Rough Idle

[eric819]

I have been having a rough idle on my VR4. It idled really low, I have replaced the IACV, checked for boost or vacuum leaks, and tried to set the timing. With the timing, I can only get it to about 7 degrees or higher. It idles rough and shakes the entire car but under load it smooths out. Car has an air filter and a turbo back exhaust and is still running stock boost. I recently removed the emissions and it had absolutely no change

The car has been idling rough like this previous owner had the timing belt done. The cams seem to be in sync but i am thinking that either the balance shafts are a little off, or the belt is a tooth off on the crank.

Any opinions?

Idle video

 

[tektic]

Is everything completely stock?

 

[eric819]

2.5" Turbo back exhaust with cat, a K&N air filter and a 2G manifold. EGR and other unnecessary were deleted in attempts to diagnose but had no changes. No boost controller.

Apparently it started getting rough after the timing belt was replaced.

I have only had the car for 2 or so weeks. I believe that everything internal is stock.

 

[tektic]

If you cant get it to 5* you have to check the markings on the crank to see that it lines up with the oil pump cover notch, your #1 piston is at top dead center and the two cam gears are as shown in this picture. If you have balance shafts you have to check that they are timed properly too. It's possible the two halves of your engine are not in sync. or one of your balance shafts is out of phase.

So you have 450cc injectors?
Set your base timing to 5 btdc
Adjust the biss screw.
Look for a thread to set the fiav.

 

[eric819]

On my next day off I will be pulling the pulley and lower cover off to check the actual marks. Balance shafts are another unknown, I dont even know if the belts have been replaced in the 143k miles the car has seen.

The timing adjustment goes from about 18 degrees max to about 9, these are just ballparks and max to max on the cam sensor. And it does not smooth out at any adjustment.

Looking into it more, I am not confident that the belt was installed correctly. I am making the time to pull the belt off and re-install it, this will also let me check the condition of everything in there like the balance shaft belts. I would rather see it with my own eyes then trust in some crappy mechanic that doesnt know what they are doing.

I spoke with the shop that did the timing belt install and they are swearing with 100% certainty that the belt was installed correctly and that the its not their fault but want to charge me before even looking at the car.... They also claim that there was no way to adjust the timing...

Thanks for the help.

 

[tektic]

First of all if the balance shaft belt was not replaced with the timing belt the job was not done correctly. But Before you remove the timing cover, take the spark plug out of the number one cylinder. Gently insert a long screwdriver so it rests on the number one cylinder. Find top dead center and make sure it lines up while the cam gears lineup. It may take up to 4 cycles to get them to align.

The base timing is set by adjusting the cam angle sensor wile monitoring with a normal timing light. The pin in a covered plug that is mounted to the fire wall needs to be grounded out so the ecu will not adjust timing while you make your changes. I believe vfaq.com has a full writeup.

If your shop doesn't know that, or care enough to look it up. you should definitely find a new shop, and make sure that the balance shafts are in phase.

The first time I did a timing belt job in the car it only took me 2.5H start to finish. That is with jacking up the car and engine. keep your timing cover bolts in order they are different sizes. But you will have a full diagram at your disposal when you print out the tsb for the timing belt job.

 

[eric819]

I will do that.

I have only had the car for about 2 weeks so I am just working on getting the car to a solid, reliable state. I would rather trust the dealership before this shop... lol. But it was not me that took it there.

I did the timing as described and thats how I have come to realize its off, pending the crank pulley marker is right... lol

I will let you know once I figure something out, I will even try to get pictures too