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Topic Review (Newest First)
05-17-2009 10:18 AM
cherokee980 Well I took an IR Temp sensor and checked the precats. They were both right at 675-685 deg each. The muffler itself was about 300 deg. So I have ruled out the coil pack. I disconnected the muffler completely and took it for a drive (good lawd it was loud), and same results occoured. I am confused bad here. All that is left is the fuel pressure check before I pull the transmission. Do any of you know where to check the fuel pressure? There is no fuel pressure port on the fuel rail...nothing at all. I have searched and searched with no luck at all of finding it!!! HELP!!!!!!!!!!!
05-14-2009 11:27 AM
cherokee980
Quote:
Originally Posted by rrich View Post
Sometimes when a cat self destructs, the pieces get caught in the muffler, plugging it. Or even can get caught in the pipe's bends.

I'm surprised nobody told you the easy test for a plugged exhaust.

No need for cutting anything -
Put a vacuum gauge on manifold vacuum, rev it up, it should still hold at least 15 inches of vacuum at 3000 RPM. If it's significantly lower, plugged exhaust. As you hold it at high speed, it will either stay low, or jump up, then slowly sink. A good exhaust system won't drop.

If it's only partially plugged, drive it while watching the gauge - make it falter - if that's it, vacuum will drop significantly.
Go to an independent muffler shop (not a chain), they can do the same test for almost nothing.
If it can't breathe out, it can't breathe in - no room. (Just like you lose your appetite when you are constipated - no room.)

Fuel test too - plugged filter, line, etc. Put a fuel pressure gauge on the rail at the engine - rev it to 3000 - it should hold that pressure without dropping if it's not plugged.

Do it the easy and logical way rather than throwing parts, time, and money at it.

'05 - you have the DIS ignition. The coil rail could be the culprit too. The internal insulation breaks down, limiting the spark. Listen closely - if you hear any "snapping" of the spark it's history.
And - Use a laser pistol type thermometer (harbor freight, about $30) from underneath. Both precats should be running about 350 degrees at their outlets. If one's is way too hot, like 700 degrees, and the other is too low, like 250, try another coil rail ($130 at a parts house, $230 at the dealer.)
I've seen several failures like that recently, identified with the thermometer, verified by replacing with a test spare.

I wish MSD would make a good coil rail replacement, they don't seem to be interested, too limited a market base.


thanks for all the info brother!! I will try some of these out and let you know what I come up with!!
05-13-2009 01:29 PM
rrich Sometimes when a cat self destructs, the pieces get caught in the muffler, plugging it. Or even can get caught in the pipe's bends.

I'm surprised nobody told you the easy test for a plugged exhaust.

No need for cutting anything -
Put a vacuum gauge on manifold vacuum, rev it up, it should still hold at least 15 inches of vacuum at 3000 RPM. If it's significantly lower, plugged exhaust. As you hold it at high speed, it will either stay low, or jump up, then slowly sink. A good exhaust system won't drop.

If it's only partially plugged, drive it while watching the gauge - make it falter - if that's it, vacuum will drop significantly.
Go to an independent muffler shop (not a chain), they can do the same test for almost nothing.
If it can't breathe out, it can't breathe in - no room. (Just like you lose your appetite when you are constipated - no room.)

Fuel test too - plugged filter, line, etc. Put a fuel pressure gauge on the rail at the engine - rev it to 3000 - it should hold that pressure without dropping if it's not plugged.

Do it the easy and logical way rather than throwing parts, time, and money at it.

'05 - you have the DIS ignition. The coil rail could be the culprit too. The internal insulation breaks down, limiting the spark. Listen closely - if you hear any "snapping" of the spark it's history.
And - Use a laser pistol type thermometer (harbor freight, about $30) from underneath. Both precats should be running about 350 degrees at their outlets. If one's is way too hot, like 700 degrees, and the other is too low, like 250, try another coil rail ($130 at a parts house, $230 at the dealer.)
I've seen several failures like that recently, identified with the thermometer, verified by replacing with a test spare.

I wish MSD would make a good coil rail replacement, they don't seem to be interested, too limited a market base.
05-13-2009 11:26 AM
MOz Anything stuck in the tailpipe? Did you fill up lately?
05-13-2009 11:00 AM
cherokee980
Quote:
Originally Posted by 03rubi View Post
Do you have a check engine light on? I would think that a code should be set in the ECM (computer) if it is running so poorly. However, sometimes it won't turn the light on even if a problem has been detected, it's called a soft code. Simply turn the ignition switch on, off, on, off, on and you should get the codes either as a flashing light or as a number on the odometer. That would be the first place I would go before I started throwing parts at the problem.


no codes at all. it "runs" fine..cranks right up, no missing or rough idle. It's just when you put it in gear, it has no power.
05-08-2009 11:56 AM
03rubi Do you have a check engine light on? I would think that a code should be set in the ECM (computer) if it is running so poorly. However, sometimes it won't turn the light on even if a problem has been detected, it's called a soft code. Simply turn the ignition switch on, off, on, off, on and you should get the codes either as a flashing light or as a number on the odometer. That would be the first place I would go before I started throwing parts at the problem.
05-08-2009 11:37 AM
whitebuffalo yeah, i wondered about that. my dodge gasser was the same way.

can you check the fuel pressure at the rail?
05-08-2009 09:45 AM
cherokee980
Quote:
Originally Posted by whitebuffalo View Post
have you replaced your fuel filter? clogged exhaust acts very similar to fuel starvation.....
everything I have read says fuel filter is "lifetime filter" in tank, and all you can actually replace is the "sock" / strainer on the pu tube in tank
05-08-2009 08:49 AM
whitebuffalo have you replaced your fuel filter? clogged exhaust acts very similar to fuel starvation.....
05-08-2009 07:47 AM
cherokee980 gotta keep this one on top..I need help here
05-08-2009 07:40 AM
cherokee980 Ok, changed the CC, and still have the same problem....can anyone help?
05-04-2009 01:43 PM
cherokee980 do any of you happen to know the factory exhaust pipe size? when I cut the cat, I gotta put a patch back in.
05-04-2009 07:55 AM
cherokee980
Quote:
Originally Posted by jpdocdave View Post
clogged cat usually keeps the rpms down, slipping trans the rpm will go up and you won't be going anywhere. clogged cat, rpms are struggling to go up, and you don't go anywhere.
Exactly why I am confused as to what the true problem is. I will cut the cat out first and go from there. If that's not it, looks like I will be dropping the tranny!
05-04-2009 07:50 AM
jpdocdave clogged cat usually keeps the rpms down, slipping trans the rpm will go up and you won't be going anywhere. clogged cat, rpms are struggling to go up, and you don't go anywhere.
05-04-2009 07:12 AM
cherokee980
Quote:
Originally Posted by jpdocdave View Post
could be clogged cat. you say you can get to 50 or so, how hi do the rpm's get while you are accelerating?
the RPM's get fairly high..higher than usual anyway. It will not kick into OD the way it is now @ 50 mph (about 3K + on the RPM's)


Taz,
it takes it's sweet time to get to 50 mph, and will not go any faster..it feels like it has lost all power.
05-04-2009 07:09 AM
cherokee980 Thanks guys. I figure it is the cat as well. I will give it the sawzall treatment one day this week. I'll keep you all posted as to what the result is.
05-03-2009 03:33 PM
bamawheeler CAT ! ! ! I have had the same problem before....
05-03-2009 10:36 AM
jwm1986 Pull out the o2 sensor before the cat and go for a short drive and see if it responds better. That will allow the exhaust to get out more normally to tell if it is the cat or not. Don't expect it to run perfect still but you should have more normal power at least if it is the cat.
05-03-2009 01:24 AM
Rawkon prolly your cat is clogged, wouldnt hurt to do a trans filter and flush. make sure you use atf 4 if you do
05-02-2009 10:41 PM
Splizblot ya, I agree with jpdocdave. I had similar problem, no power, down shifting alot and could barely make it up hills on the hiway. After doing a bunch of troubleshooting and replacing stuff on the motor I figured out it was restricted exhaust and a new cat fixed it.
05-02-2009 03:23 PM
tazmann910 maybe some dirt in the fuel line.

Can you give some more details at what happens at 50mph?
05-02-2009 01:16 PM
jpdocdave could be clogged cat. you say you can get to 50 or so, how hi do the rpm's get while you are accelerating?
05-02-2009 11:59 AM
cherokee980
transmission? Catalytic Converter? HELP!!

Okeveryone, I need some knowledge here.

'05 TJ 6 cyl, Auto -

had been running fine, cranked it up friday morning, left the house and noticed it was shifting funny, and seemed to have a power loss. Jeep will idle just fine, but when you are going, you can mash the skinny pedal to the floor, and nothing. I can't get it above 50mph or so. I checked trans fluid, and it was about a quart low, I filled that up, still the same result. I just don't understand how it goes from normal one eve to problems when I crank it up the next day. Not throwing any codes, no CEL...I am at a loss!! HELP!!!!!

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