Corsica misfiring after rain

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Bapsu
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Corsica misfiring after rain

Postby Bapsu » Mon Aug 14, 2017 4:46 pm

Even though I am not Beretta owner (some day I propably am... :) ) I think this forum is the only place left in the world I could get help from. As you see I am from Finland, have owned Corsica now for almost two years. There have been this and that to do ofc, but now I am facing a dead end soon. I hope I am welcome here. :oops:

Story is quite long:

I have been driving my Corsica mainly on summers only to prevent rusting. Last spring (May) i tried to take it as a daily driver again. Everything was quite well until i noticed the car is misfiring, specially when idling. I tried to chase down the misfire for some time. Then I decided to just to start driving until something would pop out. Surprisingly after driving the car daily for few weeks, I noticed all the symptoms were gone. Car idled perfectly and never misfired around 1500rpm TCC on, like it used to do. When we saw some rain again, all symptoms came back in one night. Car misfired while idling R/D, also sometimes on P. Car also stumbled and jerked while trying to acccelerate gently with TCC on, when rpms are around 1500-1600. If TCC went off with heavier acceleration, no problems occured.

Since the rain had an effect on misfire, I thought this must be an electricity problem. Now the car has been sitting on the parking area for month, when I went to start it, it started and ran with all 6 cylinders, but after few mins, it drops one cylinder completely. Impossible to drive as you might guess. I never had any problems if I was driving[b][/b] on rain, but when the car saw water in the parking area, all problems came back. After driving like 100km everything was well again, coz engine bay got dry.

So after all, my conclusion is that there is water going somewhere, causing the misfire? Anyone have other ideas?? The only fact i know is that water has something to do with this.

Today I took look to passenger side upper corner, where ecu is. The connector area in the firewall is completely rusted and i also felt some moisture in the connector/wiring harness. So I guess my problem lies there. I tried to take apart the connector, but I didnt manage to. Theres barely space to put your hand on, and its extremely difficult to try inspect how the connector is put there and how to take it apart. Before i take the harness apart, I would like to know if theres even a connector on the firewall? Or is it just hole in the wall and wires going thru it? Atm I dont have idea how to open the damn thing without breaking something. The fact, that the body around the connector is completely rusted off due to finnish winter and GM L-body greatness wont make things easier. When i tried to pull the connector even a bit I saw how the rusted part of the body almost came up with the connector. Seems like theres some welding jobs needed to be done... :burn:



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Re: Corsica misfiring after rain

Postby ifixalot » Tue Aug 15, 2017 4:59 pm

How old are the spark plug wires? Water maybe causing an arc in the high voltage.

Yes, corrosion in the connector is not a good thing but problems there won't go away
as the engine compartment dries out.



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Re: Corsica misfiring after rain

Postby Bapsu » Tue Aug 15, 2017 8:01 pm

Maybe 2 years. Not so old, but nowadays winters are very wet and rainy so I wouldnt rule them out completely, many things worn faster here than in USA I guess. When I put the ecu back in, I am gonna fire the car up, wait for one cylinder to drop and use spark light to check if theres spark coming.. I'll try to check more tomorrow.

I managed to take look to the ecu connector on the firewall, seems like it is built in completely? I simply cant figure how to take it apart?

Its really nice to see this forum is still somehow active ans people here are supporting each other. :)



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Re: Corsica misfiring after rain

Postby Bapsu » Wed Aug 16, 2017 6:37 pm

Aight, after some deep investigation:

Earlier on the spring i managed to rule out, that the problematic cylinder was cyl nro. 1. I replaced all coils on that time. Didnt help.

Today I investigated more and noticed that problem was lying in cyl nro. 4. These cylinders are hooked to same coil. Do I have reason to suspect icm? Its been year on the car and has been taken from a junk car.

The way i used to test spark was with spark light (got spark from each wire) and by taking off plug wires when engine was running. I managed to sort the problem to cylinders 1 and 4 by noticing that sometimes (when the car is missing) when i pull the wire out, there no effect in engines idle (it kept running with 5 cylinders or similar). That was the only way i managed to sniff out wheres the problem. The spark light has been giving spark for each wire without problems all the time.

The most difficult thing is that everynow and then the car starts running with 5 or 5 and half, or with 6 cylinders. I never manage to test all plugs, until it starts running normally. :( This is difficult to sort out for a beginner...

Btw: The car is 3.1L MPFI, year model -93. Dont know why I never mentioned that earlier.



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Re: Corsica misfiring after rain

Postby Money pit Beretta » Fri Aug 18, 2017 6:59 pm

When the ICM goes it will make a coil go bad and replacing that one leads to the replacement going bad too. My 90GT did that to me.


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Re: Corsica misfiring after rain

Postby Bapsu » Fri Aug 18, 2017 8:22 pm

Money pit Beretta wrote:When the ICM goes it will make a coil go bad and replacing that one leads to the replacement going bad too. My 90GT did that to me.
Yeah I got no trust for that ICM anymore.

Today I found something really inresting. Instead of spark problems I can have fuel pressure problem.

Went to my car when it had sat overnight, noticed that one injector at the right side of the intake manifold was wet from its base. Seemed to be "ticking" ok still while running. Another thing: i tapped fuel pressure relief valve with screwdriver(or whatever its called) and there was barely pressure left? It only flooded a bit of gas out of there, no pressure at all. When i last time tapped it (when I didnt have this misfire issue) there was a ton of a pressure and it shooted the gas right out up to the hood.

According to low fuel pressure conclusions, I have had hard starting issue for a quite long time. Today i noticed, that the only case car starts right up, is when i fire it up immidiately after shutting it down. If i wait even for 10 seconds, i need to crank quite long time.

Can fuel pressure issue like this cause running problems, like misfiring while idling (shooting to pipe) or even one cylinder lost every now and then? Also car is not accelerating too well anymore. Its jerking at highway speeds when u try to accelerate there. At normal city driving u can feel how its hesitating while u leave from lights.

Damn it, this thing drives me insane... :deadhorse:



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Re: Corsica misfiring after rain

Postby Money pit Beretta » Mon Aug 21, 2017 6:49 pm

L body's will drive you crazy. Sounds like that injector is stuck(could be half open). This is a bit much to ask: any way that you can pull the hose off the fuel pressure regulator and see if it smells like fuel? The upper intake must be removed to do that. Seems like the pressure is bleeding off quickly and the regulator is not doing its job when accelerating.
Also check for a leaking gas cap or rust holes in the vent line and fuel filler tube(what the cap screws into). Do those things before the regulator. Could all come down to a weak fuel pump. Still....that pressure loss makes me think "no" on that.

It is common on a 2.8/3.1L's to have bad injectors and a bad fuel pressure regulator. Also the ICM/ coils are a problem as you know. Other than that they tend to be good all around engines.


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Re: Corsica misfiring after rain

Postby GT_Indy » Wed Aug 23, 2017 9:41 pm

I noticed you mentioned water in the passenger side harness/ECM.
I've had an ECM fail before because water followed the harness on the passenger side and got into the ECM.
Did you try swapping the ECM with a known good unit? (Remember to swap the EEPROM chip too).


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Re: Corsica misfiring after rain

Postby Bapsu » Thu Aug 24, 2017 6:06 pm

Yeah L bodys are what they are. Still beast cars...

Some good news. Managed to sort out the cause for the problem. :)

I was just spraying water over intake and those vacuum pipes lines over there. Still had spark light in place, and I noticed the spark was cuttin every now and then while the engine misfired! Damn it took a lot of time to find that. Been playing with spark light for atleast two hours... coz the thing has been, that the misfire moves from cylinder to another, so it was quite difficult to track down. But now i managed to find out it was a spark problem.

Since the spark is cutting, in different cylinders (but never more cylinders than one are misfiring), its ICM fail then? Since every plug wire cant be worn, either each plug. Can cam position sensor cause missing like this?

And yes, have had some water problems, but seem like ecu is ok. Yesterday took of the ecus connector a half way. This is what it looked like:

http://imgur.com/G7HHtmr
http://imgur.com/VkqRHD1

Welcome to Finland... got some rustwork to do again. Though i guess yours look same since winter got nothing to do with this rusting...



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Re: Corsica misfiring after rain

Postby GT_Indy » Sat Aug 26, 2017 2:44 pm

That connector needs some cleaning and some high quality silicone glue that dries clear/black to seal it.

If your spark is erratic, it could be the cause. I have a 94 Sunbird with the 3.1 that has a slight misfire but I know mine is like that because it needs coils/plugs/wires as they are the original ones that have 130k miles on them. lol

The Crank Position Sensor usually goes out all at once and opens causing no sparks at all. The ICM can sometimes do that too but they can also behave erratically. How old are the coils?

Note the firing order is 1-2-3-4-5-6 and the spark wires are paired in 1-4, 6-3, 2-5.
1 coil fires 2 times per firing sequence, 1 through 6.


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Re: Corsica misfiring after rain

Postby Bapsu » Sat Aug 26, 2017 7:47 pm

GT_Indy wrote:That connector needs some cleaning and some high quality silicone glue that dries clear/black to seal it.

If your spark is erratic, it could be the cause. I have a 94 Sunbird with the 3.1 that has a slight misfire but I know mine is like that because it needs coils/plugs/wires as they are the original ones that have 130k miles on them. lol

The Crank Position Sensor usually goes out all at once and opens causing no sparks at all. The ICM can sometimes do that too but they can also behave erratically. How old are the coils?

Note the firing order is 1-2-3-4-5-6 and the spark wires are paired in 1-4, 6-3, 2-5.
1 coil fires 2 times per firing sequence, 1 through 6.
Is it really a connector in there or is it only wired through the firewall? If theres connector I'll check it carefully for sure. Dont want any future problems with that connector anymore.

Yeah the spark was indeed cutting, I can upload video of it when i got time... I replaced coils when the misfire started, didnt have any effect. Since the misfire is travelling from cylinder to another I think its the icm then, not wires or plugs... no much choices. And also plug wires and plugs are replaced within 2 years both.

Gotta check that firing order also (sounds quite complicated :shock: ), I guess I'm going with the plugs, wires, coils, icm bunch. Or maybe first plugs and wires and then rest if it doesnt help.



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Re: Corsica misfiring after rain

Postby Cliff8928 » Mon Aug 28, 2017 2:22 pm

There's no connector on that side.


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Re: Corsica misfiring after rain

Postby GT_Indy » Tue Aug 29, 2017 10:59 pm

Yah I forgot and wrote connector. lol
Its just a plastic mount thing to hold the harness through the metal.

Its pretty simple, 1-3-5 in back and 2-4-6 up front, then pairs.
As long as each pair is in the right coil it will work. But I agree with what you said, the erratic misfire would make me also want to replace the ICM as well to see if that fixes the issue, but I can't say much else without being there and seeing/hearing, etc.
I've used my timing light on my Beretta in the past as well, just remember, 3 coils each fire 2 times equally spaced in degrees per spark cycle around the circle (I'm relating it to an old school distributor that rotated once every 2 revolutions of the crank, I think of it as a 6 cylinder cap with a 2 prong rotor under it firing 2 leads at once), so there will be longer/shorter pauses depending on when each one fires, but if the pattern is erratic then thats not good in my opinion.


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Re: Corsica misfiring after rain

Postby Bapsu » Thu Aug 31, 2017 8:58 pm

Aight got video here: https://www.youtube.com/watch?v=PKmsTYt ... e=youtu.be

For me it looked quite erratic, and u can see how the engine is stumbling and shaking while spark is "cutting". I got R on while I took the video (to get lower rpm and therefore more misfire). With my knowledge, that kind of spark doesnt look like normal. Also when I earlier plugged light to other cylinders (also to this cylinders I managed to bust the misfire from) the spark light didnt act like that.



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Re: Corsica misfiring after rain

Postby GT_Indy » Thu Aug 31, 2017 9:15 pm

Bapsu wrote:Aight got video here: https://www.youtube.com/watch?v=PKmsTYt ... e=youtu.be

For me it looked quite erratic, and u can see how the engine is stumbling and shaking while spark is "cutting". I got R on while I took the video (to get lower rpm and therefore more misfire). With my knowledge, that kind of spark doesnt look like normal. Also when I earlier plugged light to other cylinders (also to this cylinders I managed to bust the misfire from) the spark light didnt act like that.


Yah its broke. lol The spark cuts out and it stumbles is what it looks like I'm seeing.
If its verified that its not dependent on any coils which I believe you mentioned earlier, its a very good chance a new ICM will fix the issue.
Just keep in mind that the CPS can also cause this but I've never known those to be like this, in my experience the CPS dies all at once without warning if it goes bad.
If this was my car I would have bought a new ICM after seeing this, but because its me I'd also replace all 3 coils with it and stick a whole new assembly in there so if a coil is failing I don't have to do it over again, but thats just how I do things because I got burned in the past with different stuff that was hard to get to. Basically I installed an olds 455 in my car, then had to drop the crank because the rear main seal got stuck, and I did it without removing the engine. Messy job. lol


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