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Ecu going out? Popping noise from dash

yeti

Well-known member
Joined
Oct 13, 2010
Messages
800
Location
san diego california
So on the end of a 4 hour road trip my car started acting up.

First is sounds like popcorn or some type of popping in my dash , then comes the hesitation, then the complete power loss

At first it just felt like the o2 sensor died and cursing and idle was running like sh*t unless more than 40% throttle was applied.

Then the car just dies randomly, ( little warning with rpms and power loss) while doing 80mph. Foot down, no power.

I bump it into 4th and floor it and the car comes back like nothing ever happened.

I did notice a couple hours prior my cruise control stopped working , I was using it earlier that road trip.

My first thoughts was the the injectors are gunked up from 3 tanks of e85 in a day, but after searching I’m guessing ECU?

My laptop died 20 mins before this started happening of course , so I didn’t get any logs.
 

gvr4ever

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Joined
Aug 6, 2002
Messages
6,048
Location
central Indiana
Kinda sounds like it, except the ECU isn't in the dash. It's on the passenger side near the floor. Might be injectors or spark plugs or something under the hood that sounds like its coming from the dash.

I've never witnessed a ECU failure first hand, but it's supposed to smell bad. A little fishy.
 

fuel

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Joined
Feb 23, 2009
Messages
2,161
Location
Toronto, ON, Canada
Did you smell an awful smell around about the same time as the popping noises? I would pull out the ECU and check the caps and IACV drivers anyway. Your IACV could have coolant leaking into it which shorts out the driver resisters and does other damage too. Alternatively it could be capacitor juice leaking onto the board and doing damage there too.
 

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
Fuggin snap, I just was messing with the TB and isc fiav, quickest way to check to make sure I’m not doing that?

Tbh my idle is surging for 10 years I’m about to remove fiav and isc because they can short ecu. Fudge that.

I’d rather the car barely stay alive at idle then an embarrassing surge everytime I stop.

Ive got a local with an ecu I was gonna buy and pop in, guessing I shouldn’t do that until I delete isc/fiav because I could just short the new ecu?

As for the smell was hard to tell because I’m still getting used to smelling e85 , my gf kept claiming it smelt like elmers glue and I just kept saying it was the gas.

Also my goddam trunk is locked and the key don’t work, battery is in the trunk.

Do I NEED to disconnect battery before pulling ecu? Or reinstalling new one?
 

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
</font><blockquote><font class="small">Quoting gvr4ever:</font><hr />
Kinda sounds like it, except the ECU isn't in the dash. It's on the passenger side near the floor. Might be injectors or spark plugs or something under the hood that sounds like its coming from the dash.

I've never witnessed a ECU failure first hand, but it's supposed to smell bad. A little fishy.

<hr /></blockquote><font class="post">

As for the clicking, it sounded like popcorn was popping in my dash, I didn’t think much of it until power started to fall.

Then searched online and dsms say the dash starts clicking like crazy before an ecu goes out.

It’s not a relay type click, more like something is getting power on and off “ popping “ noise.

Hooked up a wideband input while car was running and logging, could I have shorted the egr circuit by clipping the wire while / running new 0-5v line while it was live?


Also what’s up with the cruise control circuit taking out ecus? Should I not use cruise control once I replace ecu?
 

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
Fudge.

So I’ve pulled the isc connector, should that be good to not fry another ecu?

And I’m guessing this means my idle sure was caused by a bad isc, it tested fine and moved properly

Please someone correct me if I’m wrong.

Gonna send this ecu out to ecm link I guess and use a locals in the meantime
 
Last edited:

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
So I’m using my friends ecu that is known to be good and repaired from ecmlink

The problems seemed to go away for about an hour and then, I hit ground timing connector and then 20 mins later the symptoms start up again.

Could I be shorting ecu or causing issues by grounding timing connector box on ecu, I jeep doing it because it’s the only thing time stop my idle from surging.

Could something I did with the o2 sensor wiring be causing me to short the ecus? I used the actiry wiring harness

Will the car still start when the ecu is shorted? My intake and coolant temps are working so I’m guessing I’m not blowing sensor ground, I’ve unplugged the isc even tho I double checked the resistance and it reads good.

This time it’s different the car will start to studder at idle then if I touch throttle at all the rpms drop.

I picked up a fuel filter otw home gonna swap that in tomorrow, does this sound like fuel stuff or does it sound like wiring and ecu?

Fudge.

I’ve got logs if anyone wants to see
The don’t look different when the issue starts I think but I could be missing something cause I suck.

Cheers

 

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
Just double checked logs and I’m showing -40f IAT so bad sensor ground?


Guessing this was caused by my wiring up of the o2 sensor, idk how cause I’m using the stock wires just crimped together with a universal Bosch o2 sensor.

Any and all help is appreciated. Think I’m just gonna clip wires to o2 sensor and simulate it for my WB.



Alsoo my Wide band is wired in directly into the ignition wires, there’s no inline fuses or relay boxes wired in. Couple this be causing me to blow sensor ground?

It says “ the circuit which you will pull power should be able to support an additional 3 amp draw, make sure the connection is fused with a minimum fuse size of 5A”

The wires are literally just running from the ignition (12v) and chassis ground, no relays or fuses, can the ignition circuit support 3a of draw?

Also is it normal for a lc1 wideband sensor to get hot while it calibrating or after wards?

Mine was hot after calibrating and installing

I’m overwhelmed anybody know of a reliable mechanic near SD? I’m about to call road race and see what will a couple grand buy me.

 
Last edited:

yeti

Well-known member
Joined
Oct 13, 2010
Messages
800
Location
san diego california
So i suck, someone how I shorted the o2 wiring. I don’t understand how. But forsure, I understand I apparently hooked up a heater wire or a ground to sensor ground?

So i clipped the wires further back on my harness to my o2 sensor and the problem has not returned..

I also unplugged my isc because I thought that fried my ecu originally, and I’m using a locals spare ecu still.

My isc tests fine resistance wise, and moves.

What’s your opinion on completely blocking off the isc and fiav, I already have the egr blocked off. I’m just trying to eliminate all sources of programmed vacuum leaks.

I feel like it will be easier to sort with just the biss screw in place.

Please correct me if I’m wrong.

I’m also wondering if this surge is in my wiring because the isc is still logging movement when unplugged. Does that mean it’s reading something else?

Also I think I just found all of my sensor grounds being ground to chassis, or am I supposed to have a bunch of wires from harness going directly to chassis? ( my sensors could be reading static so the idle is surging? )

PS sorry for the absolute books of comments, and if I’m annoying the spit out of everyone.


 

slugsgomoo

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Joined
Oct 16, 2003
Messages
3,737
Location
Tacoma, WA
not the problem here this time, but it can be- if the ISC goes out, it'll torch the 105 driver in the ECU- If your FIAV fails and leaks, it will definitely happen. So either do the blockoff/bypass plate (lame and costs money) or the free method here at DSMTuners and save yourself some pain.

Found that one out after a friend had an ECU go bad, and we tossed my good ECU in to troubleshoot the car- which was promptly also nuked (GRRR). The lesson I took away was that if you have something die in the ECU, you need to track down and troubleshoot whatever it connects to before putting in a new or repaired ECU, otherwise it might happen again. /ubbthreads/images/graemlins/frown.gif
 
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