 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Jeep / December 2006cold start sluggishness
I know a few other folks have posted other cold-related issues and received lost of responses, but none seemed to match quite right. 86 cj7 258, carter bbd, nutter bypass I am trying to figure out if there could be a relationship between a very loud whistling (a vacuum leak I haven't found yet) and some serious sluggishness while the engine is cold. It was 15 or 18 degrees this morning (-10C) and it exhibited the typical symptoms. Starts and idles perfectly and in fact runs great for the first 2-3 minutes. Then the whistling starts and with the whistling comes a huge bogging issue under any load at all. I believe the only delayed vacuum line should be the thermal vacuum switch that purges the canister and controls the EGR. I know it is not the EGR as it blocked off. Anyone else hearing something familiar or following the train of thought here? Could a vacuum leak cause a serious bogging issue until warm and then go away?. Would love to hear any thoughts or ideas on this. Thanks What do you mean the EGR is "blocked off"... EGR system is fairly crucial, disconnecting it can cause a lot of problems. I've never tried it though, so I don't know what happens when you do... quick look at the haynes troubleshooting section under "Engine Lacks Power"... suggestion #10 there is "EGR system not functioning properly." Hook the EGR system up the way it's supposed to be and see what happens. > I know a few other folks have posted other cold-related issues and > received lost of responses, but none seemed to match quite right. [quoted text clipped - 16 lines] > > Thanks Blocking off the Exhaust Gases Recirculation valve, isn't really a bad idea, I use a plug hidden inside the vacuum hose and a plate under the valves. Upon inspection it just must look as though it works, it isn't actually tested: http://www.billhughes.com/smog.jpg God Bless America, Bill O|||||||O mailto:LWHughes3rd@aol.com > What do you mean the EGR is "blocked off"... EGR system is fairly > crucial, disconnecting it can cause a lot of problems. I've never > tried it though, so I don't know what happens when you do... quick look > at the haynes troubleshooting section under "Engine Lacks Power"... > suggestion #10 there is "EGR system not functioning properly." Hook > the EGR system up the way it's supposed to be and see what happens. > Blocking off the Exhaust Gases Recirculation valve, isn't really a > bad idea, I use a plug hidden inside the vacuum hose and a plate under > the valves. Upon inspection it just must look as though it works, it I used to do this back in the 70's and 80's too. I figured that sticking it to The Man was a good thing, and that if it ran better, what the hell. Fact is, every engine I ever did that to (that was carburated) ended up running too rich. It ran better, but too rich. I rejetted an old 318 Dodge motor that I'd de-EGR'ed, and it was better, but then when the Smog Nazi hooked up a vacuum tester to the EGR and discovered my handiwork, it cost me $50 bucks to undo the thing, rejet and retest. Bleh. Big hassle. Doing this on an OBD-II controlled motor will set codes and make your dash light up like a Christmas tree. You can still get away with it on an OBD-I motor that is fuel injected without a problem, but just remember to undo it when the time comes. EGR valves are old-school. You'd think that by now, they'd be unnessasary; creating a deliberate exhaust gas leak into the intake is like throwing a wet blanket on a fire. Now you have me thinking about installing a 'block-off' gasket on the TJ just to see if it would run better and get better mileage. A block-off wouldn't set a code (shouldn't?), and it won't run rich either. I'll get back to you on all this... >> Blocking off the Exhaust Gases Recirculation valve, isn't really a >> bad idea, I use a plug hidden inside the vacuum hose and a plate under [quoted text clipped - 10 lines] >handiwork, it cost me $50 bucks to undo the thing, rejet and retest. >Bleh. Big hassle. Lack of EGR will not cause a rich condition, injected or not. >Doing this on an OBD-II controlled motor will set codes and make your >dash light up like a Christmas tree. You can still get away with it on >an OBD-I motor that is fuel injected without a problem, but just >remember to undo it when the time comes. Some OBD I systems (Chrysler & Jeep for example) do monitor EGR flow, and will light the MIL if EGR is blocked off. >EGR valves are old-school. You'd think that by now, they'd be >unnessasary; creating a deliberate exhaust gas leak into the intake is >like throwing a wet blanket on a fire. On many vehicles, it is unnecessary now. But, as emission laws get tighter, it may become necessary again. When they first started using EGR, it didn't work as well as it does now. Some vehicles actually have EGR valves, not because they were needed to pass NOx standards, but because they found they could actually get slightly better MPG. >Now you have me thinking about installing a 'block-off' gasket on the TJ >just to see if it would run better and get better mileage. A block-off >wouldn't set a code (shouldn't?), and it won't run rich either. "If" your TJ had EGR, and you blocked it off, it would certainly set a code, but it doesn't. >I'll get back to you on all this... > Lack of EGR will not cause a rich condition, injected or not. It did on my old 78 Dodge with the 'lean burn' system; it was set up so that the valve was wide open at any throttle setting except idle, and the mains were oversized a bit to compensate. After rejetting, I ended up with better throttle response and another 1.5 mpg, which was a big deal because it only got 10 mpg to begin with. Another old '74 wagon I drove ran like a champ with the vacuum tube removed. No one I knew ever left theirs hooked up. I know the vacuum controls on EGRs now are more refined, but the idea of shoving exhaust gasses back into an engine to lower combustinon temps still seems silly to me. Even water injection made more sense to me. >> Lack of EGR will not cause a rich condition, injected or not. > [quoted text clipped - 3 lines] >up with better throttle response and another 1.5 mpg, which was a big >deal because it only got 10 mpg to begin with. Since EGR doesn't cause a lean condition, larger jets would do nothing to 'compensate' for it. Exhaust gas is inert. It doesn't change the mixture, it only takes up space to keep peak combustion temperature down. >Another old '74 wagon I drove ran like a champ with the vacuum tube >removed. No one I knew ever left theirs hooked up. I know the vacuum >controls on EGRs now are more refined, but the idea of shoving exhaust >gasses back into an engine to lower combustinon temps still seems silly >to me. Even water injection made more sense to me. No doubt EGR in the 70s & 80s wasn't good, but today, you probably wouldn't notice a difference by disconnecting it. Other than the MIL being on, that is. I always wondered about water injection too. Perhaps it's more costly, or has other drawbacks. Maybe the water vapor that gets past the rings condensing in the combustion chamber could be a problem. > >> Lack of EGR will not cause a rich condition, injected or not. > > [quoted text clipped - 22 lines] > or has other drawbacks. Maybe the water vapor that gets past the rings > condensing in the combustion chamber could be a problem. Reliable storage and delivery problems. How are you going to supply water, when the ambient temperature is -20º and the car is left out all night? Earle >> >> Lack of EGR will not cause a rich condition, injected or not. >> > [quoted text clipped - 27 lines] > >Earle Good point! :-) > Since EGR doesn't cause a lean condition, larger jets would do nothing > to 'compensate' for it. Exhaust gas is inert. It doesn't change the > mixture, it only takes up space to keep peak combustion temperature > down. We will have to agree to disagree on this one. IMO, EGR porting is nothing more than a poorly-controlled vacuum leak; increase or decrease the flow into the intake manifold below the carburetor venturi and the fuel mixture changes. This can be easily demonstrated by disconnecting the diaphram vacuum tube, apply enough suction to open the pintle valve to introduce lots of inert exhaust gas, and observe the engine die immediately from an excessively lean mixture. Smog techs often used this method to verify proper EGR valve operation. >> Since EGR doesn't cause a lean condition, larger jets would do nothing >> to 'compensate' for it. Exhaust gas is inert. It doesn't change the [quoted text clipped - 9 lines] >immediately from an excessively lean mixture. Smog techs often used >this method to verify proper EGR valve operation. If what you're selling is correct, then why use exhaust gas? Why not just create a vacuum leak? Because lean is not the answer to preventing NOx formation. In fact, leaning out the mixture will increase combustion temp and NOx production. The engine dies when EGR is applied at idle because the cylinder is filled with inert gas that won't burn. Not because it's lean. That's the way EGR works. No agreeing to disagree. It is what it is. Outatime proclaimed: >> Blocking off the Exhaust Gases Recirculation valve, isn't really a >> bad idea, I use a plug hidden inside the vacuum hose and a plate under [quoted text clipped - 3 lines] > sticking it to The Man was a good thing, and that if it ran better, what > the hell. Some folks used little soft plastic plugs or balls...if they did get into the engine they wouldn't cause any harm. > Fact is, every engine I ever did that to (that was carburated) ended up > running too rich. It ran better, but too rich. I rejetted an old 318 > Dodge motor that I'd de-EGR'ed, and it was better, but then when the > Smog Nazi hooked up a vacuum tester to the EGR and discovered my > handiwork, it cost me $50 bucks to undo the thing, rejet and retest. > Bleh. Big hassle. If you have two hoses, put the block in one, then swap for the smog test. Experienced smog operators could spot the disabled or reduced EGR just by listening to your engine as you drove in. > Doing this on an OBD-II controlled motor will set codes and make your > dash light up like a Christmas tree. You can still get away with it on [quoted text clipped - 4 lines] > unnessasary; creating a deliberate exhaust gas leak into the intake is > like throwing a wet blanket on a fire. Reduces nitrous oxide. Hopefully somebody will figure a better way, as there is pretty good fuel savings running with higher compression and combustion but that also increases NOx...and with the new congress already blowing about "environment" this doesn't look like good times ahead for auto enthusiasts. > Now you have me thinking about installing a 'block-off' gasket on the TJ > just to see if it would run better and get better mileage. A block-off > wouldn't set a code (shouldn't?), and it won't run rich either. Think most systems do check for the amount of exhaust being recirculated, so would expect a code on most mods. With modern FI it tends not to be as bad as the older stuff when EGR first started. > Think most systems do check for the amount of exhaust being > recirculated, so would expect a code on most mods. With modern FI it > tends not to be as bad as the older stuff when EGR first started. Figures. I'll probably get a code, but I'd like to see how much better it runs just for laughs. There's always a way to get around something if you really want to. Truckers figured out a long time ago that getting around computer governors was an easy task, IF you didn't mind the speedometer being disabled. Nowadays we get a code set on that too if we mess with input sensors. >> Think most systems do check for the amount of exhaust being >> recirculated, so would expect a code on most mods. With modern FI it [quoted text clipped - 6 lines] >the speedometer being disabled. Nowadays we get a code set on that too >if we mess with input sensors. First thing you'll have to overcome is how to block off EGR on a vehicle that's not equipped with it. > Blocking off the Exhaust Gases Recirculation valve, isn't really a > bad idea, I use a plug hidden inside the vacuum hose and a plate under [quoted text clipped - 10 lines] >> suggestion #10 there is "EGR system not functioning properly." Hook >> the EGR system up the way it's supposed to be and see what happens. Both Conspiring and Counseling to commit a crime. Interesting. Suborning a criminal act. Fascinating. Posting it on Usenet. PRICELESS!! And this now goes somewhere else; they'll love it. There you go again, the jealous, really jealous, I can't believe how jealous this little draft dodging coward schizophrenic psychopath liar is, in Vancouver who's only way to get attention is to make a fool of it's self. With an obsession the other perverts here. With extreme jealous ranting over the documents/possessions proving I'm an American man. You remind me of a little rat dog, like a Mexican Chiwawa with it's senseless barking, me too, me too. And the poor thing, you're too girlie to take responsibility for yourself again, by signing your statement like a man. You're not worth any more time when a cut and paste this same paragraph it fits so well! God Bless America, Bill O|||||||O mailto:LWHughes3rd@aol.com http://www.billhughes.com/ §qu@r3 Wh33£s wrote: ><snip queer fantasies over my body, and the jealous senile babbling over my accomplishments and conquests> I think I would first be looking at the air filter flaps and their controls or vacuum lines for a leak. These are active on a cold engine. The EGR even has a thermostat inside the air filter. Second I would be checking the carb's base screws to be sure the carb is bolted down tight. Third I would be looking really close at the choke vacuum pull off valve. It is on the back corner of the carb with a vacuum line running to it. I would want to make sure it isn't leaking. You can carefully spray some carb cleaner or WD40 along the carb base and along the intake manifold gasket to check for leaks. If the engine rumbles when you spray, you have a leak. Besides the noise, your carb sounds like the typical automatic choke issue. The thing is on a bimetal spring timer that doesn't care how warm the engine actually is so when the engine is half way warm, the choke is open too much so it bogs like mad. You have to feather the gas pedal up and down to keep it running under load and 2 foot drive them. You 'can' adjust the choke for how rich it runs until it opens by loosening the three screws on the cover and turning it. It has indexing lines on it. Unless the carb number is 8349 or 8351, it should be 1 notch rich. Or you can go manual choke easily. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > I know a few other folks have posted other cold-related issues and > received lost of responses, but none seemed to match quite right. [quoted text clipped - 16 lines] > > Thanks Yeah - that is what I was thinking on the whistle. I will check all the temp controlled vacuum lines and switches first. They may be two separate problems that happen to coincide. I guess the reason I figured my choke wasn't the culprit is that at idle it runs perfectly throughout the warmup period and the bogging doesn't start happening until the whistle begins and then goes away when the whistling becomes quieter again at operating temperature. > I think I would first be looking at the air filter flaps and their > controls or vacuum lines for a leak. These are active on a cold [quoted text clipped - 48 lines] > > > > Thanks |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.