Egr Valve...

Hey,

'88 XJ Cherokee Laredo 4.0 Auto.

Was thinking of changing my EGR VALVE but before I do how can I tell if this one is still any good? 5k miles on Reman 4.0.

Funny thing though I was passing Emissions Testing when the EGR was disconnected for the past 5 years! The EGR was replaced when the Reman was put in but not connected. Two years ago I discovered it disconnected and reconnected it and now I'm failing the Emissions Test. Go figure? It's still bright and shiny. I can see the spindle move in and out around 1/8-3/32 of an inch when I rev the engine.

The vehicle is running well (knock on wood, lol) no pinging or hesitation on heavy acceleration or even idling. Tailpipe Smoke is clear and normal looking; only see some water vapor on cold days (that's normal right?)

Thx, Phil:confused:

Well, it sounds like it's behaving as it should. However, here's the test specs.

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/15/25/ce/0900823d801525ce.jsp

Take out the egr and push the diaphram in, then plug the hole on the bottom. If it stayes pushed in that means its still good, or at least the diaphram is, thats the number one thing that goes out in the egr. My old 89 Chevy truck's egr diaphram went out and thats how i found out.

Hey,

'88 XJ Cherokee Laredo 4.0 Auto.

Was thinking of changing my EGR VALVE but before I do how can I tell if this one is still any good? 5k miles on Reman 4.0.

Funny thing though I was passing Emissions Testing when the EGR was disconnected for the past 5 years! The EGR was replaced when the Reman was put in but not connected. Two years ago I discovered it disconnected and reconnected it and now I'm failing the Emissions Test. Go figure? It's still bright and shiny. I can see the spindle move in and out around 1/8-3/32 of an inch when I rev the engine.

The vehicle is running well (knock on wood, lol) no pinging or hesitation on heavy acceleration or even idling. Tailpipe Smoke is clear and normal looking; only see some water vapor on cold days (that's normal right?)

Thx, Phil:confused:

Hey Phil,
I was going to look up some of my old notes for you, but I just haven't had any spare time. Water vapor is normal, but your egr movement seems too little to me. I'd run through the checks linked below to start with. I suspect if the vac controls are functioning correctly, your high flow cat may have lower backpressure affecting the opening signal.

In specific I have somewhere in my stash some normal vacuum readings I took on the road with a properly functioning vehicle. I remember replacing a few egr/transducer assemblys for incorrect flow. I'd hate to have you order and pay for a new one if it is a backpressure related condition.

I have also seen a restriction in the ECU egr shut off solonoid (the electric one). You can use a hose to bypass around it and see if the valve opens further.

Hey Phil,
I was going to look up some of my old notes for you, but I just haven't had any spare time. Water vapor is normal, but your egr movement seems too little to me. I'd run through the checks linked below to start with. I suspect if the vac controls are functioning correctly, your high flow cat may have lower backpressure affecting the opening signal.

In specific I have somewhere in my stash some normal vacuum readings I took on the road with a properly functioning vehicle. I remember replacing a few egr/transducer assemblys for incorrect flow. I'd hate to have you order and pay for a new one if it is a backpressure related condition.

I have also seen a restriction in the ECU egr shut off solonoid (the electric one). You can use a hose to bypass around it and see if the valve opens further.


Hey OlJeepTek,


The EGR Solenoid is Brand New. I replaced it in my QUEST for lower/passing emissions and also when I discovered the EGR Valve not being hooked up.

Could the passages in the MANIFOLD be stuffed and dirty with carbon deposits? Even though I had a Reman 4.0L put in the Mech used all the old misc parts from the old engine like the MANIFOLD.

But, correct me if I'm wrong... if the MANIFOLD was dirty wouldn't it affect my other EMISSIONS READINGS (other than NOX)? IOW - Would they be higher? They register very low and passing only the NOX was high.

And, like you said fixing the cooling system may have already solved my prob of too much NOX but I won't know until next Sept/Oct when my Emissions Test is due again.


Thx, Phil

Hey OlJeepTek,


The EGR Solenoid is Brand New. I replaced it in my QUEST for lower/passing emissions and also when I discovered the EGR Valve not being hooked up.

Could the passages in the MANIFOLD be stuffed and dirty with carbon deposits? Even though I had a Reman 4.0L put in the Mech used all the old misc parts from the old engine like the MANIFOLD.

But, correct me if I'm wrong... if the MANIFOLD was dirty wouldn't it affect my other EMISSIONS READINGS (other than NOX)? IOW - Would they be higher? They register very low and passing only the NOX was high.

And, like you said fixing the cooling system may have already solved my prob of too much NOX but I won't know until next Sept/Oct when my Emissions Test is due again.


Thx, Phil

A couple thoughts come to mind, Phil,
Your truck should have an egr solenoid, which it you have replaced, and a backpressure transducer both. The solenoid is only for the ecu to be able to disconnect vacuum when egr is not needed. Ie cold engine, etc. It should not be active during normal operation.

The egr transducer is in control of the amount the egr will open under varying load. Yes, the high nox could be caused by by plugged manifold passages without effecting the other CO, HC, Co2, and O2 readouts.T he ecu can hide this very easily. Do you by chance have the last full emissions readout available? I could possibly give you a little more input with those figures.

Keep in mind also that a new cat would have been very good at eating excess HC's and CO. The Co2 reading would tell us if that were occuring, as would an emission test before the cat.

I used to run into problems with aftermarket replacement egr valves not being supplied with a new transducer, or even being too generic and not having the correct flow.

I would take a few minutes to pull the egr on a coool engine, and check the following..
Use a couple layers of duct tape across the manifold face covering the two ports. Start it and at idle, pull back the tape from the vacuum side to see that you have major vacuum. It will most likely stall.

Plug the vac and pull the exhaust side off and check for good exhaust flow.

Check the egr gasket to make sure the small hole(s) are not blocked for the transducer tube. (Make sure it has the tube while your at it).

If you find any blockage you can scrape out what you can and use spray carb cleaner to try to open it up. Wait till it cools so as not to start a fire.

Make sure the transducer port from the egr bottom side is not ruptured.

You can also block the small sense port at the egr and use a hose from the transducer to your mouth or a hand vac pump to put pressure and vacuum to see how the egr valve reponds compared to how far it opened in your previous test in the earlier posts.

I still think your car has one of three typical problems:
1. Running too hot. (I think you have fixed this)
2. Not enough egr
3. Cat not functioning properly. (I am assuming you are probably ok here too)

4. Not as typical, but possible, is a stretched timing chain which changes cam timing. The ecu has no way to accomodate this. A new cat could also hide it. What is your normal idling manifold vaccuum doing? It should be 18"-19" (at our normal elevation which is about 1000 ft above sea level), and increase to 19-20" at 2500-3000 rpm in neutral

Sorry about the novel, but that's my thoughts for now.

A couple thoughts come to mind, Phil,
Your truck should have an egr solenoid, which it you have replaced, and a backpressure transducer both. The solenoid is only for the ecu to be able to disconnect vacuum when egr is not needed. Ie cold engine, etc. It should not be active during normal operation.

The egr transducer is in control of the amount the egr will open under varying load. Yes, the high nox could be caused by by plugged manifold passages without effecting the other CO, HC, Co2, and O2 readouts.T he ecu can hide this very easily. Do you by chance have the last full emissions readout available? I could possibly give you a little more input with those figures.

Keep in mind also that a new cat would have been very good at eating excess HC's and CO. The Co2 reading would tell us if that were occuring, as would an emission test before the cat.

I used to run into problems with aftermarket replacement egr valves not being supplied with a new transducer, or even being too generic and not having the correct flow.

I would take a few minutes to pull the egr on a coool engine, and check the following..
Use a couple layers of duct tape across the manifold face covering the two ports. Start it and at idle, pull back the tape from the vacuum side to see that you have major vacuum. It will most likely stall.

Plug the vac and pull the exhaust side off and check for good exhaust flow.

Check the egr gasket to make sure the small hole(s) are not blocked for the transducer tube. (Make sure it has the tube while your at it).

If you find any blockage you can scrape out what you can and use spray carb cleaner to try to open it up. Wait till it cools so as not to start a fire.

Make sure the transducer port from the egr bottom side is not ruptured.

You can also block the small sense port at the egr and use a hose from the transducer to your mouth or a hand vac pump to put pressure and vacuum to see how the egr valve reponds compared to how far it opened in your previous test in the earlier posts.

I still think your car has one of three typical problems:
1. Running too hot. (I think you have fixed this)
2. Not enough egr
3. Cat not functioning properly. (I am assuming you are probably ok here too)

4. Not as typical, but possible, is a stretched timing chain which changes cam timing. The ecu has no way to accomodate this. A new cat could also hide it. What is your normal idling manifold vaccuum doing? It should be 18"-19" (at our normal elevation which is about 1000 ft above sea level), and increase to 19-20" at 2500-3000 rpm in neutral

Sorry about the novel, but that's my thoughts for now.
Hey OlJeepTek,

NP, I like it descriptive. I found the most recent Emission Test and also one from way back in 02 when the EGR was disconnected but I still passed. Here they are:

9/02

Limits HC CO NOX
3.20 80.0 6.00

Results 0.67 25.9 5.58


10/05

Limits HC CO NOX
1.60 40.0 2.50


Results 0.38 10.9 2.48



It seems like the Limits have been halved with the newer test have they made them more stringent?

On the old test the Jeep was still borderline overheating just like this latest. Hopefully, with my new Open Radiator System, new Cat (did that last week guys at Muffler Shop said it was still good and not clogged, but I changed it with the same Walker High Flow CAT) to rule out a malfunctioning one) I would be running cooler and have less NOX. I use 87 Fuel should I go to 89?

btw - I heard that during Emissions Testing they are supposed to place a Big Fan in front of the vehicle. I can't seem to find any place that does this. I'm sure the Fan would help. I'm using a Dual Electric Fan set-up on the Jeep. I did away with the Clutch Fan. They work Great.

I read somewhere that the vehicle must be warmed up to get accurate readings for NOX. Come to think of it my vehicle was sitting for a few hours before they ran the latest test. Does the vehicle warm-up enough on the dyno when it's accelerated rapidly (and in my case towards borderline overheating)?

It's idling ok. Could I have a stretched timing chain on a new reman 4.0?I can't measure the vacuum since I don't have a tester but I will try that duct tape test. Is there a way to squeeze the diaphragm on this EGR (the diaphragm is shielded closed)?

Not sure what you mean by this:

"Plug the vac and pull the exhaust side off and check for good exhaust flow. "

Do this test with the EGR back on the Manifold? What do you mean by pull the exhaust side off? Exactly where is the exhaust side?

A little off track:

1. When most of the suspension was replaced the Mechs broke one of the Upper Control Arm Bolts (the one that goes thru the frame and they also kept dropping the socket down the frame and cussing, lol). Well they replaced it with one of slightly smaller diameter around 1/16" less. I've been driving it around since August w/o probs. Do you think it's ok or should I get the thicker bolt?

2. I got some used Fuel Injectors off of a '91 Laredo 4.0L with the Fuel Rail and Regulator. How can I clean them up or should I soak them in Gasoline or other? Paid $100 for all plus the Fuel Pump Resistor on the driver's side fender. Good price or wasted money?

Thanx so much for your help I've been asking alot of questions but most mechs/friends know little or the wrong info. I'm glad this board has a Great Mech like you to help us!


Thx, Phil:)

Hey OlJeepTek,

NP, I like it descriptive. I found the most recent Emission Test and also one from way back in 02 when the EGR was disconnected but I still passed. Here they are:

9/02

Limits HC CO NOX
3.20 80.0 6.00

Results 0.67 25.9 5.58


10/05

Limits HC CO NOX
1.60 40.0 2.50


Results 0.38 10.9 2.48



It seems like the Limits have been halved with the newer test have they made them more stringent?

On the old test the Jeep was still borderline overheating just like this latest. Hopefully, with my new Open Radiator System, new Cat (did that last week guys at Muffler Shop said it was still good and not clogged, but I changed it with the same Walker High Flow CAT) to rule out a malfunctioning one) I would be running cooler and have less NOX. I use 87 Fuel should I go to 89?

btw - I heard that during Emissions Testing they are supposed to place a Big Fan in front of the vehicle. I can't seem to find any place that does this. I'm sure the Fan would help. I'm using a Dual Electric Fan set-up on the Jeep. I did away with the Clutch Fan. They work Great.

I read somewhere that the vehicle must be warmed up to get accurate readings for NOX. Come to think of it my vehicle was sitting for a few hours before they ran the latest test. Does the vehicle warm-up enough on the dyno when it's accelerated rapidly (and in my case towards borderline overheating)?

It's idling ok. Could I have a stretched timing chain on a new reman 4.0?I can't measure the vacuum since I don't have a tester but I will try that duct tape test. Is there a way to squeeze the diaphragm on this EGR (the diaphragm is shielded closed)?

Not sure what you mean by this:

"Plug the vac and pull the exhaust side off and check for good exhaust flow. "

Do this test with the EGR back on the Manifold? What do you mean by pull the exhaust side off? Exactly where is the exhaust side?

A little off track:

1. When most of the suspension was replaced the Mechs broke one of the Upper Control Arm Bolts (the one that goes thru the frame and they also kept dropping the socket down the frame and cussing, lol). Well they replaced it with one of slightly smaller diameter around 1/16" less. I've been driving it around since August w/o probs. Do you think it's ok or should I get the thicker bolt?

2. I got some used Fuel Injectors off of a '91 Laredo 4.0L with the Fuel Rail and Regulator. How can I clean them up or should I soak them in Gasoline or other? Paid $100 for all plus the Fuel Pump Resistor on the driver's side fender. Good price or wasted money?

Thanx so much for your help I've been asking alot of questions but most mechs/friends know little or the wrong info. I'm glad this board has a Great Mech like you to help us!


Thx, Phil:)


Sorry, I brain-farted on the reman info. Timing chain's not likely an issue.

Your emissions data looks like its running pretty cleanly, but I'd need the CO2 reading to tell you if it's the cat cleaning up any sin's. The emission limits on the loaded testing started out somewhat loose in most areas of the country, and it's not uncommon to have had them tightened by the EPA.

It looks to me your egr was causing high nox in '02. It passed most likely on the loose limit set.

The cars in enhanced testing should be at full operating temperature for the test, but it's the cat temp that is critical for it to function properly. A cool cat can't do it's job very well. If your electric fans are operational, the tester's lack of a big fan shouldn't be an issue. Rinse the radiator fins out with a water hose a few days before the test for maximum heat transfer out of the rad. Do the ac condenser too if you have one.

89 octane wouldn't do very much IF the knock sensor is functioning correctly since the ecu will add more advance to make use of the higher octane. Which gives me another thought... If whoever installed the engine didn't connect the sensor, or more likely if they put teflon tape on the threads of the sensor, it may not be sensitive enough and running a little too much advance. (think higher than normal cylinder temps) Take a look-see and see if there is any tape showing on the threads. It should be a large round single wire sensor on the passenger side of the block, fairly low and toward the rear. Looks kind of like a sending unit on steroids with a green wire. It should be screwed into a dead hole, not needing any tape etc. You could snug it up a little tighter (maybe 1/8-1/4 turn) to increase sensitivity, but don't reef it too hard, you'll crack it internally. Unfortunately you need some fancy equipment to test it's output.

On the egr test stuff, If you remove the egr valve, there are 2 main passages in the manifold. One is into the intake ports(thus "the vac side"), the other goes into the exhaust via a passage through the intake on some vehicles, or through a large metal tube. (the exh side). I can't remember which you have to be honest. The checks re with the egr valve removed, and sitting on the bench. You're plugging off the 2 holes in the manifold and opening them one at a time. I used the duct tape trick since a few layers is quick and will stick long enough to check it out.

Technically you should replace the suspension bolt with the correct bolt for proper hardness, shear strength, etc. (Legal blah, blah, blah).

Personally, the clamping force is what is required on the inner bushing sleeve, and the rubber bushing flexes around it. The shear strength only comes into play during an impact. Could come from accident, or offroading etc. I'd put in a Mopar bolt, but I'm a little retentive there. You're probably just fine if they used a Grade 8 bolt. (Hardened). A hardware store "butter bolt" should definitely be replaced if the just went on the cheap though.

I can't give you much input with you injector question. I haven't played the swap game and don't know the flow data interplay. I would toss in that injectors need to be cleaned from the inside (Flowing fuel) and soaking won't do beans. I would suggest that the resistance of the circuit be checked so the current flowing through the ecu doesn't cause any harm. Changing the flow rate too much may get you outside the ecu ability to correct for it and may br an issue with future emission tests.....

At least, save the old parts to reinstall prior to the test.

If you don't have the equipment to clean the injectors, put a few ounces of GM top engine cleaner in a full tank of gas and just drive it. It helps clean the cat too. I don't know if Mopar makes an equivilant. Most of the store bought brands don't work too well I found.

Hey,

I forgot one thing for you. I don't rember being able to easily push open the ger manually, but you should be able to use a vacuum hose from a full manifold vacuum port to put idle vac direct to the valve. It should suck wide open, and kill the engine. At least make it run crappy anyway. You probably can't suck it open with a hand pump due to the internal bleed holes. This should give you an idea of how far it can open under load too.

Sorry, I brain-farted on the reman info. Timing chain's not likely an issue.

Your emissions data looks like its running pretty cleanly, but I'd need the CO2 reading to tell you if it's the cat cleaning up any sin's. The emission limits on the loaded testing started out somewhat loose in most areas of the country, and it's not uncommon to have had them tightened by the EPA.

It looks to me your egr was causing high nox in '02. It passed most likely on the loose limit set.

The cars in enhanced testing should be at full operating temperature for the test, but it's the cat temp that is critical for it to function properly. A cool cat can't do it's job very well. If your electric fans are operational, the tester's lack of a big fan shouldn't be an issue. Rinse the radiator fins out with a water hose a few days before the test for maximum heat transfer out of the rad. Do the ac condenser too if you have one.

89 octane wouldn't do very much IF the knock sensor is functioning correctly since the ecu will add more advance to make use of the higher octane. Which gives me another thought... If whoever installed the engine didn't connect the sensor, or more likely if they put teflon tape on the threads of the sensor, it may not be sensitive enough and running a little too much advance. (think higher than normal cylinder temps) Take a look-see and see if there is any tape showing on the threads. It should be a large round single wire sensor on the passenger side of the block, fairly low and toward the rear. Looks kind of like a sending unit on steroids with a green wire. It should be screwed into a dead hole, not needing any tape etc. You could snug it up a little tighter (maybe 1/8-1/4 turn) to increase sensitivity, but don't reef it too hard, you'll crack it internally. Unfortunately you need some fancy equipment to test it's output.

On the egr test stuff, If you remove the egr valve, there are 2 main passages in the manifold. One is into the intake ports(thus "the vac side"), the other goes into the exhaust via a passage through the intake on some vehicles, or through a large metal tube. (the exh side). I can't remember which you have to be honest. The checks re with the egr valve removed, and sitting on the bench. You're plugging off the 2 holes in the manifold and opening them one at a time. I used the duct tape trick since a few layers is quick and will stick long enough to check it out.

Technically you should replace the suspension bolt with the correct bolt for proper hardness, shear strength, etc. (Legal blah, blah, blah).

Personally, the clamping force is what is required on the inner bushing sleeve, and the rubber bushing flexes around it. The shear strength only comes into play during an impact. Could come from accident, or offroading etc. I'd put in a Mopar bolt, but I'm a little retentive there. You're probably just fine if they used a Grade 8 bolt. (Hardened). A hardware store "butter bolt" should definitely be replaced if the just went on the cheap though.

I can't give you much input with you injector question. I haven't played the swap game and don't know the flow data interplay. I would toss in that injectors need to be cleaned from the inside (Flowing fuel) and soaking won't do beans. I would suggest that the resistance of the circuit be checked so the current flowing through the ecu doesn't cause any harm. Changing the flow rate too much may get you outside the ecu ability to correct for it and may br an issue with future emission tests.....

At least, save the old parts to reinstall prior to the test.

If you don't have the equipment to clean the injectors, put a few ounces of GM top engine cleaner in a full tank of gas and just drive it. It helps clean the cat too. I don't know if Mopar makes an equivilant. Most of the store bought brands don't work too well I found.
Hey OlJeepTek,

I saw this on another site regarding cleaning carbon deposits. You disconnect the cat and mist distilled water down the air tube while the engine is running every 30 secs or so. You continue to do so until the black smoke comes out clear. Then reconnect the cat. Looks like it might work but can I harm the engine in any way? Unfortunately, the new Walker High-Flow Cat is WELDED on. So it looks like the coat hanger and carb cleaner into the manifold openings for me.

This is a new one on me.

Stupid Q... How do I loosen the belt to change it (when the time comes)? My Isuzu had a belt tensioner to loosen but this Jeep doesn't. I have the Chilton's Manual but it only gives maintenance intervals not how to get the serp belt off.

Thx, Phil

Hey OlJeepTek,

I saw this on another site regarding cleaning carbon deposits. You disconnect the cat and mist distilled water down the air tube while the engine is running every 30 secs or so. You continue to do so until the black smoke comes out clear. Then reconnect the cat. Looks like it might work but can I harm the engine in any way? Unfortunately, the new Walker High-Flow Cat is WELDED on. So it looks like the coat hanger and carb cleaner into the manifold openings for me.

This is a new one on me.

Stupid Q... How do I loosen the belt to change it (when the time comes)? My Isuzu had a belt tensioner to loosen but this Jeep doesn't. I have the Chilton's Manual but it only gives maintenance intervals not how to get the serp belt off.

Thx, Phil
That is an old farmers trick. It is supposed to clean carbon when the water goes into steam. Only problem is that its for the combustion chamber and won't do anything for egr passages. I can't imagine you have much carbon in your reman engine cylinders anyway.

Your Jeep has a tensioner. It should be springloaded. Pull on the belt hard by hand (Engine not running of course) and you'll see where it is. It should be the idler on top of the water pump. You can use a box end wrench on the bolt head holding the pulley on to release the belt tension. Leave the wrench on the bolt until you get the new belt installed. Its a pain in the arse to get it on if it slips off. Belt change is a simple job.

Hey, Phil

Not to open this up again, but there WAS a recall on some of these trucks for high nOX. See if your local dealer has any info on recall #316T JUL 92.

Sorry, I don't have anymore info handy than that.