Rough idle....

[Sai]

Hey folks,

So my pretty stock (at the moment) 2000 CE 1.5 Lancer has a problem with idling rough.

It drives ok and runs fine over 1,000 rpm but when you come to a stop say at traffic lights it'll drop down to as low as 400 rpm and usually fixes itself and then idles at about 800, though it may idle roughly sometimes even then..

When you start it when the engine is completely cold it won't idle for about a minute (or if it does it'll be rough as *fudge*) and then it seems to decide it likes running.

Sometimes when you're crossing along at say 80kph and you accelerate a little to go up a hill it seems a little sluggish then it'll run fine if you adjust the accelerator a little.

I've had the car for only a couple of weeks now, I've run 2 bottles of injector cleaner thru it, I now run it on 98 as well..

Just to tick off a few boxes I've already given it an oil and filter change, new air cleaner, new spark plugs. I'm yet to pull off the dizzy cap and check that it's not all corroded inside.

I'd really like any suggestions that you've got, sadly after not finishing my apprenticeship with Mitsubishi and not having had many efi vehicles in a little stumped... My next thought was to start swapping out sensors from one at the wreckers..

Once I've rectified this issue I will be looking at what mods I can do.

Cheers,
Sai

 

[pelican]

this may have nothing to do with your idle issue, but if you’ve started running 98 then the extra detergents in it are probably pulling decades of crud off the inside of your fuel tank. might wanna check/change the fuel filter?

 

[SDate42]

Dizzy cap is a super easy one to check and clean. 10 minute job. The distributor is a common point of failure on these 1.5’s. I rebuilt one out of 2 spares, one with a good rotor and one with a good coil. Check that isnt full of oil.

Also pull your plugs off again, check for oil on them. Valvestem seals is another common issue.

Idle control motors often play up too, might be worth a new one of those.

Give the TB a good clean with carb cleaner, upper engine cleaner could be a good step too.

Maybe check the timing with a timing light or go all out and check both timing marks. I had a buddy do his own t belt and it stared and ran as you described yours + was low on power. 3-5 marks off the timing.

Let us know what you find.

 

[Sai]

this may have nothing to do with your idle issue, but if you’ve started running 98 then the extra detergents in it are probably pulling decades of crud off the inside of your fuel tank. might wanna check/change the fuel filter?

Oops, forgot to mention that I'd changed it.. And what a prick of a job when you're tall and have big hands!

 

[Sai]

Dizzy cap is a super easy one to check and clean. 10 minute job. The distributor is a common point of failure on these 1.5’s. I rebuilt one out of 2 spares, one with a good rotor and one with a good coil. Check that isnt full of oil.

Also pull your plugs off again, check for oil on them. Valvestem seals is another common issue.

Idle control motors often play up too, might be worth a new one of those.

Give the TB a good clean with carb cleaner, upper engine cleaner could be a good step too.

Maybe check the timing with a timing light or go all out and check both timing marks. I had a buddy do his own t belt and it stared and ran as you described yours + was low on power. 3-5 marks off the timing.

Let us know what you find.

Thank you. I'll check the dizzy cap and give it a clean first as easiest.

The old plugs weren't fouled or anything so it may not be anything too bad hopefully.

There is a wrecked one about to be fed to the crusher at a local wrecking yard, I might see if I can get all the sensors, idle control thingo and dizzy out of it..

If anyone is after a genuine CE Coupe rear spoiler contact Clarence Valley auto wreckers before it's all gone.. (no I don't have anything to do with them apart from being a customer, just don't want to see good bits go to waste)

 

[Sai]

I've noticed particularly when the engine is cold it's like there is a flat spot in acceleration.. Thought I'd post that too because it might help narrow down the issue at hand...

 

[SDate42]

I've noticed particularly when the engine is cold it's like there is a flat spot in acceleration.. Thought I'd post that too because it might help narrow down the issue at hand...

99% chance of Distributor

 

[Sai]

Just an update ..

Took off the dizzy cap today and found a bit of corrosion in it, I'm going to order another one, however having that cleaned up has increased power a lil bit while driving. It hasn't really helped with idling so much...

Is there any online stores that'll have a dizzy and rotor arm cheaper than going to SuperCheap or Burson's?

But of more concern was that there was a small amount of oil in the cap...having no experience with these engines can anyone give me some advice on that?

One I've got a new cap etc then I'll work on all the sensors.. Oh and the lil engine is using a little oil

 

[SDate42]

Oil in the cap is caused by a leaking distributor o-ring seal. Cost me about $7 for a genuine one. Easy as to change, just pull the dizzy out and there it is. The oil is typically what kills them slowly and causes flat spots ect, as it leaks into the coil, fills it and then comes out into the cap.

Is oil dropping out out of an external seal?
You can test the valvestem seals by idling the car with closed throttle for about 5-10 minutes, and then giving it a full throttle rev. If you see smoke out the back, theyre leaking. The ammount of smoke will tell you how bad.

 

[Sai]

Thank you for the info..

I've not seen anything that indicates various stem seals as yet, but I'll give it a good look on my next day off..

I might look at getting another distributor from the wreckers that hopefully has no oil showing in it, I'll check first.. Then look at changing the o-ring when I do that. Do you think that the dizzy if it is full of oil would be likely to be causing the idle issues too? Presumably if the coil is mounted there and commonly fills with oil then it could well be the root cause??

Not sure on oil leaks in other places, I'll degrease the entire motor next week too and see what crops up after that..

 

[SDate42]

Im still unsure on the idle issue - weird things like that you need to cover all the basic maintainence and easy things to check and then get more technical.

Thinking logically, the car needs compression, ignition and carburettion to run/run well. Ensure you have good comp. if okay, move onto igniton. If not, work out why you have comp issues.

Next onto ignition, same deal.

Then onto air/fuel. Same deal.

The way the dizzy works on the mirage, it has one end inside the rocker cover, that rotates with the camshaft. The single coil is fitted inside the distrubutor unit, constantly charging up. The rotor on the external end delivers the charge through the contacts inside the cap. Cap to leads. Leads to plugs.

I am unsure how an internal oil leak directly affects the coil function, but Im sure its not good.

 

[donki]

Vac/air leaks can cause a similar issue, and can be a bit harder to find because they mimic other issues. The cold/warm issue is that everything will expand when warm, so a pinhole leak can close up and be okay.

 

[Sai]

I was thinking about vacuum leaks because sometimes when you let the brake pedal up the revs rise... Only say 1 - 200 rpm, but that's still a fair bit at idle.. Not sure best way to tackle that apart from simply replacing as much vacuum hose as possible!

 

[donki]

Easy(ish) way to check, grab a can of brake cleaner and spray it around the engine bay when its idling. If the RPM rise up when you spray in a certain spot, you've found where the leak is.

RPM rising when pushing the brakes is normal, its part of the vac-assisted braking system which has been around since the 80s. If the pedal comes up slowly or not at all, you may have found your problem

 

[Sai]

Easy(ish) way to check, grab a can of brake cleaner and spray it around the engine bay when its idling. If the RPM rise up when you spray in a certain spot, you've found where the leak is.

RPM rising when pushing the brakes is normal, its part of the vac-assisted braking system which has been around since the 80s. If the pedal comes up slowly or not at all, you may have found your problem

Actually the rpm drops with the brake pedal... But rise when you release the brakes.. It doesn't do it a second time only when you first come to a stop.

Would normal degreaser work the same as brake cleaner (as I've got 3 cans of it and no brake cleaner atm)

 

[SDate42]

Actually the rpm drops with the brake pedal... But rise when you release the brakes.. It doesn't do it a second time only when you first come to a stop.

Would normal degreaser work the same as brake cleaner (as I've got 3 cans of it and no brake cleaner atm)

Needs to be brake clean or carby clean. Something that wont eat away the rubber hoses, and is still volitile enough to be a fuel if it gets sucked into the engine

 

[Sai]

Ok, thanks, I'll grab some..

 

[Jtrain]

Did you get it fixed, champ?

 

[Sai]

Did you get it fixed, champ?

Not yet, sadly.

Hoping to get the brake cleaner today or tomorrow but I'm not convinced it's vacuum related.

New dizzy cap is at Supercheap waiting for me to collect it (get paid tomorrow) and I'm considering just getting a new distributor from there on Afterpay and fitting that..

 

[Sai]

Ok so I've got some airflow sensor cleaner and I picked up some bits from the wreckers... But I seem to be devoid of a pretty big part... According to Bursons I should have one of these (1st pic).

The bits I've got in the second pic are going to be cleaned up shortly.. I'm kind of thinking that the idle control motor and the air flow pressure sensor may be kind of important here, can't remember what the other one was called, LOL