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Old 04-09-2021, 06:25 PM   #1
LakixPompa
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Default 2004 WRX JDM engine Misfiring issue Please HELP

Hello, I have a 04 wrx, which I ended up engine swapping, I put in an ej205 AVCS with 29k miles. On startup, the car runs extremely rough and seems like it's going to stall, constantly hearing some clicking sound from the engine. The engine seems to shake so much when it's idling. Once the engine warms up, it runs better but still rough. Today I went with it around the block, and the car seems to have some sort of weird hesitation. When I floored the pedal, the RPMs went up to 3.5k stopped at 3.5k for 1 second, and then went up normally 6-7-8k. I shared a link to two videos showing how the car runs, as well as the problem codes. The compression seemed to be 140 on all 4 cylinders. Please give me some sort of suggestions and help. I appreciate any help. I'll look at this thread daily and provide any further information needed about the car and its engine so please any idea you guys have, feel free to share it.
Thank You so much

Things are done to the car and engine:
Greddy exhaust
Straight pipe
Catless downpipe
Mishimoto radiator
STI top mount intercooler
HKS BOV
Aftermarket Intake
20g turbo

https://streamable.com/xsy34u



3 minutes later -> (After first vid) https://streamable.com/u7j5fa
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Old 04-09-2021, 06:45 PM   #2
snow_bound26
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Are you tuned for these mods on this engine? The BOV alone can cause the engine to run horrible if not tuned properly. If you had these mods on the previous engine and it was tuned for then you need to get this one tuned for those mods as well.

Other things to consider:
Functional AVCS?
What ECU?
What engine management?
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Old 04-09-2021, 07:57 PM   #3
LakixPompa
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The the avcs are not plugged in, and not planning to do so either. When I bought the car, it came with all of the modifications I listed. This means that the new engine is running on the same ecu as the old engine was . I also have a spare avcs ecu but I don’t know whether that will change anything since people just swap the jdm engine in and it works fine with the usdm ecu. And what do you mean by “what engine management “ apologies I’m quite new to this tbh. I assume it was tuned , I asked before based on this data. If more data as such is needed please inform me and I’ll gladly upload it
https://ibb.co/5xFCwKJ

Last edited by LakixPompa; 04-09-2021 at 08:04 PM.
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Old 04-09-2021, 08:48 PM   #4
snow_bound26
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When it comes to buying a car that's been modified, don't assume anything. It's great way to end up with an expensive paper weight. If the seller can't provide physical proof of everything that's been done to the car then tbh, assume they've the absolute bare minimum or less.

Engine management is how it was tuned and what platform; Cobb Access Port, Open Source, ECUTek, etc.

You have many red flags; modifications with no paper trail or knowledge of tuning. Stop driving the car and find a good tuner/specialized shop to help you figure out what exactly has been done and how to move forward in the safest way.

As for the JDM 205 being able to just simply plug in and run fine, that's not the case. They have a different compression ratio than the USDM 205. The cams are designed for AVCS, so if there's nothing to control the oil flow then they run fully retarded compared to the USDM cams. AVCS is easy to install, especially since you say you have the ECU, and it does make a big difference on how the engine performs. If you don't want to use the AVCS, then you need to address the cams by either installing USDM cams and deleting the AVCS solenoids, or plugging the oil ports in the JDM cams. Otherwise they will always be fully retarded without using the AVCS. Either way, you'll need a tune for the differences in the engine and the mods for the USDM ECU. And if you use the JDM ECU you'll still need a tune to account for the difference in US fuel quality and the mods currently installed.
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Old 04-10-2021, 02:12 AM   #5
LakixPompa
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Okay that can be arranged. Whereas that is not really answering any of the issues I addressed . Regardless of what it is , it shouldn’t misfire.. and you are talking about red flags and etc... what’s been done , has been done, I bough a project car to learn on . Not a 10/10 perfection . Goal is not to splash money left right and center to mechanics . I’ve seen several of threads and posts saying that setting up the avcs is not necessary. And a jdm swap with avcs and not plugging them in shouldn’t be a problem. So yeah , thank you but that didn’t help much.

Last edited by LakixPompa; 04-10-2021 at 02:21 AM.
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Old 04-10-2021, 07:55 AM   #6
snow_bound26
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Beige

Default 2004 WRX JDM engine Misfiring issue Please HELP

No I pointed out many different things can be contributing to what's going on with your car. For instance, the BOV. These cars are tuned and designed for a BPV that is recirculated into the intake system pre turbo. By adding a BOV, which vents to atmosphere, you are removing air from the intake that the ECU is looking for. Thus, the car won't run properly. Will actually run like s***. Not to mention BOVs are known to leak as well. Will effect you idle.

Next, aftermarket intake of unknown make. ECU is looking for a specific amount of air moving through the system. Changing the intake changes that amount of air. The MAF, for instance (among other things), would need to rescaled for the current airflow. Another thing adding to the car running like s***. Will effect your idle.

20g turbo. You didn't mention whether you have larger injectors and fuel pump to accommodate a larger turbo like this. You are now moving more air through the system again. You need more fuel with a larger fuel pump and larger injectors to compensate for the larger turbo. Without them you don't have enough fuel to cool the combustion chamber and you will get knock because the car is running very lean. Potentially enough to destroy your engine. What you are expressing as misfire could be severe knock and the ECU trying to pull timing to save the engine. Will show effects an time you start to give the engine any kind of load. Combine with the other issues I mentioned will make the car run like s*** from start up to driving around town.

I can keep going about the parts you listed.

And if you really think the cams position in this isn't playing a role, or the fact that your ECU rom is for an engine with an 8.0:1 not a 9.0:1 compression ratio then you should sit down and do a lot of reading before you turn the key to your car again. I didn't say you have to use the AVCS, I mentioned what you need to do if you don't use the AVCS for the engine to run properly. Once again, all of this centers around ha big it tuned properly. You can do most of the work yourself. I do. Many of us on here do. But until you learn how all these parts work together and tune for yourself, then some things you will need a shop for. Tuning being the primary one. But to figure out if it's a "misfire" then you at least need to create a starting point where the engine is running properly for the modifications it has.

But what do I know, I've only been modifying cars since the late 90s. Enjoy your paper weight since the info I gave you wasn't what you wanted to hear.

And if you are actually getting a misfire code, then search that code and track down your fix via the search function. There's a whole thread dedicated to various codes.

Last edited by snow_bound26; 04-10-2021 at 08:20 AM.
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Old 04-10-2021, 09:30 AM   #7
murrdogg24
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check for cracks around the spark plug holes....get a DMM and do resistance check on the coil packs....check for correct spark plugs and correct gap.......check for faulty wiring on the coil packs....not sure what else to say
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Old 04-10-2021, 11:16 AM   #8
LakixPompa
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Quote:
Originally Posted by snow_bound26 View Post
No I pointed out many different things can be contributing to what's going on with your car. For instance, the BOV. These cars are tuned and designed for a BPV that is recirculated into the intake system pre turbo. By adding a BOV, which vents to atmosphere, you are removing air from the intake that the ECU is looking for. Thus, the car won't run properly. Will actually run like s***. Not to mention BOVs are known to leak as well. Will effect you idle.

Next, aftermarket intake of unknown make. ECU is looking for a specific amount of air moving through the system. Changing the intake changes that amount of air. The MAF, for instance (among other things), would need to rescaled for the current airflow. Another thing adding to the car running like s***. Will effect your idle.

20g turbo. You didn't mention whether you have larger injectors and fuel pump to accommodate a larger turbo like this. You are now moving more air through the system again. You need more fuel with a larger fuel pump and larger injectors to compensate for the larger turbo. Without them you don't have enough fuel to cool the combustion chamber and you will get knock because the car is running very lean. Potentially enough to destroy your engine. What you are expressing as misfire could be severe knock and the ECU trying to pull timing to save the engine. Will show effects an time you start to give the engine any kind of load. Combine with the other issues I mentioned will make the car run like s*** from start up to driving around town.

I can keep going about the parts you listed.

And if you really think the cams position in this isn't playing a role, or the fact that your ECU rom is for an engine with an 8.0:1 not a 9.0:1 compression ratio then you should sit down and do a lot of reading before you turn the key to your car again. I didn't say you have to use the AVCS, I mentioned what you need to do if you don't use the AVCS for the engine to run properly. Once again, all of this centers around ha big it tuned properly. You can do most of the work yourself. I do. Many of us on here do. But until you learn how all these parts work together and tune for yourself, then some things you will need a shop for. Tuning being the primary one. But to figure out if it's a "misfire" then you at least need to create a starting point where the engine is running properly for the modifications it has.

But what do I know, I've only been modifying cars since the late 90s. Enjoy your paper weight since the info I gave you wasn't what you wanted to hear.

And if you are actually getting a misfire code, then search that code and track down your fix via the search function. There's a whole thread dedicated to various codes.

Damn no reason to be mad over a post. I appreciate your response, and I definitely will try to acknowledge all the things you have said , and fix it, (tune seems most important atm) So thank you. I will also swap the injectors for darker blue injectors that came with the old engine. Whereas I heard somewhere that I should first tune the car for the aftermarket intake, and then tune for the injectors , but I could have received misleading information (not sure which first)
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Old 04-10-2021, 11:18 AM   #9
LakixPompa
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Quote:
Originally Posted by murrdogg24 View Post
check for cracks around the spark plug holes....get a DMM and do resistance check on the coil packs....check for correct spark plugs and correct gap.......check for faulty wiring on the coil packs....not sure what else to say
Thank you so much , I’ll do so as soon as possible, but I do agree with the previous answers that it could be the tune as well, the previous engine came with dark blue (bigger) injectors , so I’ll swap them out and see what’s going on
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Old 04-10-2021, 12:25 PM   #10
snow_bound26
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Quote:
Originally Posted by LakixPompa View Post
Damn no reason to be mad over a post. I appreciate your response, and I definitely will try to acknowledge all the things you have said , and fix it, (tune seems most important atm) So thank you. I will also swap the injectors for darker blue injectors that came with the old engine. Whereas I heard somewhere that I should first tune the car for the aftermarket intake, and then tune for the injectors , but I could have received misleading information (not sure which first)

You tune for whatever changes you make to air and/or fueling except fuel pump. That's just to make sure the injectors get enough fuel. Dark blue STi injectors aren't enough for a 20g. You'll want at least 850cc injectors. 1000cc is better still.

You don't have to worry about tuning for each part separately. The tuner will tune for all parts that are present at the time of tuning. You'll still want to consult with whichever tuner you choose and give them a complete list of all parts for the car and what octane you want to be tuned for. This way if your tuner sees something that won't work they can tell you.

Start getting use to searching the forum for the info you're trying to find. Because of the age of these cars, almost any combination of anything can be found. It can be daunting at first trying to sift through the relevant info and the misleading posts. I'd recommend searching through google to find stuff in this forum. I have better luck that way. I find searching directly in the forum to be hit and miss. Keep track of your unanswered questions and create a post with them. Keep it to one thread for the general topic; engine in the appropriate engine forum, brakes in the brake forum and so on. This keeps from creating a new topic for each question. When you do this try to be as specific and concise as possible to get the best responses. For right now, start going through all the stickies. You'll find a lot of good info that will answer quite a few of your questions in those threads. Some of it is outdated, but it mostly still creates a solid baseline for you to build knowledge from.

And something that I forgot to mention before, check all your vacuum lines for cracks/leaks. Make sure the turbo inlet isn't torn. And various other things like that. Any unmetered air will make the ECU unhappy. Given the age of the engine (mileage has nothing to do with age), you should make sure all basic maintenance has been done: replace all rubber hoses/lines, MAF sensor, plugs, ignition coils, etc, etc.
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Old 04-10-2021, 03:35 PM   #11
AliBenn
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Very sound advice snowbound......across the board
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Old 04-11-2021, 11:34 AM   #12
LakixPompa
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Thank you all for all the wonderful things to point out. I’ll try my best to address them all. Hopefully even hook up the avcs
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Old 04-11-2021, 08:08 PM   #13
AliBenn
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Please keep us posted Lakix!
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Old 04-12-2021, 03:07 PM   #14
LakixPompa
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I DEFINITELY WILL. Tomorrow 4/12/21 ill start to check things out and work on the engine (testing everything with a multimeter, and etc) Ill clean the MAF sensor, spark plugs and etc. I also noticed that the hks bov got stuck and won't blow out air anymore.... so will have to disassemble and get it unstuck. But yeah, tomorrow ill get going on, and ill make sure to post.
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Old 04-13-2021, 11:57 PM   #15
LakixPompa
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STILL STRUGGLING TO FIND OUT .I checked with the multimeter all the coil pack connectors, I checked the coils, I checked spark plugs, I tried to see whether the spark is occurring when I crank the engine. All of the coils read the same, all of the coil connectors read the same, spark plugs do have spark but it would be great if you guys took a look at the videos that I shared right now.

Pics of multimeter reading:

https://ibb.co/NpgGZRt?fbclid=IwAR2w...9ruZwM5g6EM-Yg

https://ibb.co/1QWL1ct?fbclid=IwAR27...hdqgS5T5qaHplE

https://ibb.co/nf59QFQ?fbclid=IwAR2C...KMQRBeVrnwPpfU

https://ibb.co/XsFczT0?fbclid=IwAR3T...1HSGN9PXV1ed5I

https://ibb.co/NsRT3N9?fbclid=IwAR2D...K5I7FDtk8-crxo

Vids of cranking in order to see spark:

https://streamable.com/xbn6st?fbclid...0dkhco5JrGOc3U

https://streamable.com/uw01di?fbclid...9ruZwM5g6EM-Yg

https://streamable.com/g6upui?fbclid...v1La4f8FE___pg

https://streamable.com/wixpgh?fbclid...1F9KUxTRyvC-gM

Still no idea what's going on. Maybe after tuning it , and swapping for larger injectors it will go away . Hopefully...

Last edited by LakixPompa; 04-20-2021 at 01:27 AM.
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