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Hey everyone. 

 

1996 Legacy Wagon L

260k

2000 EJ 251 with EJ25D heads

2000 4.11 5mt 

 

I'm having some problems that I'm not sure where to turn to. I have an idling issue. When at operating temperatures, my idle will be low (around 500) but not rough. When the lights are on, and I depress the brake, the lights will dim and the idle will drop and stumble. Never shut off. This problem has been present with two separate motors. First with an EJ25/EJ22 frankenmotor, and now my current one. I have swapped out my alternator (both read 14v), removed the crappily-installed uhaul trailer package, and created new grounds/cleaned up grounds in the engine bay. No change. I had the battery checked at the auto store, and it is said to be good. I've also cleaned the terminals/cables. 

 I have suspicions that I'd like to see if they are valid/relevant. IIRC, this problem surfaced a couple years ago after I had replaced the then dead fuel pump. I did not replace it with an OEM pump. This one came from the local auto store. Around this time as well, the aftermarket radio quick working. The cd player works, and I can also use the auxiliary port, but no radio. I didn't listen to the radio at the time, so I never bothered. All fuses are good. Could either of these be related? Or, since this only happens when the engine is warm, could it be the coolant temp sensor? I believe I transferred the Crank/Cam/ Temp sensors from the last motor... Sometimes after a long drive on a warmer day, at idle it will sometimes idle up and down for a short period of time then normalize. Computer related? 

 

Thank you for your time. Any advice will be appreciated. 

 

Greg

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Hi,

- CTS is a cheap 'fix' (if not easy to access).

- What about your O2 sensors.

- clean IAC valve?

- Clean-up all grounds.

 

 

Tangent: What EJ25 did you use on the previous build (ej25+ej22) and What HG?

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Hi,

- CTS is a cheap 'fix' (if not easy to access).

- What about your O2 sensors.

- clean IAC valve?

- Clean-up all grounds.

 

 

Tangent: What EJ25 did you use on the previous build (ej25+ej22) and What HG?

What is the CTS? 

 O2 sensors are about 4 years old. Would they throw a CEL? I do not have a CEL/Codes. 

 IAC was cleaned

 I created grounds from the block, alternator, and Intake Manifold to spots on the body, and I ground off the paint to do so. 

 

I used the cometic custom hybrid gasket, that was supposedly the same thickness as the 25D. I'm not the right person to ask on that though. Those expensive gaskets poured oil out of them. if I can say something though, that build is pretty lack-luster at highway speeds; at least it was for me. Anything above 3500 and it had nothing. I strongly suggest the EJ251/EJ25D hybrid with 04-06 STI mls headgaskets. Power all the way to redline. Not as much low-end torque (the first frankenmotor, I could drive around town in 4th and 5th gear no problem..) but much more functional power IMHO. 

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The cts an fail in a lot of ways that won't cause a code, but screw up drivability and or idle and or starting.

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possibly a wiring problem in the hatch harness boot?

Forgive me, Hatch Harness boot? Is this where the EFI harness enters the firewall to the cab?

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I forgot to mention: About two and a half years ago, I was having horrible up/down surges of the motor as soon as it reached operating temps. I researched, and the conclusion was that it was the AFM. Well, I replaced it, and that corrected the surging. Does it matter that I replaced it with a non-subaru AFM? I bought it new from rock auto. . 

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We call them a MAF - mass airflow sensor - on here (and most Subie forums). 

 

Non-OEM shouldn't be a problem, but the issue is different now, correct? If the same, clean it w/some MAF sensor spray (brake cleaner is considered too harsh), or just swap in another used GREEN label plastic JECS or AUTECS MAF (22680AA160) from any '92-'98 Subaru Impreza, Legacy or Forester....'99 OB/GT/SUS, too.

Edited by wtdash

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How far do you have to press the pedal for it to stumble?

If you press lightly just until the brake lights come on does it stumble? (Would indicate a possible electrical supply/ground issue)

Or do you have to press the pedal far and/or quickly? (Possible vacuum leak/booster problem)

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How far do you have to press the pedal for it to stumble?

If you press lightly just until the brake lights come on does it stumble? (Would indicate a possible electrical supply/ground issue)

Or do you have to press the pedal far and/or quickly? (Possible vacuum leak/booster problem)

 

I will have to experiment tomorrow. I usually notice it when coming to a stop at a light... BUT the times were it will randomly surge up and down on warmer days, I've taken my foot off the pedal and put the parking brake on, and it continued and then stabilized,... If there is a vacuum leak, can I test with a propane torch? Opening the propane valve slightly and passing it by the vacuum hoses? 

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We call them a MAF - mass airflow sensor - on here (and most Subie forums). 

 

Non-OEM shouldn't be a problem, but the issue is different now, correct? If the same, clean it w/som MAF sensor fluid (brake cleaner is considered too harsh), or just swap in another used GREEN label plastic JECS or AUTECS MAF (22680AA160) from any '92-'98 Subaru Impreza, Legacy or Forester....'99 OB/GT/SUS, too.

The issue is a little different. Before the new MAF, it surged up and down uncontrollably and was basically not driveable. This is just an extreme annoyance of mine now at stop lights. 

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How far do you have to press the pedal for it to stumble?

If you press lightly just until the brake lights come on does it stumble? (Would indicate a possible electrical supply/ground issue)

Or do you have to press the pedal far and/or quickly? (Possible vacuum leak/booster problem)

Depressing the pedal enough for the tail lights to come on does it. Last night I had just gotten home and started testing what you suggested. I turned the headlights off, and noticed that every time I depressed the brake (the usual stuttering), the aftermarket radio's eject-button light would come on. Today, I pulled the fuse for the radio out. Looked good. I kept it out. No Stuttering. There is still a light flutter of the headlights. Could the radio have been incorrectly wired when it was installed? It came with the car when I bought it. The radio part of it died soon after, leaving just the CD player and auxiliary input... Is this related, or did I just remove a load from a system that has a problem somewhere else? I mean, I can turn the lights on, the defroster and the heater, and depressing the brake doesn't bother the idle now. ...

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Dimming of the other lights when the brake lights come on is pretty normal. There will usually be a drop in voltage when the current demand goes up as the brake lamp bulbs come on. There are 5 of them, so it's a significant draw.

 

There should not be any noticeable change in engine speed when any lights come on. If there is, then it's because the supply voltage to the ECU is dropping, or there's a problem with the body ground to the battery. Most of the time the problem will be at the battery. Corroded battery terminals or corrosion inside the cables. Check the battery cables carefully and make sure they're clean at BOTH ends including the smaller wires.

 

Since the problem changes with the radio fuse pulled out, that probably means the radio is pulling too many amps for the supply circuit. It could help to run a larger power supply wire (with a fuse) from the battery + to the radio. That doesn't mean the problem is solved, but it will decrease the electrical load going through the wiring that runs inside the car from the underhood fuse panel.

 

If the battery cables check out clean the next step would be to remove the fuse box under the hood and check the pins in the connectors on the bottom of the box for any corrosion.

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Dimming of the other lights when the brake lights come on is pretty normal. There will usually be a drop in voltage when the current demand goes up as the brake lamp bulbs come on. There are 5 of them, so it's a significant draw.

 

There should not be any noticeable change in engine speed when any lights come on. If there is, then it's because the supply voltage to the ECU is dropping, or there's a problem with the body ground to the battery. Most of the time the problem will be at the battery. Corroded battery terminals or corrosion inside the cables. Check the battery cables carefully and make sure they're clean at BOTH ends including the smaller wires.

 

Since the problem changes with the radio fuse pulled out, that probably means the radio is pulling too many amps for the supply circuit. It could help to run a larger power supply wire (with a fuse) from the battery + to the radio. That doesn't mean the problem is solved, but it will decrease the electrical load going through the wiring that runs inside the car from the underhood fuse panel.

 

If the battery cables check out clean the next step would be to remove the fuse box under the hood and check the pins in the connectors on the bottom of the box for any corrosion.

Have you cleaned the Throttle Body lately?

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