I have a 3.0l TF

Just replaced the rear rocker gasket, and thought all went well, but now the car idles and accelerates roughly with no pulling power.

Feels like it is running on 5 cylinders, but all plug leads appear to be seated. Did not remove any plugs, and only removed the leads from the rear bank. They came off very easily

I had removed all of the usual TB wires and tubes, but cannot see anything that has not been properly re-connected.

I had removed the Distributor cap to check the condition, but I am sure it went straight back on without a problem.

Is there any way I can narrow down the likely problem before removing the inlet manifold and re-assembling

I earthed connector 1 on the diagnostic socket, but just got constant flashing of the engine light, which I understand indicates no error codes

Thanks

Any chance you've crossed two spark leads, or not pushed the leads back on fully (can take a bit of a shove to seat them properly)? Otherwise, check that no injector leads were crimped under the plenum chamber when it went back on, this is easy to do and can short an injector.

I have a 3.0l TF

Just replaced the rear rocker gasket, and thought all went well, but now the car idles and accelerates roughly with no pulling power.

Feels like it is running on 5 cylinders, but all plug leads appear to be seated. Did not remove any plugs, and only removed the leads from the rear bank. They came off very easily

I had removed all of the usual TB wires and tubes, but cannot see anything that has not been properly re-connected.

I had removed the Distributor cap to check the condition, but I am sure it went straight back on without a problem.

Is there any way I can narrow down the likely problem before removing the inlet manifold and re-assembling

I earthed connector 1 on the diagnostic socket, but just got constant flashing of the engine light, which I understand indicates no error codes

Thanks

Did you re-connect the MAF Sensor loom?

Thank you for the suggestions

Plug leads - did not remove the leads from the distributor cap, and I don't think leads are long enough to put on the wrong plugs(?) Will need to remove the intake to check this. FWIW, I have tried removing the plug leads one at a time, and the car runs rougher each time, indication that it is unlikely to be an individual plug/lead

Injector lead - quite possible that I have kinked or loosened one. I expect the plenum will need to be removed to confirm this. Would it show as an error code?

MAF. I assume the MAF loom is the large harness on the airbox - which is connected (car stalls immediately if I leave it off). Is it possible that the messing around removing the air intake has knocked/damaged/dislodged something in the MAF unit?

Thanks

Thank you for the suggestions

Plug leads - did not remove the leads from the distributor cap, and I don't think leads are long enough to put on the wrong plugs(?) Will need to remove the intake to check this. FWIW, I have tried removing the plug leads one at a time, and the car runs rougher each time, indication that it is unlikely to be an individual plug/lead

Injector lead - quite possible that I have kinked or loosened one. I expect the plenum will need to be removed to confirm this. Would it show as an error code?

MAF. I assume the MAF loom is the large harness on the airbox - which is connected (car stalls immediately if I leave it off). Is it possible that the messing around removing the air intake has knocked/damaged/dislodged something in the MAF unit?

Thanks

A disconnected MAF Sensor will make the car run rough, but it would still run. It would set off the check engine light on the dash board if it was unplugged.

It could be a vaccum leak. I take it you removed the upper intake manifold? Maybe it did not seal properly when you put it back on.

Would it show as an error code?

MAF. I assume the MAF loom is the large harness on the airbox - which is connected (car stalls immediately if I leave it off). Is it possible that the messing around removing the air intake has knocked/damaged/dislodged something in the MAF unit?
I don't think a snagged injector line would show an error code but I could be wrong there, and you might be able to tell if any leads are snagged with a torch and a bit of a fiddle around, without taking the plenum back off. Re the MAF, with the lead removed the ECU will run on 'default' mode, ie. it will use preset values for airflow, air temp etc., and should still run (not very well and VERY un-economically, but it'll run). In other words, I don't think your MAF is the problem. I'd do another full check of all vac lines and plugs, particularly the brake booster line on the back of the plenum and all 4 (I think) to the throttle body (three on top, one on the front - mine's a TJ which is a bit different I think). Also check that the intake pipe from the air filter to the throttle body hasn't split and the PCV system is hooked up.

EDIT: Also, oil in the spark tubes can cause problems, this can happen if the tube seals are worn. Is it possible any oil found its way down a spark tube while replacing the cover gasket?

possibly it *is* running on 5 cylinders - I replaced the seals on my 3.5L and being a tight arse didn't replace the spark plug seals which have to mate with the rocker cover and oil leaked down onto the spark plug and I had 5 cylinders for a 400Km trip - and it was not pleasant.

Vacuum leak possibly.

Some gunk might have falling down in to the idle stepper chamber, my brother had this recently and it caused the car to run like a pig.

If one of the leads was wrong I don't think it would run is it would be firing in the wrong order, or well.. even if it did run it would be very obvious :|

It looks like I mayl have to remove the inlet manifold to check some of these suggestion.

Vacc leak - The manifold seemed to drop back into place without issue, and correctly torqued. As per advice on other threads, I did not replace the gasket

I replaced the plug seals, and do not think oil could have filled the tubes during assembly.

Don't think it is a plug because, as mentioned above, it runs even rougher when I remove each plug lead in turn. If one was faulty, I expect there would be no change when removing the lead for it

Injector wires look okay when peering under the manifold - not touching the chamber

Neo - what/where is the idle stepper chamber? I was aware when removing the air intake and the plenum/TB that they were upside down and shaken around at times, so dirt could have dislodged

Double checked all hoses and nothing obvious

Could I have done something to the TPS? I didn't remove it - just disconnected the wire connector

Engine idles roughly, but seems to run fairly smoothly if you slowly build revs up in neutral, but it shudders and misses if you attempt to do it rapidly. Driving around the streets is a real pain with stalls and shudders.

Don't think it is anything to do with problem, but what is the diamond shaped metal plate bolted to the back of the plenum. Mine is missing a bolt, but seems to be sealed tightly. Bolt was missing before rough running occurred so I don't think it is related

Don't think it is anything to do with problem, but what is the diamond shaped metal plate bolted to the back of the plenum. Mine is missing a bolt, but seems to be sealed tightly. Bolt was missing before rough running occurred so I don't think it is related

Diamond shaped metal plate on the back of the plenum! On the side closest to the throttle body should be the EGR Valve, on the other side is the EGR Intake Pipe. I don't think it suppose to be just a "plate" although I have heard of people blocking up EGR valves with a plate.

In any case they should both have a gasket and the second bolt. The idiot that previously owned my car had put back on both items without gaskets and my car ran like crap. When I discovered it and installed gaskets it made a marked difference. You don't want any extra air getting sucked in there as it will throw your car's computer out of whack when it is doing calculations...

The gaskets cost $6.83 and $16.69 from Mitsubishi as per attached invoice.

https://lh4.googleusercontent.com/-l4y1qOattI0/UvLpSfjUzOI/AAAAAAAAAsM/1TAZcMHJEfk/w1357-h496-no/2014-02-06+12.36.28.jpg

http://i228.photobucket.com/albums/ee207/HD-SPDFRK/Galant/0608091247-00.jpg

It's a TF, they don't have EGR do they? Also, if the problem happens other than when idling, ie. if it runs like a pig with a bit of throttle, I would expect that to rule out the ISC as its only function is to regulate the idle speed. If the throttle position sensor has moved significantly it would cause problems but that would be difficult to do accidentally as they are normally locked down pretty good. A bolt missing from the blanking plate on the plenum (where the EGR pipe would connect on a later model unless I'm wrong about that) could be the issue if the plate is not sealing. Bearing in mind that the problem was not evident before removing the plenum chamber to fix the cover seal (I assume it was just the plenum you removed rather than the whole intake manifold) it stands to reason that the fault relates to something disturbed in this process. This eliminates bad fuel/fuel filter and I guess the distributor, so if all hoses and plugs are correctly attached and not leaking my best guess is a bad/broken/dirty/not fully seated HT lead. What's the age/state/brand of your high tension leads?

Madas. On the TF, it is just a blank plate on the back of the plenum. Inserted a second bolt, but no change

Ensoniq. It was the plenum and not the intake that I removed. Which makes me wonder - where others have stated in other threads that you do not need to replace the metal gasket, are they talking about plenum to intake manifold, or manifold to head gasket.

Didn't touch the TPS. Cannot rule out bumping it (but seems unlikely). The car doesn't seem to run any worse if I disconnect the TPS harness

At 80km on constant throttle, car seems to run smoothly but gives a shudder/surge every 2-6 seconds

Car has done 150k - cannot recall the HT leads being replaced. Had half ruled out leads or plugs because removing any lead makes things worse

Thanks

Removing the plenum, not the manifold, is the right thing to do and the other threads will have been referring to the manifold/plenum gasket, so no probs there. You're quite right about the leads, if disconnecting each in turn just made things worse that does seem to eliminate them as the cause (I think). At this stage I would do one final check of all hoses and plugs for connectivity and no leaks, maybe give the various electrical connectors removed in the operation a clean with contact cleaner, reset the computer (negative lead off battery for 10 seconds), remove/block each vac line in turn to see if there's any improvement, make sure the PCV hose from the intake pipe to the back valve cover and the other one between the covers are in place and not split or blocked, and if the cause doesn't show up it's probably time for the pros. I dunno if there's anybody Magna-savvy in your area, others might be able to steer you in the right direction if you don't already know someone.

Straw clutch No1

For a while the car has been a rough idler under load, which in hindsight I expect is a flakey ISC. I was wondering if my problem may be due to a further deterioration of the ISC.

Does the ICS do its thing at idle revs or does it work when the throttle is largely closed. Reason I ask is that the car runs smoothly on a trailing throttle, but carries on when you crack it open regardless it seems of engine revs

Can someone describe how I can test the ISC. I removed it from the TB and, when switching the ignition on and off the plunger moves in and out no more than 1-2mm. Is this the normal movement range

To test the ISC, the manual just says to listen to it using a screwdriver or a stethoscope (wondered why my doc wears a screwdriver around his neck). Are there other ways to test it?

Thanks

From memory the standard test is to undo the plug and measure the resistance between each of the centre pins to the pin either side of the centre pins. The pins are arranged in two rows of three, so consider them numbered 1 to 3 on the top row, and 4 to 6 on the bottom. Measure the resistance between 1&2, 2&3, 4&5, 5&6. The measurements should all be equal and between 28-33 ohms (roughly, varies with temperature). If any of the measurements are out the ISC is probably stuffed.

Re how much it moves, it will only move a little bit at a time. From what I can gather the ISC only comes into play when the throttle is fully closed, at which time the throttle position sensor tells the computer to regulate the idle speed with the ISC. Once the throttle is opened the ISC ceases to function and I guess will be locked in position. Below is the procedure to set your throttle position sensor for a TH/TJ (without traction control), I can't guarantee that it's identical for TE/TF but somebody might be able to verify this.

1. Disconnect the connector of the throttle position sensor.
2. Connect an ohmmeter between terminal 2 (second from left with plug notch up) and 1 (left most) by using jumper wires.
3. Insert a feeler gauge with a thickness of 1.4 mm between the levers shown in the illustration to a depth of no more than 3 mm. NOTE: Inserting the feeler gauge more than 3mm will result in incorrect adjustment.
http://i59.tinypic.com/208cp5f.jpg
4. Loosen the throttle position sensor mounting bolt; then turn the throttle position sensor body fully counter clockwise.
5. In this condition, make sure that the closed throttle position switch is ON. (There is continuity between terminals 1 and 2.)
6. Slowly turn the throttle position sensor clockwise until the point at which the idle switch is turned OFF (continuity between terminals 1 and 2 changes to non-continuity) is found. Tighten the throttle position sensor installation bolt at that position.

Checking the TPS for correct operation other than the idle position is a bit more complex, possibly a more desperate straw to clutch at this stage. Rough idle is generally cause by a dirty and clogged throttle body, Madmagna has a great cleaning tutorial somewhere on this site. Having said that, I don't believe it will be the cause of your running issues unless it is really, REALLY filthy and it wouldn't come on suddenly.

Just another thing to check, are you certain you fitted the throttle body/plenum gasket the correct way up/around? I believe if this is installed wrong it can cause problems. The big black convoluted intake pipe is also prone to splitting, they get a bit stiff and can crack when they are removed. A crack will upset the mixture since the air is coming in after the MAF, so the ECU doesn't allow for it when deciding the air/fuel ratio. I'm running out of things that can be disturbed by changing the rocker cover gasket, it could be time to consider other things like fuel filter etc. and consider the timing a coincidence however I would be thinking it could be time for the pros to take a look.

Thanks for persevering ensoniq

I'll strip everything off on the weekend and try again, as well as try testing the two switches

With respect to the gasket, I did not touch it - just lifted the plenum off and later dropped it back on. I'll check for damage on attempt 2

Thanks

No probs, good luck. The gasket I was referring to was the one between the plenum and the throttle body, most likely it stuck to one side or the other and isn't the problem, just one more thing to eliminate.

When removing the plenum, I left the TB attached so I am not expecting any issues with that gasket

Flipping the plenum around to inspect it may have resulted in dirt ending up in places it shouldn't in the TB


I will strip everything off on the weekend and recheck all connections.
Thanks

I normally leave the TB in place, less to disconnect (ICS and TPS plugs, coolant pipes, throttle cable). It stays there no probs on the support bracket at the back. It's very possible that some crud has lodged where it shouldn't in the TB, when you've got it off give it a good inspection to make sure all the vac pipes are clear and nothing's clogged. There's a great TB cleaning tutorial here (http://www.aussiemagna.com/forums/showthread.php?t=31580) by Mal (Madmagna), well worth doing whether it's the cause of your problems or not.