Rough Idle and High Idle Stabilization Readings

My 2006 BRM engine is running rough at idle and otherwise. I've already attempted to advance and retard the timing at the cam with no noticeable affect. I'm planning on picking up and replacing the fuel filter in the morning.

My idle stabilization readings are quite high and well out of spec:
Cyl 1: 2.99
Cyl 2: 2.99
Cyl 3: -3.01
Cyl 4: -3.01

I'm wondering what might cause this. Is a new fuel filter likely to fix the issue? Keep in mind the car has 381,000 miles on it right now.

New filter will NOT fix this.
When/how did the problem start? Any fault codes in the ECU?
It might be injectors, wiring loom, poor compression on two cylinders or more or something else.

I would start with a look at your cam. Mine was bad (not that bad about 2.0+-) and did cam now .25+- It could have been just the injector lash adjustment but I think it was due to a bad cam.

Woah, I found my problem. The question is why would this happen? 3 of the 4 bolt heads holding the rocker down are broken off. I just hope I can find them by pulling the oil pan.

That thing was running with ONE bolt holding the rocker shaft on?

You are VERY fortunate to not have more damage! *think jumped timing belt*
DAMN!

Any pics of this?

I wonder if somebody re-used those bolts when they weren't supposed to?

At 381,000 miles, I'm sure this BRM had at least one cam change.

That or, would a rocker arm seize on the shaft after a while due to poor lubrication? ie: Due to the BRM rocker shaft oil galley plugs that always fall out...

vtxtdi said:

Woah, I found my problem. The question is why would this happen? 3 of the 4 bolt heads holding the rocker down are broken off. I just hope I can find them by pulling the oil pan.

Click to expand...

Was just one of the rocker arms that the bolts broke (ie 3 of 4) or just 3 of both rockers arms? Yes confirm you have your oil plugs and I assume the cam is bad also.

Sounds like someone reused bolts either during a cam replacement or maybe when inspection the cam by removing the rocker arms. It also could be that your bearings are so bad that the play in the cam caused this.

Good luck find the missing parts.

I'll post pics later. So here's what happened. I pulled the rockers out to inspect the cam about 100k mikes ago. I replaced the cam at 142,000 miles but it was running poorly so I needed to check the cam. Turned out to be the EGR. Apparently, I turned the rockers over 180 degrees from where they were supposed to be when I did that so the bolts weren't on a completely flat surface. I think this allowed one of the bolts to loosen up over time which caused a chain reaction over the last few weeks with the other 2. The first one went a few weeks ago and the other 2 went on Tuesday. When the first one went it sounded like an exhaust leak so I wasn't in a huge hurry to check it out. Once the other two went it was bad. It ran well enough to get me home on just 3 cylinders but it ran rough!

I pulled the oil pan last night and found the 3 bolt heads. Along with a piece of cast that I spent an hour trying to see where it broke off from. The piece of cast had threads in it so for peace of mind I wanted to find where it came from. Turned out to have come from part of the case that holds the oil pump. Not a super stressed area and not a moving part so I'm pretty sure I dodged a bullet. I buttoned everything up last night and it runs like a clock. Believe me, I know it could've been bad. The timing belt wouldn't have jumped a tooth. The cam is secured separately from the rockers.