91 firebird, tbi vin code e , 305,3.73 posi, 700-r4(rebuilt by level 10) ,stock cam and heads(roller rockers tho),hooker 1 5/8 headers, flowmaster, no cat,accel heated oxy sensor,hypertech chip, msd 8mm wires, accell shorty plugs, msd cap n rotor,msd 6a box,1/2" tbi spacer, injector spacer, flow matched injectors, hypertech(i know its crap), aluminum driveshaft,

the motor pulls good thru first and second gear to where ever i want it to, redline is 5 i shift around 4800 or so, but in 3rd gear it goes to about 4300 and starts to breakup and i have to shift to od..............i do have the timing advanced 4 degrees but i hear no pinging and it runs good in first and second......what could be causing this? i doubt its the fuel cutoff cuz im only doin about 90 when i need to shift out of 3rd(yes i recalibed the speedo gears).......then i thought maybe the fuel pump isnt keeping up but i would think it would do it in first and second as well......im stumped

 

might be aginst the limiter at that speed. does the mph continune to climb after you shift from D? it could be a fuel volumn problem.

 

yes continues to pull and mph increases when i go into od,what limiter? i thought that was 115mph........

 

isnt the motor drinking just as much fuel at that rpm in 1st and 2nd as it is in 3rd? thats why i cant figure out what it could be

 

It is drinking as much fuel, but not for as long. I would change the fuel filter and try it if you haven't already.

Charlie

 

ok ill try the filter, my neighbor has a few cars and is on this board, he was thinking maybe the computer is sensing knock and is retarding the timing even tho i dont here any ping or knock, is it possible it would pick it up in third and not 1st and sec? he suggested backing the advance off and seeing what happens, ill do the filter first.............

 

is there such a thing as a high flow fuel filter? like a k&n would be for air filters? or is the plain old filter from advance all i need to put in?

 

Yes, they do have high flow filters. Your combo that you listed above does not jump out at me as the type that requires a high flow. Any 'OEM' design/replacement should suffice.

 

agreed however down the road ill be doing more work , cam heads, maybe juice, might as well throw one in now, unless they are only for super hi hp ........

 

well advance has 3


purolator $6

fram $12

wix $17



any reason to spend the extra here?

 

also, should i go with 190 or 255 walbro pump? im running 16psi with aftermarket regulator..........

 

^

 

You're advanced 4*? Make certain the factory setting wasn't higher which would make you actually retarded by a couple degrees. Also, with 3.73's your car thinks its at 115mph when its closer to 95mph actual. I've verified this with a scan tool, without changing your speedo gears your car still uses the factory reference pulses to determine vehicle speed. With a gear swap and not a speedo gear correction. You may be hitting that barrier. However, since it still pulls in OD, past this supposed 115mph barrier, this is nothing more than a few leads to track down and investigate.

 

like i said, i did change the speedo gears using the calculator on 700r4 .com............was a while ago but i know its correct, secondly when i advanced it i had much more pull in top end, which i still do in 1st and second, im leaning towards the thought that the stock tbi pump isnt keeping up in top of third.........now could someone give me a pointer on the above question? which filter should i go with and which gph pump? thnx in advance