Is the ISC "seeing" base idle?

You may need to check it's idle switch.

Yep I tested the switch and it's working properly.

I adjusted the Variable Resistor to midway... Set the TPS again to be on the safe side... during the procedure I heard a vacuum leak as I applied pressure to adjust the throttle screw, and after some careful searching I found a MASSIVE split through the brake power booster vacuum line, it wasn't visible as the hose was braided!... I'm going to replace that hose today, and so far the engine seems to be idling at around 850rpm after setting the TPS... I'll let you know how we go once that hose is replaced!

So I set the TPS @ 0.48v

Took the cordia for a drive and she no longer stalls... but the revs do hang when you change gears, which is a pain when you're at 4000rpm... 

I've replaced the split vacuum line to the brake power booster, but it still has a bit of a miss when trying to get the car moving, once the revs pick up she boosts really well until about 4,200rpm when it misses again and there's a VIOLENT deceleration, then the engine kicks back in... causing some terrible torque steer.

Well atleast she isn't stalling now, just got a couple of other strange behaviours now! lol...

I'm thinking maybe it's the fuel filter or something, I'll check for ECU errors and go from there I think! 

Does it do it in neutral when you rev up to 4200rpm?

No, I can rev it out to redline, it doesn't hesitate when stationary.

Disconnect the airflow meter and take it for a drive, if it doesn't miss at 4200 rpm, then you have another vacc leak when reconnected. 

Before I say anything, let me explain what I mean when referring to the following 2 words:

Miss = Engine intermittently stops firing in any cylinder momentarily.
Hesitate = When opening the throttle, the engine lunges before it begins to pull.

Okay, now I'll continue ... 

Well I figured out the problem, I disconnected the AFM and she stalls... I was gonna take it for a drive then got thinking about the vacuum line arrangement again... Decided to spray some "Start Ya Bastard" at the ends of all the vacuum lines but didn't seem to find anything... I replaced a couple of old lines but still rough to rev up... Then I thought about the Vacuum Advance again and checked that.. yep, works fine... but the vacuum nozzle from the manifold doesn't seem to have any vacuum coming from it at all... So I switched the Boost sensor and Vacuum Advance lines around on the manifold and she started smoking (but the missfire had gone)... I wondered if I connected the two if the problem would be any different, so I rearranged the Vacuum Advance so it connected via a T-Piece to the same line as the Boost Sensor and put that on the nozzle with good suction... Ran the other nozzle to the emmissions stuff...

Started the car and the smoke was gone, the engine miss was gone too... and now only has a slight hesitation when you first get the car moving, and pings high in the revs when pushing it hard. Seeing as it is not missing now, I decided to not drive it with the AFM disconnected, cops are everywhere as it is, and still gotta get the exhaust changed over.

It's currently set to around 10 degrees BTDC... What could I do to fine tune the way she runs to stop it pinging/hesitating? thanks for all the help! :)

Three things steve:

Use high octane fuel

Put an intercooler on it

Retard the timing (but this will cause low end response to suffer)

Funny how the engine is pinging with the new injectors...........you might have to look at turbo outlet temps as you are now running a larger turbo which MAY cause the engine to lean out due to larger "positive" air charge.

true true... yeah well I have always put in BP Ultimate 98 octane... looks like I may need to look at an intercooler then.

I don't think I mentioned this before, but it revved to about 6000rpm and was STILL pulling hard (started pinging right up the top) (it's never performed that well with this turbo before), so you're probably right in saying it's likely heat related..

I have some money available now to get my muffler done... and would have enough to get an intercooler too, 

Which of these coolers would fit? I'm not too sure what I'm looking for size-wise or angles of the inlets (i'm running power steering too, I hear that makes a difference)...

I can buy one today if I know what I'm looking at. Ebay have a stack http://shop.ebay.com.au/?_from=R40&_trksid=p3907.m570.l1313&_nkw=intercooler&_sacat=See-All-Categories

If you run an intercooler could you make a write up for the install? Also even though the vacuum nozzle on the manifold doesn't seem to have vacuum it'd pay to block it off if you haven't already incase it clears itself lol. Good job though, you seem to always have trouble with this cordia.

Just have a quick measure between your headlights, never liked intercoolers down the bottom due to road debris bouncing off them.

I have a magazine with an intercooler fitment on a cordia, I'll see if I can find it.

Found it:

wow thanks heaps Andrew! That article will come in very handy, I might print it out and take it to the exhaust guy and see what he reckons we should do... Sounds like I could get a heap more power out of the engine by cooling it!

Mi.Rage - I ended up plumbing that vacuum line into the emmissions system, to the PVC or PCV (whatever it's called) haha... near the carbon canister... ;) I'll be happy to knock together some sortof a write up for the install, would include photos of the cooler etc...

I'll be in touch! 

Oh just wondering what can I do to get the revs to drop when I change gears, it hangs pretty bad... ?!? I set the TPS @ 0.48v

UPDATE - I took it for a drive this morning and it nearly stalled coming in the driveway, then dad drove it and it stalled and backfired on him a couple of times! Grrr... Doesn't look like the idle issue is resolved afterall! :(... Oh and it's hesitating down low in the revs, up high it boosts really well, but doesn't like to get moving at all, it kindof doesn't want to pull at all and then it boosts really hard to redline!

Sounds like the ISC is keeping the throttle open during gear changes...........did you re-set the TPS when the engine was running temp and with the ISC disconnected?

If connected, This can cause the ISC to retract when the engine becomes hotter, therefore closing the throttle plate further causing idle to drop.

I actually like re-setting these by removing the ISC altogether, that way base is base...........and if the ISC needs adjustment is just a matter of "intercepting" is extension or retraction signal.

The only other way to fix the "high" rpm is to set the TPS at 0.45 volts.

So I had the new rear muffler fitted this morning, and it sounds beautiful! Also set the TPS the other day at 0.45v and took her for a drive today, but is still hanging on gear changes, not all the time but seems selective. I discovered a funny vacuum line on the vacuum advance that kept falling off, replaced it with a slightly longer one and now it won't fall off so that's good... Now the timing set at 8 degrees BTDC runs great, I figure the vac advance must have been disconnected before, which is why the timing wouldn't line up!

So yeah, seems to be running good now, except for the hanging. lol

I've given up on trying to set my stupid TPS. During the procedure to set it, once you've got the voltage right you then open up the throttle, let it close and check the voltage is still good.

What i found is if you let the throttle snap back, you get one reading. If you gently place it back you get a different reading. I adjust it clockwise, no voltage change. I adjust it anti-clockwise i get a voltage variance of about 0.4V with about 1mm of movement. I try a different TPS, same thing. I try a third, same thing. Maybe they're all buggered but you can't buy them new anymore, not that i know of anyway.

End up setting it on 0.50V by gently placing the throttle back against the ISC. Tighten the screws, then i snap back the throttle and it goes as low as 0.39V. I even found that the voltage changed due to me tightening the screws back up, just an incremental amount of movement and the voltage changes.

Drives ok but i get the hanging that you are describing between gear changes. Sometimes when i approach a red light, i whack it in neutral and the engine has a complete spazz attack. Jumps up to 2k rpm, i tap the throttle, back to idle then straight up to 2k rpm again. Does this about 3 or 4 times and i'm thinking the guy next to me must think i want to race him, with me revving this engine, trying to get the idle to settle.

And then there are times i'll drive 30 or 40k's without a single hiccup. I just can't work it out. I've been driving like this for about 3 years now. What i'm finding now too is that when i'm decelerating, still in gear, the ISC is trying to give the engine more revs. This is the cordia cruise control. I've actually sat on the highway, maintaining about 90kmh with no right foot input. It's not good when you are braking and the engine is still trying to rev.

So my engine is blowing smoke on idle, most likely valve stem seals. Don't see that it's worth fixing. The TPS problem is not going to go away, so i'm giving up on the 4G62.

If all goes well i'll be driving a VR4 cordia within a couple of weeks. Just thought i'd share this with you. Exciting stuff.

ok... umm out of interest guys.

I've never had a Cordia Turbo so have never had a detailed look at the throttle system in it.

But.. i am a Techy and have a bit of electrical know how.

If you CANT buy the TPS new, and it seems to just be a variable resistor. Couldnt you just go down to JayCar Electronics and buy a Variable resistor taht operates within the ranges you need (maybe adjust it to be exact requirments from changing its resistance with some other reisistors in line, maybe smooth it with a CAP if nessersarry????), and Rig it up in place of the original TPS? As that seems to be all it sounds like the TPS is.....

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The Garage

- 1987 Mitsubishi Cordia AC GSL
- 1993 Lexus SC400 4.0GT
- 1984 Mitsubishi Cordia AA GSL

I'm just about to do this on my new AC...........the problem with the procedure is it doesnt state to remove the ISC altogether.

The problem with shutting the throttle after adjustment is the idle switch in the ISC won't contact, snap it shut and it will.

What I've found to work is run the engine until normal temp, slacken the throttle cable, remove the ISC, adjust the base idle then adjust the TPS...........this way the ISC can't interfere for when the throttle is closed it will always return to base. After final adjustment reinstall the ISC.