PO300 code, car undriveable, need advice

[super97gst]

I have been dealing with this problem now for a little over 2 months. We have had a thread going on this same thing as well for a while, but i still can't figure out what has gone wrong on my gst. It also hasn't been driveably since this all happened. 2 months ago when all this started i was sitting in the car with it idling. I was messing around with the BC and as soon as i put the car in reverse and started backing up the bottom fell out of it. It's kind of hard to explain the symptoms. The car now idles at 100 rpm's or less, but it will stay running, it will not die while idling or any other time. The engine also shakes horribly bad, like i've got 1 or 2 dead cylinders. After this happened i just shut the car back off. The next day i went back out and cranked it up and it was just fine. I drove it for 3 days with no problems at all. Then i was about 15 miles from home and cruising down the road and it started again. I barely made it back home. The car took forever to get to 60 mph. It will only rev up to about 3k, and it's really slow about getting to that. Also the boost will only go up to 5-6 psi.

I ran a diagnostic check on the car and it threw a PO300B code. It also gave me a PO141B and a P1104 code. The 141 code says 02 sensor bank 1 - S2- Htr. malfunction. I assumed this was from eliminating the cat with my downpipe. The 1104 is a manufacturer controlled fuel/air metering. I looked that one up though and it said turbocharger wastegate solenoid malfunction. I dont know if that could cause the PO300 or not. Also, the scanner said this too. Fuel system Status - Bank 1 - OPDC, Bank 2 - Disabled. I dont know if that has anything to do with this problem either.

These are the things i have done so far, and these were all brand new oem mitsubishi parts. CAS, ignition coil pack, NGK BPR6ES plugs, NGK plug wires, coolant temp. sensor and i was told an alternator could cause this so i put a new alternator on as well. I have also tested the IAC motor and TPS, both were good. I just pulled the battery out of the car to make sure i hadn't broken any wires or ground anything accidentally, couldn't find anything. What do i do next guys, i really need this car back going. 2 months is a long time to just have the thing sitting here doing nothing. I'm open to any and all suggestions if it will just get it fixed. thanks a lot.

Blake

 

[Artago]

Yes, I did test the injectors. They all passed with flying colors. I was actually hoping one of them would fail the test.

I replaced the plugs with BPR6ES plugs a week or so after I got the PO300. Just like we discussed in your thread, 2 of mine were affected. One was a lot worse than the other though. Both had a lot of gunk built up on them though, they actually looked like they were fouling. But I don't understand how that could be since I'm running extremely lean. The only thing I know of that could cause the running lean situation is either the ecu or possibly the mas. I found an ECU, BCS and a good MAS today. I'll get some money sent to the guy monday, so we'll see if it's one of those parts. I'm planning on swapping out the ecu then checking to see if that fixes it. Then do the MAS, so that I know which piece fixes it, if either do. That way I can post that on here for others with this same problem in the future. I really don't think there's any type of deep damage, like internal damage for example just for the very fact that when all this started the car wouldn't run right, then the next day it was fine for a few days. If I had some type of mechanical damage to something it wouldn't be intermittent. The only thing really that could do that in my situation, just like yours, would be electrical in nature. I don't know though, just like the 3 of us have been doing from the beginning, we're fishing in the dark. All I can do is just wait for parts.

Btw, Tom, what's taking that fuel pressure solenoid so long to get to you?? Does it always take this long to get parts to you in Canada?? Just seems like it's really taking forever.

I know what you mean by the plugs fouling being perplexing. Plugs say the car is running rich but the high temps say the car is running lean. Can it be both? And no, not at the same time . Is it possible that the car is running rich sometimes and lean other times? Just a thought.

Regarding fuel pressure solenoid. Although it is true that parts take longer to get up here in Canada (usually 2-4 days longer) but this time it's just JNZtuning being slow. My order was not processed right away because of some problem they have with their web site and then (after they processed it) they told me that they wont be getting the part until Tuesday the 22nd. So I emailed JNZ and the said that it went out on the 22nd but they can't give me a tracking number because USPS doesn't supply them the tracking numbers (total BS cause MAPerformance just mailed me a Mishimoto Rad via USPS and they gave the tracking number right away... I installed the rad + slim fan today... it's nice ). So anyways, I don't know when the solenoid will get here but I'm expecting it early this week.

On another note. Have you tested your EGR system? That's next on my list (after I fix ALL the vac/boost leaks)

Tom

 

[super97gst]

My EGR solenoid is good, as well as the EGR valve. I couldn't find any problems there. After all this is over and I've got the car back up and running I'm gonna do a total emissions elimination though. On the plug deal, I know the car is running extremely lean, but I don't know what the deal is with the plugs looking like they're fouled. I'm not so sure the MAS doesn't have something to do with our problems.

Is that new rad you bought polished?? I bet that is one sweet rig, what about the fans. Are they Spal slim line fans? Oh, and about the USPS sending out tracking #'s, that's total BS. At the car audio shop I used to work at every time I sent something out I had to get tracking #'s given to me from USPS.. I talked to the guy that's sending me some parts today. I'm getting the ecu, bcs and mas for 170$. I should have it by the end of this week or beginning of next. Hopefully one or the other is the problem.

 

[Artago]

Hey all. It's been a few days so I decided to post an update. I removed and cleaned the EGR valve. It works fine. No help with the P0300.

I FINALLY got my FPR solenoid. Installed it, threw a P0300 the next day. Oh well... At least it got rid of the P1105 code.

I think I'm going to attack this problem from a different angle. Instead of trying to figure out what is causing the P0300, I'm going to focus on simply fixing all the other problems the car has. Such as boost/vac leaks, overheating, funky idle. Maybe, with any luck, I'll fix the P0300 in the process.

Any updates from anyone else?

Tom

 

[bboyalan]

It's nice to hear from you guys again! I was starting to wonder what happened. But yeah, glad to see you were able to clear that solenoid code. Your new approach seems worthwhile.

As for me, I haven't seen the misfire code ever since. I'll occasionally, however, get a P0420 code for my high-flow cat, but nothing major really.

Hope to see more good news!

 

[Artago]

It's nice to hear from you guys again! I was starting to wonder what happened. But yeah, glad to see you were able to clear that solenoid code. Your new approach seems worthwhile.

As for me, I haven't seen the misfire code ever since. I'll occasionally, however, get a P0420 code for my high-flow cat, but nothing major really.

Hope to see more good news!

So your ECU swap was finally did it eh? Or was it something else? You mentioned the TB hole you plugged and SMIC pipes slipping off. I wish an ECU swap helped me out.

Tom

 

[bboyalan]

It was definitely the combination of ALL three. I knew the ECU was the biggest fix because AFTER the swap, my idle after startup shot straight up to 2000rpms where the SAS & BISS needed to be readjusted; they were in an unchanged position with the old ECU. I knew the slipping SMIC coupler fixed the last portion [acceleration] well because yeah... self-explanatory . That + the hole on top of my TB were knocked out at the same time for my "boost leaks".

Anyway, to bring the attention back to you and Blake, any ideas on what else this could be? I mean if you really look at it, we've all replaced some vital components to our system [from sensors to ecu]. I'm pegged on it being narrowed down to something smaller, such as the wiring, especially if certain cylinders are evidently misfiring with the buildup on the plugs. It seems as if it's right in front of our eyes but we're just overlooking it

 

[Artago]

Any update on this problem from anyone?

I'm thinking of testing my ground. The chassis ground is fraying and doesn't look good. So I figure I'd test them to make sure they are ok.

I found this thread which seems helpful: http://www.dsmtuners.com/forums/articles-electrical-wiring/179916-finding-bad-grounds.html

Thanks,

Tom

 

[super97gst]

Hey guys, sorry I haven't posted in a while. I've been really busy preparing for my new job in a couple weeks. Anyways, I have an update, but it definitely isn't a good one. I got my ECU, MAS and BCS in a couple days ago. I swapped it all out today. I did the MAS first and cranked the car, nothing. Then I swapped the ECU, again nothing. Finally I installed the BCS where mine was gone and bypassed my Greddy boost controller. That did nothing different as well. I'm really about ready to roll this damn car off a cliff. The only thing ignition wise I haven't checked is the transistor. I'm gonna check it tomorrow afternoon, but I'm not really getting my hopes up for it being bad. I guess I need to pull the EGR valve out and check it and start combing for vac leaks and broken wires.

Alan, I'm glad your luck is holding. I guess our problems in the end were caused by a different source, just causing the same symptoms. I'll post back tomorrow after I test the PT. If you or Tom has any more ideas I'm definitely listening.

 

[Artago]

Well I'm sticking to my new strategy of fixing shiat that's broken in the hopes it will get rid of the P0300. I fixed some Vac leaks. Car runs better. I found a major vac leak in the TB shaft. Ordered new TB shaft seals (along with TB gaskets and EGR gasket which was missing entirely ).

Also, my car runs HOT. I have a new water pump and new thermo already and still running hot so I'm thinking it might be the rad cap because it's old. I bought a new one but haven't driven the car yet. Hopefully it will get my temps down.

Next on the list is a turbo oil feed restrictor so I get more oil to the motor and less to the turbo (I'm flooding it with oil so this will help with the oil burning via the turbo). If that doesn't get my temps down I'll have to get a oil cooler (I'm running without one right now).

That's it for the short term. I'll do all this and see what happens.

Cya all later.

Tom

 

[super97gst]

Well I'm sticking to my new strategy of fixing shiat that's broken in the hopes it will get rid of the P0300. I fixed some Vac leaks. Car runs better. I found a major vac leak in the TB shaft. Ordered new TB shaft seals (along with TB gaskets and EGR gasket which was missing entirely ).

Also, my car runs HOT. I have a new water pump and new thermo already and still running hot so I'm thinking it might be the rad cap because it's old. I bought a new one but haven't driven the car yet. Hopefully it will get my temps down.

Next on the list is a turbo oil feed restrictor so I get more oil to the motor and less to the turbo (I'm flooding it with oil so this will help with the oil burning via the turbo). If that doesn't get my temps down I'll have to get a oil cooler (I'm running without one right now).

That's it for the short term. I'll do all this and see what happens.

Cya all later.

Tom

I guess thats really about all we can do. After I installed the new ecu and mas yesterday and didn't get anything different I got to thinking about it. A couple years ago for some reason some mice got into the engine compartment of my gst. They chewed most of the leads from my MSD DIS-2 to the coil pack in half. I was thinking maybe there's a possibility that there could be a wire somewhere that was chewed up a little and that could cause the intermittent problems I was having at first. However, a vaccuum leak could do that same thing.

When you are doing a boost leak test on the tb and into the intake manifold are you hooking your boost leak tester up to the tb elbow?? I think I'm gonna run through that again this afternoon and make sure I didn't miss anything. I did a boost leak test when all this first started. Testing from the turbo I couldn't find anything but a small leak around the adjustment screw on my Greddy type RS bov. But I haven't tested around the tb and intake mani. Also, I thought you were gonna just go ahead and block off the EGR?? If there's no gasket behind the EGR at all maybe that's causing a lot of your problems.

 

[Artago]

I guess thats really about all we can do. After I installed the new ecu and mas yesterday and didn't get anything different I got to thinking about it. A couple years ago for some reason some mice got into the engine compartment of my gst. They chewed most of the leads from my MSD DIS-2 to the coil pack in half. I was thinking maybe there's a possibility that there could be a wire somewhere that was chewed up a little and that could cause the intermittent problems I was having at first. However, a vaccuum leak could do that same thing.

When you are doing a boost leak test on the tb and into the intake manifold are you hooking your boost leak tester up to the tb elbow?? I think I'm gonna run through that again this afternoon and make sure I didn't miss anything. I did a boost leak test when all this first started. Testing from the turbo I couldn't find anything but a small leak around the adjustment screw on my Greddy type RS bov. But I haven't tested around the tb and intake mani. Also, I thought you were gonna just go ahead and block off the EGR?? If there's no gasket behind the EGR at all maybe that's causing a lot of your problems.

Yes, I'm hooking up the boost leak testers to the TB elbow.

I decided to keep the EGR for now. I have a new gasket coming in with the TB shaft seals.

I put a new rad cap on yesterday, seems to be helping with the temps. Still a bit high but much better.

I'm installing coolant and oil temp gauges today, hopefully I can get the oil restrictor done too.

I'll post back later tonight... gotta go work now. TTYL

Tom

 

[super97gst]

I worked on the car all afternoon testing all the things I had left, and AAAAGGGHHH!!!!!. Why don't they have a smilie that's screaming?? . Anyways, I obviously couldn't find anything else wrong. Everything I tested was good. I'm stuck now, the only thing I haven't tested is the CPS. Just for the fact that it's so hard to get to. I'm sick of messing with it, I'm gonna just take it to my mechanic and let him mess with it since he has an oscilloscope. I'm pretty much convinced it's a broken/shorted wire or vaccuum leak in my case.

On another note, I did notice when I cranked the car today that the air/fuel guage wasn't reading as lean as before. Since this PO300 started the guage reads so lean that it's off the guage. Now it's reading on the first 2 bars. Still really lean, but before it wouldn't show anything. I assume the ecu swap had something to do with that.

 

[super97gst]

idk the cause of these either. for the past month ive gotten this same code and it will come on one or every 2 weeks. i just disconnect my battery for now and it will be gone for a good while. im definatley interested to see what the culprit of this is!

Man, the three of us (Tom, Alan and I) should be experts on this by now. From dealing with this for so long I have found that there can be absolutely numerous things that can cause the PO300 code. Have you read through mine and bboyalan's threads in their entirety?? You should do so if you haven't already. Might give you a little insight into what's going on with yours as well. Only Tom and I haven't gotten it fixed yet. It wouldn't be a bad idea to go ahead and start testing things on yours. I thought mine would be the same thing as Alan's, but it wasn't. Just something to think about. Once Tom and I figure out each of ours we will definitely post the fix on each. Good luck with yours.

 

[bboyalan]

Hey Blake!

I was thinking... we know that you've eliminated many of the possible causes already, so I'm wondering about 2 primary remainders - ignition and fuel. Which cylinders exactly were showing significant buildup over the others? Also, what was the scenario with your Power Transistor for the ignition system? If you have the time, maybe you should check for power to those cylinders' injectors/plugs [light bulb test or multimeter's voltage]. Their resistance checked out, so maybe it's just the power/signal. It does seem like a PITA, if not already, to continue testing, but you're so close! The price for a mechanic's service seems scary [at least for me!!]

Let me know what you think yeah? Just throwing this out there as an idea hehe.

 

[super97gst]

Hey Blake!

I was thinking... we know that you've eliminated many of the possible causes already, so I'm wondering about 2 primary remainders - ignition and fuel. Which cylinders exactly were showing significant buildup over the others? Also, what was the scenario with your Power Transistor for the ignition system? If you have the time, maybe you should check for power to those cylinders' injectors/plugs [light bulb test or multimeter's voltage]. Their resistance checked out, so maybe it's just the power/signal. It does seem like a PITA, if not already, to continue testing, but you're so close! The price for a mechanic's service seems scary [at least for me!!]

Let me know what you think yeah? Just throwing this out there as an idea hehe.

Well, I'm not concerned about the mechanic's price. He's my neighbor and he'll just make me do the work using his high tech equipment while he watches and advises. He teaches auto mechanics at the local tech college. I just don't ever have him do any work for me because I have a lot of mechanical abilities myself. But he does have a big nice shop with a couple of lift racks in it..

Anyways, as far as ignition I have either replaced or tested everthing there is. I tested the pt today and it was good. I think it was cylinder 3 that the plug looked so fouled in. On your suggestion about the injector harness check, I guess I could go get a noid light to test the injector harnesses themselves. It tests to see if each injector is getting pulses of voltage.

As for fuel, I don't know of anything else to check. I can't believe the pump could be going out since the car will run it just won't run right. If the pump were going out it just wouldn't run, period. I don't know man, I'm just getting sick of testing/replacing things and always coming up short. I hope that I am close to the end like you said. . Anyways, I'll post back tomorrow night after I check the injector harness.

 

[PieEyedPiper]

Just something I thought I'd throw out here. My P0300 is back in full force after about a 7 month break. And I'm dead serious when I say this is the third "season" for P0300 I've had. Lasts from beginning of summer-ish (now) to fall then it quiets down and I get no code for months.

Anyways, I got mine much more often after I topped up my oil 2 weeks ago. Mobil 1 has a habit of evaporating plus I just switched back to Mobil from Pennzoil Platinum (good stuff), so it would be natural to be eating a little oil.

The dipstick was maybe 1/4" below the "full" line. I grabbed a half quart of Mobil and tossed it there. Checked the level and now I'm 1/4" or more above the line. Oops.

Anyways, I've noticed that sometimes my P0300 coincides with a recent oil change in which the level is a tad high.

What that means? I have no idea.

 

[Artago]

Just something I thought I'd throw out here. My P0300 is back in full force after about a 7 month break. And I'm dead serious when I say this is the third "season" for P0300 I've had. Lasts from beginning of summer-ish (now) to fall then it quiets down and I get no code for months.

Anyways, I got mine much more often after I topped up my oil 2 weeks ago. Mobil 1 has a habit of evaporating plus I just switched back to Mobil from Pennzoil Platinum (good stuff), so it would be natural to be eating a little oil.

The dipstick was maybe 1/4" below the "full" line. I grabbed a half quart of Mobil and tossed it there. Checked the level and now I'm 1/4" or more above the line. Oops.

Anyways, I've noticed that sometimes my P0300 coincides with a recent oil change in which the level is a tad high.

What that means? I have no idea.

Could it be heat related? I've noticed I throw the code more often when the car is over heating (due to variety of reasons)

Food for thought.

Tom

 

[super97gst]

I would say if an oil change really does have anything to do with a PO300, it would be more likely to be internal pressure related. That would make more sense than heat. I guess it could be a little of both though. It's possible though that with too little or too much oil the pressure could jump a little one way or the other and if there's already something quirky causing the code any small variance in internal pressure could throw it back up., just a thought.

I've pretty much narrowed mine down to a broken/shorted wire or a possible vaccuum leak. It's going on the oscilloscope tomorrow or thursday, so maybe that'll give me a little more information.

 

[Artago]

I know I have Vac leaks. TB seal are on the way.

 

[Artago]

Ok I have a request for everyone fighting the P0300.

I was doing a boost leak test and I pressurized the system and started spraying everything with soapy water to look for bubbles. Well I found bubbles coming out of the strangest place. I found bubbles coming from the fuel pressure regulator (not the solenoid). And I don't mean from the seal where it connects to the fuel line. The bubbles were coming from the top "hat" portion where the top meets the bottom. (I'll take pictures next time I do a BLT)

So my request is: To those of you with the P0300. Can you do a boost leak test and spray the fuel pressure regulator with soapy water and check for bubbles? I'm curious if anyone else has this vac/boost leak and if it has anything to do with the P0300.

Thanks,

Tom

 

[bboyalan]

Woah! That IS strange! Are you sure it wasn't coming from the line connected to it from the solenoid? I guess a picture would help visualize =X

 

[Artago]

Woah! That IS strange! Are you sure it wasn't coming from the line connected to it from the solenoid? I guess a picture would help visualize =X

Yeah I'm sure 100%... Coming from the fuel pressure regulator. Small leak but it's there.

 

[super97gst]

Yeah I'm sure 100%... Coming from the fuel pressure regulator. Small leak but it's there.

Good to know Tom. It'll be Sunday before I'll be able to mess with mine again, but I will check it then and post back. Were you getting any vac leaks from anywhere else?? What about the one you have under the intake mani?? Have you got it fixed yet?

 

[Artago]

Good to know Tom. It'll be Sunday before I'll be able to mess with mine again, but I will check it then and post back. Were you getting any vac leaks from anywhere else?? What about the one you have under the intake mani?? Have you got it fixed yet?

The one under the intake mani turned out to be the TB shaft seals. New seals are on the way from JNZ... DAMN THEY'RE SLOW.

 

[PieEyedPiper]

I'll check my regulator as soon as I can.
Thanks for the heads up.