Skip in my idle?

APC9199 · **Posted:** Thu Mar 13, 2014 12:34 am

Sorry if this has been discussed before but I'm having trouble finding info on this.

I've noticed over the past few months, that my 05 crd liberty has an odd skip in the idle. It is almost like the sound and feel of the AC compressor kicking on and off, but this happens all the time even without the AC on. I realized tonight that it is even happening while driving. If I watch the rpm's in cruise control, they will fluctuate slightly when this happens.

The skipping seems to occur every 10 to 15 seconds and lasts from a second to 5 or 6 seconds. I've read that it could be related to a fuel filter or filter head issue, but I don't want to start spending money blindly to find the issue.

Anyone have any ideas to start narrowing this down?

P.S. I have a failed thermostat along with the replacement inline housing. I'm just trying to get some free time to install it. Could this be a potential related problem?

papaindigo · **Posted:** Thu Mar 13, 2014 8:51 am

Before checking anything else are you aware that the AC compressor runs in several vent modes even if the AC button is "off"? Try putting the vent mode in "panel" or "bi-level" or "off" and see if the issue goes away.

jim_87 · **Posted:** Thu Mar 13, 2014 10:26 am

Could it be the timing belt skipping? Maybe a low spot ground down on the timing belt/teeth missing?

Rich · **Posted:** Thu Mar 13, 2014 8:42 pm

papaindigo wrote:

Before checking anything else are you aware that the AC compressor runs in several vent modes even if the AC button is "off"? Try putting the vent mode in "panel" or "bi-level" or "off" and see if the issue goes away.

Won't having the temp on "hot" also kick the heat pump off and on?

APC9199 · **Posted:** Thu Mar 13, 2014 11:43 pm

This time of year in Arizona, the ac/heat is either off or on low heat for the early mornings. This happens whether the heat is on or off for any length of time. I should emphasize the fact that this is a very subtle stutter. It is only noticeable in park if there is no noise other than the engine. When driving...95% of people probably wouldn't have ever noticed it. I only did because I had the stereo off and was in cruise so I could hear the engine. It isn't nearly as loud as the ac compressor or radiator fan.

I'm due for a timing belt, 98000 miles. Maybe I should get that done ASAP?

papaindigo · **Posted:** Fri Mar 14, 2014 7:45 am

APC9199 - we may be talking past each other but take a look at my original post and your owner's manual. I don't know that the skip in your idle is the AC compressor but you say it feels like it might be. With the AC switch (button with the sun symbol) off and temperature control dial in any position between cold and hot the AC compressor will cycle from time to time UNLESS the vent control (middle dial) is off (O symbol) or set to dash only (arrow toward face) or bi level (arrows toward knees and face). Set the AC switch to off and the vent dial to "O" and see if the issue goes away - if so it's the AC compressor cycling but if not it's something else

98,000 miles - I wouldn't say ASAP as in this weekend but I'd go ahead and order the idParts kit this weekend and figure on doing the job or getting it done (STRONGLY recommend you contact geordi ASAP and get in on viewtopic.php?f=5&t=77950 as he is in Scottsdale April 2) soonish like this month or next. Your 05 is now 8-9 years old and I'm of the opinion that the TB really should be done at like ca. 6-7 years or 100,000 which ever comes first.

flash7210 · **Posted:** Fri Mar 14, 2014 8:40 am

APC9199 wrote:

I realized tonight that it is even happening while driving. If I watch the rpm's in cruise control, they will fluctuate slightly when this happens.

The while driving part seems very strange.

At what speed did you have the cruise set?
If above 50mph, the torque converter is locked and you should notice no RPM changes.
Maybe changes in engine sound but the RPM should remain steady along with speed.
If below 50mph, the torque converter is un-locked. RPM may fluctuate a lot according to
hills, large bumps, and several other factors.
You need straight, level, smooth road to test.

I'm going with the A/C compressor cycling as your issue.
Or maybe its the viscous heater cycling if its cold.
You can pull the relays for both to see if that stops the RPM fluctuations.

Or maybe the EGR valve is malfunctioning?

APC9199 · **Posted:** Sat Mar 15, 2014 11:19 am

I'm doing the inline tstat mod today so we'll see if that makes any difference. It sounds like this isn't something I should lose sleep over. It seems like I've noticed it no matter what position the vent is in, but I'll do a more statistical approach to that after I'm done with the thermostat to make sure.

papaindigo:

I asked to PM'd about the TB work. I could make it down to Scottsdale on that date I'm sure, but I'm also waiting on a few local shops to get back to me with estimates. There are a few places up here in Prescott that are comfortable with these types of diesels, VW, etc...

Thanks for the heads up!

geordi · **Posted:** Sat Mar 15, 2014 2:33 pm

You have a PM - and one thing to be aware of: This job has some similarities with the VW timing job... They both use Gates belts and the cams have no keys to hold them in place. Other than that, there really isn't anything similar. I would question any shop if they have the proper VM timing pins from Miller and have they actually done this vehicle before. The design is a bizarre one, compared to the TDI.

I have a TDI and have done the timing and fully removed the injection pump on those too, and this CRD is a strange beast by comparison. I'd be interested in knowing what your local shops have to say about it, or about you bringing your own parts. There aren't many shops out there that would guarantee their work with "unknown" parts suppliers. The dealership parts will cost you easily twice what IDparts charges, so that should be factored into any estimate... Including evaluating their skill level and how many they have worked on before.

I've done more than 15 of these now, and don't even need to reference any paperwork for procedures or torque values. I'm almost to the point of being able to do the job blindfolded.

APC9199 · **Posted:** Sat Mar 15, 2014 3:00 pm

geordi wrote:

You have a PM - and one thing to be aware of: This job has some similarities with the VW timing job... They both use Gates belts and the cams have no keys to hold them in place. Other than that, there really isn't anything similar. I would question any shop if they have the proper VM timing pins from Miller and have they actually done this vehicle before. The design is a bizarre one, compared to the TDI.

I have a TDI and have done the timing and fully removed the injection pump on those too, and this CRD is a strange beast by comparison. I'd be interested in knowing what your local shops have to say about it, or about you bringing your own parts. There aren't many shops out there that would guarantee their work with "unknown" parts suppliers. The dealership parts will cost you easily twice what IDparts charges, so that should be factored into any estimate... Including evaluating their skill level and how many they have worked on before.

I've done more than 15 of these now, and don't even need to reference any paperwork for procedures or torque values. I'm almost to the point of being able to do the job blindfolded.

Trust me, I'd rather have you do it! We just have to work out the dates and details. I'm looking for a reliable local shop to have other work done at as well, since time has become a real commodity for me (and I hate working on modern vehicles anyway). So the idea was to start them off with a few smaller jobs and see how they do. But again, I would rather leave something this important up to someone who has done many of these before.

Talk to you soon...

MicroBruin · **Posted:** Mon Mar 17, 2014 12:20 am

My Lib does the same thing when the AC compressor cycles. Turn the dial to the completely off position (all the way to the left), and turn off the AC button. If that stops it, then you know it's the compressor. Not sure how much longer the compressor lasts once this is occuring....but, I guess I'll soon find out.

geordi · **Posted:** Mon Mar 17, 2014 1:04 am

If it is the AC compressor, get a gauge set and check the pressure of your AC system. The system cycles more when the pressure is low because it reaches the low-pressure cut off point on the low side.

If you can only get one of the cheap-o low-side-only gauges, the pressure should read around 25-30 psi when the compressor is ON (front disc is spinning) and should be around 90 psi when the engine or compressor is off. The static (off) pressure doesn't really mean much, but if the pressure is lower than 20 psi when the compressor is running, try adding 1 12-ounce can of gas first. I prefer the blue "Arctic Air" cans sold by Autozone or Advance Auto, they do seem to perform better than just basic R-134 and aren't much more expensive.

DO NOT USE ANY LEAK-SEALER CANS. These do not work, and just gum up the compressor. I have seen many vehicles that have very very slow leaks, losing about 1 can in a year or more. This is what I would consider normal, if it leaks out much faster than that, you wouldn't have AC at all and would probably know it.

Skip in my idle?

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