P0300 Random Misfire

[99eclipsegst99]

Hello I checked through I didn't see anything similar to the issue I have been having.

From the begining I am driving my 99 Eclipse GST Spyder (4g63) and all of sudden I hear a pop. When I get home I notice that two of the bolts snapped off the exhaust mainfold on the left passenger side. So i ordered new bolts and replaced them.

After that my car throws a P0300 Random Cynlinder Misfire. It sounds like VW bus, sluggish and now power what so ever on take off.

Changed the plugs, the wires and nothing. I take it to PEP Boys to diagnos and they tell me its my ignition coil and that i need to replace 2 of them for $200 a pop and $80 x 2 in labor for each. Which I found out later by doing research its only one coil pack and I got from the dealer for $100.

I put in the new coil pack in yesterday and still nothing, still throwing that p0300 code. I heard someone say that it might be my catalytic that is clogged and might have popped the bolts of the exhaust from the pressure.

Before I go through of ordering a new one, thought I get a thought or two. Any help greatly appriciated.

-Noob-

 

[99eclipsegst99]

snowborder714- I just checked it looks like the second picture. Thanks for your help!!

Frskrgps- Crank Position sensor or the CAM Positions Sensor? I have to do some research on checking the Crank Position Sensor, i've never done that before. WHen you say your motor walked, was that from the "Crank Walk" syndrome I have heard about?

 

[PieEyedPiper]

The events that lead up to this was when I had the car shipped from California to Jersey. In Cali my car was lovely, only problem I ever had was the alternator and the tranny, both of which we replaced and rebuilt.

When it got here it was fine for 2 days and 1 day I am driving I hear this pop. When the pop happened I had no power what so ever and it sounded like I had an exhaust leak (cause it sounded like VW bus) I have to put the pedal to the floor to get it moving, rough idle at stops, to where the car was shaking when I was stopped at a traffic light.

I saw the check engine light come on and plugged the logger into the car. It came up with P1500 and P0300. I changed the plugs and the wires, no change.

I take it to my dad's friend shop and they say the P1500 was due to the alternator wires touching the O2 wires, which created a short. I think GREAT problem solved!

When I picked up the car it still sounded like $hit. The mechanic comes out with a cigar in his mouth and says, you got 2 snapped bolts on your manifold and your CAT sounds like it's blocked. I take it home; order the two manifold studs from the dealer.

When I put them on, guess what?

It was a little quieter but it still had a very hard idle (to where it's below the 1 on the RPM Gauge on the left side) still shakes the car at the stop lights and no pick up what so ever. Grandmas are blowing past me giving me the finger.

I get frustrated so I take it Manny, Moe and Jack (Pep Boys) and they tell me it's the ignition coil. I have to tell you Manny, Moe and Jack almost got me, they said I need 2 coils at $200 a piece and x 2 @ 80.00 for labor. I take the car home and I ordered my own coil from the dealer for $120.00 and replaced the coil myself.

I close my eyes, praying while turning the ignition and FML, the car is still running like $hit.
My last course of action is taking it to the Mitsubishi Dealership, they are the experts right, they work on Mitsubishi's all day long. I take it in, they tinker with it for about 3 hrs and the service tech comes out and says my timing belt is off and shows me the two little white dots are about a 1/8 off.
I think at last these guys know what they're doing; they keep the car, promise me it back in 3 days, and guess what they kept it for like 7 days and at the last day the service manager is telling me, they fixed the timing, put in a new water pump and I need a new turbo for $1800.00. I'm like no that's ok, if it needs a new turbo, I will put it in myself.

I pick up the car from the Mitsubishi Dealership and it's running a little better no hard idling, still faced with no power when you step on the gas and guess what??
The check engine still reading a P0300. FML.

That's the whole story start to finish, soup to nuts. At this point, I am going to do like RadDsm suggested and go through the points of the P0300. Which is:

Step 1. Check the oxygen sensor(s).
Step 2. Check the catalytic converter(s).
Step 3. Check the EGR valve / passages.
Step 4. Check the Fuel injector(s).
Step 5. Check the camshaft position sensor.
Step 6. Check the exhaust valve.

Oh i forgot to ask one more question? Before I go through and order a new turbo, does anyone think it's the turbo??

LMK.

Thank you for all your help everyone!

I'd re-arrange that list a bit, if it were me in your shoes. I think it's first most important to perform a boost leak test and a compression test. Please follow proper procedure with your BLT and compression test. Makes a world of difference.

Next, I'd consolidate all the "information" you've been given by so-called mechanics. For instance, we know that we heard a pop that coincided with a drastic loss of power and random misfires. We also know that you have an exhaust leak at the manifold. It is very unlikely that your CAT is clogged. Entirely plausible, but I'll stake a fair wager that it's a red herring. We also know it's not the coils. Satan, apparently thinks your turbo is gone.
Your P1500, should it ever return can also be caused by a bad alternator. Which also happens to be a documented trigger of the 7bolt P0300 phenomena.


My list would consist of:
1. Check your turbo for shaft play - determine if Satan is just effing with you.
-if no, move to step 2.
-if yes, or if "yes, that shits barely there anymore" consider where any missing pieces must go through before exiting the car before moving on to step 2.
2. BLT
-post results. Holding 20psi before slowly bleeding off the pressure down to zero is deemed acceptable.
3. Compression test
-post results. factory service limit is 14psi between cylinders.
4. Investigate repairing/helicoiling the broken studs on your exhaust manifold.
5. Investigate DSM specific, known causes of 7bolt P0300.

Some things I know, personally, to have caused P0300 in a 7bolt DSM are a lightweight flywheel/aftermarket clutch w/out lightened flywheel and bad alternators. I think there was maybe one guy who solved it with a new power transistor but I'm not positive.
I know of no one experiencing 7bolt P0300 to have ever cured it with sensor replacement/repair. I cleaned and replaced my CAS/CPS sensors to no avail. It's more likely for your car to not start, than throw a misfire code if you have a CAS/CPS malfunction. Similar reports echo throughout the forum.

6. Investigate the generic P0300 causes listed in previous posts.

7. I'm not touching the C/W vs. dying CPS bit until all of the above are checked off.

However you go about this, I'm keenly interested in your results.

 

[99eclipsegst99]

Problem Solved!

Big thank you to snowborder714!

Thank you to everyone else who helped out.

What was the problem, the ignition transistor. I ordered one from Mitsubishi for about $100.00. It got here and I installed it today. I closed my eyes and turned the key...

Guess what?

Car was running like it walked off the showroom. I have to tell you that I can't remember when the car pulled that hard, to the point I was spinning the tires in 1st. Imagine that!

My problem totalled out to be $500.00 new alternator, $500 new timing belt, water pump, $125 New Coil, $120.00 new transistor. Total $1245.00

Final Note:

What bugs me is that the ya ya's at Mitsbuishi Service couldn't figure out the problem. They didn't even mention to me P0300, or explore any of the P0300 scenarios we discussed. Simply said "Ah it's the timing belt." and when they couldn't "figure" it out, they opted to try to sell me a new trubo.

Pep Boys ya ya's were close only their info was bad. They said I needed two coil packs for $200 a pop and $80.00 x 2 in labor.

I am glad I was able to find help here and I learned alot.

Thanks Everyone!

 

[TsiJohn333]

PieEyedPiper... how could a bad alternator throw a p0300 code? The reason I am asking is because I have this code and my alternator just recently started to go out. Then not to long after this, I was cursed with the P0300 random misfire code. I replaced my CAS, Spark plugs, and power transistor with no luck.

 

[PieEyedPiper]

PieEyedPiper... how could a bad alternator throw a p0300 code? The reason I am asking is because I have this code and my alternator just recently started to go out. Then not to long after this, I was cursed with the P0300 random misfire code. I replaced my CAS, Spark plugs, and power transistor with no luck.

How is beyond me. But if you want some sort of BS explanation that might fit, try this: When the alternator starts performing outside it's intended specifications (pick any cause you like) then the result is also not what the sensors and ECU, etc are expecting to see.

There is 1 maybe 2 documented cases of this on tuners.

Do you have a 6 bolt swap?
Have you recently had any clutch/flywheel work done?

 

[Cdaug720]

I just bought a 98 gsx with the 6 bolt swap and a 1g cas, my check engine light comes and goes. And it flashes sometimes also. The guy just put a new clutch in it also. I noticed these questions were asked and I was wondering what differences these could make? It mostly misfires when I'm on the freeway doing about 70 or so at about 3k rpm. It will do it sometimes driving around the city at various rpms but not very often. It comes and goes. I have replaced the spark plugs, wires, coil packs, and I'm going to try another 1g cas tonight. But I was mostly wondering why questions about the 6 bolt, 1g cas, flashing check engine light and new clutch were asked and what differences these can make.

 

[PieEyedPiper]

I'm not sure I understand you entirely.

Do you have a green top or a black top cas? The flashing engine light is likely to be some sort of knock threshold indicator. It could be tripped by misfires.

What kind of tuning solutions do you have available? Someone or something set your CEL to respond like that. It's possible that same entity could remove the P0300 check from the ECU and resolve the issue for good.

 

[Timechg]

It most likely is the random misfire code P300. This happens because of the different CAS sensor wired in.


Solutions for this have been the potentiometer mod (I tried this and it seemed to work). Better solution is to use DSMLink and have the ECU skip the check for looking for a misfire. When the check engine light flashes on, do you have any stuttering?

 

[AK Maniak]

Thread revival and hi jack!

I have the same exact problem as Cdaug720. When I am cruising at a constant rate and the car is around 3k RPM's I get a p0300 and it begins to bog really bad. The only thing that I have found to get it to go away is to turn the key off and then on again while driving. Once I do that it goes away and the car acts normal.

It only does this when I am cruising and when it does the car goes very very lean. Sometimes over 20 on my wideband.

I have a 6 bolt swap with a black top CAS

I've checked/replaced
Plugs
wires
coil pack
MAF
ECU
alternator

 

[PieEyedPiper]

You may be able to recover from the situation more safely than shutting off the key.
Try putting the car in neutral and allowing the rpms to come down to idle. Toss it back into 5th and see if the issue has alleviated itself.

What is the work/mod history of the car over the last year?
What kind of tuning setup does the car have?

It's very rare for a 6 bolt + black top to run into a classic P0300.

 

[AK Maniak]

You may be able to recover from the situation more safely than shutting off the key.
Try putting the car in neutral and allowing the rpms to come down to idle. Toss it back into 5th and see if the issue has alleviated itself.

What is the work/mod history of the car over the last year?
What kind of tuning setup does the car have?

It's very rare for a 6 bolt + black top to run into a classic P0300.

I tried putting it in neutral and letting the RPM's go all the way down to idle but when i put it back in gear it continues to do the same thing.

If I have my laptop with me and clear the code in DSMlink the problem immediately goes away but minutes later when cruising the CEL will come back on and the problem happens again.

The car is tuned on Link v2.
FP 4" intake. Stock 2g MAF. FP Green XL. FP race Manifold. SBR/Kinetic FMIC kit w/2.5" piping. Tial QR BOV. Wallbro 255HP (rewired). FIC 850cc injectors. Aeromotive AFPR.

 

[PieEyedPiper]

I tried putting it in neutral and letting the RPM's go all the way down to idle but when i put it back in gear it continues to do the same thing.

If I have my laptop with me and clear the code in DSMlink the problem immediately goes away but minutes later when cruising the CEL will come back on and the problem happens again.

The car is tuned on Link v2.
FP 4" intake. Stock 2g MAF. FP Green XL. FP race Manifold. SBR/Kinetic FMIC kit w/2.5" piping. Tial QR BOV. Wallbro 255HP (rewired). FIC 850cc injectors. Aeromotive AFPR.

What about the clutch? When was the clutch done?
There is a locating pin for the flywheel which has been associated with p0300. Perhaps this is the problem? Otherwise I'd only have to suggest trying a different CAS. You've pretty much tried everything else.

Fortunately, you do have Link so the option to turn it off should be available. I'd just flip the switch and be done with it.

 

[AK Maniak]

Clutch and transmission were done about 10k miles ago. I used link to make the problem go away but that seems like a band aid or cover up for a problem. I guess it nothing bad will come from it then it does matter though.

 

[99GSEclipsekamloops]

Hey guys I don't mean to thread jack, but I can't start my own yet. Too new!
Anyway I have a 98 GS-T awd conversion with a 6 bolt swap done. I am having a very strange problem that seems to be similar to what is described in here.

At random speeds/RPM's The car goes into some kind of limp mode and sounds like a Subaru. If I push in the clutch and let the RPM's drop below 2000 then it just goes away. I can never tell when it is going to happen which is weird. I've had it happen cruising down the highway at 110km/h or in the city in second gear. I replaced the plugs and wires with NGK ones and its still doing it.

Also some back story. I bought it used with the 6 bolt swap done and it drove perfectly fine. However the timing belt decided to $hit the bed and I bent all the valves in the car and obviously messed up the head. I replaced the head and got all new valves put in and the car seemed fine for about a week, afterwards its slowly started doing this, at which point I tried plugs and wires...

I don't have DSMlink yet (I know I'm sorry, but its kinda pricey) I do have a code scanner and will pull the codes tonight, because the check engine light is on.

Does anyone have any insight to my problem?

TL;DR car sounds like scooby and drives me nuts!

 

[PieEyedPiper]

6 bolt p0300, very common. Do you have a black top or green top CAS?
You may have to swap in a couple to find one that keeps the car happy but a tuning solution such as ECMlink or ECUflash will be able to disable the p0300 code and thusly the behavior.

If this is not the issue, which sounds possible by your description, follow the codes. Maybe you're getting a p0301 and p0303 (cylinder 1 misfire and cylinder 3 misfire as opposed to p0300 which is multiple random misfire). At that point you could probably trace it a single coil as the culprit.

BTW, I'm from Nelson. My uncle lives in Kamloops.

 

[99GSEclipsekamloops]

awesome thanks for the reply I still haven't pulled the codes yet I will do it this morning! I will figure out if it is the P0300 code or if it is just the single cylinder misfire. I think you might be right about it being a single cylinder, because from what i've read the multiple cylinder random misfire code shuts off two cylinders and it shakes like a wild banshee, and also cannot be reset unless the car is shut off, or codes wiped... mine just goes away by letting the rpm's drop and it doesn't shake too bad just a rough vibration and it sounds like a subaru with a massive loss in power.

Is there a specific way of testing coils?

On the way back to work I let it rev up to 5k rpm in second gear and it started doing it. Tried it several times and it appears it doesn't like that rev range in 2nd or 3rd gear also cruising on the highway in 5th.... super weird...

so I went outside and pulled the codes... fml I have a laundry list: P0300 Random misfire(duh), P0505 idle air control system, P1400 manifold differential pressure sensor circuit malfunction, P0450 evap. emissions system pressure sensor/switch, P0446 evap. emission system ventilation control circuit, P1105 fuel pressure solenoid malfunction.

No clue where to even start...

 

[PieEyedPiper]

New thread.

 

[bucken13]

What about the clutch? When was the clutch done?
There is a locating pin for the flywheel which has been associated with p0300. Perhaps this is the problem? Otherwise I'd only have to suggest trying a different CAS. You've pretty much tried everything else.

Fortunately, you do have Link so the option to turn it off should be available. I'd just flip the switch and be done with it.

Tread jack sorry i know this is a year old but this is the closest to my current problem what locating pin are your talking about ? i just did a stage 2 comp clutch on my 95 talon tsi and at 100 miles into the break in i got p0300 i do have linkV2.5 btw. I did the clutch myself and didnt see any locating pin ..

 

[ishnish]

Reviving this although I have this issue on another thread, I figure it'd be more relevant on this thread. I had a p0300 random engine misfire code pop up ever since I installed my new FIC 2150CC injectors and tried dialing them in. I installed new spark plugs right before the injectors as well (BPR7ES) and gapped them to 0.022" because a friend suggested to gap them that close.

Before this I never had any random engine misfire codes! Please help guys. I noticed that this code randomly comes on at idle for no reason it appears. I highly doubt it's any sensor because as I've said, this ONLY started happening after installing new spark plugs and injectors.

 

[rEclipserGST]

Did you disable the misfire code in EcmLink?

 

[ishnish]

Did you disable the misfire code in EcmLink?

No I did not. That feels like it would be a band-aid solution and that is not what I want to do.

 

[rEclipserGST]

You got two threads trying to hammer done on your tuning issues. Read the wiki EcmLink has.

Do some research on why I told you to do that. Start with "2g misfire".

Your deadtime & injector pulse width is going to be very crucial. Along with injector voltage. It sounds like this may be out of your hands. If you are having problems ONLY after switching out your plugs. Spend another $12 and find some no projected plugs. Gap them done further.

We can't tune it & fix it for you.

 

[ishnish]

You got two threads trying to hammer done on your tuning issues. Read the wiki EcmLink has.

Do some research on why I told you to do that. Start with "2g misfire".

Your deadtime & injector pulse width is going to be very crucial. Along with injector voltage. It sounds like this may be out of your hands. If you are having problems ONLY after switching out your plugs. Spend another $12 and find some no projected plugs. Gap them done further.

We can't tune it & fix it for you.

Yes I know I do, I just posted an update on my car since that was my original thread then realized this would be more relevant so I posted on here as well.

I already did some research on it and have seen the thread where even a wiseman suggested to disable the misfire code. Don't know if that's the thread you're referring to but I've seen it and am continuing to do some research.

I've also read through the ecmlink wiki a few times. My next step is going ot be taking out the plugs and gapping them further. I've been at work all day but get free time so this is why I haven't done anything with my car yet and figured it'd be wise to post about it and maybe get some suggestions if there were any.

So not asking for someone to tune and fix it for me, just asking for a few suggestions since what I noticed with my car seems to be a little different than what other people have had with the same code.

And if you haven't noticed, I've had a few people help me with my other thread but for the most part, I was left to figure out my issues regarding dialing in my injectors myself. So whether my injector values are off or not, I don't even know, but based off of my research, I guess I have everything in line. So I don't really know what I'd have to do to those values in order to make the misfire issue go away.

 

[rEclipserGST]

These are low impedance injectors i can tell. During your downtime, just read. And if need be, find a local tuner so he can tell you that the issue lies elsewhere or he can fix it for under $200

 

[ishnish]

These are low impedance injectors i can tell. During your downtime, just read. And if need be, find a local tuner so he can tell you that the issue lies elsewhere or he can fix it for under $200

Incorrect, they are FIC 2150cc High Impedence injectors. Have them installed with the plug n' play connectors and the resistor pack delete as well.

Thank you for the suggestion. Can't afford that right now so I will keep on hunting. I really do believe it's something minor I'm not catching.