biggsteve97
New Member
I have an 03 Z71 Tahoe with the 5.3L flex fuel and intermittently it has low power as well as constant intermittent miss at idle that is not bad enough to set the code but bad enough to notice. I know from the scanner that it is the number 8 cylinder that is constantly missing and occasionally number 7 cylinder misses as well which creates a weird stumble. What I am wanting to find out is what the intake manifold vacuum is suppose to be, when I looked at the map sensor reading at hot idle it was 10.1 inches of mercury. To me that is low, but I dont know what the actual spec is suppose to be. I am comparing the reading to what my moderately modified TBI 350 has at idle which is 18 inches of mercury. I am curious if this is how its supposed to be or if i might have a defective sensor or something else could be wrong. The miss I have seems to be an overheated plug wire from the headers and I am waiting for the new wires to arrive. I have been fighting the intermittent low power issue for over two years and this is the first time I have had access to a competant scanner. Those two things were all that were found.
Any suggestions will be appreciated. I have tried to google the vacuum spec but all I keep finding is the fuel pressure spec.
Any suggestions will be appreciated. I have tried to google the vacuum spec but all I keep finding is the fuel pressure spec.
