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Idling at 200rpms p0300 97 GST

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Bestdayever

Probationary Member
5
0
Aug 16, 2013
Toledo, Ohio
So I bought a 97 GST fixer-upper, thinking awh itll be a turbo swap and ill be driving in no time, after replacing all the studs, oil line feed and drain, turbo manifold and o2 housing starter and battery, I finally got it to run, it ran fine drove it up and down the street with no problems. Parked it back in the garage for the night and came back down the next morning and it is idling rough at about 200 rpms consistantly. If I give it gas it will idle smoother at about 1000rpms. revs very slow when I give it a good punch of gas.
Any Ideas? I've already done plugs and wires, Don't really know much about DSM's.
 
"Slow" revving, or RPMs raising fairly slowly, has always been a cause of either timing being off a tooth(or two) or running very rich in my cases.

Check your mechanical timing and then do a boost leak test.

EDIT: Missed that you have a code. Still could be from the above reasons, but check your ignition system as well.
 
"Slow" revving, or RPMs raising fairly slowly, has always been a cause of either timing being off a tooth(or two) or running very rich in my cases.

Check your mechanical timing and then do a boost leak test.

EDIT: Missed that you have a code. Still could be from the above reasons, but check your ignition system as well.

We looked at the marks and were kind of confused how they are supposed to line up, but they were both at about 300 degrees if you were looking at a full 360 degree circle.

Yeah if I clear the code or take the battery cable off, it comes back within a couple seconds. it's weird cause it doesn't die, it will just idle at ~200rpms, after driving fine yesterday.

also we sprayed starting fluid around the vacuum lines and manifold and didn't find anything there.
 
We looked at the marks and were kind of confused how they are supposed to line up, but they were both at about 300 degrees if you were looking at a full 360 degree circle.

Yeah if I clear the code or take the battery cable off, it comes back within a couple seconds. it's weird cause it doesn't die, it will just idle at ~200rpms, after driving fine yesterday.

also we sprayed starting fluid around the vacuum lines and manifold and didn't find anything there.

Alright, so you confirmed you have no vacuum leaks. It doesn't matter if the cam timing is right, you also need to line up the crank marks. I was having similar issues and it turned out to be the ecu. But everybody is different. For some it's just a clogged fuel filter. Did you test the coils and the transistor?
 
It could be your Crank Position Sensor going bad.

Check this thread that had the same code (post 20).

http://www.dsmtuners.com/forums/newbie-forum/260269-multiple-cylinder-misfire-p0300.html

Also, do a boost leak test, Turbo cars are different then not turbos.
Not turbo cars, you can spray carburator cleaner and it accelerates saying that it has a leak,,,,, In our cars (turbos), this trick doesn't work, You have to do a boost leak test in order to find the leak.

Hope this helps and let us know what you find.

Edit,

Here is a good video on how to do a boost leak test.

[ame=http://www.youtube.com/watch?v=T963989F3c0]How to do a boost leak test - YouTube[/ame]

Enjoy it.
 
Thanks guys. Im having a buddy come look at the marks since idk what im looking for.
Another thing i was gonna try was testing fuel pressure? What should my pressure be at, at the shrader valve port?
The gas in the tank is 8+ months old.
 
Wow, get that fuel out of there and pour some fresh fuel in it, good thing it starts with that fuel.

I know i realized that after i started it. I was like uhhh this has been sitting for so long...

So i was messing around today and i unplugged the map sensor and it did NOT changr anything. Also took theplug off the throttle body and it didnt die but changed idle slightly.
Is this normal?
 
Update.
Got it running for one day. Then it started over again.
I figured out its misfiring on 2 and 3. Replacrd the coil and it still does it. The wires are not getting power.
Any ideas? Im thinking power transistor?
 
We looked at the marks and were kind of confused how they are supposed to line up, but they were both at about 300 degrees if you were looking at a full 360 degree circle.

With both dowel pins at the top (roughly 12 o'clock) the timing marks should meet in the center, between the two gears. Like so:

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So i was messing around today and i unplugged the map sensor and it did NOT changr anything. Also took theplug off the throttle body and it didnt die but changed idle slightly.
Is this normal?

By MAP sensor, are you referring to the 2-bolt sensor on top of the intake manifold? If so, that's just an MDP sensor which is purely emissions related. I'm assuming the other plug was the TPS? If unplugging the TPS didn't do much, that's a good sign. The TPS and MAS should both be working then.

Update.
Got it running for one day. Then it started over again.
I figured out its misfiring on 2 and 3. Replacrd the coil and it still does it. The wires are not getting power.
Any ideas? Im thinking power transistor?

I would check/replace the Crank position sensor and inspect the trigger plate while your there. It wouldn't hurt to test the power transistor (although it's easiest to just swap in a know good one), but I'd suspect the CPS.
 
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