when i drive my 1998 jaguar xjr and hit the gas at full throttle, it almost feels like it lags and pulsates constantly. the engine runs great so it must be the transmission. any other thoughts or has anyone else had this problem? i would appreciate all the help i can get

 

I recommend you look at archives concerning gas pressure and the secondar fuel pump.

 

Do you have any OBD codes?

 

No, there is no check engine light on or any kind of warning. the transmission shifts fine and everything, but when i hit the gas hard, imagine the acceleration like a ticking clock. its not smooth at all

 

When was the last time you had the plugs replaced, TB & MAFS cleaned? You also have a breather stub that needs cleaning. In most cases you should have a code come up giving you a little direction. Did this all take place at once? Give us a little information….

 

if i hit the accelarator hard from a dead stop, the car does just fine, no lagging or anything. but if im driving about thirty miles an hour and punch it, it staggers. The car has been sitting in storage for about 5 months due to ****ty north dakota winters . the only thing i have done to it in its whole life is oil and air filter changes. I live in a smaller town, and the nearest jaguar dealer is in canada so i do not know where to get the plugs and everything worked on. Can a ford dealer do this work since its a 1998?

 

I would think any good mechanic that knows cars even Fords can work on it. If he has a problem direct him to us. We will do all we can to help. I have a local shop do my work when I am unable to get to it.

 

My car does the stuttering now not even at full throttle. if i get on the gas pedal even a little hard, it does the stuttering. does my check engine light need to be on to throw a code?

 

wayne:
I recommend you check the fuel pressure with a test guage. rig it so you can see the guage through the widscreen while you are underway.

 

so if i end up having low pressure, is it the fuel pump?

 

Wayne:
Not necassarily. It might be the relay that drives it, the inlet screen, the fuel filter and so on. And it might very well not be the fuel system. You have enough matching symptoms to check it though, since you have no OBD codes. I mention the fuel pressure because it sounds like it might be fuel starving at high load.
The XJR has two fuel pumps. They are in the tank, and the second one kicks on when needed. Fuel presure should be about 39 psi above manifold pressure.

 

Is it that the transmission is not downshifting?

 

Gus:
It feels like it does shift down, im just confused as why my car is not throwing the check engine light on.

 

Do you have an OBD scanner to plug in just for the hell of it?

 

Just a hunch, have you checked you air intake pipe (from air filter to the TB) for any cracks or if the lid is not closed properly? They seem to crack on the bottom side.

 

i plugged my obd2 reader in and the only thing it showed was p1000. There are three different colored lights on the reader, and mine showed yellow, which means "a possible obd2 code detected but could not be determined". The car does downshift just fine when i get on the acceleration, the car lags from 2k to 5k rpms, then after 5k it takes off fast just like it usually would.