Mitsubishi Eclipse 3G Club banner
1 - 18 of 18 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
I've got a 2001 Gt that seems to want to idle around 1500 rpm. Its setting code p0507... for high idle. To begin... I bought this car non running with blown head-gaskets. Pulled the engine, had the valves machined, new: timing belt, gaskets, water pump, spark plugs, rotor, thermostat, PCV valve. After I got her running she sat an EGR code, it turned out to be the solenoid so that's fixed.
When you start it up from sitting over night sometimes it wont idle and you have to keep your foot on the gas to keep it running for a minute or two. then it's good to go for the rest of the day usually. It just idles high.

*First I used the search button!
*I cleaned the IAC valve and throttle body... no change.
*Then I used carb cleaner to check for vacuum leaks, and found none... the idle was constant around 1500 rpm.
*I tried unplugging the IAC, no change.
*Put in a 3G_GS IAC... hell of a change, crazy jumping idle lol, I had one so I tried it... to me this suggests that the circuit is at least working because I assume the computer was trying to find idle via the incorrect IAC and resulted in large variations in the idle
*So i replaced the IAC, no change.
*Checked for vacuum leaks again. none found.

So now I am wondering about the MAF sensor, I tried unplugging it, the car idles closer to where it should__1000-1100 rpm. NOTE: this car does have a cold air intake of an unmarked brand... it came that way. I examined the sensor and there are 2 tiny nicks in two of the honey combs, but they are very small. If you disconnect the intake tube from the throttle body you can make the car idle correctly by controlling the percentage of air that actually goes through the MAF. Could this be my issue? Its an expensive part so I hate to just buy one on a whim. Once again it idles low sometimes on cold start-up, and then high the rest of the time, it will go down some with the AC on, but its still too high

PS: I'm in Mabank Texas, kinda close to Tyler. This isn't my first 3G, actually its my third. Had some questions so I finally decided to join!
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #3 ·
I replaced the EGR Vacuum solenoid. But I haven't done anything to the purge solenoid.
At one time I had a EGR circuit failure code, I pulled the EGR Valve, and it was moving freely, and holding vacuum. So I put it back together and still got the code as expected. I then replaced the EGR Vacuum solenoid (the brownish one) this took care of the code.

I just searched the purge solenoid and I saw where someone left theirs unplugged and their car ran terribly.... I actually unplugged mine yesterday and the car ran the same so maybe that's the problem. I was going to install the extra one I have yesterday but its from a GS and it looks a little different so I didn't. Ill try jacking with it some more, if it is the issue I assume it will be stuck open?
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
I still haven't figured this problem out. I removed the plenum again and throttle body, installed a stock intake, and I tried another Mass airflow sensor. I didn't find anything wrong and the car still runs the same. The purge valve seemed fine also. I followed the IAC testing procedures and it seems fine however I have never felt, heard or seen it move while attached to the car. I am getting power from the MFI relay, but I don't have long enough leads to check continuity to the ECM Plug at the moment. Honestly, I'm beginning to think that I have ECM issues.
 

·
Premium Member
Joined
·
306 Posts
Heres something to try loosen the screws on your TPS(Throttle Position Sensor), loosen them enough to where it turns itself and then tighten them back up. This happened to me. The TPS was turned the wrong way. After it turned, the car idled normal.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #8 ·
I contacted the previous owner, and he thinks he tuned it to run at 1500 rpm. (He obviously shouldn't be allowed under the hood, it takes skill to wire headlights backwards) When you first start it it idles lower. So I'm thinking he turned up the idle to make it run when you first start it up cold. So from that I decided to go ahead and mess with the idle screw since its already been jacked with. If you screw it in all the way the car wont idle cold but when warm it idles at 900, and 800 with AC. I've got it backed out about 1 round so that it will idle after about a minute of running, and will slowly increase to about 1200 rpm.

I've also run into another issue, I'm getting code P0421... its for the bank 1 catalytic converter. probably just an o2 sensor, but with 176k miles it may be due for a cat too. Could a clogged Catalytic converter be my idle issue too?

I tried loosening the TPS but so far i cant really tell a difference.

As far as how it drives....I'm not sure what I should expect out of it. It seems to drive fine. It is obviously faster than my GS was but it isn't that much faster, it was kind of a let down. It drives pretty good, but I feel like a V6 mustang would kick its butt.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #9 ·
I gutted the cats, and adjusted the biss screw to 1.5 rounds. It has more power and is idling better. But... It is still cold natured. If it's cold it still won't idle correctly.
 

·
Registered
Joined
·
84 Posts

·
Registered
Joined
·
45 Posts
My idle was really high like this (1200rpm or so) but I cleaned the throttle body, idle control sensor, and the maf sensor and it lowered it. I don't know if its "normal" but my idle is 600rpm and doesn't fluctuate at all.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #14 ·
Yeah I gutted the cats and I've been running it without the "Trick" because I hadn't gotten a chance to install them. It never sat an 02 code over about 200 miles... As soon as I installed the non foulers it started throwing codes. I think I'll be taking them back off. The only reasons I can think for it not setting a code is that maybe most people don't completely clean out the cats, or the fact that it has a flowmaster supper 44.

As for the idle, I'm pretty certain the IAC isn't actuating. Now that the biss screw is in the correct place I'm planning on trying a new IAC. If that doesn't work then I'm just gonna sell it as is.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #15 ·
OK so I got a brand new IAC in the mail today. Put it in, unhooked the battery ground to reset the ECU...
It started out idling around 3k, and will sometimes surge around 2500-3k.
I drove it for a while, and the idle went down to 1500-2k surging. but as soon as I pulled the Ebrake the idle shot back up. I drove it several miles stop and go with no change. Itl'll cruise in 5th at 40mph with no foot on the pedal. there is no change if you unhook the IAC.
THE IAC's ARE NOT MOVING!
The difference in the idle is obvious... the new IAC and the old one are in different places. Because neither have changed position this lends to the assumption that the issue is either in the wiring or the ECU.
What would be the best course of action? This seems like an odd problem, and I hate to go out on a limb and buy an ECU.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #17 ·
I just went through the procedure, and it still seems to be the ecu.

*also the procedure was for a 2.4l engine, so the ecu terminals for the 3.0 are actually: pins: 14, 15, 28, 29. terminal C-51 for MT, and C-52 for AT. Mine is a MT. As far as I can tell that should be the only difference.

Now I need help buying an ECU. I've searched and I know I have to buy a paired ECU an Immobilizer. And it must come from a MT, V6 car. I figure ill buy one with a key, and just leave the key in the steering column essentially deleting the immobilizer. So that my old key will still work. That is unless there's an easier/cheaper way to do this? Do the immobilizer numbers matter as long as they are from the same ECU?

My ECU #'s: MR507644 E2T73083 H2ZC E070T903FC
I haven't pulled the immobilizer yet.

What should I pay? I found this one on eBay and it seems like it would work for $220. Most don't seem to come with the immobilizer. There is one other one without a key for $182, But for $28 it would be better than paying to get a key programmed.

2001 Mitsubishi Eclipse GT 3 0 MT Engine Computer Module ECU ECM MR507644 w Key | eBay
 
1 - 18 of 18 Posts
Top