americanfisher93

Alright so, I have replaced the top end of my motor, 95 5.0 gt, I replaced the heads with gt40y ported, tfs2 cam, 1.6rr. cobra intake, 75 tb new oem maf, tune up. Thats about it. When the rpms are below 3000ish it bucks hard, but if I push the throttle all the way down then it picks up speed and doesnt buck. I have not driven it much but it seems to do worse when i am coasting in 4th gear. Firing order is correct, and I have no vacuum leaks. Thanks!

mattdel

Thats right in the RPM range of EGR related issues that can cause a buck. The valve gets a bit of carbon in it and it makes the sensor about 10% off from where the ECM is expecting and the bucking is the vacuum solenoid trying to correct that.

americanfisher93

its egr delete. would it still cause that?

mattdel

Without the simulator in there, yes.

americanfisher93

could you explain what that simulator is?

mattdel

http://www.rjminjectiontech.com/products/egr-eliminator

86 newbie

so my car is doing this too but i just have the stock 5.0L i did take the smog off but not the egr. still think mine could be the egr too?

mattdel

Yup..

86 newbie

so can i just buy that simulator and be done with it or do i have to but a egr delete kit

mattdel

Test it first. Generally if the EGR is the cause, the CEL will flash on momentarily while the problem is occuring, and turn off as soon as it goes away. A quick fix is to take the sensor off the EGR and take the pintle to a grinding wheel. Shave a couple millimeters off it and that will allow it to fall into a rested position, fixing the code issue and bucking. It will only solve it if it's truly the problem, though. If you shave the pintle and the EGR isn't the problem, you've just added a 10% correction in the other direction, effectively creating a problem that wasn't there before.