up to speed, very annoying lol. however, i normally have to stay in a lower gear, in 5th gear it just wont go anywhere |
Re: Strange mis-fire problem
What injectors are you using? Are you using anything as far as tuning equipment?
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Re: Strange mis-fire problem
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http://www.vfaq.com/mods/ICtester.html |
Re: Strange mis-fire problem
i had the same problem with my 2g gst and it would only hold 30% of air in the third cylendar may be u should check compression??
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Re: Strange mis-fire problem
It's probably that coupler that isn't cinched down, any amount of boost would be leaking out easily and cause said problems.
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Re: Strange mis-fire problem
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I can't believe after he admits a coupler is loose and he hasnt done a boost leak test people are suggesting other things.. Also just cause your boost controller is turned down doesn't mean your not running any boost. Can't expect your car to run good if it thinks its getting a lot more air then what it's actually getting. Do a boost leak test and go from there. |
Re: Strange mis-fire problem
^yes enough dicking around and boost leak test it already. Or... just tighten that coupler and see if your car improves.
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Re: Strange mis-fire problem
couplers tight, leaking no boost. problem still persists. Figured i would clear the air on the boost leak here. Bottom of the line, getting money this week, getting new parts.
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Re: Strange mis-fire problem
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Indeed, the car was still making boost which was not good because i'm still breaking in the engine. however, with the couplers tight the problem was less severe. So that was part of the issue. Car NEEDS a tune and a new MAF. Which I'm a newbie with dsm's, so im not sure what to do about a MAF. Seems people run different MAF's. Question is, do i get a stock 1G, a stock 2G, or this 3" GM one people are using? What would i need to use the 2G or the GM one? Thanks for bearing with me guys.. I'm used to VW's, So this is an entire new world to me :) |
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Brand new stage 1 modern block, positive compression is good |
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