Rough Idle, Occasionally dies
#1
Rough Idle, Occasionally dies
I recently got a 2000 dodge ram 1500 sport 4x4 and I noticed it has a rough idle. It'll move up and down about 100rpms and doesn't ever settle. I assumed it was because one of the injector wires were completely cut but I got it fixed temporarily and it still does it. I checked for vacuum leaks and found none. It does have a straight pipe and is missing a downstream 02 sensor but even when I clear the codes it'll idle rough way before the code ever comes back. Interesting enough I found if I pump the brake pedal it'll slightly raise the rpm's then drop really low, 200-400 rpms, and will sometimes die; this leads me to think there is still some vacuum issue. I was told it "probably" had a plenum repair, but I checked the plenum plate with my magnet and it does indeed still have a steel plenum plate, so if it does, it wasn't done properly.
#2
The plenum issue is a combination of cheap gaskets, and bolts that were too long. The whole "dissimilar metals" thing just doesn't fly, as the difference in movement is measured in ten-thousandths of an inch...... Shorter bolts, and a GOOD quality gasket solves the problem permanently.
Unstable idle is indeed likely a vacuum leak. Does the engine idle rough right away? Or will it run smooth for a couple minutes, and then start freaking out?
Unstable idle is indeed likely a vacuum leak. Does the engine idle rough right away? Or will it run smooth for a couple minutes, and then start freaking out?
#3
The plenum issue is a combination of cheap gaskets, and bolts that were too long. The whole "dissimilar metals" thing just doesn't fly, as the difference in movement is measured in ten-thousandths of an inch...... Shorter bolts, and a GOOD quality gasket solves the problem permanently.
Unstable idle is indeed likely a vacuum leak. Does the engine idle rough right away? Or will it run smooth for a couple minutes, and then start freaking out?
Unstable idle is indeed likely a vacuum leak. Does the engine idle rough right away? Or will it run smooth for a couple minutes, and then start freaking out?
#4
#5
Will check fuel pressure soon. To my knowledge the plugs were changed last year, however the person I got it from said it needs a tune up. I got a full tune up kit and planning on installing that this weekend. Also I checked for a plenum leak by disconnecting the PCV and flipping over the oil cap and it appeared to had no vacuum leak. However once I reconnected the PCV hose, the truck died
#6
#7
Under the heading of...it couldn't hurt...try removing every vacuum hose from the keggar and plug them so no air can be sucked thru them. Try your beast that way n see if there's any difference. Also, what are your long and short fuel trims...idle/1500/2500 RPM and the intake air temp? Do this test in your driveway, not on the road.
Trending Topics
#8
Under the heading of...it couldn't hurt...try removing every vacuum hose from the keggar and plug them so no air can be sucked thru them. Try your beast that way n see if there's any difference. Also, what are your long and short fuel trims...idle/1500/2500 RPM and the intake air temp? Do this test in your driveway, not on the road.
Last edited by Don’t H8 the V8; 06-25-2020 at 11:32 PM.
#9
Yeah I know that's how you're supposed to do it but I didn't plug them off when I tested it but I'll give it a shot. Unfortunately I can't see my long/short term fuel trims as the obd - II port is broken so I can't put my scanner on it, unless there is someway I can check otherwise. By chance would you know what my fuel pressure should be once I test that?
#10