Is there such thing as out of balance (engine, AC fan, etc.) that cause rough idle?

[OR VietVet]

Check you tube for belt removal info or someone with a newer rig will chime in. Couple of questions: That graph was in drive with the a/c on and with it off. What does it do in Park? In park with the a/c on and with the a/c off?

I don't know for sure yet but it sounds to me like the engine cannot handle loads and then starts the vibes when it cannot. What does the RPM do when in drive with the a/c on and does it change at all with the a/c off? What does the rpm do when in park and the same scenario? Kind of like a bad old style Idle Air Control Valve.

I would also want to know what the fuel pressure does when the engine is in drive with a load on it and when in park with the load on it.

 

[George B]

Use this for the AC belt.
https://shop.advanceautoparts.com/p...lrBoqUBastxe9ApkPcRoCt1EQAvD_BwE&gclsrc=aw.ds

 

[George B]

And make a drawing of the acc belt routing before you take it off.

 

[smokey_mountain]

Thank you, here are the answers:
1) The top graph smoother curves was at driving speeds (driving 1800+ RPMs) with the a/c on. The bottom graph was still in D but stop (±500 RPMs) at the traffic light. In Park is about the same - not smooth. Same behavior with a/c on and off.
2) What does RPM do - I do not see change in RPMs at all with a/c on and off. It is not visible on tach. When you put the car into P RPMs do go up by approximately 50 or so.
3) I will need to read the fuel pressures tonight with a/c load driving and a/c load parked.

Check you tube for belt removal info or someone with a newer rig will chime in. Couple of questions: That graph was in drive with the a/c on and with it off. What does it do in Park? In park with the a/c on and with the a/c off?

I don't know for sure yet but it sounds to me like the engine cannot handle loads and then starts the vibes when it cannot. What does the RPM do when in drive with the a/c on and does it change at all with the a/c off? What does the rpm do when in park and the same scenario? Kind of like a bad old style Idle Air Control Valve.

I would also want to know what the fuel pressure does when the engine is in drive with a load on it and when in park with the load on it.

 

[Dantheman1540]

I am new to GM V8s is there a tutorial for Gen V belt removal? Thank you.

I'm sure there is but I'm to poor to afford a Gen V so I have no idea! Plenty of other guys here should be able to chime in or try the good ole google.

 

[OR VietVet]

At this point, if the rpm difference is nill, so to speak, when the engine is loaded when put in drive and turn a/c on....etc, then I don't suspect a load condition problem. Is there a way to just turn the idle rpm up with a Tech 2 or is it a "TUNE" job?

How dirty is the throttle body at the throttle plate area?

I don't want to go back and look but what is the miles on this engine? Have you had the fuel injection system cleaned? What fuel brand name do you use? What octane level is the fuel you use?

Has the MAP sensor been tested or changed?

 

[smokey_mountain]

I see, thank you.
throttle body was cleaned with CRC DI engine throttle body cleaner following their process 4K miles ago, it looked clean before cleaning but I still cleaned since CRC explicitly states does not void manufacturer's warranty.

As for injection cleaning, I only did in-tank cleaners BJs 44 and Liquid Moly for DI engines that I understand are a waste since in DI engines valves are not washed with fuel.

I used Top Tier: Exxon, Valero, Sunoco 89 and 93. I also tried Costco 93 and BJs 93. BJs 93 was one of the best fuel based on my subjective feeling.

MAP was inspected but not cleaned or replaced. It should be easy enough to replace it. I will order.

At this point, if the rpm difference is nill, so to speak, when the engine is loaded when put in drive and turn a/c on....etc, then I don't suspect a load condition problem. Is there a way to just turn the idle rpm up with a Tech 2 or is it a "TUNE" job?

How dirty is the throttle body at the throttle plate area?

I don't want to go back and look but what is the miles on this engine? Have you had the fuel injection system cleaned? What fuel brand name do you use? What octane level is the fuel you use?

Has the MAP sensor been tested or changed?

 

[OR VietVet]

Typically the MAP sensor will cause other problems as well but it is a cheap easy attempt.

At RA for $18.21 plus shipping: https://www.rockauto.com/en/moreinfo.php?pk=3257778&cc=3438502&jsn=2190

or $13.90 at Amazon with free shipping: https://www.amazon.com/ACDelco-1264...ild=1&keywords=12644228&qid=1588796816&sr=8-3

That Lisle serp belt tool, #59370, is available at Amazon for $19.99 and free shipping.

There are a few other designs but I like the Lisle design best of all of them.

 

[armentaaw]

Motor mounts?

 

[OR VietVet]

On a rig this new you just don't think of the motor mounts but it is definitely worth a shot to check them. Good call.