some form of a...problem.

I couldn't even think of what to write for a title. It's weird. Ever since I've owned my legacy it's been this way, and now it's slowly escalating. Whenever I start out from a dead stop and give it too much gas too quickly, the engine (2.2) rpm will drop really really low and almost stall. It makes me think like I'm flooding the engine or something, which doesn't add up considering it's FI, but that's what it reminds me of. So, I let off the gas and it comes back to life. More and more recently it seems the throttle point (percentage of throttle applied) for when this would happen is lower and lower; when I first noticed it, it would die at WOT, now it's around 75% or so. It's still when it's applied very quickly, like trying to beat traffic or something pulling out of a stop sign. Any direction here? I'm going out on a limb and thinking an injector problem, but would they cause something like this?

 

On another note, at WOT before shifting (auto), warning lights pop on. Around 6k rpm, the brake, battery, and sometimes the abs light will come on for a split second before redline, and will go off after the shift. Also, all the lights will brighten for that timeframe, then dim after shifting. Why...electronic probably, but what? Loose wire? Bad connection? I'm stumped. I started noticing it a month ago, and it's been happening more and more frequently. Could these two problems be related too?

 

For anyone wondering, I don't beat the shit out of my car, but everyso often I run to redline. Who doesn't? I'm on break so I've got plenty of time to tear into this project.

The dropping rpm's sound like an intake issue. You might want to check to make sure all hoses are connected good. Also your throttle body may be really dirty.

 

I may sound crazy but I know when you have dropping rpms when you hit the gas its intake related

Maybe a bad TPS? The dash lights may be coming on because it could be stalling for a second and restarting. I'm not sure though. I'm not to good at diagnostic. Do you have any trouble codes?

The intake is interesting...I have my own setup with a cone filter right before the maf, but...hmm. I'll check all the hoses now.

Nope, that's what's really bothering me. There's no warning to indicate that there is something wrong in the system. I'll check the throttle body and the hoses now, and go for a little drive to napa and test it out to see if I can't recreate it. I need to pick up bulbs anyway

Many warning lights are triggered by the battery light or oil pressure light just to let you verify that they are actually working when the engine is off.

 

I suspect that the alternator is starting to give up it's ghost so you should plan a replacement or a rebuild of the alternator.

 

As for the hesitation - check all hoses since a vacuum leak can mess up the sensors and also the fuel pump pressure. But if the battery voltage is low you can also get strange problems.

I just replaced the alternator around 2k ago because the old one finally gave out. I'm not sure what you mean by your first comment...voltage was going to be my next step. I don't have my computer with me so I can't hook up to get any info, and I can't find my stupid voltmeter

I have a similar issue with the battery/brake lights on my car, they started flashing at high RPM's a month or 2 back, but I haven't been able to figure out what the issue is. Fortunately, I haven't noticed anything weird going on, other than the lights everything seems to be functioning as normal.

yup sounds like the voltage regulator in your alt. too much revolutions, too much juice, lights get bright, shift, rpms go down, everything normal again

 

no clue about your other problem though

I just bought the damn alternator, that really pisses me off. I had a feeling it was some kind of an issue with it though because of the way the lights were brightening with RPM, but I didn't want to believe it.

 

UPDATE: I need to figure this out. I almost died today driving around when the engine bogged in front of a semi...I've learned a few things though. If I keep my foot planted, it will rev to 1500, nosedive to around 500, then bounce back and forth like that until around 10mph. After that speed, everything acts normal, and it picks up without any problems (except the electrical bug haha). I tried cleaning out the throttle body with some carb and choke cleaner, and hit it really well. When I first started out, there wasn't an issue for the first two launches, but every single one after that was bad. I think it's more related to temperature than the throttle body being clean then...all hoses are fine, no intake/vacuum leaks. When I got to napa, I was suggested to take a look at the throttle position sensor, so I'll dive into that, but I don't think (for one reason or another) that it's the problem. If I didn't mention before, the bogging only happens in drive. In neutral, it picks up just fine without the dip in RPM, and I think that makes a huge difference.

 

That's my story and I'm sticking to it. Could it be transmission related?

glad your car is not totaled. a semi would work a number on a car like this.

 

this problem is most odd. but i cant help but think your getting to much gas. it is like the motor is forgetting that it has a car to push.

 

you can test the throttle position sensor with your voltmeter. it works off resistants.

I just bought the damn alternator, that really pisses me off. I had a feeling it was some kind of an issue with it though because of the way the lights were brightening with RPM, but I didn't want to believe it.

 

UPDATE: I need to figure this out. I almost died today driving around when the engine bogged in front of a semi...I've learned a few things though. If I keep my foot planted, it will rev to 1500, nosedive to around 500, then bounce back and forth like that until around 10mph. After that speed, everything acts normal, and it picks up without any problems (except the electrical bug haha). I tried cleaning out the throttle body with some carb and choke cleaner, and hit it really well. When I first started out, there wasn't an issue for the first two launches, but every single one after that was bad. I think it's more related to temperature than the throttle body being clean then...all hoses are fine, no intake/vacuum leaks. When I got to napa, I was suggested to take a look at the throttle position sensor, so I'll dive into that, but I don't think (for one reason or another) that it's the problem. If I didn't mention before, the bogging only happens in drive. In neutral, it picks up just fine without the dip in RPM, and I think that makes a huge difference.

 

That's my story and I'm sticking to it. Could it be transmission related?

 

Just check that you have sufficient amount of oil in the gearbox. An oil change on the gearbox could be a good idea, but it wouldn't do wonders - and if the problem isn't that the gearbox is slipping it won't make much difference.

 

However this problem you have seems to indicate that your engine runs lean. A fuel filter replacement and check of fuel pressure would be the primary steps. A clogged fuel filter can give problems like these. A bad pump as well. Start with the fuel filter - it's no big deal. But change it outdoors - you will get some fuel coming out.

I just did a transmission flush and fill a few months ago, and kept an eye on the fluid level. It's right up there :ghost:

 

I did the fuel filter around that same time too, but haven't touched the pump. I'd imagine though...hmm...ahh I'll start with the TPS. Any specs on what kind of resistance I should pick up from it?

 

Only in drive...that's what makes me think it can't be the TPS, but I want to try it anyway. What else changes when you shift from neutral to drive besides actually moving a 3300lb car?

The point is that an unloaded engine revs easier than a loaded engine. And if it's the fuel pump it needs a lot less fuel to rev than if it's loaded so this can be a symptom of a failing fuel pump.

 

Does this behavior with engine failing to rev also occur when you are running the reverse gear? If it does occur when in reverse too then it's not likely to be related to the gearbox.

oh I never tried reverse...I'm going out right now so I'll make sure to check that one out. Does the fuel pump usually slowly fail, or is it an all or nothing kind of thing?

 

it all has to do with loading the engine; does that rule out the TPS?

UPDATE: it occurs in reverse too. it really sounds like it's starved for fuel the more I'm listening to it. So it uses more fuel when it's under load...the fuel pump is located under the rear seat right?

A fuel pump can fail in many ways - sometimes slowly, sometimes abruptly. The pump is usually located in the tank.

 

A pressure test would reveal if the pump is a problem, but it has to be done under load.

ok so...hmm...how would I go about testing it? I found out where the pump is, and it's pretty easy to access, but how do I figure out if it's good or not?

 

my brother has the car right now; I already told him about the problem, but I'm afraid he's gonna beat on it and some shit is going to happen. Still working on buying off his part from him

just take off the fuel line coming off the fuel filter from where it connects to the engine and connect a fuel pressure gauge, then crank the engine

Im not sure if you are supposed to relive the pressure first before removing the line, I know thats the procedure for changing the fuel filter, perhaps somebody could confirm this?

Had the problem with hesitant starts. Mine was running way too rich, and it turned out to be an O2 sensor. Just a thought, and I have no clue towards the other issue.

Did you get a code for the O2 sensor? I was also thinking about that too, but was hoping it wasn't because I don't like O2 sensors haha. How many are there?

You only have one sensor - or maybe two - depends on model year. One before the cat and one after at most.

 

As for pressure test - it shall be done correctly since the pressure regulator is in the engine compartment and if you connect the pressure gauge in the wrong place you may not have the pressure regulator in the loop and you can get the wrong value.

 

Check in with a local workshop to do a pressure test unless you feel like purchasing a kit for it. Be aware that in your case the test should be done under load.

 

Check out these alternatives:

http://www.harborfreight.com/master-fuel-injection-pressure-test-kit-97706.html

http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

ok cool I'll dive into this project tomorrow and hopefully figure something out. Thanks for all the help!

re alternator. when the brushes are almost worn out they will not make good contact on the slip rings and will float because of the vibration and movement of the rotor. this may cause the alt to stop charging for a millisecond or more and cause all the dash lights to go into test, like when you just turn the key on.

 

as for your hesitation problem, it could be so many things, even more than one. first i would swap in a known good MAP sensor (not the MAF) it has to monitor manifold pressure and can cause exactly this problem.

 

tom

The intake is interesting...I have my own setup with a cone filter right before the maf, but...

 

clean MAF and put stock intake back on

Happened when i first got my car. If i got cocky and floor it from a stop i would buck the car almost stalling

 

kinda learned to change driving habits, I think its because i dont have an air/fuel controller. I think that is necessary when subarus naturally run rich, and then also having an aftermarket air intake on a stock tune