1G running lean

[91lzer]

Last week I blocked off my FIAV and accidentally overheated my car.

Since then my car has been misfiring randomly when warmed up. It doesn’t happen all the time but when it does the only way to get it to stop is to shut the car off and start it again.

I have also been running super rich under hard acceleration over 4500rpm.

Sometimes it’s also hard to start when the engine is hot.

I did a boost leak test and there was only a small leak, not sure where from. Why is my car misfiring when hot and running rich?

 

[95_gsx_2g]

When you bypass or block the fast idle air valve your changing idle speed warmup. Most do get bypassed or blocked as they start to leak. If your overheating you got other underlying issues on the car. Overheating is usually something like bad thermostat/fans or too low on coolant.

A bunch of different things can cause a misfire but go over basics like inspect plug wires plugs good. If that doesn't work check coil packs and keep going down the line till you find the problem. Make sure your tune is good as well because that can throw everything off. There's even a chance your rich misfiring if its dumping fuel it can't burn in time. Use the hot start enrichment to help warm starts.

You need everything to work together a simple tiny tear in a plug wire can cause a bunch of random misfiring or stumbles. Also lots of good posts on here with resolutions and members to help and go off off.

 

[91lzer]

The car overheated because my dumbass forgot to bridge the coolant lines going to the tb and the car ended up puking out the coolant. I checked out the plug leads and they were good and my injectors were giving the right resistance. How do I check my coil pack? Because that’s the code I was getting

 

[95_gsx_2g]

Oh it happens but that definitely explains what was going on . Ive never tested one but if you got a multimeter and resistance specs you should be able to without a problem. Ive used one to test my idle speed controller. Another option is try another pack or ask a friend for a good known working one to rule that out.

 

[91lzer]

well, today I was driving and my misfire started up again. so I pulled over and started pulling out the injector plugs. it turns out my cylinder 2 and 3 injectors weren't working and I gave them a wiggle and they started working again. so I think im just going to spray some contact cleaner and make sure they're snug. what could explain the car running rich?

 

[dwb]

Since you spewed coolant all over the right side of the engine, you might have coolant in your CAS. IIRC that happened to me once and it definitely didn't run properly until it was dry. I always cover mine up now if I'm planning on a coolant leak (or pressure washing the engine bay).

 

[DiSeM]

I have experienced a misfire after warmup due to a bad fuel injector resistor pack. You could try replacing that unit, it worked for me.

 

[curt-s]

Also check all contacts in the plug ends for all ignition related components. Sometimes they break, they're old. Did for me, on the power unit.. caused an intermittent misfire.

 

[steve]

Do your injectors connectors have the little metal lock springs still?

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[91lzer]

Do your injectors connectors have the little metal lock springs still?

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Nope, i can pull those bad boys right off. I'm pretty sure that's what caused m misfire because it stopped once i wiggled the connectors.

Also check all contacts in the plug ends for all ignition related components. Sometimes they break, they're old. Did for me, on the power unit.. caused an intermittent misfire.

okay, thanks for the reply. i did a bit of digging and found nothing but it doesn't hurt to double check.

I have experienced a misfire after warmup due to a bad fuel injector resistor pack. You could try replacing that unit, it worked for me.

I think i narrowed down the misfire to the loose connector but i'll check that too.

Since you spewed coolant all over the right side of the engine, you might have coolant in your CAS. IIRC that happened to me once and it definitely didn't run properly until it was dry. I always cover mine up now if I'm planning on a coolant leak (or pressure washing the engine bay).

thanks man, i checked that and it was dry, luckily didn't get any coolant in there.

 

[91lzer]

My bad, i confused lean and rich.

When i open the throttle the my A/F gauge reads 16.5 to 17.0. What could cause this issue and is it bad if I continue to drive like this?

I'm thinking I could have ruined my wideband O2 sensor when I overheated.

 

[dwb]

Do you have a check engine light/code?

 

[steve]

Nope, i can pull those bad boys right off. I'm pretty sure that's what caused m misfire because it stopped once i wiggled the connectors.

I saw somebody post not to long ago a aftermarket source for the lock springs. Without them you'll continue to have this problem.

In the past I recommended switching to the 2G version of the injector connectors but splicing the harness isn't the best solution either.

 

[91lzer]

Do you have a check engine light/code?

I have a code 31(knock sensor) and a code11(O2 sensor) I replaced the O2 sensor a few months ago not realizing that the aftermarket wideband sensor will throw a code because its not OEM. when I had the misfire I got a code 44(coil pack) but that went away with the misfire. I replaced the fuel pump yesterday to no avail, car still bogs down over 3000 rpm and my A/F gauge says in running 16.5 A:F at idle and over 17 when I open the throttle. Im going to run seafoam through the fuel system and replace the fuel pump because im not getting enough fuel. if that doesnt work then ill replace the O2 sensor again and if that doesnt work either then i m stuck.

 

[dwb]

I have a code 31(knock sensor) and a code11(O2 sensor) I replaced the O2 sensor a few months ago not realizing that the aftermarket wideband sensor will throw a code because its not OEM. when I had the misfire I got a code 44(coil pack) but that went away with the misfire.

I would get that knock sensor replaced. I know they are kind of hard to come by these days but can definitely cause some of the issues you've described. I had mine go out a few years ago and while it was intermittent, it definitely affected how well it ran.

I believe the the coil pack error code could also be attributed to the power transistor. Especially if you are running on only two cylinders at times.

 

[91lzer]

I would get that knock sensor replaced. I know they are kind of hard to come by these days but can definitely cause some of the issues you've described. I had mine go out a few years ago and while it was intermittent, it definitely affected how well it ran.

I believe the the coil pack error code could also be attributed to the power transistor. Especially if you are running on only two cylinders at times.

I've been searching for a knock sensor for a long time, but since i live in Canada that makes it even harder to find. do you know where i can get one? but i've had that code since i bought the car (6 months ago) and have never had any problems relating to it.

I think its my O2 sensor thats the problem. I unplugged it today and went for a drive and the car was behaving the exact same way as it was before (bucking really badly when the turbo spools up and bogging down). I'm going to replace it on the weekend and hopefully that fixes my car running so lean.

 

[pauleyman]

I think its my O2 sensor thats the problem. I unplugged it today and went for a drive and the car was behaving the exact same way as it was before(bucking really badly when the turbo spools up and bogging down). Im going to replace it on the weekend and hopefully that fixes my car running so lean.

O2sensor won't do that. Wot ecu doesn't look at it. Same for when the car is cold. I wouldn't throw anymore parts at it.

 

[dwb]

I've been searching for a knock sensor for a long time, but since i live in canada that makes it even harder to find. do you know where i can get one? but i've had that code since i bought the car (6 months ago) and have never had any problems relating to it.

I found mine on Amazon but that was 2019. I got lucky. Here's a thread that might help. https://www.dsmtuners.com/threads/best-source-for-replacement-knock-sensor.525046/

 

[91lzer]

I found mine on Amazon but that was 2019. I got lucky. Here's a thread that might help. https://www.dsmtuners.com/threads/best-source-for-replacement-knock-sensor.525046/

Okay, I’ll check that out. Thanks man!

 

[Lui-Kang]

RTM Racing for a knock sensor. I believe they are based in Canada.

RTM Racing :: MITSUBISHI / EAGLE :: DSM: 1g (1990-94) :: Engine Management :: Engine Sensors :: Knock Sensor: 1g DSM/Galant