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Resolved 1g manual - stalling randomly CAS?

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AWD-Tony

Proven Member
6,801
3,735
Sep 11, 2017
Cincinnati, Ohio
I’ve been having an issue where the car randomly stalls. At first I thought it was the new fuel pump (hellcat 525) since it started happening after I installed it.

Today, I had the key in the on position and while I was turning the crank by hand (plugs were out) the fuel pump turned on and off.

I’ve read this thread https://www.dsmtuners.com/threads/1g-basic-ecu-mpi-circuit-function.435961/

So I have a feeling it’s my black top cas. I unplugged it and turn the engine over again and pump didn’t turn on. As soon as I plug it back in, the pump turns on and off which I’m not sure is normal. Could there be a short inside tripping the mpi relay?

It used to take some time before it stalls but now it does it within 5 minutes of starting. It starts right back up no problem.
 
I’ve been having an issue where the car randomly stalls. At first I thought it was the new fuel pump (hellcat 525) since it started happening after I installed it.

Today, I had the key in the on position and while I was turning the crank by hand (plugs were out) the fuel pump turned on and off.

I’ve read this thread https://www.dsmtuners.com/threads/1g-basic-ecu-mpi-circuit-function.435961/

So I have a feeling it’s my black top cas. I unplugged it and turn the engine over again and pump didn’t turn on. As soon as I plug it back in, the pump turns on and off which I’m not sure is normal. Could there be a short inside tripping the mpi relay?

It used to take some time before it stalls but now it does it within 5 minutes of starting. It starts right back up no problem.
It's normal for the fuel pump to turn on when you turn the CAS. It thinks the engine is cranking and is trying to supply it with fuel.
 
It's normal for the fuel pump to turn on when you turn the CAS. It thinks the engine is cranking and is trying to supply it with fuel.

Isn’t that only when it sees the starter signal?
 
Thats normal, your generating a rpm signal, that causes the ecu to trigger the fuel pump until you stop turning the crank.
 
Isn’t that only when it sees the starter signal?
Nope, anytime it sees CAS activity. It sets/resets a timer, turns on the pump and when the timer expires it turns the pump off. SO as long as the engine looks like it's running (Continuous CAS signals) the pump stays running. The 1G MPI relay also has an input from the ignition switch start position so it will prime the pump before it sees the first CAS pulse and continue while your cranking.

I don't really discuss the fuel pump side in that other thread because it's more about how the ECU gets turned on.
 
Nope, anytime it sees CAS activity. It sets/resets a timer, turns on the pump and when the timer expires it turns the pump off. SO as long as the engine looks like it's running (Continuous CAS signals) the pump stays running. The 1G MPI relay also has an input from the ignition switch start position so it will prime the pump before it sees the first CAS pulse and continue while your cranking.

I don't really discuss the fuel pump side in that other thread because it's more about how the ECU gets turned on.

Is it normal that the pump turns on and off when you plug the connector back on the cas with the key in the on position?

The only thing I notice in the log is the inj duty drops to zero which could be either side of the mpi circuit since injectors and pump are on different sides
 
Is it normal that the pump turns on and off when you plug the connector back on the cas with the key in the on position?

The only thing I notice in the log is the inj duty drops to zero which could be either side of the mpi circuit since injectors and pump are on different sides
Yes it is normal. When you plug it in your creating a signal so it turns the pump on. Then if you don't turn it, it turns off when the timer expires as @steve said above. If you where to sit and continuously spin the CAS without stopping the pump would stay running
 
Yes it is normal. When you plug it in your creating a signal so it turns the pump on. Then if you don't turn it, it turns off when the timer expires as @steve said above. If you where to sit and continuously spin the CAS without stopping the pump would stay running

Dang it. Gonna have to keep digging. Thanks everyone for your input!
 
When the car stalls is the Check Engine Light on?

No. No store codes either. I think it’s losing signal somewhere and turning the pump or ignition off

Thinking it had to do something with the pump, I swapped back my other pump, replaced relay and wires for rewire. Still same thing. The 12v wire from battery does get warm and the inline fuse is fine as well.

I mentioned this before but now it does this within 5 minutes of starting the car and starts right back up no problem. I’m hoping it gets worse so I can figure out the problem.
 
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No. No store codes either. I think it’s losing signal somewhere and turning the pump or ignition off
Do you have any basis for that? Have you looked at either when it stalls?

Do you have anyway to log what's happening?

My 1G will stall if you leave it idling long enough but will restart right back up. Adjusting the BISS will eliminate it but then it get idle surge so it's a air related issue that I haven't felt like solving.
 
Do you have any basis for that? Have you looked at either when it stalls?

Do you have anyway to log what's happening?

My 1G will stall if you leave it idling long enough but will restart right back up. Adjusting the BISS will eliminate it but then it get idle surge so it's a air related issue that I haven't felt like solving.

Just taking an educated guess at this point since I don’t see anything in the logs. I’ll post a log in a few days.

I failed to mention that it first started stalling only while driving after 15 minutes or so, and now it has progressed to stalling at idle within 5 minutes.
 
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The only thing I notice in the log is the inj duty drops to zero which could be either side of the mpi circuit since injectors and pump are on different sides

Missed this before. When does the IPW drop to 0, before or after it's stalled. After is normal, before means something else said to cut off the fuel.
 
Missed this before. When does the IPW drop to 0, before or after it's stalled. After is normal, before means something else said to cut off the fuel.

The last time I looked at it, it was hard to tell definitively
 
My engine has been doing this shutting off thing for about a year now, but only after the engine has warmed up. Initially, all the gauges would shut off, too. Before today, I replaced the fuel pump, the MPI relay, the ignition coil and power transistor, and the spark plugs and the plug wires (I had various reasons for suspecting each of these components).Still, it would shut off consistently whether idling or under load after warming up.
I taped a cell phone to the hood hold up rod and took a video at idle of the fuel pressure gauge I have on the fpr with an induction timing light pointed at it and managed to see that the ignition spark cut out about a second or so before the fuel pressure dropped out - I also collected a log of the event (attached, see about 136 seconds) and noticed that the ignition timing would normally fluctuate 1-2deg every 100-200 milliseconds but it froze at 17deg for about 600 milliseconds right before the shut off. I replaced the CAS today, then warmed up the engine and let it idle for about 20+ minutes and it didn't shut off. I went back out a few hours later and warmed it up again and let it idle for another 15 minutes or so; it still didn't shut off.
I notice in your log that your timing remains completely static for significant (relative to mine) periods of time - often for a full second or more. Does anyone know if this is normal?
This has been a very frustrating issue for me; I hope you figure it out - best of luck!
 

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Had the car apart so didn’t drive it for some time.

I have a feeling it’s my injectors. One was completely stuck closed when I put my motor back together a few moths ago but was able to free it up. I took them out a few days ago and now two of them seem to be sticking. I was able to free them both. Installed them yesterday and tuned them again. Perfect! Let it cool down for a few hours and started it, afrs is lean now (wasn’t logging when I restarted). It hasn’t stalled...yet. I’m looking at a new set

My engine has been doing this shutting off thing for about a year now, but only after the engine has warmed up. Initially, all the gauges would shut off, too. Before today, I replaced the fuel pump, the MPI relay, the ignition coil and power transistor, and the spark plugs and the plug wires (I had various reasons for suspecting each of these components).Still, it would shut off consistently whether idling or under load after warming up.
I taped a cell phone to the hood hold up rod and took a video at idle of the fuel pressure gauge I have on the fpr with an induction timing light pointed at it and managed to see that the ignition spark cut out about a second or so before the fuel pressure dropped out - I also collected a log of the event (attached, see about 136 seconds) and noticed that the ignition timing would normally fluctuate 1-2deg every 100-200 milliseconds but it froze at 17deg for about 600 milliseconds right before the shut off. I replaced the CAS today, then warmed up the engine and let it idle for about 20+ minutes and it didn't shut off. I went back out a few hours later and warmed it up again and let it idle for another 15 minutes or so; it still didn't shut off.
I notice in your log that your timing remains completely static for significant (relative to mine) periods of time - often for a full second or more. Does anyone know if this is normal?
This has been a very frustrating issue for me; I hope you figure it out - best of luck!

Did you notice your isc is at zero the entire log?
 
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@steve Can you see anything in these log? If you look at the second log, it's starts off pig rich then goes full lean. Injector Duty drops to zero right before it shuts off on all 3 logs.
 

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  • log.2020.12.19-02.elg
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@steve Can you see anything in these log? If you look at the second log, it's starts off pig rich then goes full lean. Injector Duty drops to zero right before it shuts off on all 3 logs.
@TK's9d2TSi Tony, did you take those logs in the same moment? It seems to me that you have a bad IAT sensor or something related to it. In the 1st log, it seems it sends the voltage properly. but in the 2nd and 3rd log, the IAT voltage is pegged max. I imagine at least the pig rich issue in the last 2 logs is caused by it. You should try another IAT sensor and see if it would fix the issue.
 
@TK's9d2TSi Tony, did you take those logs in the same moment? It seems to me that you have a bad IAT sensor or something related to it. In the 1st log, it seems it sends the voltage properly. but in the 2nd and 3rd log, the IAT voltage is pegged max. I imagine at least the pig rich issue in the last 2 logs is caused by it. You should try another IAT sensor and see if it would fix the issue.

Ah sheet! I had it disconnected LOL. Good eye! I try again a little later. Thanks buddy!!
 
Picked up a set of 1600 injectors and dialed in the idle today. It hasn't stalled so I will blame the injectors. Fingers crossed, and prayers to DSM Gods.

The tool thread to mark this resolved isn't on top. @1990TSIAWDTALON Marty, can you please mark this resolved? Muchas grassyass!
 
I'll get right on it Tony.
Thanks for always posting the results!
 
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