Hi guys,

I’ve got a 2003 TL Magna Wagon 3.5L that has recently developed some engine problems I’m at a loss to fix.

A few months ago the car would intermittently stutter at idle in Drive (but not in Neutral), and also stutter when taking off at low RPM (below 2000). It would go away during cruising and higher RPM. The problem didn’t occur on every idle and take off, sometimes I would need to leave the car in D for 20 sec or so before it would stutter. On advice from a mechanic I cleaned the throttle body but this didn’t help. I ended up changing the front set of 3 spark plugs and the problem seemed to go away and I never thought much of it.

But then over the weekend I decided to change the rear rocker cover gaskets as these were leaking (thanks heaps to this forum for the information on how to do this!). One spark plug hole was full of oil from the leak so I replaced all the spark plugs with AC Delco platinum plugs, and put it all back together. The spark plug lead for the plug with the oil looked a bit dodge but I chanced it and cleaned it up and put it all back together. During the test drive the car started developing the problem I had months earlier, intermittent stutter at idle in Drive and on take off, but would be fine when driving along. I thought it would be the dodge spark plug lead so I took it all apart again and replaced all the leads with Bosch leads. Unfortunately this didn’t solve the problem.

I’m thinking perhaps it’s a problem with the new spark plugs or perhaps I didn’t reassemble something right in the intake manifold? The breather hose on the rear rocker cover was a bit cracked in the opening but I’m not sure if this could cause the problem. The car was driving fine until I worked on it (other than leaking oil out the back), so surely it must relate to something I worked on rather than a coincidence?

I’m thinking of swapping the spark plugs back to the old ones for the front bank and then testing again. Also, perhaps unrelated but when I drove to work this morning (with spluttering along the way) the TCL and engine light came on. They disappeared after I turned the car off and on again.

Any thoughts appreciated!

Hmmm, where to start..


This oil build up has be interested. I assume from one of the spark plug housing built up with oil that one of the seals was leaking. Did you replace the three seals at the same time you did the gasket? These should always be done at the same time, as removing the rocket cover and putting it back on can upset how the seals were sitting. Oil leaking down on to one of the plugs could cause the plug to not fire currently.

When reading you initial problem I immediately though idle stepper motor. Taking these out, testing and cleaning them has done wonders for cars with idle issues. Does your idle dip like crazy with the aircon going?

Shot engine mounts have caused bad idle in the past.

Also blocked injectors, which is less common assuming that you've had your fuel filter replaced often (when it should be replaced anyway).

Hmmm, where to start..


This oil build up has be interested. I assume from one of the spark plug housing built up with oil that one of the seals was leaking. Did you replace the three seals at the same time you did the gasket? These should always be done at the same time, as removing the rocket cover and putting it back on can upset how the seals were sitting. Oil leaking down on to one of the plugs could cause the plug to not fire currently.


Yes, one of the tube seals had failed significantly causing the spark plug tube to be completely filled with oil. I replaced all the tube seals as well as the gasket, and cleaned out the oil as much as I could before replacing the spark plug. But the car was actually idling fine with this problem present. Its only after 'fixing' this that my idle problem returned, which has me puzzled. When I subsequently changed the plug leads, I took this spark plug out again to clean it as it was oily. Perhaps some oil leaked into the cylinder which is fouling up the plug? But taking it out and cleaning it didn't help at all.

Its hot in Brisbane now so I always have the air con on, but perhaps i will try with it off and see if this makes any difference. At idle in D it sits about 900rpm and when it stutters it drops to about 600rpm before recovering, its like having a bit of a cough. Same on early acceleration. But the problem is somewhat intermittent, there are times I can stop in D and take off without any spluttering.

I'm not sure about fuel filter, I've had the car 20,000kms and it has an unclear recent service history (184,000kms on the clock). But given the car was running fine before I did the work, would it more likely have something to do with my mucking around?

perhaps unrelated but when I drove to work this morning (with spluttering along the way) the TCL and engine light came on. They disappeared after I turned the car off and on again.

Any thoughts appreciated!

Good the lights came on, as it means an error code is now stored in the ECU.
Rather than randomly doing stuff, find out how to read the error codes.

(Same problem with spluttering and CEL going on but then going off on a Lancer, got error code 23, cam angle sensor. Easy fix.)

But given the car was running fine before I did the work, would it more likely have something to do with my mucking around?

Maybe but you're in for a world of hurt if it isn't because it sounds like your issue was intermittent from the get go. It's more likely that there is another underlying issue than there is for a faulty set of spark plugs or leads out of the box

Good the lights came on, as it means an error code is now stored in the ECU.
Rather than randomly doing stuff, find out how to read the error codes.

(Same problem with spluttering and CEL going on but then going off on a Lancer, got error code 23, cam angle sensor. Easy fix.)

Ok, assume this procedure will tell me?
http://www.aussiemagna.com/forums/showthread.php?t=98435

Will do this when I get home. Thanks heaps!

Ok, I did the error code procedure and got back code 71 (from the engine light). This code is not on that link, but according to a code list I found on the Internet, it relates to 'Vacuum Control Solenoid Valve'. Any ideas what this is and whether it could be the cause of symptoms described?

There are three solenoids attached to the intake manifold front section, it may be these that are the vacuum control solenoids. (I say "may", because I'm guessing).
Check the wiring on these as well as the air lines.

EDIT: I can't help if the error code lookup you did got this result:
"71 Traction control (TC) vacuum valve solenoid fault."
(from http://www.mivec.co.nz/tech/Mitsu_DiagCode.pdf)

Obviously, if your TL doesn't have traction control then I'm looking at the wrong code table.

Wait for someone with more knowledge (>0) to chime in.

If the EGR control solenoid (which is one of the three MadMax mentioned) is stuffed or a bit dicey it can cause the effect you describe, ie. staggering a bit at low throttle openings. Not sure which one it is on a TL (my TJ only has two) but you should be able to trace the vac line from the EGR valve. Perhaps check the electrical connections to the solenoids and even check that they operate by removing them and running 12V through the coil. I think code 71 has something to do with the traction control (don't quote me on this, I'm not at all sure) so I'm not sure it's relevant, it might be worth clearing the codes (disconnect battery for about 10 seconds) and run the engine to see if it recurs. NOTE: disconnecting the battery will clear your radio station programs and you might need to enter a radio security code (not sure if TLs had this sort of unit). It will also reset your transmission settings (if it's an auto, obviously) which can take a while to be re-learned (or there's a procedure you can run through to speed this up).

I should also mention that I had an issue some time ago that was symptomatically similar to yours. In my case, though the EGR valve being incorrectly open was the basic issue, the fault was actually caused by the mass airflow sensor (MAF) slowing dying and feeding false data to the ECU. There were no error codes until it finally died completely and the ECU shifted to failsafe airflow settings. Not sure if it could have been diagnosed before it failed totally so that's probably not much help but maybe worth mentioning.

Yes, the TL Wagon has traction control but maybe the check engine error code is a red herring. There may be a problem with the traction control but surely this won't affect idle and low revs.

Thought I had a eureka moment when I pulled off the PCV valve and it was all gunked up so I cleaned it. But to no avail as my test drive didn't even make it out of my driveway in D and it was sputtering on the way out. I've been reading more about how the PCV works, perhaps a blockage in one of the hoses in this system (either between the rocker covers or the one from the intake), would it cause idle problems? I noted the end of the hose which attaches to the rear rocker cover is actually split and I put a hose clamp on it but perhaps its leaking?

Perhaps I should also mention that when I was changing the rear rocker gaskets and removing the plenum chamber, I noticed that the gasket for the EGR pipe at the back of the chamber was not installed correctly (it was hanging from one bolt and not through the other and therefore causing a leak). This was done by the dealer I bought the car from because I had asked them to change the rocker cover gaskets when I bought the car. I've put the gasket back properly during this recent change of gaskets. The gasket looked in ok condition.

If you get absolutely nowhere, and are tempted to torch the car, just remember that a weak coil will not throw any specific error codes while making the car run like a dead dog.
Get another distributor from a wreckers, and try that, perhaps?

Why am I thinking ignition coil?

From your first post "I ended up changing the front set of 3 spark plugs and the problem seemed to go away and I never thought much of it. "

It's a classic symptom of a weak ignition coil.

Hmm, generally when coils start to go the suffering starts at mid to high revs with low revs and idle being ok, which is kinda reverse to the OPs symptoms. Having said that, I agree, it certainly could be the coil... it does weird things when it's going and I've overlooked it as the culprit a few times. Re the EGR pipe gasket not being fitted properly, I don't think this would be a big problem, at least I can't see it causing the problem you describe. Not sure of the chemistry involved but if I understand it correctly, the EGR adds a bit of exhaust gas to the air/fuel mix which effectively lowers the combustion temperature, reducing the production of nitrogen oxide created (which is nasty, apparently). Diluting this with fresh air would probably just reduce it's effectiveness and lean the mixture a bit, but if the valve is working correctly you probably wouldn't notice.

A blocked PCV system is not a good thing, but generally it will result in smoking at take off after idling for a while (similar symptoms to valve stem seal problems) as the pressure in the crank case isn't relieved. It also tends to mean a lot of varnish on the inside of the engine, if you noticed a layer of shiny brown lacquer over everything when you had the covers off it means it's been blocked for a while. The cross pipe (from the back to front covers) is the most likely culprit, mine was blocked solid. Best bet is to replace all three hoses (available from Mitsubishi, don't use standard heater hoses) and grab a PCV valve (Repco do them MUCH cheaper than OEM, something like $15 compared to $95 in Vic). I don't know if a blocked PCV system would result in running issues, it probably would eventually but a leaking system would probably have a bigger effect.

EDIT: If all else fails and you are near a wreckers, grab a MAF (easiest is to grab the whole snorkel from the filter to the throttle body) and pop it in. I generally don't really like the 'replace everything until the problem goes away' approach but sometimes it's really the only way to eliminate the fault. Not sure what a MAF will cost but yours will go eventually so probably a good spare to have about the place anyway.

Ok, I did the error code procedure and got back code 71 (from the engine light). This code is not on that link, but according to a code list I found on the Internet, it relates to 'Vacuum Control Solenoid Valve'. Any ideas what this is and whether it could be the cause of symptoms described?

If it was from the check engine light you are right, there is indeed no code 71 that should be returned from the check engine light.

If it was from the TCL light there is a valid code 71 which relates to the ECU communication circuit system.

I didn't have much time to muck with the car last night, but I swapped the spark plugs for the front bank back to the old NGK ones (regular not platnium), the problem seems improved somewhat but still present. Bad coil not liking the new/platnium plugs?

Also, got the check engine light and TCL light on the way to work again today, at about the same time of driving as yesterday. I will clear the codes tonight and see if it happens again tomorrow and note down the code.

Thinking of trying the following in this order:

1) Clean the throttle body: easy to do and might as well try it
2) replace the PCV valve and 3 hoses
3) replace MAF sensor
4) replace fuel filter
5) replace Distributor (might need some help on this one, haven't done this before)
6) replace engine
7) replace the car

Seem like the right order?

Don't forget to check the idle stepper motor. No use flushing junk down to it (cleaning the throttle body) if it's just going to make it worse.

How about:

Remove number 4 plug lead (centre of front bank).
Get any old plug. Open up gap really wide, 5 mm or more. (or just break the ground strap off)
Put plug on an earth connection where you can see it easily.
Run engine. (it will run rough on 5 cylinders)
Look for big fat consistent spark at the spark plug.
No spark = weak coil.

It's an old way of testing a coil. I know the coil off a TS 4 cyl will throw a spark 2 to 3 cm long. Sparky showed me on a test rig.

Don't forget to check the idle stepper motor. No use flushing junk down to it (cleaning the throttle body) if it's just going to make it worse.

Couple of bits of tape over the two inlets at the throttle body mouth are supposed to stop cleaning fluid from getting in there. Tape up, then spray away!

Ordered the 3 hoses relating to the PCV system today, $20 for the breather, $20 for the crossover hose, and $8 for the one attaching to the PCV. Also ordered a new PCV on ebay for $20. My gut instinct is that it relates to this system, because the breather and crossover are both split where they attach to the rocker covers, and I just used a hose clamp to try and seal them.

Otherwise, MitsFix have MAF sensors for $89 used, so I may try that next. Will also test the distributor on the weekend.

Appreciate the help available from this forum!

Well, on the weekend I had a play around and cleaned the throttle body and took off the idle stepper motor and gave it a clean. The car ran great on the test drive afterwards and I thought the problem was fixed, but then after about 1/2hr of driving later the sputtering and rough take off came back... Any thoughts? Surely I must be on the right track if the problem goes away for a bit. Gave the TB a clean again last night and same result, fine for the first 20min or so then back to the same old problem.

Question: When taking off, is the situation better with a very light throttle, or is it worse? In other words, can you avoid the sputtering by accelerating really, really gently or is that more likely to make it almost stall? The reason I ask is, if it's better with gentle acceleration it could be the coil, if it's worse I'd be thinking EGR or MAF issues or an air leak into the manifold (eg. split vac line somewhere). The 30 minute delay is a bit odd though, if it wasn't for the fact that that's a long time for the engine to get up to operating temperature I'd be thinking maybe a dodgy engine temperature sensor or maybe the wax pellet in the throttle body is buggered (that's a guess, I don't know how this would manifest). If the ECU thinks the engine's still cold when it's actually hot it will be running rich, might be worth checking the sensor. Also worth checking to see if the engine is actually getting up to temperature, maybe a stuck thermostat?

Question: When taking off, is the situation better with a very light throttle, or is it worse? In other words, can you avoid the sputtering by accelerating really, really gently or is that more likely to make it almost stall? The reason I ask is, if it's better with gentle acceleration it could be the coil, if it's worse I'd be thinking EGR or MAF issues or an air leak into the manifold (eg. split vac line somewhere). The 30 minute delay is a bit odd though, if it wasn't for the fact that that's a long time for the engine to get up to operating temperature I'd be thinking maybe a dodgy engine temperature sensor or maybe the wax pellet in the throttle body is buggered (that's a guess, I don't know how this would manifest). If the ECU thinks the engine's still cold when it's actually hot it will be running rich, might be worth checking the sensor. Also worth checking to see if the engine is actually getting up to temperature, maybe a stuck thermostat?

Taking off with light throttle doesn't make any difference. The sputtering occurs under 1500rpm whether I accelerate hard or lightly, but then disappears after 1500rpm approx. Its not on every takeoff though, maybe 1 out of 5 takeoffs there is nothing and its smooth. Same with the idle. It can idle ok for 10 secs or so then start sputtering with rpm dropping below 500, then the ECU seems to kick in and revs rise automatically to prevent a stall.

The delay was actually only after cleaning the TB, which made me think I fixed the problem. I drove around the block for 10 mins ok and was ready to do high fives. Then next day drove to work and the problem returned. So the TB clean seems to temporarily fix the problem for the first maybe 10kms, which is why I thought it must be something to do with the TB. Repeated this again yesterday and same result - seemed fixed but only for a short while. Tempted to just replace the TB with another secondhand unit available for $85. Is there any special requirements to swap over a TB? I can do the actual physical changeover but don't want mess with adjusting settings or anything like that.

I've eliminated the PCV system as now I've replaced everything in the system, with no change.

Ensoniq5, I did a bit of reading through the archives and came across your thread re your MAF sensor. Thought this seems similar so did a clean of my MAF sensor with a MAF cleaning spray, but no change. Also gave it a bit of a tap on top for good luck but no change.

Been also reading about EGR causing the problem if its stuck open. Perhaps I could try blanking this off temporarily and seeing if there is improvement?

Test the spark plug leads if you haven't. Sounds like something dodgy that could be caused by a lead.

Blanking off the EGR is a valid way of eliminating it as the issue, worth a try, though generally issues there result in a lean mix that really only shows up with small throttle openings (where the extra air has a bigger impact on the mix). In my case no amount of cleaning fixed my MAF, whatever was wrong with it was basically permanent. Eventually it died completely and threw the error code so I grabbed one from Mal here in Vic along with the whole snorkel, can't remember the $ but wasn't much. I'm struggling to see how the TB could be the cause, or more to the point how cleaning it could have a temporary effect, but I'm a bit hazy on the operation of the wax pellet in the bottom of the TB which I know can be adversely affected by throttle body cleaner (though I don't know the symptoms... anyone?). Changing it over would be fairly drastic and you'd need to get it set up properly by someone who knows what they are doing and has a MUT-II scanner.

One possibility that's happened before is an injector signal wire being crimped under the plenum chamber, it's very easy to do when changing plugs and leads. Check that all the wires are clear, free and properly plugged in. As I think MadMax mentioned, there's a good chance it's the coil, particularly since the issue seemed to develop on its own and doesn't seem (at least originally) to have been the result of something going wrong during a service or repair. It could also be dirty injectors or a fuel issue like a clogged filter, though I would expect this to be worse at higher RPM/wider throttle openings. In your position I would be thinking seriously about letting the pros have a look at it, if there's a good Magna bloke nearby it might be cheaper than replacing bits one by one.

In your position I would be thinking seriously about letting the pros have a look at it, if there's a good Magna bloke nearby it might be cheaper than replacing bits one by one.

I'm starting to think the same. Crossing fingers hoping it doesn't stall as I cross intersections on the way to work is not a nice feeling. Will ask around for a Magna guy in Brisbane.

Cheers

Test the spark plug leads if you haven't. Sounds like something dodgy that could be caused by a lead.

Yep, replaced all the leads with new Bosch leads and no difference at all (except to my bank balance).

EDIT: blanked off the EGR today with no result, so can rule that out also.

I have similar issues to this that I am going to search for this week . My car is worse when lights , indicator, electrics are on though?

I have similar issues to this that I am going to search for this week . My car is worse when lights , indicator, electrics are on though?

Check battery voltage with everything on.

Just an additional thought... would an exhaust leak cause idle problems? Reason I ask is that the wife mentions my car smells a bit fumy so perhaps a leak in the exhaust close to the engine causing poor idle/take off?

Any fix so far?

Nope unfortunately. Booked in for a mechanic on Thursday, will let you know. Have ordered a used MAF sensor and new O2 sensor as well. Looks like the car runs really rich which is why I thought its one of these two. The instant fuel on the trip meter shows up to 40-100L/100km when the car is crawling in traffic!

Sounds like the ECU may have gone to failsafe mode, which it will do if it can't calculate the correct air/fuel mix (eg. if the MAF is disconnected or totally cactus). This is usually accompanied by the engine light coming on, if yours is not lit then it could be something else, though I don't know what. After Thursday when it's been diagnosed and hopefully fixed, make sure you post what the problem was.

Well... mechanic put an inspection camera in the intake manifold and said it was all gunked up, put some cleaner through it and said the car blew black smoke for a while. Then it ran fine. Driven it a few kms and it seemed ok, but then this morning on the way to work problem was back again...

Have ordered a new O2 sensor and will put that in on the weekend. Otherwise I'm kinda out of ideas. Will take it back to the mechanic next week.

On another note, my check engine light and TCL off light problem has been fixed (code 72). I bought a secondhand TCL solenoid off ebay and put it in, easy as.

I don't believe (but I could be wrong) that a dodgy O2 sensor would cause you to use 1 litre of fuel per kilometre... that must be almost pouring out the exhaust pipe. A dirty TB/plenum/manifold won't be as efficient as a nice clean one, but still won't give figures like that. I would call 40-100L/100km a catastrophic failure of something vital, like an injector that's just pouring petrol or the ECU reverting to failsafe mode (though if you have no engine light/error code that would seem to be eliminated).

EDIT: Ignore this comment, I misunderstood the OP's post.

I would call 40-100L/100km a catastrophic failure of something vital

I guess you haven't spent time crawling in traffic while watching the inst. fuel consumption. I can get 60L/100 km just backing out the driveway.
You do get numbers like that edging forward slowly in traffic.
In fact, if you are stationary with the engine running, the display blanks out because it can't show Infinity L/100 km. lol

Actually, you're quite right, I took "crawling in traffic" to mean kinda standard city driving but, indeed, if actually moving at below walking speed the numbers will go that high. I therefore unreservedly withdraw my previous comment with apologies!

Dunno if you're still having a problem, but what fuel are you using? The cheap stuff, e10?
Iv had a similar but not identical problem and I'm putting it down the cheap crap fuel as when iv added injector cleaner to the tank, the problem instantly goes away, therefore making me think that the Inj cleaner is increasing the potency of the fuel...

Ok, update. Called the mechanic and he wasn't helpful and didn't sound like he wanted me to take the car back for another look. So I thought I would get back to basics again after theorising about all sorts of things. Problem came back only after I did the gaskets on the rear cylinder bank, so it must be something I did during that time. One thing I changed was the spark plugs, so I bit the bullet and pulled the manifold off again (3rd time) took out the plugs and put in some regular NGK's. Although they should be platinum, I didn't want to incur the cost again and I can change the rear bank easily myself in 30,000km.

Put it all back together and wow, drives like new...

So, after cleaning and changing the MAF, cleaning the TB, changing the O2, changed PCV system, blanked off EGR, new leads, and time wasted spraying stuff at vacuum lines, putting stuff in the fuel, and at the mechanics, it was the AC Delco platinum plugs that were new out of the box that caused me the trouble.

Lessons learnt:
1) Only buy NGK plugs
2) Don't believe a new item out the box cannot be faulty
3) Get back to basics when looking for these types of problems

I can change the rear bank easily myself in 30,000km.

Lessons learnt:
1) Only buy NGK plugs
2) Don't believe a new item out the box cannot be faulty
3) Get back to basics when looking for these types of problems

Great post!
You may find the standard plugs don't need swapping out at 30,000 km, if you check the fronts after 30,000 km you can check for gap erosion and take it from there.

+1 on using NGK only.

...it was the AC Delco platinum plugs that were new out of the box that caused me the trouble.


Did you check the plug gap when you installed them initially? Many people don't and this is where problems can lie.

Did you check the plug gap when you installed them initially? Many people don't and this is where problems can lie.

Except the makers of platinum plugs say not to regap as they are gapped from the factory, and rough handling may weaken the joint between the platinum electrode and the central conductor. Don't want to have a piece of platinum break off and do damage to the engine, now do we?

Except the makers of platinum plugs say not to regap as they are gapped from the factory, and rough handling may weaken the joint between the platinum electrode and the central conductor. Don't want to have a piece of platinum break off and do damage to the engine, now do we?

One can still check the gap, Max. I still check the gaps on my platinum and iridium plugs prior to installation as I would with copper plugs.
If it is out of spec, don't use it, save the guesswork.

Except the makers of platinum plugs say not to regap as they are gapped from the factory, and rough handling may weaken the joint between the platinum electrode and the central conductor. Don't want to have a piece of platinum break off and do damage to the engine, now do we?

I confess I didn't check the gap but probably should have, for the reasons MadMax mentioned and also I don't have a feeler gauge handy. I guess I should have checked the gap even though it shouldn't be re-gapped, just to make sure it is correct.

I just grab 2 plugs and compare them side by side. Quick and easy. No need to poke that electrode with a feeler gauge either.
Haven't ever found a NGK not gapped correctly, so I've never been faced with the adjust or throw away question.

Be wary of shelfworn stock with bashed up boxes that someone might've dropped on floor before.

Juggling over a dozen fresh NGKs this week, found 1 whose cardboard collar had dint from impact. Checked all gaps just to be safe.

Just to update my thread with the final outcome after nearly a year of mucking around. The car became idling rough again despite the new plugs, and changing them again did nothing. I tried a whole bunch of stuff including fuel injector cleaner, swapped the MAF, O2 sensor, leads, PCV, blocking off EGR. Was about to give up on the car and sell it.

I then had to change the distributor 0-ring due to oil leak, and while doing so gave the dizzy rotor and cap a clean up with sandpaper. This fixed the idle for a few hundred kms until it became rough again.

I then swapped the distributor with one from a wrecker for $50. The replacement was from an older car (2000 model), but seemed to be in good condition. As soon as I put in the new distributor the car started and idled very differently. Runs very smooth now and also feels different (more responsive and powerful) under throttle as well as idle. It must have been misfiring intermittently even when under throttle. Anyway, its been about 2000kms and all good. Its the longest I've had a smooth idle for ages.

Hope this is useful to someone else chasing a similar problem. Ultimately it was an ignition issue and was temporarily fixed by changing the plugs, but the real source was the dizzy (probably the rotor and cap, although could have been the ignition coils).

Thanks for the update.
Unfortunately ignition problems on the third gen Magna won't throw error codes, so you are reduced to the change-bits-and-see-if-it-helps method.
On the coil-on-plug engines like the 380 error codes will tell you which cylinder is misfiring, so you know where the problem is, but of course it is then a question of . . . plug or coil? lol