5.0 Idle issues

[friskyfrankie]

Electric and vacuum unit that works with (as part of) the EGR system. Forgot if it is referred to as the EVR?

[monotonorobo]

Electric and vacuum unit that works with (as part of) the EGR system. Forgot if it is referred to as the EVR?

I think it’s vacuum solenoid I’m gonna see if I can fix it

[gadget73]

Those are the Thermactor Air Diverter and Thermactor Air Bypass solenoids. I don't remember which is which but they control the smog pump. If there are broken vacuum lines they need to be fixed. Check all of the hard plastic ones, they're usually petrified and fragile by now. They can be replaced with rubber hose in the proper size.

The single solenoid below the twins is the EGR Vacuum Regulator. Thats the one with the green line. Red is manifold vacuum, white and black go to the thermactor valves.

[monotonorobo]

Those are the Thermactor Air Diverter and Thermactor Air Bypass solenoids. I don't remember which is which but they control the smog pump. If there are broken vacuum lines they need to be fixed. Check all of the hard plastic ones, they're usually petrified and fragile by now. They can be replaced with rubber hose in the proper size.

The single solenoid below the twins is the EGR Vacuum Regulator. Thats the one with the green line. Red is manifold vacuum, white and black go to the thermactor valves.

I patched a few of these hoses that cracked with a rubber line and now the car is driveable. Still stalls every now and then while Idling but other than that it’s doing well. I drove it up hills and everything, since driving it uphill was what caused me to find an issue with the car in the first place. Something that may or may not be related is with the A/C on the idle fluctuates constantly. Also when I let go of the gas sometimes in drive the car shudders a bit while not on the brakes.

[monotonorobo]

Did some reading and from what I’m seeing possibilities are.. TV cable, TPS (out of the question), distributor rotor, spark plugs/wires, PCV screen and grommet, and fuel filter. I’m gonna give a bit more info on this issue by saying that the engine only stalls maybe once every 5-6 mins? So it’s not constant, the shudders seem to be constant though. The shudder only happens when letting go of the throttle, not when accelerating and only in drive it seems. Didn’t shudder when I revved it in park but that could be because the engine isn’t under a load. I already did a smoke test for a possible vacuum leak but I didn’t see anything but after I replaced the MAP hose and fixed up some vacuum lines it ran smoother and better, but would stall less than before.

[friskyfrankie]

If any of the items you listed haven't been changed "recently", I'd change them except the TV cable. See where you are at then.

[monotonorobo]

If any of the items you listed haven't been changed "recently", I'd change them except the TV cable. See where you are at then.

Plugs and wires been changed about 6 months ago (wasn’t running until like this month) fuel filter was changed about a year ago. So I guess I’ll go for the PCV and first.

[friskyfrankie]

Forgot what year your car is but if it has a screen under the PCV you need to change that as well as the valve. Check the grommet as well.

[monotonorobo]

Forgot what year your car is but if it has a screen under the PCV you need to change that as well as the valve. Check the grommet as well.

My PCV never had a grommet ,year is 89

[friskyfrankie]

My PCV never had a grommet ,year is 89

Did it disappear? Never seen a GM without a PCV grommet.

[monotonorobo]

Did it disappear? Never seen a GM without a PCV grommet.

Maybe previous owner did it. They did a lot of things to this car that messed me up, multiple vacuum lines, wheel studs, using the plugs that came with the car in 89 etc.. I don’t even think the PCV had a screen on it, I only remember there being an o-ring on it and that was about it. Could it cause problems such as the bucking and jerking described earlier? Either way I’ll still fix it.

[friskyfrankie]

You can find the OEM PCV and grommet, if you wish to go that way but the screen will be aftermarket. I use OEM valves and grommets (the OEM grommets just seem to fit better). Do ALL three.

[monotonorobo]

Got it. Had to look down to see if the screen was there and it was so I pulled it out. I can run it without a screen for a bit correct? Only thing it’d do is increase oil consumption but it’s only for a while, just so I can find the main issue.

[sly]

If you don't have the grommet that the PCV sits in, it's basically a huge oil leak out the back of the engine since that's where the PCV lives (on the rear of the lower intake manifold) and without the grommet to seal the hole and screen below it, oil tends to slosh and splash out of that hole. Replacement PCV valves come with a plastic adapter for multiple systems, just pull that bit off and use the metal core part.

If you don't have the screen, you need one. That keeps the oil from being sucked into the PCV system as much and will keep from burning as much oil. If you do have the screen, you can clean them and reuse them if they're not crusty. WD40, brake cleaner, favorite solvent degreaser... whatever works for you.

[friskyfrankie]

Dorman does make the screen and I always make sure I have all the parts before pulling the old ones. As previously stated, I'd change all three items and would not suggest running it with missing parts. SLY nailed it!