the car seems to idle rough at times. its idling at 900-1000 and 1500 in park. just replaced tps and iac was replaced by last owner. double checked vacuum to map. also surges on the highway i see the rpm spike. the engine will stall at redlights sometime and right when im pulling up in the driveway to park. the car is a 91 camaro rs auto 305 tbi

 

MAF (MASS AIR FLOW)sensor is electrical only and there is no vacuum line

MAP (MANIFOLD ABOSOLUTE PRESSURE) sensor has electrical and a vacuum line connection to the TBI.

No such thing as a TBI car with a MAF sensor... all TBI cars are speed density systems and have a MAP sensor

You need to check the voltage at the MAP sensor. ODDs are the electrical connection is fine. but you need to make sure the vacuum line is holding vacuum with a vacuum pump. looking at it will not prove anything.

With the car off disconnect the line from the MAP to the throttle body. and connect the line to a vaccum pump. pump up the vacuum pump. (10-15 psi on the gage) If the vaccum drops, replace the line. it has a pin hole leak.
if vaccum still drops with a new line then you need to replace the MAP sensor.

If the MAP checks out OK then you need to test the IAC motor...


One last thing.. has the Service Engine light come on? rent a scan tool and check for trouble codes because a bad sensor or electrical connection to that that sensor should throw a code.

if Sensors and IAC motor are OK a bad 02 sensor or a failing fuel pump will also cause Idle and driveability issues... and throw sensor codes... a bad pump will most likely throw an 02 sensor code (too lean a mix because not enough fuel)

If you have an 02 sensor code, to rule out a bad pump check the fuel pressure, if fuel pressure is OK then it's the 02 sensor or the connection to it.

good luck !

 

gotcha thanks and yes i meant to put map not maf sorry about that. im waiting for my o2 sensor to come in the mail cause the original 1 is in the car. also car has a 2 month old fuel pump on. only check engine code i have is 32 and thats because last owner removed egr

 

the map sensor has been replaced by someone else the car only has 102 on it. how much would it cost to get fuel pressure tested so i wont get ripped off. today i drove the car and it died at a stop sign took forever it seem to get it back running after the first stall it will crank then stall even with me pushing on the gas. but yes i sense either a fuel or spark problem. replaced 02 sensor did nothing. replacing the CTS and MAP today.