Chugging Saturn

SKYRANGER243

MEMBER
SATURN

1992 Saturn SL2, 1.9 Liter DOHC, 138,000 miles, original owner. Car chugs at lower speeds. Plugged EGR solenoid valve end of manifold line between manifold and EGR solenoid, and car runs great. EGR solenoid valve never seems to be commanded closed, but functions properly when 12VDC and ground placed on solenoid. 12VDC available on red wire to solenoid. Black wire runs to PCM. Rang out black wire between solenoid and PCM--not shorted or open. EGR valve opens and closes by adding and removing vacuum from EGR solenoid. Replaced throttle position sensor and engine coolant temp sensor. Checked operation of MAP sensor--resistance changes smoothly with changes in vacuum. No faults logged on PCM. Any help would be appreciated.

1 Reply

SKYRANGER243

MEMBER
5 POSTS

I've seen that this posting has been read several times so I thought I would input the final repair. I spoke with Saturn today and the technician suggested I replace the EGR valve. I mentioned that the valve opened and closed as directed by the EGR solenoid. He said that the internal structure of the EGR valve has a back-pressure chamber that manually keeps the valve closed at low speeds. No real way to check this operation without placing the removed valve on a bench and running a pressure test on it, which I can't do. So, I replaced the EGR valve. Car runs well, and the chugging is gone. So, EGR valve fixed this problem.