Hey guys, started having a new problem today and can’t think of what it could be. I was trying to fix the lifter tick on the project car with the revving trick, worked for a while but after 5 minutes or so it came back. I decided to call it a day and drive it back into the shed. When I was rolling down hill in neutral it started revving by its self, up to 1500 and dropping back to 900 every 5 seconds or so. It does it everytime the car is rolling with either the clutch in or when in neutral but as soon as you stop moving it stops as well, some sort of sensor maybe? Really Appreciate the help
Try adjusting the idle bypass screw. Disconnect the battery to reset the ecu and let it relearn the idle.
The stepper motor idle control on mitsubishis is notorious for getting "dead steps" in the range so itll try move out to increase idle onto a dead zone which does nothing so it moves further out which creates a big jump in rpm then itll immediately try reign it in by stepping forward to lower rpm. Again through the dead spot which makes it too low. And you get that cyclic rev up and down.
So if you adjust the manual air bleed screw you can move the steppers range of operation away from the dead spot.
Alternatively try a new idle stepper
The stepper motor idle control on mitsubishis is notorious for getting "dead steps" in the range so itll try move out to increase idle onto a dead zone which does nothing so it moves further out which creates a big jump in rpm then itll immediately try reign it in by stepping forward to lower rpm. Again through the dead spot which makes it too low. And you get that cyclic rev up and down.
So if you adjust the manual air bleed screw you can move the steppers range of operation away from the dead spot.
Alternatively try a new idle stepper
I know it doesnt explain the moving/not moving issue but give it a try
- Thread starter
- #10
Not tuned that I know, I haven’t and the previous owner hasn’t had it done either. Manual from factory. I’ve noticed it gets worse the warmer it is. Just starting to warm up the revs alternate maybe every 4-5secs but then once it’s running temp it’s about ever 2-3 secs
So it's possessed! As stated above the most likely cause is the stepper IAC valve. The gasket used to seal them is quite thin and can drop when installing getting squashed.
You may also want to look at cleaning the 2 air passages that go into it from in front of the butterfly.
Use a decent rag to soak up the throttle body cleaner that flows down and out.
Have a good look at you're connector too, I did have 1 pin bend way back and have no idea how.
Ensure your TPS and MAF connections are good too.
If you've gone through the process of changing out your lifter's, double check you vacuum lines in case you missed one, you can run around in circles chasing faults if one of these is out.
Keep us posted?
You may also want to look at cleaning the 2 air passages that go into it from in front of the butterfly.
Use a decent rag to soak up the throttle body cleaner that flows down and out.
Have a good look at you're connector too, I did have 1 pin bend way back and have no idea how.
Ensure your TPS and MAF connections are good too.
If you've gone through the process of changing out your lifter's, double check you vacuum lines in case you missed one, you can run around in circles chasing faults if one of these is out.
Keep us posted?
- Thread starter
- #12
Ok so I’ve just gone and ordered a new idle stepper should be here in a couple weeks. I’ve checked all the other connections and they all seem fine, went over all the hoses and pipes, nothing I can see there. Could it be something with the wheel speed sensor? Or possibly the abs?
Only reason I can think of ABS or wheel speed having an effect on the engine idle would be via the auto trans if it was a PFL with traction control and something was malfunctioning there but in your first post you said "clutch" so i assume your car is manual
Tony_T
Leaving Skid Marks
Does it do it if you unplug the MAF? When the MAF fails it becomes vibration sensitive so rolling may be enough to trigger it. If unplugging it clears the issue, see my thread somewhere on this fine forum on how to fix it, it's really quite easy. May be nothing like that, but just something really easy to try.
Being the MAF guru Tony, has anyone used an alternative to our $1000 unit? I had read somewhere a particular Evo model worked.
Tony_T
Leaving Skid Marks
@Baba Galant no, I'm no guru on the actual use of the units, I just worked out how to fix the common fault in the factory standard one since I had one fail and wanted to see why it failed. I thought I'd have to buy a new one until I found and fixed the fault so I just passed on the info to the forum so other members could save themselves quite a few dollars. In taking it apart I did see how it worked so that's all I know. @BCX will be correct that you would be able to modify the software tables in the ECU to accept many other types which just give a frequency output, you'd have to adapt the air temp sensor and the baro sensor tables to suit too since these items are contained in the same housing.
Just got my car back home,.died while driving on the freeway! No dash lights, no indicators but it cranks. Stereo, interior lights ok.
Checked fuses etc can't find what's wrong.
Was just coming in to the end off a freeway and managed to roll it to a non existent shoulder and bail. Not room to open to open the drivers door, got a good fast tow back home.
Checked fuses etc can't find what's wrong.
Was just coming in to the end off a freeway and managed to roll it to a non existent shoulder and bail. Not room to open to open the drivers door, got a good fast tow back home.
Power windows and indicators not working, no faults with fuses. Any chance it would be the ECU?
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