Going to the Mechanic - Help Me Not Get Screwed!

[Ron Burgundy]

The Path is struggling to make it anywhere right now. It starts and drives but just barely. It's hard to describe but i'll do my best. The car starts up normally and for a brief period of time (1-3 minutes) seems to drive normally. However, after a short while, it hesitates and can only reach a certain speed. For example, I could floor it and maybe get to 45-55. It basically stops itself - I can let off the gas and the car will basically brake (the engine continues running but the car comes to a stop). It's as if the car is being a stubborn child who doesn't wanna do something but i'm the parent whos making it (best analogy I could come up with).

I've done a little research and came up with the following:

CEL light is not on, but I decided to check for codes anyway; came up with two:

P0325
P0325(pd)

Knock Sensor Malfunction

From what i've read this can be caused either by a short in the circuit or a faulty sensor.

From what I understood, there is a testing procedure in the FSM, but unless I can actually gain access to the sensor, I can't test either and of course the sensor is burried under the intake manifolds. Removing the manifolds is outside my realm of comfort for the time I could go without my daily driver and have decided not to tackle this and to take it to a mechanic.

I'm not a fan of this decision because of unfavorable experiences in the past but really have no other option. But I have a few questions first to make sure I don't get screwed over (too badly).

1. I read that the knock sensor malfunction is fairly common and for most is hardly noticable. In fact most people just clear it - this is definately not my case. Perhaps there is a deeper cause and the knock sensor is just a side affect? If so, do the symptoms above ring a bell to anyone? Or could it be possible that the knock sensor has gotten so bad that the engine has gone into some sort of "safe mode"?

2. I've done a bit of research on parts and labor, but i'd like to hear others input as well - what kind of damage am I looking at here?

Thanks in advance!

[yeldogt]

How many miles on it ??

Could be the sensor -- did you do a search and verify what the engine does when the sensor fails.

What does the engine do when it is parked and you rev it? How high are the RPM's when you are only doing 45 and you open it up?


If it's not something like the transmission slipping - it sounds like you may have a clogged converter. Have someone push on the gas while you feel the exhaust out the tail pipe - see how much comes out. Don't burn yourself !

[Ron Burgundy]

How many miles on it ??

Could be the sensor -- did you do a search and verify what the engine does when the sensor fails.

What does the engine do when it is parked and you rev it? How high are the RPS when you are only doing 45 and you open it up?


If its not something like the transmission sipping - it sounds like you may have a clogged converter. Have someone push on the gas while you feel the exhaust out the tail pipe - see how much comes out. Don't burn yourself !

1. 139,000 Miles

2. Engine acts normally when parked and reved, and to be honest I don't really know how high they get. Forgive my ignorance, but how would I know. The tachometer acts a little funny - as if its pushing a little to hard for how slow its going. Sorry i'd rather give you my honest answer then provide you with misleading information.

3. What exactly do you mean by how much comes out?

[Towncivilian]

Try replacing the fuel filter? FSM says it should be replaced "if the vehicle speed can no longer be increased as the driver wishes."

[Chuck Tribolet]

Does the CEL come on during the lamp test when first turn the ignition on? You may have a burned out CEL bulb.

Just for grins, try clearing the codes and see what happens? Do the codes come back? How's the driveability after you clear the codes.

I don't think it's fuel filter. 45 MPH is maybe 20-25% max fuel flow. You would have been seeing problems at 60+ MPH first.

And I don't think the knock sensor would have that dramatic an effect.

Dragging brake? If it actually comes to a stop when you take your foot off the gas, I'd be looking there first. Drive it a couple of
miles at 35 MPH. Stop without using the brakes much, hop out and check the disk and drum temps.

Dumb question that has to be asked: Is the parking brake off?

[yeldogt]

As the engine speeds up the car should follow -- If when you are going 40 mph and the tachometer is reading 4000 RPM the transmission is slipping.

If when you are in park and the engine will freely rev up above 3000 RPM then something other than the engine is most likely the problem.

A clogged converter will restrict the flow of air through the engine and the car will not accelerate past a certain point -- it will not have any power.

When you are driving along at 30mph and you hit the gas -- does the engine rev with the car not accelerating.


You could have a stuck brake -- the wheel will get very hot and normally you will smell something

[Pwnin O'Brien]

The symptoms of a bad knock sensor are sluggish acceleration. The vehicle will feel very sluggish under about 3000RPMs and then when it hits about 3100/3200RPMs it will start to speed up as it should, almost like a kick in the pants.

[Ron Burgundy]

Try replacing the fuel filter? FSM says it should be replaced "if the vehicle speed can no longer be increased as the driver wishes."

Doubtful - Replaced twice in the last two years. Once because it had been a while, second time just for fun.

Does the CEL come on during the lamp test when first turn the ignition on? You may have a burned out CEL bulb.

Just for grins, try clearing the codes and see what happens? Do the codes come back? How's the driveability after you clear the codes.

I don't think it's fuel filter. 45 MPH is maybe 20-25% max fuel flow. You would have been seeing problems at 60+ MPH first.

And I don't think the knock sensor would have that dramatic an effect.

Dragging brake? If it actually comes to a stop when you take your foot off the gas, I'd be looking there first. Drive it a couple of
miles at 35 MPH. Stop without using the brakes much, hop out and check the disk and drum temps.

Dumb question that has to be asked: Is the parking brake off?

No the bulb does not turn on - chances are its burnt out.

Codes have been cleared and haven't come back yet. No change in drivability.

Parking break is off.

Dragging brake seems plausible - i'll dig into this:

I changed the pads and rotors about 1 1/2 - 2 months ago. Was hearing a slight whistling/grinding and a LOUD grinding. I dug back in and found out that one of the new pads had gotten chewed through - most likely my fault during installation. Put new OEM pads on. Light whistling sound gone, loud grinding still there. Dug back in again and removed the dust plate. Problem solved (Perhaps the rotors are too big?). However, I accidentally damaged a brake line in the process causing a very slight gradual leak. Drove it without fixing it until this week. Replaced the lines with stainless steel brake lines and bled the system and refilled with Super Blue. And here we are today.

So theres the maintenance history - hopefully it will help.

I drove the car again tonight to test a few of the suggestions here. The car seems to operate normally with performance degrading as the engine reaches operating temperature. This includes the car coming to a stop issue.

When in park the RPM will shoot up as high as it wants as I press on the gas.

I was going downhill and let off the gas and the car came to a stop - put it in neutral and it still wouldn't roll.

I did use the brake a bit so it's hard to say but I did notice a burning smell from the wheel area and the the disk was REALLY hot.

Thanks for the help!

[Ron Burgundy]

The symptoms of a bad knock sensor are sluggish acceleration. The vehicle will feel very sluggish under about 3000RPMs and then when it hits about 3100/3200RPMs it will start to speed up as it should, almost like a kick in the pants.

It definatley doesn't get to a point of speeding up as it should.

[Towncivilian]

No the bulb does not turn on - chances are its burnt out.

Engage the parking brake, then turn the ignition to "ON" and check if any of the other bulbs are dead. Replace with #74 type bulbs (do not use an LED bulb for the SES light since it will constantly receive power even if no codes are stored, and it will annoy you at night with its dim glow).

[Ron Burgundy]

Ahh.... That's good advice as it was an LED.

[Towncivilian]

To clarify, you can use an LED bulb everywhere but the SES light. But I digress, if you need help or other clarification regarding lighting options post in the "changed the dash lights" thread or PM me.

Just a guess, but perhaps your thermostat is not operating correctly? Where is the coolant temperature sensor at when performance starts to degrade? How's the coolant level?

[Ron Burgundy]

Coolant Temp gauge is right at the middle as performance degrades. Coolant level is good - just topped off the other day.

[Towncivilian]

Make sure your O/D OFF bulb functions, and watch it while driving and starting the car:



Your transmission may be operating in fail-safe mode, which would have it locked in third gear, but then again you say it drives fine for a few minutes. But that doesn't mean it can't enter fail-safe mode shortly after starting to drive I think.

If your O/D OFF light does not illuminate for 2 seconds upon setting ignition to "ON" and your bulb is functional, there is a lengthy diagnostic procedure in the FSM.

[yeldogt]

You may have a problem with the engine -- but you do have a problem with your brakes. Your car should roll freely on a hill in N.

Don't want to preach --- but you should never drive a car with a brake fluid leak ... ever. Who knows what is up -- why would you suspect the rotors being too large? The quick pad destruction after replacement is an indication of the caliper being stuck or a caliper piston problem - and it needed to be addressed when you did that replacement. Did you replace the rotors after all that grinding? And why would you remove the dust ..backing plate???

You need to get someone who knows what they are doing to look over the brakes and make sure the calipers are OK and most likely replace the pads and rotors ........ and repack the grease in the bearings. Hopefully, the heat from all of this has not destroyed the bearing and hubs ...... Or damaged your transmission.

[Chuck Tribolet]

Definitely brake problem. The hot rotor tells you which one. I'm guessing that the rotor isn't free floating.

Here's one more test. Let the engine warm up completely in park. Then drive. You will probably see the same behavior where its OS for a little while. So you now know it's not caused by a warmed up motor.

[Ron Burgundy]

Ok just to update y'all and close this thread, i've found the problem and fixed it.

I had one last hunch the night before I was going to drop it off at the shop and sure enough it worked! Turns out the brake pedal was adjusted to a point where it was essentially always depressed.

I simply loosened the lock nut and rotated the input rod near the clevis and viola! Back to normal.

Now no, the brake pedal didn't just get tight on its own - I originally tightened it (forgot to mention that in the maintenance history ) but it looks like I went a little to far. But hey you live and you learn!

I appreciate everyone's help and advice! I love this place!

Definitely brake problem. The hot rotor tells you which one. I'm guessing that the rotor isn't free floating.

Here's one more test. Let the engine warm up completely in park. Then drive. You will probably see the same behavior where its OS for a little while. So you now know it's not caused by a warmed up motor.

Yes you were correct. I haven't taken the tires off yet to examine any possible damage I may have caused while driving the vehicle like this but so far the vehicle is braking normal and there are no immediate signs of damage besides some cracked paint on the drums.

You may have a problem with the engine -- but you do have a problem with your brakes. Your car should roll freely on a hill in N.

Don't want to preach --- but you should never drive a car with a brake fluid leak ... ever. Who knows what is up -- why would you suspect the rotors being too large? The quick pad destruction after replacement is an indication of the caliper being stuck or a caliper piston problem - and it needed to be addressed when you did that replacement. Did you replace the rotors after all that grinding? And why would you remove the dust ..backing plate???

You need to get someone who knows what they are doing to look over the brakes and make sure the calipers are OK and most likely replace the pads and rotors ........ and repack the grease in the bearings. Hopefully, the heat from all of this has not destroyed the bearing and hubs ...... Or damaged your transmission.

I couldn't agree with you more. However, the fluid leak was VERY minimal and not once did I ever loose pressure in the lines. I also consistantly monitored the amount of fluid in the resevoir and topped off as needed. Don't get me wrong thats no excuse, but hey - I needed a car. I did have a shop check the brakes and they are indeed installed properly so no worries there. The grinding was caused by the rotors rubbing against the backing plate - hence the removed backing plate. There was no damage from that.

Again, there doesn't appear to be any noticale damage but, I will definately be monitoring it closely for a while.

Make sure your O/D OFF bulb functions, and watch it while driving and starting the car:



Your transmission may be operating in fail-safe mode, which would have it locked in third gear, but then again you say it drives fine for a few minutes. But that doesn't mean it can't enter fail-safe mode shortly after starting to drive I think.

If your O/D OFF light does not illuminate for 2 seconds upon setting ignition to "ON" and your bulb is functional, there is a lengthy diagnostic procedure in the FSM.

O/D light working - no fail safe mode.

Thanks again!