ok just a quick question, my 88 6 cylender jeep is having an issue with the egr valve. as soon as i hit the gas the egr opens even when the engine is cold causing it to studder and sometimes die. once rpms are up its fine. just durring accelleration from low speeds it happens. there is also an intermittent high idle that i think might be related. from what i can find i think it might be a cts or mat. but i dont know. and if it is should i replace both sensors or is one more likely than the other? thank you all very much for any help
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early opening egr???
- Thread starter coryshad
- Start date
8Mud
NAXJA Forum User
- Location
- Central Germany
The solenoid is default open, so when the power is interrupted or the coil in the solenoid is burnt out the vacuum is supplied to the EGR continuously.
The ECU grounds the solenoid, activating it and shutting off the vacuum when the motor is in open loop (cold), low vacuum, likely low RPM's and I believe with some TPS inputs, like closed throttle (but I'm not really sure about that).
I'd start troubleshooting at the solenoid. Power in? Ohm test the solenoid for continuity.
You can plug off the vacuum to the EGR and disable it. I ran mine like that for almost a year and never missed it. Though I did eventually fix mine, I had a bad transducer (vacuum leaked).
The ECU grounds the solenoid, activating it and shutting off the vacuum when the motor is in open loop (cold), low vacuum, likely low RPM's and I believe with some TPS inputs, like closed throttle (but I'm not really sure about that).
I'd start troubleshooting at the solenoid. Power in? Ohm test the solenoid for continuity.
You can plug off the vacuum to the EGR and disable it. I ran mine like that for almost a year and never missed it. Though I did eventually fix mine, I had a bad transducer (vacuum leaked).
Easiest way to check is to disconnect the vacuum from the EGR solenoid to the EGR valve and plug the lines. The EGR should remain closed and allow you to decide if this is the issue or something else.
I had this issue on my '88. The EGR solenoid went bad, allowing the EGR valve to open under all conditions. Jeep ran and idled like complete crap. The replacement was defective from the dealer and allowed the situation you describe - a light throttle app would kill it, while goosing it allowed it to keep running. Isolated it using the method above, and got a free replacement for the replacement from the dealer, and all my issues were solved.
I had this issue on my '88. The EGR solenoid went bad, allowing the EGR valve to open under all conditions. Jeep ran and idled like complete crap. The replacement was defective from the dealer and allowed the situation you describe - a light throttle app would kill it, while goosing it allowed it to keep running. Isolated it using the method above, and got a free replacement for the replacement from the dealer, and all my issues were solved.
so does anyone know if it could be the cts telling the ecu that the engine is hotter than it is? it doesnt open at all at an idle its only durring acceleration so im pretty sure the solenoid is still good. and i tested it by unpluging the solenoid. it opens the egr and the engine wont even idle right. any help would be great. i want my jeep back:bawl:
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Take this as you will, its for the 1990 from the FSM:
Warm the engine to normal operating temperature.
Operate engine at idle speed.
Check vacuum at solenoid vacuum source.
Disconnect the hose and attach a vacuum gauge to it.
Vacuum should be at 17 inches.
If vacuum is low, check the line for kinks, twists, or a loose connection at vacuum connector on intake manifold.
If vacuum is ok, remove gauge , reconnect the line and proceed to next step.
Check vacuum at solenoid output port.
Disconnect the line and attach a vacuum gauge to output port. Vacuum reading should be 0 at this side of solenoid.
If vacuum reading is 0, leave the gauge connected and proceed to the next step. However, if vacuum is present check solenoid/ECU operation with the DRB-ii tester.
Disconnect electrical connector at solenoid and note vacuum at output port. Vacuum should now be present at output port.
If vacuum is present, proceed to EGR valve test. However, if vacuum is not present, replace the solenoid. Test the EGR valve as follows:
Leave solenoid electrical connector disconnected. Note engine idle.
The engine should idle roughly or stall. If this occurs the valve is ok. If the idle does not change, proceed to next step.
Disconnect hose from the EGR valve and connect a hand vacuum pump to EGR nipple.
Apply a minimum of 12" of vacuum to the valve and note engine idle. If engine now idles rough inspect the vacuum line between the EGR valve and the solenoid.
If the idle did not change, remove the EGR valve and inspect the valve and the exhaust passage in the manifold for blockage, repair as necessary. If no blockage is present replace the EGR valve.
Note: I left out some parts relating to the vacuum transducer as it was only on the 89-90.
Warm the engine to normal operating temperature.
Operate engine at idle speed.
Check vacuum at solenoid vacuum source.
Disconnect the hose and attach a vacuum gauge to it.
Vacuum should be at 17 inches.
If vacuum is low, check the line for kinks, twists, or a loose connection at vacuum connector on intake manifold.
If vacuum is ok, remove gauge , reconnect the line and proceed to next step.
Check vacuum at solenoid output port.
Disconnect the line and attach a vacuum gauge to output port. Vacuum reading should be 0 at this side of solenoid.
If vacuum reading is 0, leave the gauge connected and proceed to the next step. However, if vacuum is present check solenoid/ECU operation with the DRB-ii tester.
Disconnect electrical connector at solenoid and note vacuum at output port. Vacuum should now be present at output port.
If vacuum is present, proceed to EGR valve test. However, if vacuum is not present, replace the solenoid. Test the EGR valve as follows:
Leave solenoid electrical connector disconnected. Note engine idle.
The engine should idle roughly or stall. If this occurs the valve is ok. If the idle does not change, proceed to next step.
Disconnect hose from the EGR valve and connect a hand vacuum pump to EGR nipple.
Apply a minimum of 12" of vacuum to the valve and note engine idle. If engine now idles rough inspect the vacuum line between the EGR valve and the solenoid.
If the idle did not change, remove the EGR valve and inspect the valve and the exhaust passage in the manifold for blockage, repair as necessary. If no blockage is present replace the EGR valve.
Note: I left out some parts relating to the vacuum transducer as it was only on the 89-90.
