Rough running, no idle with new EGR connected - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > Rough running, no idle with new EGR connected

ROCKRIDGE4WD Introduces a NEW Jeep Wrangler JK *led* tail ANOTHER Rockridge4wd Creation!! Spare Tire Carrier Delete Building a Bumper?

Reply
Unread 04-26-2014, 12:22 PM   #1
gelande-strasse
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2010
Location: Los Angeles
Posts: 28
Rough running, no idle with new EGR connected

Hi all, this one has me scratching my head. I recently purchased a 1990 YJ with a 2.5l. The previous owner pointed out that he had capped the vacuum line leading to the EGR, and told me to plug it back in when I get it smogged (CA). The jeep ran fine with the EGR line plugged, but ran rough and died when rolling up to a stop if the EGR was hooked up to the line.

I assumed the EGR was bad, and installed a new replacement EGR and vacuum line. I'm having the same problem: the jeep runs fine when the line is capped, but it runs rough and dies at idle when the line is hooked up to the new EGR.

Keeping the line plugged is not an option for me in CA. I appreciate any suggestions.

gelande-strasse is offline   Reply With Quote
Unread 04-26-2014, 02:48 PM   #2
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
Sounds like you are not using the correct vacuum line. There should be a vacuum line schematic sticker under the hood, if it is gone, it is also in the factory maintenance manual. The right line should correct your problem
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 03:11 PM   #3
gelande-strasse
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2010
Location: Los Angeles
Posts: 28
I just confirmed that the right line is hooked up. But I also noticed there is vacuum to the EGR at idle. I guess this means I need a new solenoid?
gelande-strasse is offline   Reply With Quote
Unread 04-26-2014, 05:33 PM   #4
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
Quote:
Originally Posted by gelande-strasse View Post
I just confirmed that the right line is hooked up. But I also noticed there is vacuum to the EGR at idle. I guess this means I need a new solenoid?

Should be no vac at idle. See if the solenoid is staying powered up, or if it breaks the vac when unpowered (however it works). You will ned a milti-meter to check if it is getting power


ETA: In other words, verify the solenoid is bad before you replace it.
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 05:43 PM   #5
gelande-strasse
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2010
Location: Los Angeles
Posts: 28
The line still has vac when the connector is unplugged (which I suppose is how it's supposed to work, based on the FSM). How do I check for power? Voltage across the connector pins on the PCM side? Electronics aren't my strong suit...
gelande-strasse is offline   Reply With Quote
Unread 04-26-2014, 06:39 PM   #6
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
Quote:
Originally Posted by gelande-strasse View Post
The line still has vac when the connector is unplugged (which I suppose is how it's supposed to work, based on the FSM). How do I check for power? Voltage across the connector pins on the PCM side? Electronics aren't my strong suit...
EGR System Component T e s t i n g - Y J Vehicles with 2.5L
Engine
Bring the engine to normal operating temperature.
Operate at idle speed. Test the EGR solenoid as follows:
Check vacuum at solenoid vacuum source hose (Fig.
36). Disconnect the line and attach a vacuum gauge to
it.
Vacuum should be a minimum of 15 inches.
If vacuum is low, check the line for kinks, twists, or
a loose connection at the throttle body vacuum port.
If vacuum is OK, remove gauge, reconnect the line
and proceed to next step.
Check vacuum at solenoid output port (Fig. 36).
Disconnect the line and attach a vacuum gauge to
output port. Vacuum reading should be zero (no vacu*
um) at this side of solenoid.
If vacuum reading is zero, leave the gauge connected
and proceed to next step. However, if vacuum is present,
check solenoid/ECU operation with the DRB II Service
Diagnostic Tester and repair as necessary.
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. How*
ever, if vacuum is not present, replace the solenoid.



***This is from the manual.^^^

When you remove power, the solenoid opens, and vac goes to the EGR valve. When you apply power, the vac is stopped by the solenoid valve
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 06:43 PM   #7
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
2.5L
Engines
The vacuum supply for the EGR valve is controlled by
the EGR Valve Solenoid on MJ/XJ vehicles and by the
EGR/Evaporative Canister Purge Solenoid on YJ vehi*
cles. The solenoid of either system is controlled by the
vehicles' engine Electronic Control Unit (ECU). When
energized by the ECU the solenoid closes and prevents
vacuum from reaching the EGR valve. When not ener-

gized, the solenoid is open and vacuum is applied to the
EGR valve. The ECU monitors engine coolant temper*
ature and other operating conditions to determine when
EGR operation is desired. Refer to TBI Modes of Oper*
ation in Group 14 for a description of solenoid operation
based on engine operating conditions.
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 06:45 PM   #8
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
Power at the connector should be present at idle. Use a volt meter or a multimeter set to DC voltage
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 08:37 PM   #9
gelande-strasse
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2010
Location: Los Angeles
Posts: 28
No power to the connector at idle. The connector is good, and one of the wires has battery power.
gelande-strasse is offline   Reply With Quote
Unread 04-26-2014, 09:19 PM   #10
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
The computer normally supplies ground to energize devices. Should be able to verify this in your manual and check the pinout for the ground wire to the solenoid at the computer
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 09:21 PM   #11
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
Sounds like you are zeroing in on the problem
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote
Unread 04-26-2014, 09:24 PM   #12
gelande-strasse
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2010
Location: Los Angeles
Posts: 28
Hopefully, thanks for your help. Seems like this will be expensive or hard to track down, or both.
gelande-strasse is offline   Reply With Quote
Unread 04-26-2014, 09:33 PM   #13
Chrisnvegas
Web Wheeler
1992 YJ Wrangler 
 
Join Date: Dec 2012
Location: Las Vegas, Nv
Posts: 1,037
Isn't the seller responsible for smog equipment?

"When a used vehicle is sold in California, the seller is legally responsible for making sure that the vehicle's emission (smog) control equipment complies with state requirements. There is no provision in the law allowing a seller to sell a vehicle "as is." The buyer must submit the certificate of compliance (smog certificate) to the Department of Motor Vehicles (DMV) when transferring registration of the vehicle. Without the smog certificate, the transfer of ownership cannot be completed."

"Remember--it is the seller's legal responsibility to make sure that the required emissions control systems are on the vehicle and functioning properly and to provide you with a Smog Certificate."

http://www.bar.ca.gov/80_BARResource...Equip_Req.html
__________________
Do not write in this area, for office use only.
Chrisnvegas is offline   Reply With Quote
Unread 04-27-2014, 02:53 PM   #14
gelande-strasse
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2010
Location: Los Angeles
Posts: 28
Yes, it's the seller's responsibility. I'm not quite ready to go down that road yet.

Anyone have tips for unplugging the computer? The ECU harness is pinched behind the blower housing, and I can't get enough slack to unplug the thing.
gelande-strasse is offline   Reply With Quote
Unread 04-27-2014, 03:53 PM   #15
Old4X
Registered User
1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 4,620
Quote:
Originally Posted by gelande-strasse View Post
Yes, it's the seller's responsibility. I'm not quite ready to go down that road yet.

Anyone have tips for unplugging the computer? The ECU harness is pinched behind the blower housing, and I can't get enough slack to unplug the thing.
The tray that holds the computer is held in place by 2 studs that go through the firewall. Can you remove the nuts from them, release the computer from the tray and get enough room to work?
__________________
Rust free YJ for sale. Need more room in barn.
Old4X is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.