after dealing with this issue with a passion after a 17.3@78mph at bandimere i have attempted fixing it by replacing my failing fuel pump (yes it was shot, leaking from housing) cleared the lines as per another thread with a similar problem and yet this one still remains, i do believe it to be fuel related, any help will be greatly appreciated

btw i do have bad vacuum, tops at 14 inches. i believe the leak is in the intake gasket and is allowing the exhaust gas from the egr port to leak into the intake side, i will be replacing that along with the intake manifold for a better one *any suggestions? rpm air gap?*

http://www.youtube.com/watch?v=JA_w9dJoxmY

 

well hit up the basics, fix that damn vac leak lol

Just to throw it out there: your MAP sensor is run off of manifold vaccum, if there is a lack of vaccum due to oh say.... a leaking manifold, its gonna get a false reading

The jist of it is: the manifold has a vacum line running from it to the MAP, then the MAP has a connector running it to the ECM feeding it readings from the manifold. As engine load increases, the manifold vaccum (should) increase putting a greater load onto the MAP, as that happens, the MAP kicks out a signal to the ECM telling it to shoot more fuel into it. If your manifold absolute pressure (MAP) sensor cant get a straight reading due to the lack of vaccum, WOT up a hill or not youll be boned sooner or later.

My advice dont bother getting a different manifold, try to fix what you have and seal up that vaccum issue

good luck

 

been workin on that vacuum issue, i'll get those intake gaskets soon

Alldata is showing the map sensor as being at top right of engine compartment (when looking at motor from front) between hood strut and firewall

i'll check the vacuum at the sensor, to test it says to give it 10 inches and check voltage with key on and engine not running
also says that the sensor will give max reading at 7000ft
the altitude in the video is 8500ft

 

sounds right on the location, ittl be along the firewall, my tbi has it on the pass side but its fairly easy to spot, black box, GM stamped on it with avacum line and a weatherpack connector on it lol, sounds like you got the alldata hook up so no need to go further into that, i use mitchell myself but thats just cuz i got it for free 99 through my courses, keep in mind you need to figure in the altitude for your final readings

good luck keep us posted

 

finally had time a few days ago to work on it, removed the fuel filter (in carb) and replaced it with external inline clear plastic one.

that seems to have fixed it

taking it to bandimere on Wednesday to update my times