“Preventative” fuel/spark maintenance and compatibility.

[killjoy323232]

I’ve had an EJ20x swapped into my XT for a few months now, and it’s been great. BUT, I have a feeling some of the 217,000-mile and 17-year-old parts are starting to show their age, as I’ve developed a weird, random stumble while accelerating. Very concerning, as it’s under boost, and at this point, equally likely to be fuel or spark, so I’m considering this “preventative maintenance”. SO, couple of questions:

1.) On changing fuel pumps on the 4th gens with an aftermarket one (eyeing something like an AEM 300), is it just a matter of disassemble basket, swap pump (with new sock), reassemble? I realize I probably sound like a rube, but I’ve never installed an aftermarket pump before on anything.

2.) Are ignition coils interchangeable from, say, later EJ25 STi’s? They appear to be visually similar on RockAuto, and I figure lightly used OEM might be better/cheaper than new aftermarket.

Thanks in advance!

[Max Capacity]

For the coils, call NGK and talk with Tech Support. They will have the correct coils.

 

Do not buy the cheapest parts you can find, lot's of junk out there now days.

 

There should be a DIY for the fuel pump. 

[killjoy323232]

Got it…I’ll try searching for the DIY when I get home. Might have better luck than on mobile.

On the coils, that’s kind of why I was considering used factory ones that have, say, 20,000 miles or so off of a ‘18 STi, rather than brand new NGK, if they fit. Save a little money (and lasting the life of the car) while not ending up with complete junk.

Of course, failing the compatibility check, I’ll be buying new, quality coils, anyway.

[subisubisu]

There are DIYs on YouTube for replacing the pump, pulling the bucket, etc.  There are O-rings in the bucket that should be replaced.  I have had some challenges with mine (getting everything in the bucket to seal after putting the new pump in), and I'm currently running a cheapish Amazon pump/bucket assembly (disappointing Max, no doubt) just to get past the problem as I was getting my car back on the road, but it's in my plan to put a quality pump back in there.

[Max Capacity]

I have found that if you google the OEM part number, you might find local auto parts stores that carry the same part. I know that worked with ABS sensor a few years back.

[xt2005bonbon]

When was the last time your injectors have been 'refreshed'? If never, you may want to send them to DeatschWerks for a cleaning and getting fresh new orings.

[Max Capacity]

I still put a can of Chemtrol Berryman B12 in my gas tank every Oct. I had 306,000 miles on the stock injectors, never had a issue with them.

[xt2005bonbon]

Then, that's probably why you have been fine then.

[killjoy323232]

Hadn’t ever had the injectors out myself, and to be honest, not sure if they’re original or the JDM 20x injectors.

Figured I’d start at the pump/filter (holy crap, speaking of the stupid filter, the OEM ones are $$$) since theyre almost certainly original to the car, and given the car’s sordid history, could be contributing to the miss.

Looks like I’ve got some shopping around to do.

[Max Capacity]

Yes, normal routine maintenance and cleaning, think MAF sensor, zip-tie all vacuum hoses. Kept both my 4th Gen's running well. That and not only doing short drives.

Seems us that drive for distance had many fewer issues.

[xt2005bonbon]

Three of my injectors have 183K miles on them, including the fuel pump. A couple of weeks ago, I suffered from erratic misfires in cylinder 2 after a few gear pulls. Did some troubleshooting with the coil and spark plug first. Turned out they were both fine. So I removed the injector; the orings looked quite old and bad to me. So I installed some fresh orings, sprayed the inside of the injector with some MAF cleaner the best I could. Put it back. Been 200 miles and the car has been running just fine. I hope it'll stay that way.

I never used that B12 chemical before. Maybe I should have. Either way, I will send my injectors for some cleaning and flow testing next month.

[killjoy323232]

So, as an update to this, just until I can get a good aftermarket one, I scored a really good deal on the complete pump assembly from a really low mileage, wrecked 2018 STi locally. Figured, ah, what the heck, it's A.) really cheap, B.) OEM, and C.) not broken.

What I've learned:

1. The VA STi pump assembly physically drops in and works and pumps fuel...and that's about the end of it.

2. Don't be like me - I should have known better and should have swapped the level sender and the sensor on the side of the assembly over, because the VA bits don't work. At all. Who could have seen that coming?

[xt2005bonbon]

On 12/13/2023 at 1:35 PM, xt2005bonbon said:

Three of my injectors have 183K miles on them, including the fuel pump. A couple of weeks ago, I suffered from erratic misfires in cylinder 2 after a few gear pulls. Did some troubleshooting with the coil and spark plug first. Turned out they were both fine. So I removed the injector; the orings looked quite old and bad to me. So I installed some fresh orings, sprayed the inside of the injector with some MAF cleaner the best I could. Put it back. Been 200 miles and the car has been running just fine. I hope it'll stay that way.

I never used that B12 chemical before. Maybe I should have. Either way, I will send my injectors for some cleaning and flow testing next month.

I should report that it's been more than 1k miles of driving now and the engine is running just fine.

[killjoy323232]

That may be my next step…I got the fuel temp sensor and level sender swapped over to the STi pump, started the car, took it out for a drive, and the car ran like utter crap. It felt like I had run out of gas, but it gradually cleared up after I drove it some more and filled the tank. It only had like 1/8 tank when I swapped the pump.

Now, I THINK it’s running better…I still have the boost turned way down, and I’m not sure if it’s the crap roads or PTSD, but every now and again, I think I feel a slight stumble (not quite a miss - it’s extremely light) when accelerating. I also have a Company23 tee that I have yet to install for the FPR vacuum line though, because it could also be that famous stutter.