compruter not holding boost??

[ShelbyShawn]

Ok now that i have my FWDperfomance stage5 computer installed, how long before it learns to hold full boost. when i floor it the boost builds to 18 then after 2-3 seconds drops to 9 then goes back up to 18. there is no buck,jerking like fuel cutout, it just loses boost. IT HAULS ASS when it does go to full boost. i have looked at o2 sensor, knock sensor, pulsewidth, a/f guage, waste gate solenoid. o2 sensor is .96 volts at full boost, no knock seen, a/f guage is showing rich. waste gate solenoid shows no activity yet it will not stay at full boost 18psi. anybody run into this before?
Cindy is this normal??
Shawn

[Dave]

Well I dont think "normal" is going up to 18, coming down to 9, then going back to 18.

The computer should learn everything within 11miles.

[Shel-Game]

If your WG solenoid isn't opening, and the boost is dropping, you have a leak somewhere.

[ShelbyShawn]

I would think a leak also except ,1 no noise from air leak, 2 boost builds back to 18 psi. the car feels just like you feathering the throttle from full to half throttle and back while my foot is steady on the floor. will need pasenger to ride along to look at scanner more closely, cause driving with your eyes not on the road when this car is accelerating is not wise. car will go from 45 to 95 in 3rd gear like there is no tomorrow, well with one problem when you go to 4th you get full boost and then 9psi and up and down. the gear is tall enough to make you wait just a little while to shift to 5th.

[87shelbyt2]

how exactly is your wg line routed? start at the pressure/vac source (whatever it is) and go to the wg can. list everything in order...

[ShelbyShawn]

Ok now for all who have read this thread.
The only change to car since boost problem is computer, car has and still does hold 12 psi with MP computer. I now have stage 5 computer back in, and have driven 100 plus miles back and forth to work on highway at speeds up to 70 (speed limit 60 so pushing just alittle) car still will not hold full boost and has now started a lean miss(car is jerking) at light throttle less then 15% between 1200 and 2000 rpms does not matter what gear your in 2,3,4,5th. i have confirmed lean condition with plug check (they are perfectly white inner now light tan color at all) plugs have 2500 miles on them. DRB shows O2 sensor voltage changing rapidly, adaptive memory shows +1to+2 on the fuel adapt when car is jerking, as soon as you push the throttle or let off problem goes away. fuel adapt at idle is -8, adaptive while accelerating but not in boost fuel adapts are first -4 then -1 until boost then 0 adapt. for all not familar with adaptives the computers have abiltity to add and subtract a percentage of fuel based on o2 sensor info and rpm and load.
What i can't figure out is why do i get a lean miss at light throttle,when adapt show trying to add fuel,then after that load and rpm range it is taking fuel away?? what should min tps voltage be? .69 is what mine is.
I thought of the not having enough fuel, new walbro 255 pump and fuel filter before installed computer,3bar map,40% injectors and afpr. fuel press is 55 w/o vac, 48 with vac at idle. Any help would be much appreciated.
Help me stop beating my head with this hammer
Shawn

[Shel-Game]

TPS Should be between 0.16 and 4.7 volts. Anything outside that sets and error code.

What MP SMEC are you using? T2 or T1? I ask because the vacuum diagram for the WG control is different (and, the WG control code is different). Do you know if the Stg5 SMEC uses the T2 or T1 style WG control? That would definitely make a difference.

[ShelbyShawn]

The MP computer is for 89 T2
Shawn

[ShelbyShawn]

Called Cindy at FWDPerformance and went down my list of problems,what sensors are reading and temps and a/f guage. she said she would look at her ecu programs and see if she can figure something out. She did ask me to take the wastegate sol out off the picture to see if i could build 18 psi and hold it, well it will peg 30 psi if i don't pull my foot off the floor. I can almost get it to stay at 18psi but it gains boost with rpm's and i let off gas to stay at 18psi.
Shawn

[87shelbyt2]

Then your mbc needs adjusted down? You were using it when it ran to 30psi right?

[ShelbyShawn]

The waste gate was completly disconnected,when i saw 30psi.
To top it all off i think i hurt the head gasket with 30psi, it leaks coolant into cylinders on cooldown. hopefully i can baby it for a couple of days, so i can get a new gasket. it is always something. Shawn

[87shelbyt2]

Quote:

it is always something.

+1