I thought it would make sense to try and get many of the common issues all into once topic in regards to:
- idling issues
- performance problems
- stutter/shudder/stalling/cutting out
- gearbox
- and some more of that
I've been driving a VR4-engined Galant (and Legnum) for quite some years now and over the years learned how to diagnose problems and how to solve them, for a good part thanks to this great community on here!
So time to share this specific bit of knowledge as I very often see the same questions asked. The answer is usually already answered in (several) topics, but a combined 'clean' topic for this kind of troubleshooting doesn't exist yet, I think.
So here we go!
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If you experience ANY kind of (probable) engine-related issue while driving, these are the tests to do, and I recommend in this order. This is to have a good baseline and to exclude some variables.
1. do a boost / vacuum - leak test!
Our cars are getting older, which results in the rubber hoses getting torn, ripped, punctured or loose-fitting. I think it is one of the most common 'problems'. There is a lot of hoses for vacuum and the intercooler and each one that is leaking will be a problem. Some minor, some major.
Another thing to mention here is that with these performance engines, it usually attracks some people to start replacing hoses with non-factory stuff. I won't go as fas as saying this is bad, but be alerted! Some cheap silicone vacuum hoses will completely collapse causing issues that you will no be able to know by just doing a boost / vacuum leak test! If you have doubts, replace them with original hoses.
How to test?!
I use a self made bung / plug that will require an air compressor. If you have it, read on in a bit, otherwise, spray on a (not heated!!!) but running engine some carburetor fluid from a spray can. Do this hose for hose, especially on the connecting-ends. If the engine starts to run faster when you spray in a certain area: examine that hose!
The bung-with-air-compressor is a bit easier. Engine off. All you need to do is take off the flexible hose coming from the intercooler (coming up from the left side when you stand in front of the engine). That hose is connected to the metal Y-pipe that is on/over the engine. Put the bung in the hose, tighten it up and put in some compressed air. Don't overdo this, about 1-2 bar of pressure is enough for any leak to present itself with a hissing sound. So be sure you do this when and where it's quiet.
You can localize any hissing sounds usually by following your ear, but if it's hard to pin point it, use a bit of watered car-wash or bubbly-soap and spray it on the general area. Once you give it some air pressure from the compressor you'll see soapy bubbles.
This bung is nothing too complicated to make yourself if you have a bit of tools: measure the inner diameter of the hose, cut out a piece of wood or plastic of even metal and connect/screw/weld/glue an air connector to it. I used a very tight fit, hot glue and a hammer to get the air connector inThen I have connected it to a spare cheap *ss tire pressure gauge/hose which makes it super-easy to have control over how much pressure you apply and it will automatically 'lock' the air off.
vacuum-boost-bung-01.JPGvacuum-boost-bung-02.JPGvacuum-boost-bung-03.JPG
I have solved many issues that I had with both my VR4 engined cars by just finding & fixing leaks. In some cases it was just a matter of replacing a hose, re-connecting a hose or tightening up a hose-clamp. Low performance, stalling, bad idling, intermittent stuff, leaking injector seals, leaking throttle body adjuster screw o-ring, throttle body gasket leak, etc, I've had it all and I found out about it thanks to this method.
If you've checked and found no issues, we continue to the next logical step:
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reading errors from the engine computers (ECU)
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It's so easy to do, we'll just quickly do it, just to know for sure if there are errors that might have got something to do with your problems.
Only thing needed here is lamp and a paperclip. Engine off.
Underneath the steering wheel close to the center console, you'll see 2 connectors. A black one and a white one. The black one it the one we're after. Bend your paperclip open and connect pin 1 with pin 4.
obd.jpg
Now turn the key into ignition (do not start) mode and you will see your gauge cluster light up like a christmas tree!
Every icon that blinks has an error, except when they are on constantly (non-blinking) or when they blink constant, without any delays. Faults are shown in pulses/flashes: long flash then short flash, showing each code and then repeating. If you get a code like AYC flashes 8 long pulses and 2 short you've got AYC code 82 and 7 long and 7 short is 77.
This is the list of errorcodes:
http://www.clubvr4.com/forum/showthr...e-codes-update
Also if you get any error codes they may be old ones so write them down then disconnect the battery for 10 minutes to reset the error codes then take it for a drive then re-check the codes just to make sure they weren't any old error codes stored.
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Throttle Body (TB) valve, adjustment screw
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The throttle body valve is another thing that is easy to check. Even without opening anything up. There is however 2 situations to test the TB valve: with cold engine/TB and with warm engine/TB.
Let's start with a cold engine/TB:
The butterfly valve in the TB is controlled by a wire. Simply pull the wire slowly and feel if there is more resistance than what should feel like smooth. The spring will keep resistance of course, but opening and closing should go smooth, without any shocks or hesitations. If you feel this: take off the plastic elbow that is on the TB, open up the butterfly valve and clear both the edge of the round valve itself and the surround of the opening of the TB. I use a rag, toothbrush and some carburetor or brake cleaning spray can. Make sure to clean this all off very, very good and leave nothing behind to avoid gunk getting into your engine. Re-test the valve by pulling the TB valve cable and the difference should be noticable.
The warm engine/TB situation is exactly similar as described above, but it could be that with a warmed up TB you do not experience these symptoms, or less obvious, or even the other way around: no problem when cold TB, only with warmed up TB... So be sure you test it in both situations and if you have any doubt: clean it, it won't cost you much more than 15 minutes.
Just cleaning up the TB can resolve (including intermittent) several issues like high idling, poor gas pedal response and even poor performance if the valve is stuck at some point.
Adjustment screw
On the TB there is a phillips-head screw (a bit hidden in a surround, so here's a picture):
tb-tps-idle.jpg
This screw should normally not be needed to be adjusted, but... maybe someone has done something to it at some point... To test / set the screw it would be good to have firstly checked the idle/stepper motor first. If it's good, then disconnect the battery for 10 minutes, then start the engine and let it run for 10 minutes (the ECU will reset/relearn it's settings). Stop the engine, start it up again, wait for another few minutes idling and now the rpm's should be around 650. If it is lower or higher, you can use the adjust screw to get the rpm's in the correct readings for idling.
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Idle/Stepper motor/ISC
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An actual component that occasionally fails is the idle or stepper motor or ISC (Idle Speed Control). It's the brown or black canister shaped thing just under the throttle body. Just to note: the V6 N/A and VR4 throttle body's both use the same ISC (MD628056) which superseded older versions both for PFL and FL either V6 N/A as well as VR4.
The idle or stepper motor regulates smooth idling when you release the gas pedal. Especially when more is required from the engine (e.g. the A/C is activated) the stepper motor will regulate the rpm's to stay at the set minimum.
A faulty stepper motor can cause bad idling (too low, too high), 'hunting' and stalling.
Here's where you can find it and how it looks like:
tb-tps-idle.jpg
And this is how to check/diagnose it (again, quite easy, all needed is a multimeter and the need to remove the plastic elbow air pipe):
stepper motor testing.jpg
In some cases simple (carefull!) cleaning and slight lubrication can solve issues, but often a new stepper motor is needed. Thankfully, these are often available from members and buying new is not super expensive (around 100GBP). A replacement needs to relearn it's settings, so again, disconnect the battery for 10 minutes, reconnect and let the car idle for 10 minutes and it's all set & done.
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MAF sensor (Mass AirFlow)
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The MAF sensor is the black plastic box right after the air filter box. It is measuring the volume of air going through it which should give the engine computer a good idea how much fuel to inject. The MAF sensor can be measured with a simple multimeter: the output signal should be somewhere between 0.5V-4.5V. If the output reads 0V or a full 5V the ECU reads this as a failed MAF and you should then find a replacement.
If your engine has a problem while all of the previous tests in this topic have been done, simply disconnect the MAF sensor plug and start the car. It should run, high in rpm, high in fuel, not like the performance car you knew, but at least it should run. If it does not run, something else is wrong, follow to the other topics mentioned here below.
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TPS setting
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The TPS (Throttle Position Sensor) or IPS (Idle Position Sensor) is telling the engine management computer how far open the throttle body butterfly valve is opened. This component rarely is defect, and only very occasionally is set up wrong.
If this sensor is setup wrong, idling can be too low, too high, top speed can be limited, strange behavior in acceleration, etc.
So if and ONLY if you are sure you have done all test mentioned here before (idle motor, idle screw, trottle body valve cleaning) then proceed into investigation on the TPS setting.
Here's where you can find it and how it looks like:
tb-tps-idle.jpg
This is how this is done:
tps.JPG
If you need to correct the TPS, loosen the 2 screws that hold it in place and ever so slightly more it forward (or backwards), measure again, and repeat this until you get the correct readings from your multimeter. If you have an Tactrix/OBD/EvoScan cable with EVOscan software on you laptop, then setting it up is a bit easier:
Once the Tactrix cable is hooked up to the 'OBD' port underneath the kick panel below the steering wheel, and your laptop is running the EVOscan software & you've made connection with the ECU (key on iginition, starting not needed) then you should see in the EVOscan table on of the very first entries the reading from the TPS. This should be at or very close to 12% at idle and at 96% when the gas pedal is completely pushed in (Wide Open Throttle or WOT).
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Coilpacks, spark plugs & wiring
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Having checked all of the above and still have bad performance? Maybe you'll need to take it one step further and see if the sparkplugs, coilpacks and leads are still as they need to be. I have intentionally saved this because it's not hard to check, but very time consuming to check. The 3 rear cylinders are covered by the inlet plenum/manifold. In order to get to them you'll need to take it out and it's straightforward enough, but it'll take some time!
The sparkplugs need to be NGK Iridium-IX BKR6EIX or equivalent. I would stick to these NGK's or Denso's as those are what are often succesfully used for our cars and also is what you'll get when you order them from Mitsubishi
Okay, now they we know what should be in there, how can you check if your spark plugs are technically good?
Here's a nice overview for a visual check:
spark_plugs.jpg
Here's a good video on how to check the plug leads/wires with the help of a multimeter:
https://www.youtube.com/watch?v=U27Gp_uQDLU
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Shuddering, vibrations & noises
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There are many things that can cause shuddering and vibrations. If performance is good, the common ones are:
1. Tires & balancing
Often on performance cars, and more often when also lowered, the tires can wear off skewed and/or uneven and/or cupped. When tires wear off uneven the balancing that had been done when the tires were fitted will be off. When balancing is off it usually presents itself a specific speeds. If this happens, there isn't much else to do than just replace them and have the new tires balanced. If the tires show evenly wear, have them re-balanced.
2. Alignment
If the cars' tracking isn't aligned you can also experience uneven wear on the tires resulting as said before. Usually the car will pull to the left or right if you let go of the steering wheel on a flat, straight road. Having the cars' tracking aligned will give you the best handling and save tire wear. Do it.
3. Engine mounts
The engine mounts are metal with a center of rubber. Some of these mounts have a oily-substance encased into the rubber for specific dampening. After 10+ years, the rubber wears out and starts to sag. Especially the lower front and rear mounts need to cope with a lot of engine-roll and are prone to wear out faster.
If your car vibrates especially when you accellerate or brake, it's a good idea to look at the condition of these mounts. Replace them with original new ones or replace the rubber for urethane/prothane/polyurethane bushings. Those are cheap but will not be as comfortable and don't have the damping charasteristics of the original ones. In fact, these type of bushes can give other vibrations, although usually more subtle and specifically at certain speeds.
4. CV joints
Each axle has 2 of them! So on a VR4 there's a total of 8! Again, as they're getting older and they start to wear, you'll find they can start to clunk, vibrate and shudder at certain speeds. Failure of the inner CV joints will appear as a vibration through the whole car. It will be progressively worse the harder you accelerate and will happen further up the rev range. Accelerating hard from 40-60mph should shows this up, whereas the same conditions with e.g. gearbox shudder won't.
The outer CV joint will usually get noticed earlier when taking corners and a rather loud ticking is heard. As soon as you return to driving in a straight line the sound goes.
For both joints it's fairly easy to test if you're underneath the car where with one hand you firmly grab the axle shaft and with the other the CV. Try to move the CV back & forwards. If you do this and you feel and/or hear a clunk, the CV has worn. The inner CV's can be given a second life if you swap them over from the left side of the gearbox to the right and vice versa. It's a limited amount of work (just taking the axel out, undo the rubber boot strap, undo the locking clip and slide the CV housing off. Same on the other axle and then connect and mount it all back up. The 3 metal ball-joints inside the metal CV-housing push to 1 side of the inner metal of the CV where it eventually starts to wear. By rotating these CV housings these ball joints will have barely worn fresh sides to connect to, so that's the idea with swapping them over. Ofcourse, there will be play, but you won't usually notice it, maybe when you're reverse driving
5. Ball joints
We have a lot of those on our cars, and they can cause noise, knocking, ticking, shudder. How to diagnose?
Have the car (or each wheel individually) hanging free in the air.
- Firmly grab the tire with 2 hands in a 8:10 clock-position and wiggle (harder on the '10' hand). Nothing? Good. You feel or hear play? Lower ball ball joint failure.
- Firmly grab the tire with 2 hands in a 4:45 clock-position and do an evenly 'centered' wiggle. Nothing? Good. You feel or hear play? Upper ball joint failure.
6. Steering ball joints
These can cause noise, knocking, ticking, shudder. How to diagnose?
Have the car (or each wheel individually) hanging free in the air.
- Firmly grab the tire with 2 hands in a 9:15 clock-position and do an evenly 'centered' wiggle. Nothing? Good. You feel or hear play? One of the steering ball joints is failing. Most probably the inner one though.
7. Wheel bearings
These can cause rumbling, noise, knocking, shudder. How to diagnose?
On steady speed go into corners left and right. If the sound increases when you move into a corner and the frequency of the sound is affected by speed (higher sound as you go faster) this is usually the wheel bearing.
Have the car (or each wheel individually) hanging free in the air.
- Firmly grab the tire with 2 hands in a 12:30 clock-position and do an evenly 'centered' wiggle. Nothing? Good. You feel or hear play? The wheel bearing has failed. Replace the bearing ifself (you'll need a press) or buy a complete assembly where it's just nuts and bolts. If you replace any of the rear bearings: get your tracking aligned, it will almost certainly be off!
8. Wheel hub plates
The 5-stud (or 4-stud if you have a V6/VR2 Galant) hub plate can be ever so slightly bent. Even a tiny wobble will translate to big shuddering. To diagnose there is a section in the workshop manual that will help:
hub-play.jpg
If it's bad, replace the hub plate, and probably the whole assembly...
9. Shuddering while braking
Again, this can be caused because of a problem with the hub plate which will follow on to the the brake discs that will warp in the same manner, only much more noticeable. Another reason for warped disc is overheating, this can occur more easily with automatic gearbox versions as you need to apply the brake while idling, maybe just after a hard brake, causing the discs and pads to heat up and hold heat on a specific area of the disc causing deformations. Also sticky calipers or pads can cause warped discs and thus shuddering and vibrations.
I don't know if there is already a nice complete brake check/overhaul topic to be linked to.
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Not starting at all
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If your car won't start at all, while you hear it cranking over you might consider checking the crank position sensor (CPS). This sensor is known to break on occasion, especially after so many years in the (very) hot engine, the plastic casing gets brittle and the whole sensor brakes. Also after a timing belt replacement and or a torn belt this sensor can get hit or busted and break. A non working CPS will result in no starting.
If the car won't even turn over, it might be as simple as a flat battery (do your lights & wipers still work fully?) or a failed starter motor. If your battery is flat, it will be good to immediatly check the output voltage of your alternator once you've boosted the battery and brought the engine back to life. The alternator should deliver 14.4V to the battery or a little bit more. If it's lower, have your alternator overhauled or find a replacement. Because maybe it's not a bad battery but a bad alternator!
If the battery is good, but the engine won't crank, check your immobilizer. A spare key/remote might solve the mystery.
Contact slot / ignition barrel is another one that can be a problem. It's again not something we see 'all the time' but certainly happens and usually it's giving intermittent starting problems. Replacing the ignition barrel and you're good to go!
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Earthing
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Not a common problem on our usually electrically very sound Japanse cars, but still after so many years of service the earth/body connections can get very oxidized/corroded and cause strange problems and errors. Every couple of years it would be good to clean up the earth connections to the body. I use a thread tap to get all the threads clean to bare metal, brush up the bolts to clean metal too and use a bit of vaseline (petrolium jelly?) to protect from future corrosion yet keeping conductivity.
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ABS/AYC error/lights
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If you have ABS and or AYC lights coming on (for AYC, only the red one of course) then you should know what these errors are thanks to the OBD readout you did before (as shown in the top of this topic). However, if you're wondering what might cause these errors, these a few of the most common:
- AYC switch failure. A change of the AYC switch can prolong the lifespan a bit more. Read more here: http://www.clubvr4.com/forum/showthr...ing-AYC-Switch
- AYC errors can also be caused by having unevenly worn tires and will almost certainly and immediately show uf if you use different sized tires (back/front/left/right).
- ABS errors are often caused because of the teethed ABS rings that are on the outer CV joints. These rings are crimped on, and can snap or the teeth can brake off resulting in errors. It's easy to replace, although these ABS rings aren't available from Mitsubishi as a part, this club or generic part suppliers can deliver them for a few pounds. It's a matter of heating the rings up, tap them off (as they expand by the heat) and put on a fresh one (again, pre-heated so it will fit). Refitting these rings should be done with care, a plastic or wooden hammer protects the teeth from deforming or breaking off.
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Running rich (over fueling) / failing emisions
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Yes, our Japanese friends at Mitsubishi thought it was needed to have this engine consume quite a fair bit of fuel in order to get proper amounts of performance and at the same time keep everything safe and sound. And I guess they did a good job, still, there are exceptions where things get so bad you want or need to fix it in order to save some money or just simply pass MOT certification
Common issues for running rich:
- Lambda aka 'oxygen' or O2 sensor fault. This sensor is located in the exhaust and measures the (remaining) amount of oxygen and accordingly translates this into voltages that our engine ECU interprets into signals to other systems to e.g. change the amount of fuel to be injected. If the sensor provides wrong values the computer will do the wrong things, although it will always fall back on stored safe values, which usually means running rich. A bit of basics on O2 sensor workings: http://www.youtube.com/watch?v=NIzcztO-CCs and how to diagnose your sensor: http://www.youtube.com/watch?v=QM2jO0_Cah0 . Also for MOT reasons, your O2 sensor should be working correctly as a faulty one will mess up emission readings.
- Leaks in the exhaust. Any leaks in the exhaust piping/flanges/gaskets/flex-pieces/etc, even wayyyy after the O2 sensor will cause wrong readings on the O2 sensor, causing the same problems as described above. Checking your exhaust for leaks can be done by ear (is the leak/hole is big enough) but you can also look at the exhaust. At places where you see black dusty residue, there probably is a leak. Another way to check is by holding your hand on the end of the tailpipe (only do this when the exhaust is cold!). This will force exhaust gas exiting other exits (if any). You'll notice! Another 'hands-on' method is by moving your hands a closely over the full exhaust, never touch it when it's warm! If it's hard to locate, use smoke, like from a sigaret and see where the fumes are blown away. One thing to remember: the fans on the radiator can turn on when they need to and they will create an airflow. Other moving parts might also give a swirl of air-movement, so take it into account. For optimal performance and passing MOT a leak-free exhaust is needed. Replace gaskets, fix holes or replace (parts) of the exhaust that are beyond fixing.
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Still performance issues
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Still having performance issues after all this reading & testing?!
1. It could be that you have a timing issue which you can check by taking off the cam belt covers and inspect the timing belt marks on the cams and pulleys with the engine block.
2. Maybe do a compression test, this is a nice video on that subject: https://www.youtube.com/watch?v=WgrfT0LFMhc
3. Could be one or both of the turbo's need replacing (more on that to be described)
4. Replace the fuel filter. If you've never done this, and you don't know if/when it was done: do it, cost is around 15 GBP and the task itself is a 15 minute job. These can get clogged up, although not a common thing. Just a 14mm spanner and some old towels/rags and you swap it out from underneath the car, driver side near the rear wheel arch. This is a dirty dirty dirty filter:
filter.JPG
5. Check the fuel pump (more on that to be described)
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Originally Posted by Davezj
