PO300 code, car undriveable, need advice

[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 lol. 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: Finding bad grounds

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]

Originally Posted by 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

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]

Originally Posted by super97gst

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]

Originally Posted by dSmgs-T

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]

Originally Posted by 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.

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]

Originally Posted by 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.

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 lol =X

[Artago]

Originally Posted by 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 lol =X

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

[super97gst]

Originally Posted by Artago

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?