Idle, 95 Z

[Dave Vince]

Changed the cam on a 95 Z 28. Cam was advertised at only 10 degrees more than stock, but it has a lope to it, and it will stall when accelerating from idle. Idle in gear is about 650, is it necessary to go into the computer to bring up idle speed. It also seems to be a little starved for fuel below 1500 rpm, as if the signal at the booster in a carb setup was not working properly. Above 1500 it comes alive, this cam may be more radical than advertised. This being injected should not have that problem, but it does, anyone ever have this problem and solve it.

[Z Ya Later]

Part of the problem is that, unless you have reflashed the PCM, it is not programmed for the new cam. Reflashing will help, if not solve the problem. Either Mad Z28 or PCMForLess can help you with this.

[Joe 1320]

not sure how accurate your tach is, but idle speed is controlled by the ECM. Idle quality is accected by the IAC (idle air control) solenoid. The IAC could be stuck, carbon fouled or may need a reset. The IAC is responsible for metering additional air when the throttle blades are closed to keep the engine from stalling and to moderate idle quality.

[fastTa]

Changed the cam on a 95 Z 28. Cam was advertised at only 10 degrees more than stock, but it has a lope to it, and it will stall when accelerating from idle. Idle in gear is about 650, is it necessary to go into the computer to bring up idle speed. It also seems to be a little starved for fuel below 1500 rpm, as if the signal at the booster in a carb setup was not working properly. Above 1500 it comes alive, this cam may be more radical than advertised.

What are the cam specs @.050". Advertised duration is worthless. Did you used a 1.6 rocker? Stock heads? Pushrod length 7.200"?

The stock 1995 cam specs are: 202/207 @.050" 0.450"/0.460" lift 116 LSA. A cam with a duration of only 212 degrees should not have much of a detectable lope at all unless it is some weird grind that has alot of overlap (numerically low LSA).

This being injected should not have that problem, but it does, anyone ever have this problem and solve it.

Actually quite the opposite. PCM or ECU controlled, fuel injected cars are much more picky as to doing things such as putting in a bigger bump stick or porting the heads.

BUT, if and only if that cam truly has an intake duration of roughly 212 degrees, the stock flash within the PCM should be fine.

Sounds like you have a bigger cam than was advertised.

[Dave Vince]

Cam Specs

Thanks for the response. Cam card reads @.050 218 I and 224 E with lift .495 I & .503 E. However 1.6 roller rockers were used and the heads were ported. All these things added seems to have made idle & low speed quality poor.

[LoudLT1]

like steve said you need to get the computer programed for the new goodies if not you wont be able to take advantage of any of it...plus your rough idle...
eddie

[Dave Vince]

Thanks for the feedback, getting a re programmer.

[N20LT4Bird]

Thanks for the response. Cam card reads @.050 218 I and 224 E with lift .495 I & .503 E. However 1.6 roller rockers were used and the heads were ported. All these things added seems to have made idle & low speed quality poor.

Sounds pretty close to LT4 hot cam specs.....the hotcam has a bit more lift though.....but the hotcam's lift .525" is advertised with a 1.6 rocker. Generally, a PCM flash is required for the hotcam upgrade. I would agree with Joe....take a look at the IAC first, then look into having the PCM flashed for the cam.