1G Car dies after start and sometimes doesn't catch up when engine braking

[Gustav093]

I bought my first car back in July this year, it's a 1992 Mitsubishi Eclipse GS and it has randomly started to get worse.

My first problem is that sometimes it starts for a few seconds before it dies (sorry for the wind!) If I try to start the car it just keeps dying and if I wait about 10 - 20 minutes it drives fine.

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).

If I try to accelerate while this is going on the drive belt will start squealing. The clicking in the video sounds like its coming from here (img2), the throttle cable goes from this box.

My second problem is that sometimes when I'm engine braking and push in the clutch to change gears it dies as if it isn't catching up at idle rpm. I don't think that its me who is making the engine go into too low rpms making the engine die.

The last mechanic that worked on the car did something so that the gasket pokes out (img1) but I don't think that is the problem. He also forgot to but back a bolt that was on the cam gear cover.

The exhaust manifold has two screws missing (img1) and sadly the have both been snapped in half and are stuck in the block, it might be leaking exhaust gases from there.

The car is a 1992 Mitsubishi Eclipse GS 1g and doesn't have a OBD port so i cant read the faulty engine codes.

I have checked the resistance in 3 of 4 of the injectors, the first time I checked the two in cylinder 2 and 3 and they read 14,6 then for some reason I only checked the two in cylinder 1 and 2 and they read both read 15 (the fourth one is hard to reach and I don't want to remove the fuel rail).
I still think that the problem is something with the fuel.

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img1

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img2

 

[1990TSIAWDTALON]

How to Retrieve Mitsubishi Codes OBD1 and Definitions | 2CarPros

How to retrieve Mitsubishi OBD1 (1996 and earlier) diagnostic trouble codes. Step 1 - To gather troubles codes from the system locate the diagnostic data...

www.2carpros.com

 

[97egl]

The clicking noise is probably coming from the ISC/IAC which controls the idle. It is located on the bottom of the throttle body and has a 6 pin connector going into it. Usually they are tan in color if original. Replacements are grey or black. I would verify the windings in it are good.

I will try and post up how to test it per the factory service manual when I have a few minutes.

 

[steve]

Idle control depends on a working Idle Position Switch (IPS) (where the green wire runs to the throttle body in img2). It needs a ground strap from the throttle body to the intake manifold bolts (or just a ground wire from the TB to a chassis ground) to signal the ECU that the throttle is closed. The Idle Speed Control motor (ISC) sits in the lower half of the throttle body and is what the ECU uses to vary the air bypassing the throttle butterfly. It's likely that's what your hearing clicking and not anything in the black box, which is a set of pulleys for the cruise control.

You also need a functional Engine Coolant Temp Sensor (ECT) on the thermostat housing, the correct Base Timing, and the Basic Idle Set Screw (BISS) adjusted for the car to idle correctly.

One of the things the ECU does with the ISC when the car is moving and emulate a dashpot so that when the throttle is closed the engine doesn't stall. The original ISC's on 1G's was a metal unit with a tan plastic connector. The are known for shorting out and damaging the driver ICs in the ECU.

Speaking for ECU's the capacitors inside have been a problem since early on, leaking electrolyte and damaging the circuit board traces. Make sure yours have been replaced and there isn't any lingering leakage.

You sure you don't have the diag connector flapping around. They usually are attached to the fuse box in the drivers footwell but they sometimes come off.

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[97egl]

Here is the instructions for checking the ISC. Please be sure to check over everything Steve mentioned as well.

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[Gustav093]

You sure you don't have the diag connector flapping around. They usually are attached to the fuse box in the drivers footwell but they sometimes come off.

I just removed the panel under the steering wheel and don't think it's supposed to look like this?

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[steve]

After market alarm, time to unwire all that.

 

[Gustav093]

After market alarm, time to unwire all that.

Do i really need to unwire it all?
Its a lot of stuff and I have never tried working with wires.

 

[steve]

It's either remove it or learn everything about it because if you don't it could be causing all sorts of problems for you, now and later.

When I get a "new" used car the first thing I do is start pulling out the aftermarket stuff or at least making sure it's something I want/understand and is working/installed correctly.

 

[Gustav093]

How to Retrieve Mitsubishi Codes OBD1 and Definitions | 2CarPros

How to retrieve Mitsubishi OBD1 (1996 and earlier) diagnostic trouble codes. Step 1 - To gather troubles codes from the system locate the diagnostic data...

www.2carpros.com

Can i still find trouble codes since the CEL disappears after i remove the key?

 

[steve]

The fault codes are usually stored and require clearing, they can either be active faults or stored (meaning they were active but aren't currently). If you are loosing them after you tun the key off you might want to check and make sure the ECU is getting it's backup power on C-59 pin 103. That pin should always have battery voltage on it (unswitched).

 

[1990TSIAWDTALON]

Can i still find trouble codes since the CEL disappears after i remove the key?

It could have "pending" codes still stored, as Steve stated. He has a good idea about checking the constant backup power to the ECU.

 

[Gustav093]

Here is the instructions for checking the ISC. Please be sure to check over everything Steve mentioned as well.

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I tried this and pin 1 and 2 has about 7 Mohm while the rest were between 28-33 ohm so it seem that this was indeed the problem.

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But while trying what Steve wrote i found that there were two of the same things(images below)where you can read engine codes and i tried the guide from the link too except that i used a multimeter and listening to the sound. I tried it on both of them and tied upside down but the only thing i heard was a constant sound, no pauses or anything.

The red is the first picture and the blue is the second

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[steve]

Those connectors look like they have way too many pins to be the diagnostic connector.

 

[Gustav093]

Those connectors look like they have way too many pins to be the diagnostic connector.

Is it possible that the previous owner made something custom because there are two things with wires going to and from them and there are wires that goes from both to the AM alarm.

 

[steve]

Yes, there are several aftermarket wires running to things over there. With an aftermarket alarm/remote start they would be tied into the ignition switch, door locks, lights, etc but they aren't tied into the diagnostic port which is what I thought we were looking for so you could read the codes.

If you can't find it you can go directly to the ECU pins.

 

[pauleyman]

Is it possible that the previous owner made something custom because there are two things with wires going to and from them and there are wires that goes from both to the AM alarm.

None of the pics you posted show the diagnostic port.

 

[Gustav093]

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As you can see in this picture there is nothing on the junction block that looks like the diagnostics

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[pauleyman]

You've got a rats nest. You're going to have to dig around.

 

[We're on Boost]

I tried this and pin 1 and 2 has about 7 Mohm while the rest were between 28-33 ohm so it seem that this was indeed the problem.

Yeah.
Have you shopped around for a new ISC yet?
As far as I know the Mitsu part number is MD628051.
But it can be confusing because when I looked around I found another part number as well. MD628052. I never knew of this part number.
Both are extremely expensive from Mitsubishi. Like $450 US.

I'm pretty sure the MD628051 will be correct for your car, regardless of whether your car was made before or after 5/92, turbo or non-turbo.
It's a good thing because that part is available from several aftermarket companies for about $60 US.
Standard Motor Products (SMP): AC146
Wells (WVE): 2H1098
Those are probably the 2 best ones. I have an SMP AC146 on my car and it's fine.

I think you should replace the ISC and go from there. Sounds to me like that one part could solve a couple of your problems.

BTW there is a thread from 2019 in here where a user brought up the same confusion about part numbers. In that thread, I think @DSMPT had it right. The resistance of these newer made parts is not 33 ohms anymore. It's more like 40. If you want to see a new one working out in the open you can check my video here: ISC video, 1g DSM

The 2019 thread that I referred to is here: https://www.dsmtuners.com/threads/isc-question.524884/

Don't know if you can buy from Rock Auto over there, but here is their page for the AC146:
AC146 from Rock Auto

 

[DSMPT]

As you can see in this picture there is nothing on the junction block that looks like the diagnostics

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It's just hooked on the fuse box, so the previous owner may have relocated it. And you may have missed it while you were searching it, if it still has the factory black rubber cover like the pic below.

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[Gustav093]

If you can't find it you can go directly to the ECU pins.

The ISC will be here in a couple of weeks, so in the mean time im still trying to find the diagnostics. Where are the ECU pins located?
There is this one that is marked but its connected on the back.

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[We're on Boost]

Well, the ECU is sort of low and behind the center stack, shown like this in the factory service manual:

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But it would sure be cool if you could find that little bundle of 6 (I think) wires that go to the OBD connector that you can't find.
The connector might even still be there. It might be shoved behind the fuse box. It can't go very far normally because the 6 wires that come out the back end of it only go about 3 inches, then they dive downward into a bigger bundle of larger diameter wires, and the whole bundle then goes downward towards the floor.

Anyway, those 6 wires from the connector don't go up and over the footwell like you might think. They go down a little bit and then disappear into this bigger bundle which also disappears downward.
I'm thinking the guys who installed the alarm might have thought that OBD connector was just in their way and they shoved it back there pretty hard. Even if they cut it off, the 6 wires should still be there.

The 6 OBD wires are in their own little black rubber tube which covers them while they run from the connector to the bigger bundle.

In the 2 pics below I tried to show all this.
The white OBD connector is 30mm across (width).
I've pulled back the black rubber boot (it's dangling) so you can see the 6 wires as they come out of the black rubber tube and go into the white connector, what colors they are, and that they are small, a little less than 2mm OD.

The wire that has the signal you want is the upper yellow one, which goes to pin 1 on the ECU. Look at the pic full size, you'll see a white stripe on the other yellow wire.

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In that first pic you can't really see the 6 wire bundle dive into the big bundle because the dangling boot is in the way.
This 2nd pic is supposed to show that better. I've moved the boot back to where it mostly covers the white connector. The smaller black rubber tube with our 6 wires in it dives into a larger black rubber tube that has all (I guess) the wires that come out the back of the fuse box. The 2 connectors on the back of the fuse box (a white one and a gray one) are the same connectors we see in your pic in post #22.

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If there is something here that you don't know what I'm referring to I could mark it up with arrows.

 

[Gustav093]

Well, the ECU is sort of low and behind the center stack, shown like this in the factory service manual:

You must be logged in to view this image or video.

But it would sure be cool if you could find that little bundle of 6 (I think) wires that go to the OBD connector that you can't find.
The connector might even still be there. It might be shoved behind the fuse box. It can't go very far normally because the 6 wires that come out the back end of it only go about 3 inches, then they dive downward into a bigger bundle of larger diameter wires, and the whole bundle then goes downward towards the floor.

Anyway, those 6 wires from the connector don't go up and over the footwell like you might think. They go down a little bit and then disappear into this bigger bundle which also disappears downward.
I'm thinking the guys who installed the alarm might have thought that OBD connector was just in their way and they shoved it back there pretty hard. Even if they cut it off, the 6 wires should still be there.

The 6 OBD wires are in their own little black rubber tube which covers them while they run from the connector to the bigger bundle.

In the 2 pics below I tried to show all this.
The white OBD connector is 30mm across (width).
I've pulled back the black rubber boot (it's dangling) so you can see the 6 wires as they come out of the black rubber tube and go into the white connector, what colors they are, and that they are small, a little less than 2mm OD.

The wire that has the signal you want is the upper yellow one, which goes to pin 1 on the ECU. Look at the pic full size, you'll see a white stripe on the other yellow wire.

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In that first pic you can't really see the 6 wire bundle dive into the big bundle because the dangling boot is in the way.
This 2nd pic is supposed to show that better. I've moved the boot back to where it mostly covers the white connector. The smaller black rubber tube with our 6 wires in it dives into a larger black rubber tube that has all (I guess) the wires that come out the back of the fuse box. The 2 connectors on the back of the fuse box (a white one and a gray one) are the same connectors we see in your pic in post #22.

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If there is something here that you don't know what I'm referring to I could mark it up with arrows.

I think I can see the rubber tube in one of my pictures i took and its located at the same place as yours. Will check once Im home.

 

[Gustav093]

I found where it tucked behind everything(the pictures really helped), and i tried putting the positive on 1 and negative on 12 but nothing happened but when i switched to negative on 1 and positive on 12 then it dtarted to beep then pause over and over with no diffrence what so ever.