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They do have a plate (NA8's at least) but I verified ignition timing is correct. That should have ruled out an issue like that unless I'm misunderstanding.
The crank timing plate is used on 96+ for OBDII misfire detection. Crank timing is still provided by the CAS, so it's not that.
The only thing I see from the graph is you're super-rich as you enter boost. 10.5-11 is good, richer than that is washing cylinder walls.
The crank timing plate is used on 96+ for OBDII misfire detection. Crank timing is still provided by the CAS, so it's not that.
The only thing I see from the graph is you're super-rich as you enter boost. 10.5-11 is good, richer than that is washing cylinder walls.
Thanks for the lesson on the crank sensor. I am aware there are some gains to be had by cleaning up fueling in lower boost cells, but the car is so slow that I think there's something seriously wrong.
So if timing is good the only way I could be making 200whp at 19psi (assuming VD is accurate) would be low compression right? That jives with my ability to run 19psi on stock ignition with no spark blowout. I'm also on stock fuel pump with 50% ethanol content and not running out of pump.
Compression and leakdown come tomorrow. I'm now wishing I had measured the length of the ebay rods before I put them in.
Either that, or you're not actually hitting 19psi - do you have a boost gauge as well? Before you turn the car on, are you seeing roughly 100kpa? I was 260hp at 13psi on a 2871 with rods 9:1 pistons and stock coils - so yes, this is an interesting issue.
I also logged a cold start to check vacuum at idle. ~39 kPa at 1025 rpm. Seems reasonable.
That would only equate to about 12in/hg. I see 22in of vacuum at cold start. Your engine isn't making much vacuum at idle. I hope your compression numbers look ok.
Either that, or you're not actually hitting 19psi - do you have a boost gauge as well? Before you turn the car on, are you seeing roughly 100kpa? I was 260hp at 13psi on a 2871 with rods 9:1 pistons and stock coils - so yes, this is an interesting issue.
No boost gauge. I have 2 pressure sensors. 1 for realtime baro and 1 for map. I just took a 10 second log with key on engine off. The map sensor fluctuates from 89.8-90.2 (maybe fluctuating from wind since valve cover is off). The sensor for baro is pretty much solid it 90.4. That should be accurate since I'm at ~3200 ft elevation.
That would only equate to about 12in/hg. I see 22in of vacuum at cold start. Your engine isn't making much vacuum at idle. I hope your compression numbers look ok.
It's actually 15in because of my elevation. I'd also expect it to be quite a bit better at the 850 idle it's set for warm. Do you know what your vacuum is at 1025?
Edit: Sorry I missed that you said it was on a cold start. Looks like compression is the culprit. Here's hopin for bad valves.
That would only equate to about 12in/hg. I see 22in of vacuum at cold start. Your engine isn't making much vacuum at idle. I hope your compression numbers look ok.
Actually, how did you calculate 22in? Can you share your baro and map values?
Leakdown points to exhaust valves. I got a rebuilt head through a core exchange service on ebay. Has less than 1000 miles on it but I'm pretty suspicious of the work performed. I found missing pieces in 3 or 4 hydraulic lifters.
I'm not completely convinced the numbers are bad enough to be responsible for the lack of power but I can't come up with anything else. I think I'll clean up the tune and pay the $75 to put the car on a local dyno to see what it's actually at.
I also disconnected the exhaust at the turbo and took a quick drive. No noticeable improvement.
Alright so I couldn't leave it alone. I moved cam timing a tooth in relation to the crank. It's soooo much better.
So if the pics I posted show a properly timed engine and moving timing a tooth made a significant improvement then the logical conclusion is that the damper has slipped. Correct?
This is the same 4th gear pull to 5k from my first post.
This is a 4th gear pull to 5k after changing the cam timing.
It's possible the crank pulley slipped. You could pull off the pulley and check the keyway on it to confirm. You should upload that into VD and see what she's putting ito for power now.
It's possible the crank pulley slipped. You could pull off the pulley and check the keyway on it to confirm. You should upload that into VD and see what she's putting ito for power now.
I don't think it's a key way issue. Someone correct me if I'm wrong, but I believe the issue is that the damper is made up of two pieces separated by rubber. When the rubber gets old and weak the outer piece which has the timing marks will rotate in relation to the inner piece.
That pull was 224hp 243 lbft at 5k and climbing. 17psi. Not setting the world on fire but if the damper slipped then my ignition timing is going to be off as well
I don't think it's a key way issue. Someone correct me if I'm wrong, but I believe the issue is that the damper is made up of two pieces separated by rubber. When the rubber gets old and weak the outer piece which has the timing marks will rotate in relation to the inner piece.
That pull was 224hp 243 lbft at 5k and climbing. 17psi. Not setting the world on fire but if the damper slipped then my ignition timing is going to be off as well
Yep you may be right. I have bunch of parts if you need a damper pulley, mine is off an nb engine but should work if you need it. Lmk. Glad it's running better for you, nothing worse than a new built motor not performing up to snuff.
Yep you may be right. I have bunch of parts if you need a damper pulley, mine is off an nb engine but should work if you need it. Lmk. Glad it's running better for you, nothing worse than a new built motor not performing up to snuff.
Thanks Andy. Looks like the nb damper is a different part number. This appears to be a common enough issue that I think I'll just go new OEM if someone else can confirm my diagnosis.
That difference in results definitely points to a failure of a 20 year old rubber damper. The part that doesn't move is the notch in the crank pulley, which is the part you should be lining up with the cam timing marks. The timing marks on the damper are only for the spark timing.
So show us the crank timing mark and the cam timing marks at the same time, please.
So if the pics I posted show a properly timed engine and moving timing a tooth made a significant improvement then the logical conclusion is that the damper has slipped. Correct?
You checked TDC with a screwdriver through the spark plug hole in cylinder #1, right? If the damper has slipped, the TDC mark should not line up with the actual TDC of cylinder #1.
I would say that the screwdriver test could easily be off by 5 or 10 degrees plus or minus and that one crank pulley tooth is within the margin of error.
I would say that the screwdriver test could easily be off by 5 or 10 degrees plus or minus and that one crank pulley tooth is within the margin of error.
This. The screwdriver test shows it's in the ball park but it's less than precise.
Soooo best way to confirm is to check against the actual crank timing mark on the block?
07-09-2018, 11:51 PM
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