[N/A] Car not Accelerating After Stop.

ARFlyer

ARFlyer

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This morning my 2000 Subaru start acting up. Whenever I will accelerate out of an intersection the car will start to buck and act like its dying. The RPM gets "stuck" at 2000 and the check engine light will start blinking. If I let off the gas and slowly apply it the issue doesn't occur and the check engine light will go away. This will also happen when ever I try to accelerate going up a steep hill.

Any ideas?
 
Could be the plugs, could be the coils, could be clogged injectors; whatever it is, I'm assuming by the check engine light blinking it's throwing a misfire code.
 
I had a very similar issue in my 98 Pathfinder about two months ago. It wouldn't accelerate past 2,000rpm and once it hit that limit, it would stumble like most cylinders were misfiring.

My distributor ate itself. If you don't have a distributor, check your ignition coils.

$90 later, I replaced the part and the car was as good as new.
 
Could be several things. Only way to work thru the problem without just throwing parts at it is get the codes read and see where they lead. Most auto supply places will read the generic OBD2 codes for free. Once you have the codes, you can then narrow down what the problem is.
 
Sounds like it may be a fuel filter almost plugged off. When you apply the throttle for rapid acceleration the volume flow is enough to stir up the sediment, but if you go easy on it it doesn't plug it completely. Same when you need to open the throttle wider for more fuel flow to climb a hill.

Check the engine codes.
 
Stop by an autozone or one of the other parts stores that will pull the trouble codes for free, that might provide a clue.
 
I concur with others here.

Sounds like a weak/failing coil pack.

Get the codes, any auto parts store should be able to get the codes.
 
Ok thanks for the tips. I'll try some fuel dry and check my coils. It's currently not showing any stored or active codes.

The check engine light will only blink after the roughness has been present for about 30 seconds.
 
On the drive back to the house I could tell that it's missing especially on long uphill segments. It will miss then I'll hear a noticeable POP. Right at the POP the engine will go back to running perfectly smooth.
 
SkyHog said:
MAP/MAF or TPS.

That's my guess.
Click to expand...

TPS is my guess. They used (still use) potentiometers for stuff like that, and pots wear out. The runner rubs carbon dust off the resistor track, and the dust lifts the runner and makes it give goofy readings to the computer and the engine will get angry.

My Hyundai has potentiometers in the throttle pedal. Two of them, operated simultaneously. If the computer sees more than a 4% difference between the two, it switches to a limp mode. Poor acceleration, little power, not much speed.

I hope the carmakers have switched to inductive sensors by now. They need something that doesn't change its mind if it gets dirty or worn.
 
You have the same year Subaru I have. I had hesitation and poor acceleration for a while and found that a very common failure is the Knock sensor. Your flashing check engine nearly confirms it. Knocking trips the "flash the light -- things are really bad" mode of the CEL.

It also doesn't always throw a code. Mine didn't. But I didn't get the flash either. You probably have one of two codes locked in and they'll say it has a cylinder misfire -- could be different cylinders -- that's the common codes for the knock sensor.

Swapped the sensor on mine and back to normal. Super easy to DIY, just note the direction the connector is pointing when you remove it, you'll note it has an "angle" to where it seats and the most common way to break them is to put them on turned sideways or backward from where they were, and then crank down on them with a socket wrench, cracking them. On mine the molex connector was also a little brittle and a pin popped out trying to disconnect it but I had the stuff to fix that.

TONS of YouTube videos on replacing it. You'll waste more time watching them than actually doing the swap.

Also double check that one or both of your electric fans haven't failed if you're seeing accelerator hesitation on that engine. Sounds stupid but the car doesn't like running well when the temp is going up and down.

With both operating normally the temp gauge comes up to a spot and sticks there like it is glued there. One is on all the time, after initial warm up, the other is added cooling when the A/C is on or any time it goes above a prescribed profile. I found mine by sitting in traffic with A/C on in summer, but looking back they were both having problems clear back into winter, but the airflow from the weak one that barely turned was enough to keep the gauge out of the red. It shouldn't move after warm up. At all.

My fans were blown and I didn't know. If your temp gauge is moving, one of them is probably dead. Another easy fix. Cheap too. Various Amazon sellers. If you like OEM you'll pay more but frankly now that I know what they're supposed to sound like and the gauge is supposed to do, using the cheap Chinese knock offs doesn't bother me.

By the way, Subaru makes testing them (and other things) super easy. There's a green molex connector pair hanging down near the gas pedal. Connect them with the ignition off and then turn the ignition on.

Nearly everything electric in the vehicle will start cycling on and off including both engine fans and tons of solenoids and other electrical stuff for troubleshooting.

Way less stupid than troubleshooting intermittent and failed circuits on an American car.

Can even start it in that mode. Checks all dash lights, etc. Very useful for the backyard mechanic.

Shut it off and disconnect the green molex and all goes back to normal. So awesome. Love the Japanese engineers who did that.

There's a way to test the knock sensor, but at $15 it wasn't worth my time. Swapped it to see if it helped and the electric fans and the vehicle went up 3 MPG measured, and exhibits no accelerator lag anymore.

Took a socket wrench, an extension, a little cussing for getting the molex apart, and fixed, and about fifteen minutes for the sensor and a half hour for the fans.

Subaru really designed it well for maintenance, the fans have no bottom bolts and simply slide into pegs. I did have to disconnect and bend the upper radiator hose out of the way to get the left one out, but didn't have to remove it, and remove the air intake which is literally five minutes. Again disconnecting the electrical connectors without damaging them was the bigger puzzle than the mechanical stuff.

Part of the 30 minutes for the fans was figuring out where my catch pan went so I could take that radiator hose off and looking up how to "burp" it properly after reconnecting. No big deal but just to show how easy it was. It's cave man stupid easy.

Side warning: If you have 90,000 or a multiple of 90,000 miles on that engine don't neglect the timing belt. That engine has two big engine destroying problems -- timing belt failure since it's an interference engine, and that'll essentially destroy it, and the head gasket leaks. Using proper coolant and Subaru's additive helps with the head gasket leak problem, but a local shop has a "standard service" for a couple thousand bucks to do the timing belt and all the head gaskets and common issues every 90,000 miles. If you keep up on those, that wimpy little four-banger should last nearly forever.

The throttle position sensor is NOT known for failure and is easy to test. The Internet loves replacing them though, and you'll find all sorts of people doing it without testing them.

It's usually the knock sensor.
 
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For ordering the fans :

TYC 600550
TYC 610550

... on Amazon.

REPS311204 Knock Sensor on carparts.com for that.
 
Honestly, if you add up all the parts SGOTI told you to replace in this thread, you would be much better off taking it to the shop for an hour of diagnosis.

NO ONE can know what's wrong with your car based on info given. If you can't diagnose, parts-throwing is a terrible substitute.

Lots of things can cause missing. The ones no one has mentioned are a poor PCM ground or vacuum leak.
 
MAKG1 said:
Honestly, if you add up all the parts SGOTI told you to replace in this thread, you would be much better off taking it to the shop for an hour of diagnosis.

NO ONE can know what's wrong with your car based on info given. If you can't diagnose, parts-throwing is a terrible substitute.

Lots of things can cause missing. The ones no one has mentioned are a poor PCM ground or vacuum leak.
Click to expand...

That's why I gave him a $15 fix that's so common there's hundreds of websites documenting it. It's a known-crap-quality part that fails on every Subaru of that vintage. And the replacement will fail relatively (compared to the lifespan of the engine and vehicle) soon too.

The knock sensors are simply not designed right, but they're so easy and cheap to trash, nobody makes a better one. Somewhat unlike most Japanese engineering really.

At $15, and the known failure rate, it's literally a consumable, once the vehicle is 16 years old, it lasted longer than most, if it hasn't already been replaced. Even if it's not the problem, it's going to fail anyway.

I wouldn't have recommended it if it cost more to swap than a shop visit would run. There is a break point for cost and it's well below that price. I'd be willing to bet it's the knock sensor. And they're testable, but knowing it'll die anyway, no point messing with it at $15. Waste more time testing it than swapping it.

Like I said, I have the identical engine and it never threw a code, but he had a flashing CEL so it's guaranteed there's a code in there. If it's a cylinder misfire code it'll be the knock sensor.

The TPS junk is usually just that. Bogus. They're not nearly as failure prone as people think. Especially Subaru ones. Note that the TPS ideas are from folks who don't own nor wrench on a Subaru of the same vintage.

I'd definitely "throw this part at it" when a shop visit won't get out the door for less than $100, probably $200. If it doesn't work, it's a part that needs replacement anyway around this point in the engine's life. Well documented.
 
Nate, if I had $15 for every time someone with a corroded battery terminal replaced the whole ignition system guessing at faults, I'd be richer than the Orange Guy.

Another unmentioned common fault is a blown fuel pressure regulator causing off-idle hesitation.
 
Lots of more simple things, as mentioned, to check first. Some of the bigger ticket items would be MAF, fuel pump(s), and throttle position sensor (TPS) if so equipped. Could be an electrical/"spark" issue, but I'd be willing to bet we are talking a fuel delivery/scheduling problem, or a vacuum system problem based on the symptoms.
 
MAKG1 said:
Nate, if I had $15 for every time someone with a corroded battery terminal replaced the whole ignition system guessing at faults, I'd be richer than the Orange Guy.

Another unmentioned common fault is a blown fuel pressure regulator causing off-idle hesitation.
Click to expand...

Yeah but there's a lot of mechanics who have $200 for every time a standard sensor failure happens. Haha.

I love the guesses here though. At least one of the items most of the lists given don't even exist on this 16 year old four banger.

The knock sensor meets the currently known symptoms and if he'd grab the codes it'd be a more solid diagnosis. There's even two bad knock sensor codes that can be set, besides the nearly useless per-cylinder misfire codes.

Here's a question: Is it starting harder than usual? It's subtle but if it's cranking another turn or two at every start, the exhaust smells rich at cold idle, and it's lost a marginal amount of MPG...

This type of stuff is one of the reasons I calculate MPG on these old vehicles. Sensor problems show up there first, usually with little other in the way of symptoms. Even totally brain dead ECUs like this old one, back off the timing and add fuel when they're being told the wrong things by sensors. In the 1999-2000 era, the entire purpose of the silly things was to squeak out a few MPG for the EPA numbers on the fleets.

These older motors run just fine without all this stuff tacked on, not so on newer stuff really as they pushed the numbers higher, and they limp around burning too much fuel but otherwise run fine with some hard-to-notice power loss, when they're being lied to by a sensor.

And the sensor quality isn't great. Even the Japanese saved pennies on them to keep costs down, so they just don't last 15+ years.

The flashing CEL tells you it thinks its misfiring bad enough that it shouldn't be driven, and if it's not actually misfiring or acting that bad, it's the knock sensor saying it's knocking when it's not.

If it's obviously misfiring, felt in the vehicle, I'll agree with the knock sensor naysayers and say all bets are off.

There's just not much that can trigger a flashing CEL saying "pull this thing over and stop running it now!" that doesn't actually feel wrong in the car, other than sluggish acceleration.

Mass airflow doesn't flash the CEL, it's not considered an emergency state. Same with throttle position which will usually feel like "dead spots" or "surging" in the bad portion of the potentiometer range... again not usually going to set a flashing CEL. Same with O2 sensors. They'll fail toward rich in this vehicle.

And an actual misfire that flashes the CEL is usually a lot more obvious than just sluggishness from idle. It'll behave worse than the description and probably shouldn't be driven. If it's really missing you'll usually know it on an underpowered four banger. Especially at WOT on a hill.

It'll be interesting to see what he finds. My money is staying on the knock sensor.
 
those era Soobies had cam/crank sensor issues and your stuck RPM makes it a very strong possibility along with it being an intermittent issue.

there was a TSB for it back in the day.

former subaru tech's one and half cents worth anyhow
 
Update:

Ran to the local auto store today to see if I had any codes. The scanner showed no codes. While I was out I ran a few errands. I had no issues the entire trip. So I'm going to see if it acts up on the drive to work tomorrow.

Crossing my fingers it was just bad gas or my computer being ****y.
 
denverpilot said:
And an actual misfire that flashes the CEL is usually a lot more obvious than just sluggishness from idle. It'll behave worse than the description and probably shouldn't be driven. If it's really missing you'll usually know it on an underpowered four banger. Especially at WOT on a hill.
Click to expand...

Yesterday it would try to die on hills, especially steep long ones. It sounded like an aircraft engine poping at low idle. The CEL would flash during the popping until one last quite noticeable pop. Then the car would jerk back to full RPM.

The computer shows no set codes which to me seems odd. I know lately I've been having issues with my car monitor. So I wonder if my ODB port is bad.
 
ARFlyer said:
Yesterday it would try to die on hills, especially steep long ones. It sounded like an aircraft engine poping at low idle. The CEL would flash during the popping until one last quite noticeable pop. Then the car would jerk back to full RPM.

The computer shows no set codes which to me seems odd. I know lately I've been having issues with my car monitor. So I wonder if my ODB port is bad.
Click to expand...

Popping is not good. And I'll say probably not a knock sensor. Bummer.

Does your OBD-II reader do real-time? That'd tell if "the port is bad". No data, not working. My harbor freight cheapie will read real-time sensor data while the car is on.
 
ARFlyer said:
Yesterday it would try to die on hills, especially steep long ones. It sounded like an aircraft engine poping at low idle. The CEL would flash during the popping until one last quite noticeable pop. Then the car would jerk back to full RPM.

The computer shows no set codes which to me seems odd. I know lately I've been having issues with my car monitor. So I wonder if my ODB port is bad.
Click to expand...

Does it show any pending codes?

Also, did you get around to filling up with new gas? I can't even tell you how many similar problems I've experienced that were the result of nothing more than stale gas.

I'd also try filling up with a tank of whatever the highest-octane gas you can get is, from a high-volume station. The fact that the "popping" happens under sustained load makes me wonder if it's detonation. If it stops with higher-octane gas, then that would narrow the possibilities a bit.

Rich
 
A few weeks ago my automobile was slow to accelerate from a stop, my brakes were slow to release. Bad front brake hoses, first time I've ever seen that, but then, first time I've owned a car with 175k mi.
 
GlennAB1 said:
A few weeks ago my automobile was slow to accelerate from a stop, my brakes were slow to release. Bad front brake hoses, first time I've ever seen that, but then, first time I've owned a car with 175k mi.
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I've owned several. That's not how brake lines fail. Hard lines leak, and flexible lines can get squishy. You could crimp a line, but that's not something they do on their own.

More likely, the brake fluid was factory original, filling stuff with corrosion. You probably just replaced calipers, too.
 
Oh yeah, I replaced the calipers and pads first and it didn't fix the problem. I could drive the car and use the brakes for slowing, no problem, but if I came to a stop, they were slow to release. If I sat at a red light long enough they would be fully released. Read on an auto forum that the inner hose material will break down over time and act like a check valve when the master cylinder is sucking. Anyway, I'm glad it's fixed before winter. I've been meaning to take the old hoses into work and borescope them.
 
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I love how this thread is full of "answers" that are guided by "common sense" to the absolute least likely things to happen but hey it will be "worth a try"
 
Drive it into lake, blame on faulty gps directions. Buy new(to you) car. Happy holidays.
 
ARFlyer said:
On the drive back to the house I could tell that it's missing especially on long uphill segments. It will miss then I'll hear a noticeable POP. Right at the POP the engine will go back to running perfectly smooth.
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I'm guessing valve cover gaskets are leaking oil into spark plug holes shorting out the wires, causing the misfire. without codes it's hard diag.

But I guarantee it's not water in gas or old gas. That stuff doesn't matter any more in modern fuel injection strategies. Get Me some codes and we can go farther with it
 
jaybee said:
I love how this thread is full of "answers" that are guided by "common sense" to the absolute least likely things to happen but hey it will be "worth a try"
Click to expand...

If the car runs, and the "worth a try" things are easy and free (or cheap) to try, then why not? It's not like there are an abundance of good automotive diagnosticians out there. It's easier to find a good brain surgeon than it is to find a car mechanic who actually knows something about diagnostics. I have to drive almost 50 miles to find one who's merely competent; and if I want a true scientist, the car had better be up to a three hour-plus trip to College Point, because that's where his shop is.

Most mechanics nowadays just throw parts at a problem in the hope that they'll stumble upon the fix -- and that's assuming that they have codes to work with. If the problem doesn't throw a code, all they can do is stand around with their thumbs up their asses. It's pretty pathetic, actually.

My favorite example used to be when Saturn S-Series engines would throw P0340 or P0341 codes, and so-called "mechanics" would spend hours and hours searching for the Camshaft Position Sensor so they could swap it out. The only problem was that the S-Series engines didn't have Camshaft Position Sensors. P0340 / P0341 codes could be caused by a variety of problems with the ignition system, but 95 percent of the time it was bad spark plug wires, which used to cost about $15.00 - $25.00 depending on quality; or a corroded ground to the DIS, which cost nothing to fix.

But that didn't stop countless mechanics from spending countless billable hours searching for a part that didn't exist. That was all they knew how to do.

Rich
 
Take my ex-wife out of the back seat. Acceleration will greatly improve and you will find the frequent stops and starts will dissapear since you no longer have to hit up every liquor store.


Problem solved.
 
RJM62 said:
If the car runs, and the "worth a try" things are easy and free (or cheap) to try, then why not? It's not like there are an abundance of good automotive diagnosticians out there. It's easier to find a good brain surgeon than it is to find a car mechanic who actually knows something about diagnostics. I have to drive almost 50 miles to find one who's merely competent; and if I want a true scientist, the car had better be up to a three hour-plus trip to College Point, because that's where his shop is.

Most mechanics nowadays just throw parts at a problem in the hope that they'll stumble upon the fix -- and that's assuming that they have codes to work with. If the problem doesn't throw a code, all they can do is stand around with their thumbs up their asses. It's pretty pathetic, actually.

My favorite example used to be when Saturn S-Series engines would throw P0340 or P0341 codes, and so-called "mechanics" would spend hours and hours searching for the Camshaft Position Sensor so they could swap it out. The only problem was that the S-Series engines didn't have Camshaft Position Sensors. P0340 / P0341 codes could be caused by a variety of problems with the ignition system, but 95 percent of the time it was bad spark plug wires, which used to cost about $15.00 - $25.00 depending on quality; or a corroded ground to the DIS, which cost nothing to fix.

But that didn't stop countless mechanics from spending countless billable hours searching for a part that didn't exist. That was all they knew how to do.

Rich
Click to expand...

https://yourlogicalfallacyis.com/anecdotal
 
Criitter7 said:
I'm guessing valve cover gaskets are leaking oil into spark plug holes shorting out the wires, causing the misfire. without codes it's hard diag.

But I guarantee it's not water in gas or old gas. That stuff doesn't matter any more in modern fuel injection strategies. Get Me some codes and we can go farther with it
Click to expand...

For the give it a try crowd I was going to suggest just this - pull the spark plug wires out of the valve covers and see if they are covered in oil.

In other words - something that is entirely practical and most likely in the real world.

Detonation... huh ? Bad gas... isn't intermittent that is an always. Poor ground on computer, bad battery connection... in all my years I've only seen it cause a driveability issue exactly once, so again not very likely - possible? sure dang near anything is possible but not very likely.

I could go on but I got better things to do. anyone has the potential to be right here because dang near anything is possible - seen the "impossible" happen to many times as a driveability tech. it really sounds like the OP may have two issues (based on his most recent post) - the misfire under load and the intermittent delay/disruption but that can be hard to say without an accurate description of the situation
 
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