Random Misfire is haunting me!

[halo87]

Hows it going everyone this,this is actually my first post and hopefully from the knowledge of fellow dsmers i can fix my problem.I have searched through forums and havent had any luck and well most of them talk about dsm Random misfire and well i have have a 96 Eclipse Rs.Basically I bought my car last year and after a few weeks,it suddenly started losing power in the idle on the freeway so i had to exit and took a look at it in the parking lot.I didnt know what was wrong so i had to tow it back to my house and after long searching and part replacement,i took it to the shop and they figured out it was the ECU.Well when i finally got it back a few weeks passed by and i got a po300 RANDOM MISFIRE code.I have read forums like crazy and basically concluded several things.New spark plug/wires,ignition coil,vaccum leak,low compression and fuel injection cleaning.Basically i already bought new NGK spark plugs and Boush Wires,Ignition coil,and check my compression and it was ok.I have dont mostly all except fuel injection cleaning so before i go any further to spending more money i wanted to get the opinion and help from my fellow members.My car runs fine i cant feel the misfire but i cant pass smog so thats what hurts me.I was looking to have friends that worked at a shop who help me pass it,not legal thou.Just to add for some reason when my car is really cold in the mornings it will idle for a while but than lose power in the idle and start dropping in rpms and than dies so i have to wait a while and soon it turns on back away.Lol hopefully i put a good description of my problem,thanks in advance guys i really hope i can fix the problem cause its my only car for now and it drive me my gf and my newborn.

 

[halo87]

Lol many views but no one wants to reply ummmmmm...

 

[8urwrx]

How often does the misfire happen?

 

[halo87]

Hey 8urwrx well the funny thing is that i cant really feel the misfire.And the check engine light stays on all the time,its not like it comes and goes it just lights up as soon as i start the car and stays on there till i turn the car off.

 

[f'edupTalon]

when was the last time you change the fuel filter? Hows your fuel pressure?

 

[halo87]

Hey f'edupTalon i actually havent changed my fuel filter since i got the car.Im guessing its time for a change?

 

[TofastForU_99]

have you connected it to a computer and deleted the code and then seen if the code came right back on the next time you started it?

 

[halo87]

Hey TofastForU_99 its been already cleared but came back.I already tried disconnecting the battery and reseting it again but sure enough the CEL come back.For some wierd reason when the car goes through rough roads like bumpy ones or if i hit high speed the check engine like will start flashing.Usually the check engine like is always on but at times flashes.

 

[TofastForU_99]

when the light starts flashing it means that the car is misfiring continuously so you should back off when that happens. which i would understand at high speeds but when you hit a bump that should not make a car misfire. do you have the plastic cover that goes over the plug wires on the motor or are you running without this on the car? also has the car ever stalled because of this reason? i had the same problem with my car so im trying to figure out if me and you had the same problem.

 

[halo87]

Hey TofastForU_99 what plastic cover over the wires is that your talking about?Since ive owned it since last year it has only stalled on me once.Thats when i had to replace it with a new ecu.For some strange feeling i have a feeling the shop put in a wrong of faulty ecu but i dont know.

 

[TofastForU_99]

the reason for asking about the plastic cover that bolts to the valve cover is because i had a friend who had a misfire at high rpms and when he hit bumps. and it ended u being the washer on the spark plug was not sealing and there was compression leaking out and pushing the ignition wire off the top of the spark plug and then the plug wire would go up and down on the spark plug. but i doubt this is your prob. but yes i had the same prob as you on my 95 talon TSI i first bent the valves then i replaced them then the car would not run. i had a misfire and i replaced everything plugs, wires, new coils, fuel filter, i even replaced my upper and lower crank sensor because if these are broken or have a crack they wont read right and you will have a misfire. so you might want to check these before you replace the computer. but on the other hand my buddy with the same car ran into the same prob and we replaced his comp and then got a used one from a junk yard and it worked fine and then he started seeing the misfire code then we replaced the comp and he has been fine since then. did you get a used comp?? or new?


But if i were you i would start with this:

1. check upper and lower crank sensors for wear or cracks. also check the wire coming out of the crank sensor to see if they came on done and rubbed on the belts. because it would make sense with the whole thing about hitting a bump and the worn wire grounding out causing a misfire or even at high RPM's when the motor is shaking more then normal

2. try replacing with another comp

 

[halo87]

hey TofastForU_99 thanks for the advice.Well supposely the guys at the shop told me that they had replaced it with a new one and also they had replaced the crank sensor.Like i said i had a funny feeling they didnt do this correctly and with my little knowledge of cars im not sure either.Is thier any way i can check my ECU?

 

[TofastForU_99]

i dont know of any ways to check the ecu the only way i could thing of is to put it in a diff car and see if it happens to theirs.. but you also could get the ecu re-flashed at a local shop or something

 

[halo87]

Oh ya i think thats what im gonna do!Can i test out the ECU on my friends 1997 Eclipse Gs,Oh ya and can they reflash it my ecu although i have a 1996 Eclipse rs non turbo?what exactly is it that they do to it and how can that help my problem.Thanks ahead for the advice!

 

[TofastForU_99]

yes i believe that you can use it in your buddys car since there the same motor. i would check the prongs on both before pulling them. also when you switch them your car has to idle and relearn the ecu. re-flashing your ecu would fix an messed up programing that might be messed up. but if it is anew ecu then i dont see how it is bad i would try taking it back to the shop and say hey i have the same problem and see what kind of warranty you have on the part

 

[95greentsi]

First, take out the ecu. Easiest thing to do is smell it and see if it has any kind of burning smell. If it does, your ecu is probably f'd. Then take the cover off and check caps and circuit board. Another thing is that a used ecu can go from anywhere in the 150-200 dollar range. If you paid a price like that, chances are the shop you took it to put a used one in instead of a new one. I work for a shop and almost every car that has needed a ecu we have put a used one in (not many customers want to fork over the cash for a brand new one).

 

[halo87]

Hey 95greentsi I actually paid quite a good amount($600)and it does look new.I was reading about how u can flash non turbo ECUs? is that right?

 

[TofastForU_99]

not exactly true we sell used ecu's for 50 dollars at my shop... but the whole 600 dollars for a new one is correct

 

[adzozs]

ya deff check your ecu for broken caps. even tho its brand new, i had a new one on my 92 esi and i had a cap blow and eat the board. and it basicly did the same things you are describing. i would also check your MAS. take it apart and check that the resistors and all the solded joints arent corroded or broken and also make sure that your honeycomb in the MAS is clear and free flowing. hope this helps you out!

 

[halo87]

Ya im gonna check that out tommorrow.Im also gonna take a cruise thru pick n pull tommorrow to see if they have any ECU's in case my ecu is the problem.Man Having a random misfire is the worst thing ever its like having cancer in your body errrrrrr