Anyone familiar with the 1.6L Mitsubishi engine used in the '92-'95 Hyundai Elantra? (Page 1/3)
Patrick JUL 20, 12:44 AM

I have no trouble diagnosing problems with my Fieros as I've got all sorts of spare parts to swap out and try... and there's also this fine resource here at PFF.

However, when my 5-spd '94 Hyundai Elantra requires anything, I feel like a complete newb.

I've had this car for about ten years, and by and large, it's been great. However, it's developed an intermittent problem now where the 1.6L Mitsubishi engine sounds like it's running on three cylinders. It'll start right up, and appear to idle fine. Then the idle will get rough, then it'll be okay. I'll start to drive and the engine will accelerate fine, then all of a sudden it starts to sound sort of like a Subaru flat-four engine. Then it might go back to running fine a few minutes later... or sometimes not.

At this point I don't know if it's a injector issue or an ignition issue (plugs and wires are fine, don't know the rest of the system at all). No trouble codes are being set.

Any tips from someone who might be familiar with these engines?
carnut122 JUL 20, 05:55 PM
Are you sure the ignition wires are OK? I'd mist them on a dark night and look for arcing. My first thought was EGR valve.
Patrick JUL 20, 06:26 PM

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Originally posted by carnut122:

Are you sure the ignition wires are OK? I'd mist them on a dark night and look for arcing.



I had actually bought a set of new plug wires from RockAuto a long time ago just to have on hand. When I took them out of the box a few days ago, I realized they won't fit. Wrong ends on them where they plug down into the heads. Too late now to raise a fuss with RockAuto. Anyway, I took the old wires off and tested the resistance. They were fine. They also look okay, but yeah, it might be a good idea to watch them at night with the engine running and see if any arcing is occurring.


quote
Originally posted by carnut122:

My first thought was EGR valve.



The EGR passage in the head had been plugged solid for years until I dug everything out a few months ago. At that time, the EGR valve appeared to be working correctly, but it probably wouldn't hurt to make sure that the valve is indeed closing properly when it's supposed to.

Thanks for the suggestions. I'll report back if I find anything.

[This message has been edited by Patrick (edited 07-20-2015).]

thesameguy JUL 20, 07:19 PM
Get a spray bottle and spray a fine mist of water on the wires at night. Wires can have perfectly good resistance and totally crap insulation.
Patrick JUL 21, 05:10 AM
Because I've never done it before, I wanted to remove the coil pack and power transistor and look them over. They looked okay and they both tested fine as well. I also tested the resistance of the injectors. They were all good, but geez it was a helluva job trying to get each injector unplugged from the harness. There must be a trick to getting those damn metal clips to let go, but I don't know what it is!

I'll check the plug wires again, especially now that there's two of you suggesting that I "mist" them and check for arcing. I'll do it when I get this all back together.

I read further in my Hyundai manual and came across the following about the Crank Position Sensor...


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If the CMP Sensor does not operate correctly, correct sequential injection is not made so that the engine may stall or run irregularly at idle or fail to accelerate normally.



This sounds exactly what my engine's symptoms are. When I looked at the physical appearance of the CMP sensor (which is attached to the end of the head), the multitude of wires entering the bottom of the unit are saturated with oil as the O-ring has been slowly leaking for years. It's quite possible this might be the culprit. Reports to follow.

[This message has been edited by Patrick (edited 07-23-2015).]

Stubby79 JUL 21, 05:25 AM
1.6l? I thought they had the 1.8. Basically the same as all those turbo 2.0L beasties, minus the turbo...irrc.

If it doesn't appear to be what's previously suggested, I'd be looking at the various key sensors. I know on some of the older electronically fuel injected vehicles, they'd crap the bed if the O2 sensor was bad. The MAP or MAF is certainly key. If it's not giving you codes, you could try disconnecting non-critical sensors (O2) and see if it stops it.

You can usually check that most sensors are working properly on these older systems with just a multimeter.
Patrick JUL 21, 05:38 AM

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Originally posted by Stubby79:

1.6l? I thought they had the 1.8. Basically the same as all those turbo 2.0L beasties, minus the turbo...irrc.



They came with both, but it's the 1.6L that I have. There must've been a gazillion of basically these same Mitsubishi engines made over the years. (Hyundai switched over to their own engine in the Elantra in '96.)


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Originally posted by Stubby79:

You can usually check that most sensors are working properly on these older systems with just a multimeter.



Yeah, I've got both a digital and an analog multimeter here that I used today on checking what I did. Tomorrow I'll check over a few more sensors. For anyone familiar with these engines, they're probably easy to work on. However, I've focused on Fieros for the last 20 years and my brain is crammed too full of 2.5 and 2.8 info.
carnut122 JUL 21, 08:23 AM
Have you run for trouble codes yet?
Patrick JUL 21, 02:25 PM

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Originally posted by carnut122:

Have you run for trouble codes yet?



In my first post I did state that no trouble codes have been set. There has been no indication of a lit trouble light, so I haven't actually checked for stored codes. Could there be codes stored if there was never any indication on the dash light? (I'm assuming trouble codes work in the same manner with the Hyundai as with the Fiero and that the trouble light will come on.)

I suppose a lack of trouble codes (if indeed none are stored) would indicate the sensors are probably fine, and that something like bad spark plug wires (arcing) could be the problem. I hope to make some progress today.

[This message has been edited by Patrick (edited 07-22-2015).]

carnut122 JUL 21, 07:41 PM

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Originally posted by Patrick:

In my first post I did state that no trouble codes have been set. There has been no indication of a lit trouble light, so I haven't actually checked for stored codes. Could there be codes stored if there was never any indication on the dash light? (I'm assuming trouble codes work in the same manner with the Hyundai as with the Fiero and that the trouble light will come on.)

I suppose a lack of trouble codes (if indeed none are stored) would indicate the sensors are probably fine, and that something like bad ignition wires (arcing) could be the problem. I hope to make some progress today.



I'll blame the Old-timers for missing the trouble light part. I believe it's possible to have trouble codes stored and not have the light on. When you mentioned sensors, I just figured that would be a good place to start. Let us know what you find.