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2G MPI relay bad?

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AlexGsxCummins

Proven Member
395
34
May 31, 2014
Bremerton, Washington
alright guys, so Monday my car died while going down the freeway as im in the middle of moving i completely have no tools at all so i felt the fuel line it felt soft (no pressure) so i order a new fuel pump, put it in today car started up and ran just fine went down into town and as soon as i pull up to the first light the car stalls, started right back up no problem...turned around to bring it back home and it stalls 3 more times on the way home and at one point while driving it started hesitating. i get home and i notice i herd a click / click sequence every 10 seconds or so from behind my dash, i look online a lot of people are saying ecu, i just pulled my ecu (had caps replaced and dsmlink) looks perfect smells normal, i even turn my key on with the ecu disconnected and i still hear this clicking noise like a relay. while i had it idling at home it would run perfect for a while then just shut off with no warning. possible bad relay?
 
well i ruled out the MPI relay, but it still just will stall out bog down gas pedal has no response, but it is intermediate...when it happens while driving the car starts pulling pack and bucking but if i keep the pedal down it will just stop all of a sudden and start to take off again. but if im stopped at a light it will normally just die, starting to think it has to be a spark issue..put in new fuel pump, checked ecu, new injectors, checked fuel pressure. when it happens my afr jumps to 16 (max on my gauge) and once it stops it goes back to normal, not sure if that helps.. my power transistor also gets really hot.. also new wires and plugs..
 
If you have some click going on its a relay. Don't rule out mpi just yet. Sounds like you have some wire tracing to do. Possible bad ignition switch
 
So the clicking is gone, turns out my daughter turned on my rear wiper switch :\ my rear wipers deleted so that was just a duh moment for me. Other than that, yeah it will run lean when I first hit the gas you can feel the car have no power then it just kicks out of it afrs go back to normal and it takes off like normal. And the random dying issue at lights. Maf? I'm not sure where to look next, it did this with my last set of injectors, and I have a new pump its been rewired by the p.o
 
When I bought the car, but I've been trying to track down the issue sense, it had a horrible tune, so I had English racing tune it and of course it ran fine for them, changed plugs, wires, injectors, fuel pump. It starts perfect and idles perfect. It is becoming more frequently, it use to happen maybe once a week now its daily at minimum. I did a boost leak and checked ecu they both tested good had 1 leak I fixed. I think I'm gunna buy some maf cleaner and try that I just remembered English said there was some oil in my intake pipes
 
So if its putting my afr up at 16's its probably not a spark related issue correct? Just dont want to try buying new coil pack and transistor if that's not even suspect
 
yes ...unburnt fuel would show rich ..so the injectors are being told not to put fuel in or fuel pressure is dropping off ..clean the maf and go from there ...these intermittent problems are hardest to solve ..actually be glad that it gradually getting worst cause it make it easier to tell if what ur doing is working ...if you search there are test specs for the power transistors
 
So if its putting my afr up at 16's its probably not a spark related issue correct? Just dont want to try buying new coil pack and transistor if that's not even suspect

If the engine misfires due to a spark related issue, the wideband will read lean. The unburned oxygen in the exhaust, from the misfire, will cause a lean spike on the wideband. The fact that your Power Transistor is getting hot would be a red flag for me.

Jim
 
Great info that makes sense! Yeah I wasn't sure how hot they get but I went to unplug it to look at the connection and it burned me. So its hot to say the least. To me it almost seems like a spark issue with the fact that it will just shut off at a light with no hesitation, and when it does spike to 16's the pedal has no effect on power untill it comes out of the issue its having. I hate that I know I have a extra power transistor in my storage now haha of course once I need it then I cant find it. I just wasn't sure of they can be intermediate issues or if its either working or its not.
 
I think I'm gunna buy some maf cleaner and try that
..clean the maf and go from there..

There is nothing to clean in a Mitsubishi Karman MAF unlike a Hot-wire MAF used in other cars. The solvent can actually damage the MAF so don't.

It would be interesting to know what the electrical system voltage was when this happens.
 
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Hey Steve, I'm assuming that goes the same for the gm MAF? Its so intermediate that I dont know of a way to looking at the voltage without my laptop that I currently dont have access to. I know prior it was lower than 14v constant, around 13.7ish if I remember correctly. I dont notice any dimming of lights or slow cranking when it either dies or does its "power loss" issue.
There is nothing to clean in a Mitsubishi Karmen MAF unlike a Hot-wire MAF used in other cars. The solvent can actually damage the MAF so don't.

It would be interesting to know what the electrical system voltage was when this happens.
 
So I had to test the alt. The only way I cam with no tools I unplugged the cable while it was running (I know risk risk) stayed running. I let the car run for about 25 mins and it never died so I started shaking wires to try and make something happen and I was checking fuel lines I squeezed the line and it collapse under pinch pressure and the car stalled. It was taking a while to get it fired back up but I did and got it running again and went to squeeze the line again and it had alot more pressure. I tested the fuel pressure at my buddys shop about 2 weeks ago and it was 46 psi of I remember correct. So could something cause a drop in pressure?
 
So while chasing this issue I figured I would throw a new fuel filter on so I don't have that wounded in my head, little odd but I took the soft line to the rail off and maybe 5 minutes after (line was not draining anymore) it kinda "spit" or "burped" from the rail out the soft line. I've never seen that happen before I was wondering what you guys think on that? The fpr is holding vacuum as far as I can tell and doesn't leak fuel but it still has me wondering if something is going on with it...
 
Throttle position sensor could cause lean conditions if it is not reading correctly. Usually right at throttle tip in you will spike lean but should idle ok. The ecu does not know to increase fuel if it doesn't get the information from the tps. If the car is missing it can show a lean condition as the ecu can shut down injectors. You may want to try disabling missfire check with ecm link.
 
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