Possible skipped tooth on timing belt?

EAGLIN

EAGLIN

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Feb 22, 2023
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Fairfax, VA
I’ve been diagnosing this really rough running and misfire with no codes for weeks and just took the timing cover off. Does this seem like a skipped timing belt tooth? Seems like it to me. I have a 2005 2.4L. One photo is with the lines matched and the other is with the left camshaft oriented parallel with the ground.

C1087DAE-1AA0-4678-9AC9-E30424F35FA8.jpeg


ECE13903-70C5-4D2B-B5B8-29B6A344B84D.jpeg
My scanner also shows 20-30 advance timing and I believe the spec for this engine is 9. I’m not too worried about it as I have all the tools to do the job but it’s gonna suck doing it in the apartment parking lot… any help is appreciated, thanks!!
 
  1. If you don't already have it, download the 2005 service manual from this thread in the TJ Resources forum. Refer to the Timing Belt and Sprocket(s) section, starting on page 9-58 (pdf page 978).
  2. No, I wouldn't say from those pictures alone that it jumped a tooth. You don't seem to be looking at the relative position between the crank and cams. You have to have all three in the proper position. First, set the crank to the correct position (there are arrows on the pulley and on the oil pump housing that must be aligned first), and then look at the two cam marks. Keep in mind that improper belt tension (or a worn-out belt) can affect timing. Again, see the manual for more info on that.
  3. The timing belt has a 90,000 mile replacement interval. How old is that belt?
 
EAGLIN said:
I’ve been diagnosing this really rough running and misfire with no codes for weeks and just took the timing cover off. Does this seem like a skipped timing belt tooth? Seems like it to me. I have a 2005 2.4L. One photo is with the lines matched and the other is with the left camshaft oriented parallel with the ground.

View attachment 521587

View attachment 521589My scanner also shows 20-30 advance timing and I believe the spec for this engine is 9. I’m not too worried about it as I have all the tools to do the job but it’s gonna suck doing it in the apartment parking lot… any help is appreciated, thanks!!
Click to expand...

EAGLIN said:
I’ve been diagnosing this really rough running and misfire with no codes for weeks and just took the timing cover off. Does this seem like a skipped timing belt tooth? Seems like it to me. I have a 2005 2.4L. One photo is with the lines matched and the other is with the left camshaft oriented parallel with the ground.

View attachment 521587

View attachment 521589My scanner also shows 20-30 advance timing and I believe the spec for this engine is 9. I’m not too worried about it as I have all the tools to do the job but it’s gonna suck doing it in the apartment parking lot… any help is appreciated, thanks!!
Click to expand...

You will want to rotate the motor clockwise until the cams are how you have them in the picture ( compression stroke) then line up the crank mark at 0 degrees ( clockwise direction if you pass it go back around twice. Then check your marks. Remove the spark plugs to do this or the motor mar rotate back on you due to compression. I think the are lined up. I have never seen a timing belt jump one tooth unless the belt was bad but then the motor usually stops running. I think it is ok.
You scanner is most likely showing you the computer timing advance. For base timing check procedure in service manual. It looks like base timing is fixed and cannot be changed.
 
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sab said:
  1. If you don't already have it, download the 2005 service manual from this thread in the TJ Resources forum. Refer to the Timing Belt and Sprocket(s) section, starting on page 9-58 (pdf page 978).
  2. No, I wouldn't say from those pictures alone that it jumped a tooth. You don't seem to be looking at the relative position between the crank and cams. You have to have all three in the proper position. First, set the crank to the correct position (there are arrows on the pulley and on the oil pump housing that must be aligned first), and then look at the two cam marks. Keep in mind that improper belt tension (or a worn-out belt) can affect timing. Again, see the manual for more info on that.
  3. The timing belt has a 90,000 mile replacement interval. How old is that belt?
Click to expand...

I dont think the belt has been replaced to date and the vehicle is at 120,000 miles. I will do as you have stated and see. I’m just so confused as to what it could be if it isn’t a bad belt or tensioner. If the tensioner is just worn then how will that negatively effect the engine? I’m just curious. Any ideas what it might be? The no engine codes is making it very hard to diagnose. Not even a misfire code.
 
NskLJ said:
You will want to rotate the motor clockwise until the cams are how you have them in the picture ( compression stroke) then line up the crank mark at 0 degrees ( clockwise direction if you pass it go back around twice. Then check your marks. Remove the spark plugs to do this or the motor mar rotate back on you due to compression. I think the are lined up. I have never seen a timing belt jump one tooth unless the belt was bad but then the motor usually stops running. I think it is ok.
You scanner is most likely showing you the computer timing advance. For base timing check procedure in service manual. It looks like base timing is fixed and cannot be changed.
Click to expand...

Gotcha, I will try this. Thank you for your help. I’m just curious what it could be if it isn’t a bad belt, tensioner, or camshaft position sensor. I do have a fully custom exhaust and intake on the vehicle, but the engine and ecu should be able to accommodate for the increased flow. I may try putting the stock exhaust back on and see what my luck is like there. IAC may be bad but that doesn’t explain the terrible running while driving and no power.
 
EAGLIN said:
I dont think the belt has been replaced to date and the vehicle is at 120,000 miles.
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I'd recommend changing the belt ASAP. It may not solve your current problem, but it will solve a future problem (belt breaking).

EAGLIN said:
If the tensioner is just worn then how will that negatively effect the engine?
Click to expand...
If you lose belt tension, I'd expect a code.

EAGLIN said:
IAC may be bad but that doesn’t explain the terrible running while driving and no power.
Click to expand...
Correct. The IAC only affects the engine at idle.

Can you better define/describe "really rough running and misfire?"
 
kincaid.0678 said:
Did you change your cats when you upgraded the exhaust? They could be clogged up causing the no power and rough running
Click to expand...

I have the entire system on Vbands. I have a emissions compliant CAT, high flow CAT, and a straight pipe. All cause the same issue. I don’t think it’s the exhaust. I also calculated header lengths to maintain similar valve back pressure to OEM. All CATs are new.
 
sab said:
I'd recommend changing the belt ASAP. It may not solve your current problem, but it will solve a future problem (belt breaking).


If you lose belt tension, I'd expect a code.


Correct. The IAC only affects the engine at idle.

Can you better define/describe "really rough running and misfire?"
Click to expand...

Understood
Sucked there’s no codes :(

As for how it’s running, from when you turn the engine on, in idle all the way through the rpm range. It sputters, runs really rough, and has zero power. It’s like the engine is hesitating everywhere. There isn’t a single moment where it sounds “normal”. It’s not aggressive, but you can feel the shake and vibration. I checked o2 sensor values and they are within spec. I do have a advanced auto ignition coil but it’s fine and if it was bad I would expect misfire codes. I have a Mopar ignition coil on order. New Mopar cam position sensor is on order too. All my sensors are NTK unless I can’t find an NTK sensor or wire in which case I try to buy Mopar. I gotta get this thing fixed, I’m moving out in 1 month from college haha.
 
EAGLIN said:
Understood
Sucked there’s no codes :(

As for how it’s running, from when you turn the engine on, in idle all the way through the rpm range. It sputters, runs really rough, and has zero power. It’s like the engine is hesitating everywhere. There isn’t a single moment where it sounds “normal”. It’s not aggressive, but you can feel the shake and vibration. I checked o2 sensor values and they are within spec. I do have a advanced auto ignition coil but it’s fine and if it was bad I would expect misfire codes. I have a Mopar ignition coil on order. New Mopar cam position sensor is on order too. All my sensors are NTK unless I can’t find an NTK sensor or wire in which case I try to buy Mopar. I gotta get this thing fixed, I’m moving out in 1 month from college haha.
Click to expand...

have you checked your fuel pressure?
 
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I think it does, but I'm not 100% sure. Going off an old guy's memory...
 
EAGLIN said:
I have not, let me check the manual on how to do that. Anyone know if the 2.4 has a schrader valve to check?
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sab said:
I think it does, but I'm not 100% sure. Going off an old guy's memory...
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I've never seen under the hood of a 2.4, but based on them taking them off of the 4.0's mid run and introducing the 2.4 in 2003, I'd be more surprised if it did than if it didn't. Which I think is absolutely stupid, as it's an important troubleshooting tool that basically every vehicle will eventually have need to use. I've been seriously considering (permanently) adding one to my 06 4.0.
 
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EAGLIN said:
I have not, let me check the manual on how to do that. Anyone know if the 2.4 has a schrader valve to check?
Click to expand...

No schrader valve on mine when I was checking fuel pressure back a few weeks ago. Had to plumb in a tee with the tester to the connection to the rail.

Have you taken any video/audio of it when it's sputtering/running very rough like this?
 
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