A friend of mine rebuilt my motor and installed a new cam 233/239 duration, .569/.577 lift(1.6rr), 111lsa. I have been trying to solve an idle problem and need help. Here's what I have found out so far. Plug wires are all getting fire, I put in all new plugs (I gapped .050). I swapped throttle bodies from 52mm TB to stock TB. I replaced the Idle control sensor. I tested fuel pressure 47psi. I tested vacuum and it only has 5 psi. I think the vacuum is a problem. What do you think? How can I improve vacuum pressure?

Thanks,

Mark

 

When you say, Idle Problem, what exactly is it doing? Does it take awhile for the engine rpm to fall back down to normal idle? Does it not want to idel at all? Idle eractically? Give a little more details and we can narrow it down better.

 

The motor is dieing when I stop or slow down to go around corners. Sometimes it hunts idle and finds it, but when it's warm it usually just dies. I know the brakes use vacuum to stop you and you can get a vacuum booster for the breaks. But, my vacuum is 5 psi at idle. I think 5 is too low. Idle is never too high or elevated at any time.


Thanks for your response ,

Mark

 

Vacuum leak. You should have AT LEAST 13-14 lbs of vacuum.

 

I agree totally on the leak and it must be a bad one at that.

 

One of my mechanical buddys said, it would have to be a huge vacuum leak to cause that kind of vacuum loss. I will try spraying WD-40 on the motor while it's running to find a leak. Is there anything else it could be?


Thanks,


Mark

 

Ok, I sprayed WD-40 on all the hoses and sensors I could find on the intake. The idle didn't increase. So can I assume no vacuum leak or should I look some more?

Anybody got the pcm cable for an OBDII computer that has been converted to OBDI?

I need to check for codes.

Thanks,


Mark

 

Mark, i wonder if you can plug that pcm in my car and i can scan it. might be worth trying.

 

Might be worth a try. I just cleared the codes tonight before I took it out for a test run. It's still acting up. After I ran it hard, it just dies rolling down the street. I am almost to the point of purchasing that $90.00 cable to hook the car up to my computer. Maybe you could tell me what the codes mean. Let me know when I can bring my computer over and I'll do it.


Thanks,

Mark

 

i just need to get the lap top from joey. maybe wednesday night or sometime on thursday we can try. email me and let me know whats up.

mike

 

Im having the same damn problems...car won't even idle now but its with a CC Xtreme 236/242 on a 110lsa. Keep us updated.

-B

 

I'm also having the same EXACT symptoms you are having after h/c/rockers swap, but I haven't checked my vacuum yet. I did just delete EGR and AIR tho, and I hope that has nothing to do with it. Please do keep us updated on your findings!

 

Have you checked the IAC Motor? My Impala did the same thing. It ended up being the Idle Air Control.
HVY SS

 

 

Ok, make sure you not only check vacuum hoses. You tore everything down common places to check would be:

Fuel injectors (I had a gigantic vacuum suege because one of my injectors was hovering over the port thanks to a stupid cousin)

EGR on the back of the intake

Throttle body (check the gasket)

Make sure your vacuum hose running to your brake booster and vacuum reservoir are still intact, you may have pulled them off when tearing it down.

All I can think of for now, check those area's and if that doesn't work check your IAC.