I have extremely low vaccume at low RPM w/ after installation of a CC306 cam (510intake/540exhaust i believe). This is causing my breaks to work terribly.

I also have an issue w/ oil pressure. If I slam on the breaks once I hit low RPM my oil pressure drops to zero. Is it possible the oil pressure is dropping because the vaccume gets so low?

Thanks for the help!

 

You're obviously not going to pull 20-21 "Hg with a CC306, like you would with a stock cam. How low is the vacuum at idle? What is your idle RPM? Who tuned it?

An oil pressure drop to "0psi" on hard braking may indicate the pickup has fallen off the oil pump.

 

I haven't got it tuned yet .... I'm slowly learning and tuning it on my own. However, I wasn't sure why my oil pressure drops completely off when I slam on my breaks ( which fade terribly at low RPM as well). thought perhaps the low vaccume might cause the oil pressure problem too. Almost like when I slam on the breaks there suck low vaccume that they draw pressure away from the oil pump? is this possible? I'll have to check the (are you speaking of MAFS reading?) Hg when I hit the breaks. What is a typical level durring hard breaking?

Thanks!

 

oil pump has nothing to do with vacume.
what were your rpms at? when this happend. if you havent tuned it its probably fighting to stay running. mine would always do that until the computer had a chance to learn.

 

Your brakes are not "fading".... you are losing vacuum, so there isn't as much vacuum boost being applied to help you press on the brakes. Solve the vacuum problem and you will solve the brake problem.

Oil pressure and vacuum are not related. At very low RPM (e.g. - your engine almost stalls and drops to only a couple 100 RPM) your oil pressure would abviously drop with the RPM, but it wouldn't go to "0". As I mentioned, typical cause is that when you brake hard, the oil sloshes away from the "missing" pickup, and you do have "0" pressure.

I asked a couple of questions.

1. You say your vacuum is "extremely low".... give me a number. What is your vacuum reading, in any units you want to give me, but generally, a vacuum gauge is calibrated in "Hg. (inches of mercury). If you do not know the actual vacuum reading, give me your manifold absolute pressure (MAP) reading. You can calculate engine vacuum from MAP.

2. What is your RPM at idle? That will affect the vacuum reading.

 

Does running an extra vacuum reservoir help with a hot cam? I have a CC306 and would like to be able to fix the vacuum problem. How big of a reservoir would I need?

 

I have about 11 inches at idle. Breaking isn't all that bad for me.

 

1: I'm not exactly sure what the MAP sensor is reading. However I read the MAFS earlier today with a scan tool and it had a reading of 8-9 at idle.

2: My idle is 680 RPM.

I was looking in tunercat for a setting to up my idle. Should I up the idle with this camshaft? Another individual told me to advance the Closed TPS vs rpm for idle an additinal 34 degrees.

I tried that unfortunately the car was sluggish and almost dies after giving it gas.

Thanks for the help!

 

Mass air flow sensor (MAFS) grams/second seems normal, and isn't really relevant to this discussion.

I run a 230/242 114LSA very high lift solid roller, and my intake manifold vacuum is 15"Hg at an idle speed of 800RPM. That's in a 381, though, which has an easier time handling the cam.

Based on your comments, and the difficulty you appear to be having with basic concepts, I would strongly suggest that spend the $$$ for a good mail order tune. Then if you want to tweek the tune, or learn more about it, you will have a better point to start.

 

I would put money on this, My pickup has fallen off and this was exactly what it would do. I would think that your idle should be set higher than 680.

 

I was just going to post the same thing. If the pickup had come off, pressure will drop significantly under hard braking as the oil rushes to the front of the pan.

 

I hate to say it but you guys are right My pickup tube did fall off. How can I keep this from happening again? Is there a good fix? Unfortunately I don't have access to a welder.

Thanks for the help!!!

 

Weld it on. That's the only sure-fire way of preventing it from happening again. For something like this, you FIND a welder.