Who Pooed in my Intake Manifold!?

[lexum]

My idle problems continue...

I found no leaks in the carburetor and I put new vacuum hoses everywhere. The Jeep will idle for a few minutes and then stumble itself dead. The more help (gas) I give it the worse it gets.

A close inspection of the intake/exhaust manifold revealed no obvious cracks or leaks or loose bolts. I did spot small oil spots coming out of the IM. I decide that the only possible air leak must be coming from the IM gasket and the picture tells you what I did about it.

http://www.aquatab.org/photos/00001-640.jpg

Notice all of the oil in the IM. I did have some oil leaking out of the valve cover, however, the IM/EM gasket shows no signs of oil passage. Where is this oil coming from and what do I need to replace to stop this madness?

http://www.aquatab.org/photos/00001-480.jpg

[Shadly1]

I'm guessing it's coming from the valve cover lines. I've been corrected too many times on calling it a PCV valve, so I'll call it the plastic doohickeys on top of the cover that ventilate the crankcase.

[mycj7]

I'm guessing it's coming from the valve cover lines. I've been corrected too many times on calling it a PCV valve, so I'll call it the plastic doohickeys on top of the cover that ventilate the crankcase.


I believe the dealer calls them CCV lines (crankcase ventilation lines).:)

[lexum]

Is this an indication that my CCV lines are clogged with oil and need to be cleaned out? Would this effect fuel delivery?

[mycj7]

How's the air filter look?

[roadyrob]

looks like valve seals to me, also be sure oil return passages in head are clean.

[Chile99]

How's the air filter look?

Do check it and let us know because the indications are the ccv system is working as designed, all will put a small amount of oil into your manifold. But....
if you have a stock intake system and the filter is being oiled from it's CCV line that is a big clue. mycj7 is steering you on the right path for diagnosis.
John

[Mechman71]

looks like valve seals to me, also be sure oil return passages in head are clean.

Nah, usually leaky valve seals cause a puff of smoke out the tailpipe on startup. Usually oil coking in the intake comes from the CCV lines, either due to a line/filter issue OR from excessive blow-by from worn rings. If you pull the dipstick while it's running and you get suction, you don't have blow-by issues. If it sprays oil out, well... The test works with the oil cap, too. :thup2:

[Mechman71]

Umm, as for the stalling, check your float needle valve, sounds like it's sticking and your carb is running out of gas. Next time it stalls, give the float bowl a couple "love taps" with the handle of a screwdriver, then try restarting. If it fires up and idles again, you'll have to clean up or replace the needle valve.

[Burnerman]

Carbed 4.2 engines use a PCV valve. The 4.0 FI ones use the CCV system. The PCV valve is in the front of the valve cover. It ties into the rear of the carb. This sucks air from the valve cover. The line on the rear of the valve cover ties into the air cleaner and lets filtered air into the valve cover. Sounds like you need to check out the PCV valve and maybe pull the valve cover and make sure the oil passes are clear. Since you have the manifold off and you hopefully got the gasket kit. Replace the oring and gasket on the intake pre heater. It's underneath the intake. 3 bolts and 1 wire going to it. It's those little pin things you see when you look into the carb mount on the manifold. You may be leaking vac there. Did you clean the idle tubes on the Carter? the idle tubes may be clogged and actually flooding the motor and stalling it out. Checkout the linkhttp://home.sprynet.com/~dale02/idle.htm

[Karma]

HI,
Concerning your bad running condition. It could be that the problems begins when the emissions system makes the transition from open loop to closed loop operation. When the engine is cold the system is in open loop mode. That means that most of the emissions sensors are ignored and the computer is running with a fixed program. The mixture is fixed and controlled mostly by the choke.

At a certain engine temperature, which takes a few minutes to reach, the computer switches to closed loop and controls the mixture with the stepper motor and needle valves that are mounted on the backside of the carb. When this happens all the emission sensors come into play with the O2 sensor being primary.

There are many things that can cause your problem. As a first guess, I would probably replace the O2 sensor. If it is bad it can cause what you are describing because the computer will adjust the mixture based upon bad information from the sensor and, thus, give a bad mixture. These are cheap and easy to replace.

Next, Google the Carter BBD carb. You will find several good sites devoted to the beastly thing with lots of good diagnostic tests.

In my case, after getting the BBD running about as good as it did when it was new, I replaced it with a Howell fuel injection system and never looked back. However, when the BBD is in good shape and all the emissions stuff is working right, and all the vac lines, switches and valves are good, the carb can be quite good. The problem is keeping it good especially on an old vehicle.

Be certain that all of the vac lines are good. I replaced every single one even those that looked OK. That was a step in the right direction. A good tool to have is an inexpensive hand vacuum pump to test the vacuum system.

BTW, do you have a factory Service Manual? If not, you should. You will use it every time you work on your Jeep.

Sparky

[lexum]

Yeah, I have done a ton of research on the Carter BBD and I have rebuilt this thing 5 times to try and get it right. I bought a reman recently and it is no better than the original carb. I also have the idle tubes drilled out and I am not seeing dripping in the carburetor.

The oil in the intake manifold doesn't look as bad as I initially thought. I cleaned it as best as I could and reinstalled the IM/EM with a new gasket kit. When I changed out the gaskets on the intake preheater there was a bolt missing! I replaced the bolt.

I did finally crack into the reman carburetor and found that the accelerator pump ball valve was covered in rust? I put a new ball valve in and verified the float level. Never buy a reman carb. Chances are it is in worse shape than the one you have.

After all is back in place I double check all the vacuum lines, check my timing and set the idle at about 750 rpm. It is idling almost perfect and manifold vacuum is very steady at about 21 mmHg. I let it warm up for about 15 minutes and all is still okay. I drive it around the block and the idle drops to about 600 rpm. By the time I get back to the driveway the jeep won't idle at all. Every time I let off the accelerator it drops all the way to 0 rpms with no hesitation.

I check the manifold bolts and they are still tight. I check for leaks in the carburetor and vacuum lines and I cannot see or hear anything. I sprayed WD-40 everywhere trying to find an air leak with no success.

I have also replaced several of the vacuum hoses. Upon doing so I found nothing wrong with the old hoses.

I do have a service manual, however, I find that it is only useful for torque specs and has very little troubleshooting info. I prefer http://home.sprynet.com/~dale02/ for all of my Carter problems.

My next step is to try the nutter bypass and plug up some of the ports on the carb. I have the go ahead from the wife to do the Howell TBI if I have to.

[TERIOD]

before you do the nutter, check the egr valve with a vacumn hand pump while running to make sure its operating properly this could cause your problems also and youll never get the carter set until it does(one of many possible probs)good luck

[Karma]

HI Lexum,
I think you have partially answered your own question. The problem is not the carb. It is in the emissions system. I'm not sure where though. From what you wrote, you have done everything possible (more than once) with the carb. Start looking elsewhere.

Are you SURE all the vac lines are good? If not, all the work in the world will not result in a good solution. To do what I'm suggesting means you need to understand the emissions system-not an easy job given the lack of info in all the various manuals. I feel your pain! I've been there too. The web sites do have some diagnostic procedures for the emission system that can help isolate the problem. Use them. For example, how the needles react to the O2 sensor and how you can fool the computer into doing something it wouldn't ordinarily do.

Repeat: you need to understand the system.

It may be that the best solution is the Howell injection. After all, it just costs money and time, right? One up side is that about 3 miles of vac lines get tossed in the trash!

Sparky

[lexum]

Definitely on to something now.

I started the Jeep again today cold. Up to 1700 rpms on start and I kick it out of choke start and it drops to 1100 rpms as it should with the sol-vac. So the engine temp reaches 115F and the idle drops and engine dies. EGR right?! Last time I checked (couple months ago) it was working.

I took it out and it closes fine with no leaks. However, to open the EGR to allow exhaust gas into the carburetor it needs a vacuum that is triggered by a solenoid controlled by the computer at 115F. That vacuum is either not there or the EGR plunger is leaking.

So, I guess I have a misunderstanding about the EGR Valve. What should happen if I plug the EGR vacuum? Does the carb need the exhaust gas to run above 115F engine temp? If I force this valve open while idling the engine dies. My only conclusion is that the computer expects the exhaust gas and counters with the stepper motor.

I just need to understand this before I go spend more money on the dieing system that might be better spent towards the TBI. Thanks guys!

[lexum]

I see all my hard work flashing before my eyes.

It takes a ton of force from my finger to open the EGR valve. Is this normal? I am pretty sure that the ported vacuum routed from the CTO that opens at 115F would be enough to open this EGR. I think my EGR valve might have been damaged from being under water for a few hours.

[TERIOD]

Definitely on to something now.

I started the Jeep again today cold. Up to 1700 rpms on start and I kick it out of choke start and it drops to 1100 rpms as it should with the sol-vac. So the engine temp reaches 115F and the idle drops and engine dies. EGR right?! Last time I checked (couple months ago) it was working.

I took it out and it closes fine with no leaks. However, to open the EGR to allow exhaust gas into the carburetor it needs a vacuum that is triggered by a solenoid controlled by the computer at 115F. That vacuum is either not there or the EGR plunger is leaking.

So, I guess I have a misunderstanding about the EGR Valve. What should happen if I plug the EGR vacuum? Does the carb need the exhaust gas to run above 115F engine temp? If I force this valve open while idling the engine dies. My only conclusion is that the computer expects the exhaust gas and counters with the stepper motor.

I just need to understand this before I go spend more money on the dieing system that might be better spent towards the TBI. Thanks guys!

i just went through this for a smog check, it sounds the same, the diaphram was leaking on the egr, the smpg tech checked by putting his fingers into the egr and manually operating the diaphram, you notice the difference and if you dont hear this doing it on its own, prolly not working, one other thing, when you set the carb, the low idle has to be set right so when the sol-vac drops off it doesnt drop too far thus killing the engine or causing the sol-vac to pick back up:josh: karma is correct in saying emissions is the prob this is a freak of nature carb, if you have permision for the howell, go for it, its ca legal,i woulldnt be lettin the door hit me in the butt runnin to pick it up

[lexum]

Just kidding, EGR valve is working just as it should. It moves rather quickly open and close just like the stepper motor.

I decided to do the nutter bypass. There are a couple things I was not sure about that are not detailed anywhere I have looked. This is what I did.

1. Screw the carb mixture screws all the way in while running and pull the stepper motor connection while the pins are driven completely into the carb.
2. Cut out the computer and wired the ignition module to the distributor directly according to the diagrams.
3. Disconnected the distributor advance vacuum line from the T before it goes into the manifold vacuum. The article, http://jeeps.hallbergs.com/nutter.htm, does not explain what carb vacuum hoses you need to keep or plug. I also pulled the manifold vacuum hose and plugged it. I added the distributor vacuum hose and T'd it into ported vacuum.
4. Plugged the distributor vacuum for timing. I had to retard the timing quite a bit to get 21 inHg at the manifold. The article really doesn't say what rpm to set my 8 BTDC. BTW, the article never says to drive the mixture screws back out either, but I did.
5. Plugged the vacuum advance back in and set my idle and adjusted the mixture screws using the vacuum meter.

With this setup the EGR, evap canister, TVS, and CTO should still be active. Do I need to plug any of these?

The Jeep idled for about 20 minutes as I got the timing done. I let it run a little while longer until I felt confident enough to take it around the block. I back out of the garage and the idle starts slowly falling from 700 to 600. I back up a little more, 600 to 500. More, 500 to 400. Wow still idling! 400 to 300 to DEAD.

Start her back up and drive about 20 feet back into the garage.

[TERIOD]

:wavin2: Kidding!!!!! after all that typing, I hope yur dog farts in your face while yur hookin up ypur tailpipe:wavin2:

[lexum]

Sorry, man. What the heck is going on though? I can't get the thing to run even with the nutter.

[TERIOD]

at this point, make sure your cat isnt plugged, do the howell swap or get a rebuilt carb, with loosing your idle like that, it MIGHT indicate a plugged cat or bad fuel pump, you can get rebuilts on the net for around 200.00+-
everytime you adjust on this carb you almost always have to have everything hooked up, it would be ok to unhook the egr and plug the line, but thats about it, every thing else effects it to much, ps a vacumn leak could make the idle alter, but that is usually an up and down flux

out of curiosity did you say you cleaned the metering rods??

[lexum]

This is a remanufactured rebuilt carburetor from TOMCO. I have taken it apart and cleaned it some but other than that it is practically new. A very reputable exhaust shop changed out my muffler a couple of weeks ago and checked out my catalytic converter. He said it was not clogged. My vacuum tests confirm this as I get a steady 20-21 inHg at all times, even at 400 rpms. IIRC, a vacuum leak will show up on the manifold vacuum test. I also checked the fuel pump for volume by removing the fuel line and cranking the engine. It is mechanical and puts out plenty of fuel and pressure.

I am taking my ignition control module into autozone today to get it tested. I bought this brand new from them about a month ago but never had my old one or the new one tested.

With the nutter bypass I should have narrowed this problem down to carb, ign module, distributor, egr circuit, and decel circuit. Am I missing anything here?

[TERIOD]

ive ran into bad distributors before,and they definitly screwed with my head before, before i figured them out, you might pull the cap and check for play on the center rod, you usually hear a misfire, but who knows, if the egr is working i doubt its your problem or the decel circut

[lexum]

It is the stock distributor core with the TFI upgrade (new rotor, cap, coil, plugs, cables, and gap). If I try to move the rotor back and forth it has about 1/8" play, kind of a loose feel. Is this excessive? I have heard that you can force it (the rotor) one direction and it should snap back into place. I wasn't able to force it in any direction more than a half inch and it always returned back to the original spot.

[TERIOD]

that doesnt sound good at all

my engine is hot right now, ill let it cool and check mine to see how much play

[TERIOD]

my distributor had less play in it than that(less than a 16th) you might put a timing light on each wire and look for a constant fluid pulse if you can get it to idle smooth enough

[lexum]

I will get an exact measurement tonight. Thanks for looking.

[lexum]

Ignition module checked out okay at autozone.

The below link is a video showing the play in my distributor rotor. Sorry it's about 100MB.
00001.avi (http://www.aquatab.org/videos/00001.avi)

Xvid 40MB version
xvid00001.avi (http://www.aquatab.org/videos/xvid00001.avi)

I wired up a voltmeter to my ignition module to read the voltage on the yellow line going to the coil. At startup and curb idle it reads 8 volts and climbs up to 10 volts when I increase the rpms above 2000. Are these normal voltages? If these seem low then I can assume that I did not use thick enough wire for the TFI coil or my alternator is weak.

BTW, I suspect a weak spark given my idle screw is driven all the way in to get the idle to about 700 rpms.

[lexum]

I doubt it is the rotor. I can time it fine with a timing light and the mark is steady and constant. The flashes are not sporadic.

The alternator is putting out 14.5 Volts. The voltage going to the coil is normal and should be 8 volts (but no less) coming from the ign module.

I hooked up a spare spark plug to the #1 wire and gapped it to .02. While the engine is running I get a nice blue spark as I should.

In summary, I am running the nutter bypass with TFI coil and the engine is running steady cold at about 700 rpms at idle with curb idle screw driven all the way in. As the engine warms up (about 20 min) the idle slowly drops lower and lower until the engine dies. If I rev the engine at all the rpms increase steadily but when I let go of the throttle the idle does not recover and the engine dies.

[lexum]

changed the fuel pump and still no go. I put a clear filter inline to verify that I am getting fuel. If anything I am getting too much fuel and I cannot keep her running at all like this.

[seatosky]

I believe the dealer calls them CCV lines (crankcase ventilation lines).:)

PCV is correct as well - it stands for Positive Crankcase Ventilation!

[lexum]

Case closed. I found leaks around the throttle shaft. Goodbye carb, hello TBI.