EGR Valve?????

[kenny811]

My 89 4.0 as been having a very bad "high Idle problem. After going through all the parts I noticed if I bolt a plate over the EGR opening the high idel goes away and the motor runs fine. Dose the EGR really need to be there? What happens if its plated off? The plastic diaphram is wasted so I think this might be the cause of my problem, any thoughts?

Kenny

 

[Saudade]

The EGR is part of emission controls. If your state doesn't require smog inspections, you should be OK without it. In CA, they inspect that and will fail you if you block the EGR off.

 

[mattbred]

I run my '89 without the EGR with absolutely no repercussions. Then again, we don't have emissions here in non-vancouverish BC.

 

[5-90]

The engine actually runs cleaner without the thing, but you will fail an emissions inspection if it is non-functional or just plain missing (don't ask how I know...)

I'd rather be able to be quit of the thing - I don't see the point behind running carbon-carrying exhaust through the intake stream and crapping things up. But, I don't make the rules (and the people who do don't really know anything about the technical side, other than what they're told. And they're told whatever the tellers want to tell them...)

 

[Harlee&Tahoe]

I've capped mine. (smog exempt)
No ill effects.

 

[5-90]

As I said - the engine runs cleaner without it (this isn't opinion - this is back-to-back smog check results, the first with a failed EGR valve. Emissions were damned near zero the first time, and went through the roof after I changed the EGR.)

I usually end up capping off the line between smog checks, and haven't noted any ill effects. The compression of the AMC242 is low enough to make the EGR system worse than useless, since it tends to actually increase emissions as a result of operation.

 

[Shorty]

when functioning correctly, the EGR reduces combustion temp. which, in turn decreases the likelyhood of preignition and lowers the overall output of oxides of nitrogen (exponantially increase with higher temps). That said, the 4.0L does not suffer from extreme combustion chamber temps. when running efficiently and with a functioning knock sensor, it will probably never NEED the recirculation valve to run well.I'm cheap, and I've been known to block them off to save $$$$ when they fail, but I don't see reason to remove or defeat them if they're working. In your case, I'd prolly block it off and keep an ear out for signs of knocking/pinging during spirited driving and on HOT days.

 

[5-90]

when functioning correctly, the EGR reduces combustion temp. which, in turn decreases the likelyhood of preignition and lowers the overall output of oxides of nitrogen (exponantially increase with higher temps). That said, the 4.0L does not suffer from extreme combustion chamber temps. when running efficiently and with a functioning knock sensor, it will probably never NEED the recirculation valve to run well.I'm cheap, and I've been known to block them off to save $$$$ when they fail, but I don't see reason to remove or defeat them if they're working. In your case, I'd prolly block it off and keep an ear out for signs of knocking/pinging during spirited driving and on HOT days.

I know the theory - but with a CR under 9.0:1, the damned thing is totally useless. 9.0-9.5:1, it borders on utility.

Since it's only RENIX that has the EGR valve, and RENIX also has the knock sensor, the ECU will retard timing if it detects a knock anyhow.

The EGR was deleted by a slight alteration of camshaft timing to encourage reversion in the exhaust ports (as I understand it,) thereby duplicating EGR function without running carbon-loaded exhaust gas through the intake. An improvement on the idea - but the idea is still about as useful as the vermiform appendix, with our application.

And, if you really want to lower chamber temperatures, using H2O/MeOH fog will work better than an EGR, and will keep the engine much cleaner. H2O/EtOH can also be used, as can H2O/denatured alcohol (IIRC, that's just EtOH with a mildly toxic percentage of MeOH added.)

MeOH - Methanol (CH3OH)
EtOH - Ethanol (CH3CH2OH)
H2O - Water (duh. You should know this one...)

 

[Shorty]

so.......... we're agreeing to agree?:worship:

 

[5-90]

so.......... we're agreeing to agree?:worship:

Sounds like it. We're agreeing that it's useless for our application from the off? And that there are better ways to do the job when it is needed?

(The H2O/MeOH fogger idea goes back to piston aircraft from WWII, and it's worked neatly. The EGR idea never made it to aircraft, that I can recall - but the MeOH fog has been around for a good long while...)

 

[Shorty]

We're agreeing that it's useless for our application from the off? And that there are better ways to do the job when it is needed?

si, senior:yelclap:

 

[biztyke]

i dunno, my egr system was disconnected when i bought my 90. i hooked it back up, but it must be faulty because the engine didnt like it so i left it disconnected. but im in vancouver and i went through air-care emmisions no problem, then again they dont check under the hood here, all they do is test the exhaust, mirror check for a cat and a pressure test on the gas cap. must be different in the states.......

 

[XJ AV8R]

(The H2O/MeOH fogger idea goes back to piston aircraft from WWII, and it's worked neatly. The EGR idea never made it to aircraft, that I can recall - but the MeOH fog has been around for a good long while...)

Yep, works great on turbine engines too. With the alcohol injection a lot more shaft horsepower can be produced at the same ITT temperature. It makes for getting off of short runways with a heavy load and a hot day a lot easier!

OK, I won't contribute to the off topic anymore...sorry.

 

[5-90]

i dunno, my egr system was disconnected when i bought my 90. i hooked it back up, but it must be faulty because the engine didnt like it so i left it disconnected. but im in vancouver and i went through air-care emmisions no problem, then again they dont check under the hood here, all they do is test the exhaust, mirror check for a cat and a pressure test on the gas cap. must be different in the states.......

Yah. Even when I passed with damn near zero NOx (which is what the EGR is supposed to help keep down...) I failed because they checked the EGR manually, even after I denied them permission to do more under the hood than clamp the lead on #1 and check with a timing light (I don't know why they checked - they can't adjust the thing. I have to explain every damn time I go in that it does not have a functional CEL/MIL, as it is pre-OBD - and yes, I know the lense is there. There isn't a bulb behind it, nor will I put one there.)

Just doing the sniffer test is as far as they really should go - and eliminate the visual entirely. Who cares how you make the numbers, just so you make them? If you can make the emissions threshholds without any "smog" devices or a catalytic converter, who cares? If you can make it all happen without using any "emissions reduction devices" (they tend to make each other necessary anyhow...) you should get a reduction on your registriation or somesuch, as a "smog credit."

I've been going roundy-rounds with ARB for a number of years, but it's been like attacking a lunatic asylum with a banana...

 

[bgred2]

What is the easiest way to safely disconnect the EGR valve without taking the dam thing off and probably breaking the bolts........

 

[Saudade]

What is the easiest way to safely disconnect the EGR valve without taking the dam thing off and probably breaking the bolts........

You can simply disconnect the vacuum line from the valve at the solenoid and cap the port. This assumes your EGR valve seals OK. With no vacuum to operate it, it will remain shut.

 

[Saudade]

Sounds like it. We're agreeing that it's useless for our application from the off? And that there are better ways to do the job when it is needed?

Irrelevant as we have both acknowledged in our earlier posts due to the way CA does their smog inspection. They have also added a evap system test that costs another $20. They connected a special cap on your fuel tank and pressurize it with nitrogen looking for leaks. The evap test is not required on OBD-II vehicles since the system tests for evap leaks.

I failed my last smog (3 days ago) due to high NOx. All other reading were excellent. I going through some things now to get it retested next week.

 

[kenny811]

Ok I think the answer is prettty clear, so last night I fabbed a perfict fitting plate to block it off. I did this right after I read the DMV registration due form to make sure a smog check was not due. ( in Washington evry 2 years). With gas a $12 a gollon I probley wont drive it enough to ever get it to temp but hey, whats ya gunna due. I did disconnecte the one on my 78 CJ5 (never smog requierd) and it ran great, so I will post a result when im done. Thanks for the input and thatnks for NO!!!1 icons, I see alot of thoughs on some of these post questions.

 

[Lostman]

Again me bringing up a dead thread.
I'm needing help. I bought the XJ a while back and have been having problems with getting it past emissions here in Phoenix. It's an 89 Renix 4.0 auto. I ran all the tests on the sensors and the only thing I can figure besides the 02 sensor being at only 3.5 Ohms is that the EGR system is not operational. I checked the EGR, (it is new) but I'm not getting Vacuum to the solenoid. I think when they swapped out the engine they re-routed the vacuum lines incorrectly.

Anyone with Pictures of how this is supposed to be hooked up? I can't make heads or tails from the schematics!

Thanks!