05 CTT. Please help me solve this.
When I come to a complete stop at stop lights or stop signs I notice my RPM drop to one bar from normal idle position and then goes back up to normal idle position again. The engine vibrate a little when the RPM drop to one bar. After that everything is normal again. No lose of power and now after a couple months I get CEL. I do still get the RPM drop problem. Can it be something with the Air Seperator systems?

Anyone know what causes this? Any comments is appreciated.

Many thanks

 

Start with cleaning your throttle body (purchase a new $20 throttle body seal) and also clean your mafs. Make sure to use real MAF cleaner for the MAF and carb cleaner for the throttle body. Pelican has a write up on this and it's an easy DIY.

 

What is the CEL you get?

 

Not sure about the CEL, but the slight engine RPM drop with a vibration as you're approaching a stop sign, for example, has been reported by many. Some have seemingly shown results with various fixes, but the only sure way is with new engine mounts. Has something to do with what the transmission is doing as you're slowing down, and it causes the engine to torque a bit. Normally, this movement is not felt since the motor mounts take it, but when the motor mounts wear, it becomes noticeable.

It's not damaging anything. Motor mounts are a tough DIY project since the motor has to be lifted a bit.

 

I get this too, but only once every 20-30 stops so will keep an eye on it for the time being..

 

I had same issue when I first got my 05ctt last year. Changing battery seemed to help, I was told anything from plugs, coils, mounts could be problem. I also noticed that when I powered up windows and held the button after window was already closed I can replicate shudder that. You describe. Is it possible the alternator is going bad, and not producing enough power to vehicle when it slows down?

 

Hi Guys/Girls,
Thank you for the all the great informative comments. I will look into those suggestions. Now I have a starting point.

Many thanks.

 

The take away is to not stress too hard about it. You CAN solve it with some determination AND it's not a sign that your truck is about to grenade.

 

This battery issue, as funny as it sounds might be related then. Mine is actually about to die as if leave the carcar for longer than a week, it wouldn't start..
I was able to replicate similar revs drop on my other car when AC compressor was kicking in...

 

If you're putting any strain on the motor, and it makes the vibration - that would be the motor mounts. AC kicking in, windows rolling up - the motor is constantly changing load values at idle as accessories kick in and shut off. You normally don't feel it because the engine mounts isolate this.

You also might want to check the torque mount on the top of the motor. Mine was shot at 100K miles, and it seems many are done long before that.

 

there is a HUGE thread on this on renntech.org. the vibration is from the shot motor mounts, however the rpm drop is not - that can be any number of things, and over there some of the causes were lost tension in timing chain, dirty throttle body, in need of tune-up, etc....replacing the motor mounts appears to be costly. Around $400 for both mounts and 7-9 hours of mechanics time.

 

I changed my coils and plugs and upper torque arm (which was shot) and still the problem persists. This is why I told OP to start with throttle body and maf clean since it's practically free and probably needs to be done. It's the cheapest way to take a swing at the issue.

I'm about to do it - just need a free weekend when work calms down.

 

I've got it too. I also started there and it didn't help all htat much. doing coils and plugs in the next couple of months also.

 

what a bloody coincidence! After leaving the post here yesterday, my car started running really rough today.. would not pick up revs.. or starts going at 1500rpm on idle.. just crazy.. took it to the garage.
P0347 Camshaft position sensor A (bank 2) Signal too low.. followed by P031/P0303/P0308 (1,3,8 cylinder misfire)
New sensor ordered.. just dreading it's not a loose chain or something more serious..
I though it's the notorious ignition coils but the diagnsotic would have picked this up I guess..