Hi all,

I replaced my EGR valve/gasket and vacuum line leading to the valve recently to fix a FF37 code. The car is a 94 XJS 4.0 6 cyl AJ6 engine.

Since the replacement, the code (except once) no longer pops up but the car has a rougher idle, and almost stalls after momentarily pressing the gas at stopped/low speed. My thoughts are vacuum leak still or faulty replacement EGR valve. I have the manual, and it doesn’t help a lot in this issue. So if you have dealt with this, please help!!!

 

Not sure it’s a faulty EGR install. It’s pretty straight forward, assuming you’ve tightened the bolts well enough.

When was the last time you cleaned the throttle body?

 

I haven’t cleaned the throttle body in the year I’ve owned the car. Next steps for me are replacing plugs and wires, replacing vacuum hoses, then cleaning throttle body. Just seems odd it would pop up as soon as I install a functioning EGR (the previous EGR was no longer functional).

 

EGR shouldn't be active or open at idle. Can you determine if it is open at idle? Not sure if you have the electronic EGR or vacuum activated one, but whatever sensor or programmed device that allows the vacuum to get to the EGR may be at fault. EGR should be active only at part throttle cruise and closed not active at idle.
Are you saying you are feeling vacuum at the hose to the EGR at idle?

 

It is an older vacuum style EGR. If I remove the vacuum hose at idle and put my finger on it I should feel suction if the system is operating correctly, and the valve is closed. Is that correct?

carsnplanes... what planes? I fly airbus

 

A&P Maint Tech. GA, Business/Corp Jet, Mostly Falcon Jets and occasionally a B737

ok, so EGR at idle should not be activated and if older style with vacuum, should not have vacuum at idle. Test the driveability with vacuum hose disconnected(plug the open vac line during the drive test). You'll need to find out why there's vacuum there when there shouldn't be. Follow the vac line back. It may go to a small electrical vac valve commanded by the ECU. The other side should supplied by manifold vacuum.