Author Topic: EGR valve?? I have a prob. and cant fix it (Read 7885 times)

yota_krawler · « **on:** Jan 13, 2008, 09:05:54 PM »

Where and what is an EGR valve??? well ok then i guess it isn't that, read the post on the bottom and please tey and help me, it is a hard problem to explain but i did my best. it is really a problem that you have to witness first hand. 85 CARBED

jimbo74 · « **Reply #1 on:** Jan 13, 2008, 09:27:17 PM »

it is on the pass side of the motor near the firewall and it recirculates spent exhaust gases back into the intake stream in an attempt to make some of the nasty stuff get reburned for better tailpipe emissions

yota_krawler · « **Reply #2 on:** Jan 13, 2008, 10:47:40 PM »

if it was bad, how would your truck run?

jimbo74 · « **Reply #3 on:** Jan 13, 2008, 10:56:37 PM »

Quote from: Yota_Krawler on Jan 13, 2008, 10:47:40 PM

if it was bad, how would your truck run?

not too much different really... most people jsut remove them and block them off.....

46&2 · « **Reply #4 on:** Jan 13, 2008, 11:20:01 PM »

I had to replace mine to pass smog. I had no idea that the EGR valve was in need of replacement until i tried to smog it last. tech told me to replace the EGR and come back. i did and then it passed but there was no noticeable difference in engine performance.

fordh8r · « **Reply #5 on:** Jan 14, 2008, 12:24:28 AM »

Quote from: jimbo74 on Jan 13, 2008, 09:27:17 PM

it is on the pass side of the motor near the firewall and it recirculates spent exhaust gases back into the intake stream in an attempt to make some of the nasty stuff get reburned for better tailpipe emissions

That's actually not why it's there. It is there to lower combustion temps to reduce NOX emissions. Exhaust gas is inert and does not burn. A nonburnable gas in the cylinder means slightly less air and fuel to burn which creates less heat during the burn. The amount which flows through the EGR is minimal and reburning what is still burnable in the exhaust gas is not worth the trouble of doing so.

jimbo74 · « **Reply #6 on:** Jan 14, 2008, 12:26:38 AM »

eh i was pretty close

had the same ending but for a different reason...

haha, now help me with my thread

yota_krawler · « **Reply #7 on:** Jan 14, 2008, 11:01:02 AM »

my truck hesitates on deceleration, when you are just enough in the gas to keep it at speed it stutters, and acts almost like it you were to turn off the key for a split second. Give it gas and it goes away. But them I am speeding. If you push in the clutch the RPMs (ie) 3000 rpms to pushing in the clutch it will drop almost to about 500 rpms and then raise back up to idle. However on acceleration it runs great, I don't know why it does this. I have changed all the small stuff, plugs, wires, cap, rotor, fuel filter, air filter. I don't know what it is and it it pissin me off, like to the point I want to get rid of the damn truck if it wont run!

RN37DD · « **Reply #8 on:** Jan 14, 2008, 12:59:24 PM »

what year truck? and is it efi of dose it have a carburetor?

yota_krawler · « **Reply #9 on:** Jan 14, 2008, 01:16:02 PM »

85 carbed

RN37DD · « **Reply #10 on:** Jan 14, 2008, 02:59:00 PM »

theres lots of ways to do this but the first thing I'd do is isolate your egr to see if it's the problem. if your engine idles fine it's probably not leaking by on the exhaust side.. good.. so to see if it is a egr control problem disconnect the small hose going to the egr valve and plug it. the round metal part.. it may be comming from a vsv or the vacuum modulator. anyway plug it, drive and then see if it makes a difference.

_HOIST_ · « **Reply #11 on:** Jan 14, 2008, 06:04:10 PM »

If your truck drops a bit below idle like you said when letting completely off the throttle then you may have a dashpot issue as well.

RN37DD · « **Reply #12 on:** Jan 15, 2008, 09:35:45 AM »

yeah if isolating the egr has no effect there's a few other things to look at like the idle mixture adjustment.. aap and shut off solenoid. let us know what ya find.

Fearofrunner · « **Reply #13 on:** Jan 15, 2008, 10:18:03 AM »

Quote from: Stooges4x4 on Jan 14, 2008, 06:04:10 PM

If your truck drops a bit below idle like you said when letting completely off the throttle then you may have a dashpot issue as well.

What is a dashpot?

yota_krawler · « **Reply #14 on:** Jan 15, 2008, 05:39:52 PM »

that is what i was thinking

_HOIST_ · « **Reply #15 on:** Jan 15, 2008, 05:46:32 PM »

The "dashpot" (as referred to by the manual), is a small vacuum operated valve that keeps your throttle linkage for slamming all the way down when you suddenly let off the pedal from a higher RPM. Its not hard to find my 83 carb's as well as 89 EFI both have one.

yota_krawler · « **Reply #16 on:** Jan 15, 2008, 05:56:20 PM »

huh never heard of it

DanS · « **Reply #17 on:** Jan 15, 2008, 05:59:34 PM »

Quote from: fordh8r on Jan 14, 2008, 12:24:28 AM

That's actually not why it's there. It is there to lower combustion temps to reduce NOX emissions. Exhaust gas is inert and does not burn. A nonburnable gas in the cylinder means slightly less air and fuel to burn which creates less heat during the burn. The amount which flows through the EGR is minimal and reburning what is still burnable in the exhaust gas is not worth the trouble of doing so.

Wow, that is a perfect explanation.

RN37DD · « **Reply #18 on:** Jan 17, 2008, 04:38:17 PM »

did you isolate your egr valve yet and try it? other thing you could check is the fuel cut off solenoid. it should cut fuel off in the idle circut during deceleration. if it's control functions are not right it could cause a problem too. pinch off the vacuum line to the vacuum switch and slowly increase engine speed to 3000rpm. it should misfire slightly between 2200 and 3000 rpm i believe.

83 Crawler · « **Reply #19 on:** Nov 19, 2009, 08:24:44 AM »

sorry to bring this back up. but mines doing the same thing i was just woundering how you fixed it?

yota_krawler · « **Reply #20 on:** Nov 19, 2009, 10:12:55 AM »

i dont remember but I will think about it today and get back to ya

83 Crawler · « **Reply #21 on:** Nov 19, 2009, 02:02:37 PM »

ok sweet man

SLIVER · « **Reply #22 on:** Nov 21, 2009, 09:16:30 PM »

My 85 EFI is doing the same thing. When I bypass the EGR it seemed to help a bit, so I figured the EGR was bad. So I got a brand new egr and hooked everything up, and it still does it just as bad.

Hope you remember what the real problem was so I can fix mine too.

))--SLIVER-->

yota_krawler · « **Reply #23 on:** Nov 21, 2009, 09:58:36 PM »

from what I remember, what i did had nothing to do with the EGR. I had minor wirering issues and my vacuum lines were all sorts of wrong, so I got them all hooked up right, fixed the wirering problem and I advanced the timing. The problem really never fully went away it just hid it very very well.

86rustbucket · « **Reply #24 on:** Nov 21, 2009, 10:15:07 PM »

the egr is opened by vacuum and that vacuum is controlled by a vacuum switch.
if the egr is not functioning properly there is a good chance the problem is in either the line or vacuum switch. I failed smog horribly a couple weeks back with the only problem area being NOX and the tech told me check my egr so i started cheching. my problem was the hard line from the carb to the vacuum switch (bvsv) was completly blocked so i ran a rubber line strait to the switch. I didnt really expect to pass but i did.

did i really use the word vacuum 3 times in one sentence?

83 Crawler · « **Reply #25 on:** Nov 22, 2009, 04:34:17 AM »

im missing a lot of vacuum stuff like that vacuum switch and a bunch of other stuff

yota_krawler · « **Reply #26 on:** Nov 22, 2009, 12:10:09 PM »

that might be the prob then

83 Crawler · « **Reply #27 on:** Nov 22, 2009, 12:34:47 PM »

im thinking it is to cause my egr isnt even hook up with a vacume hoses

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