some help please!!

[jr_1086]

well the other day i was on the expressway and pressed the accelerator all the way at about 4k rpms the started to jerk really bad and constantly so i shifted from 4th to 5th gear and the car did the same thing does anyone knnow what this could be oh it does this in all gears under hard acceleration but not all the time??

 

[withcheese]

Mine does that to from what I have read its because of the fuel maps, when you hit a certain RPM the computer dumps fuel into the cylinders. If this is true to your question it can be solved with an Air Fuel Calibrator I think there is one made by split second.

Although I would mind a second opinion on this I'm still kind of new to the whole MSP thing.

 

[MX5RACER]

One thing to check is the stock BPV. When they leak, they can cause bucking at full load, which is full throttle in 4th or 5th. What psi were you boosting to?

 

[jr_1086]

well see thats another thing it was only boosting at 5 psi and from what i recall dont they come stock with 6 or 7 psi so i dont know whats wrong it doesnt boost any higher

 

[withcheese]

Could be a vacuum/boost leak somewhere, turn your car on, open the hood and listen for a hissing sound that sounds like escaping air.

 

[jr_1086]

i just checked and there is a hissing sound to it i just dont know from where

 

[withcheese]

AH HA thats the fun part, I know some shops can do a leak test on your car where they run smoke through it and can find it, but that cost money. They free way is just to search it out. Go over all the vacuum lines the BPV and anything leading to or from the turbo and the turbo its self. I owned a volvo turbo before with a leak took a little bit but found a split line.

Edit: Also check the waste gate.

 

[MSP2k3]

if you want to check for boost leaks.. buy/make a boost leak tester.. google it.. get yourself a spray bottle with a water/soap mixture.. attach the tester and fill your system with about 6psi of air w/ a bike pump... take the spray bottle and spray all your intercooler piping and if you have a leak it will start to bubble... also, when i first bought my MSP i had bucking REALLY bad .. almost to the point that it was undriveable.. took it into my shop and my fuel pump assembly had gone bad.. replaced it and it has run great since.