'96 850R Very low mpg, very low power.

bmessina · Post by **bmessina** » 16 Dec 2012, 19:36

The photo was taken while the engine was running and the timing light was flashing. I took a bunch until it caught just the right moment, while the timing light was lit.

It is perfectly representative of where the timing is, according to a properly hooked up timing light.

But I'm not opposed to backup via removing the cam sensor & distributor. It just won't be until next weekend.

Post by **rspi** » 16 Dec 2012, 21:36

I have never heard of anyone putting a timing light on a white block Volvo. Not sure how that works. Anyway, if the timing marks are correct with the correct notches on the cover, you could double check the timing at the back of the cams, i.e. with the CPS and Distributor stuff off. there are pics of how it should look on line, stright line across the slots.

bmessina · Post by **bmessina** » 16 Dec 2012, 21:42

Why wouldn't it work? It has a + terminal on the coil, plug wires, and obvious timing marks on the timing belt cover. Not sure why they would put the marks on the cover if you can't use them to check the timing.

Post by **rspi** » 16 Dec 2012, 21:48

I didn't say it wouldn't work, I just said that I have never heard of anyone doing it with a light. The car's computer can adjust timing itself a little. If the cams are properly aligned when the belt is put on, it will be close enough to let the car run well.

The thing is, you have just about checked everything else that could cause the car to be slow and slugish, the timing is a good thing to double check now. Other than that, you may have a hole or turbo tube loose.

Post by **northernlights** » 16 Dec 2012, 22:01

You are correct about the stock spec being 4-8 degrees BTDC at idle.

Looking at the where the timing marks should be at TDC based on the below image, it looks like retarded ignition - maybe 40+ degrees! If that is real then it would definitely explain the low power, almost to the point that it's amazing that it runs.

I don't know why the marks on the top of the cover would be in a different location unless there is another mark on the cam gear?

Post by **precopster** » 16 Dec 2012, 22:04

If those timing marks are correct and the camera took the photo at the precise moment the strobe light went off for cylinder 1 you should have valve to piston contact or close to it .

Somehow I don't think you'll resolve this until you see this:

Post by **northernlights** » 16 Dec 2012, 22:08

I'm wondering if the cam timing is mechanically right, but the ignition doesn't know when TDC really is. I agree as far as valve crash if the cam timing was really that far off, but as the car runs, and has decent compression, messed up ignition timing seems like a real possibility.

bmessina · Post by **bmessina** » 17 Dec 2012, 10:19

rspi wrote:Other than that, you may have a hole or turbo tube loose.

I've checked this one multiple times - The biggest leak was the apparently intentional one out of the bottom of the intercooler. Plugged that, no leaks.

northernlights wrote: Looking at the where the timing marks should be at TDC based on the below image, it looks like retarded ignition - maybe 40+ degrees! If that is real then it would definitely explain the low power, almost to the point that it's amazing that it runs.

If it's like any other car (so it's probably not), that should be too far advanced not retarded. Regardless, if that measurement is to be trusted, it's way out of adjustment.

northernlights wrote: I don't know why the marks on the top of the cover would be in a different location unless there is another mark on the cam gear?

The factory notches (as shown in the picture) are the only marks on the cam gear.

precopster wrote:If those timing marks are correct and the camera took the photo at the precise moment the strobe light went off for cylinder 1 you should have valve to piston contact or close to it .

Another poster in this thread was off 3 teeth and didn't have any interference - I wonder how far off it actually has to be.

Anyway - Yes, I'm definitely checking the back of the cams. I didn't get eyes on the crankshaft mark yesterday, so I'll probably do that first.

Thanks for the help!

Post by **northernlights** » 17 Dec 2012, 15:00

If you look at the timing mark, and assume it should be in the notch of the cover (not where zero is marked) at TDC, then I think the timing is retarded. If the mark is counterclockwise of the zero point, then it is advanced, clockwise retarded.

If you were 40 degrees advanced then you would have a ton of low end power, until you encountered the near-certain severe detonation problem, and burped the rings off!

bmessina · Post by **bmessina** » 17 Dec 2012, 15:11

You're right, that makes sense in regards to what the power curve should be if it were that far advanced.

It just baffles me - Why is there such an obvious timing scale if we're not supposed to reference it?

'96 850R Very low mpg, very low power.

Re: '96 850R Very low mpg, very low power.