Quick question for you guys...What are some of the causes of vacuum problems and low idle speed? My car is idling at about 525 or so with tuning that should have it at 1K at this point(just trying to make sure)...The MAP sensor is putting out about .9 at idle, should be .6, and it seems like it is missing pretty badly...1 or 2 cylinders...The #4 header tube was glowing, indicating really lean condition. At idle, the front O2's were at about .511 millivolts...We couldn't find any vacuum leaks anywhere.

Mods are CC306, LT4 with .060 over, stock TB(for the next few weeks) A4...

She's in the shop already, just wanted some opinions...

 

Where are you getting these specs? According to a table I have, 0.60V output would represent 5.9"Hg MAP. No way even a stocker (let alone a CC306) will produce that much vaccum. 0.9V is about 8"Hg... still too much vacuum. Can you not scan it in "hg or kPa?

How did you "tune" it to run at 1000rpm? If its only at 525rpm, it isn't likely to hve excess air at idle... sounds like the IAC valve isn't opening. What are the IAC counts?

How sure are you:
-the cam is installed correctly with regard to the timing marks?
-the valves are properly adjusted

At idle, you should be in closed loop, and the O2 readings should be swinging wildly between maybe .100 and 0.900V. They change almost 10 times per second. How are you reading the output, that you can determine it is exaclty .511V (or 511mV)? .511V is not too far from the correct 14.7:1 stoichiometric A/F ratio.

Something doesn't make sense here.

 

Well, these are from my tuner's computer, which exact numbers I don't have with me, just what I saw on the screen last night. I'll try to get some more info from him.

 

The IAC was maxed out at 160...He says stock should be nearer to 40...

 

Oh, and the O2 was fluctuating, just seemed to be near that most of the time. After talking to him, he said one bank was fluctuating near 500mV, and the other at 300mv? Does that help?

 

You have an overly rich condition which is why the IAC is maxed out, pipes are glowing and idle is low. Pull a vacuum line off and I bet the idle goes up and IAC counts down. Maybe your IAC passages are clogged.

 

Hmm...I'll try that. Although, we did take off the brake booster hose, and it didn't help last night...I'll try a different hose. And I just talked to the shop...They're saying I am having injector signal problems...