Occasional P0304 (Yes I searched)

[cal_look_zero]

I thought I had the issue resolved, but I suppose it's still relevant. Ever since I built this engine, it's felt not quite right; tends to idle a bit low and rough, terrible power below 3k rpm, slow to accelerate upon heavy throttle.

 

Franken motor, ej25d block under ej22e single port heads, delta 200 grind cams.

 

First, I'll go down the list of what everyone recommends in other threads:

 

- New NGK BKR6E11 plugs within 1000 miles

 

- New NGK wires withing 1500 miles

 

- New valves/springs/retainers and valves adjusted to .010 and .008 less than 3k miles ago.

 

- Cam timing is good, I've have to get to the oil pump 4 times now so I'm getting to be an old pro at timing.

 

- New I/M gaskets 3k miles ago.

 

- New front o2 500 miles ago

 

- New fuel filter within 3k miles.

 

Where I'm at is that the ignitor, coil pack, and injectors are 15 years and 235k miles old. I'm leaning towards the injectors but don't have much money to throw at it right now. It's only ever been P0304, never the other 3 cylinders. I hadn't gotten the code for awhile until I was hard on the gas going up hill last night and my MIL/CEL started flashing for about 30 seconds then went steady with only P0304 code.

 

I have a known good set of EJ25D injectors, and am wondering if I could use those in place of the stock EJ22E ones, or if they flow too much and will cause more harm than help? I'm thinking I need to swap 2 and 4 and see if I can get a cylinder 2 misfire? Or is there a more diagnostic approach than swapping and trying to replicate?

[davebugs]

Most like 92-99 2.2 and 2.5 injectors are the same, including the rails I believe.

 

Always easier to swap fuel rail.

 

I have some headed for Ebay if you're interested. Don't forget the fuel pressure regulator is on one of those rails.

[cal_look_zero]

I've got a complete intake mani from a 98 EJ25D that I've been procrastinating on hucking at the scrap yard. Maybe I'll swap that over tonight and see what I come up with.

 

FPR is on the passenger side thankfully.

 

Can anyone verify that the injectors are the same flow?

[rallynutdon]

Does it come and go? I had that problem with a 96 2.2 and swapped out everything trying to fix it. Until after talking to the dealer head mechanic, I discovered a dropped exhaust valve guide. You could see it by dropping the exhaust and looking up and comparing 2 of them. Press in a new one (had to take the head off, of course) and the problem disappeared. With single port exhaust, there's more heat and it can cause this problem.

[cal_look_zero]

Does it come and go? I had that problem with a 96 2.2 and swapped out everything trying to fix it. Until after talking to the dealer head mechanic, I discovered a dropped exhaust valve guide. You could see it by dropping the exhaust and looking up and comparing 2 of them. Press in a new one (had to take the head off, of course) and the problem disappeared. With single port exhaust, there's more heat and it can cause this problem.

 

Except I just had the heads professionally rebuilt... Not to say it couldn't happen, but it's very unlikely.

________________________________

 

I reset the code last night before I left work, and the car runs better than ever. Came back on this morning and started to run like crap again. Reset it, and it runs fantastic. I'm going to seafoam it for now and see if that "fixes" it until I have the money to rebuild my extra red tops and drop them in.

 

Almost certain that #4 injector is on the fritz.

[cal_look_zero]

Back on this. Drove up to Eugene over the weekend and the car was more gutless than my Loyale was. Got back and started testing all the theories I could grab:

 

All 4 injectors ohm out at 11.

 

All 4 injectors make the same noise through stethoscope.

 

All 4 cylinders are at exactly 230psi compression.

 

So I unplugged my fuel pump to get ready to swap injectors, turned it over to relieve pressure, realized I didn't have enough time before work, and plugged it back in. All of a sudden, the car is running smoother and the CEL disappeared. The plug on the fuel pump wasn't loose at all, so I don't think it's a short; more like a coincidence. If the CEL comes back, I'll throw that set of injectors at it and see what I come up with.

[johnceggleston]

fuel pressure regulator???

[cal_look_zero]

fuel pressure regulator???

 

It's on the potentials list. Don't think I have a reliable way to test other than to throw a different/new one on though. I have a few laying around.

[1 Lucky Texan]

can you get freezeframe data the next time it throws a code? might be interesting to see if the fuel trims are weird on the bank with the 304 (driver's?) side bank.

[cal_look_zero]

I'm swapping in a set of redtops with a different FPR tomorrow morning. With any luck, that will fix my issue(s).

 

Being me though, I need to try and figure out if anything else would attribute to it.

 

Dirty fuel pump sock?

Failing fuel pump?

Bad fuel filter out of the box?

Coil going bad on one plug only?

 

I've gotten the ugly flashing CEL during acceleration which means that cylinder is over 10% out of spec on timing, so it's just outright not firing at times. I'm inclined to guess that I have a dead/dying injector and that's it, but I'd like to be prepared to change out other things if need be. Very irritated having this fun new engine and not getting what I paid for so to say.

[cal_look_zero]

Changed out my injectors with a set of known good redtops. Problem went away for about 3 days. Came back while I was accelerating over 3500 downhill on the freeway; minimal load.

 

Checked my fuel pressure today, 28psi at idle and 37 with the FPR vac line disconnected; within factory specs. Doesn't mean it's volume is good per se, but the pressure is.

 

Pulled the fuel pump assembly to look for any glaringly obvious problems. Took the pump "sock" to the parts store to compare it to a new one. Parts counter guy said that if the one I brought in is original, it's the cleanest he's ever seen. Looked just like a brand new one. Cleaned the sock with spray carb cleaner, blew it out with air, and reinstalled. Broke my OBD2 scanner, so I gotta do the battery disconnect reset. We'll see tomorrow if I fixed it.

 

The only other possible conclusions would be ECU related, coil related, or a false misfire as a result of the slightly lighter 2.2 flywheel behind the 2.5 engine. Which would suck since I just bought an underdriven lightweight crank pulley.

 

I wouldn't care about the CEL if it were a bogus fault, but my fuel mileage seems to suffer as a result, so I want it fixed.

 

Running list:

 

New plugs and wires.

Replaced injectors and FPR.

Fuel pressure tests out within specs.

Compression and leak down tests good.

Timing good.

Cam/Crank sensors good.

Recent Bosch o2 sensor.

Recent fuel filter.

Fixed minor exhaust leaks.

[1 Lucky Texan]

if you plan to get/borrow a new scanner, get one that can read the fuel trim data.

[johnceggleston]

maf?

[Fairtax4me]

The fact that it goes away after resetting the ECU leads to a sensor issue I think. There are some mechanical issues that can be covered up by the ECU making adjustments, but I think you would have something obviously wrong like compression or cam timing.

 

Is the misfire code always for #4? No other cylinders? Have you ever had a code for the #4 fuel injector circuit?

You say "new plugs and wires", does that mean new plugs when the engine was built, or new plugs have been installed while troubleshooting the problem?

How does the number 4 spark plug look compared to the others? How do they look as a whole? (powdery white, even tan color, or black/sooty?)