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Unread 04-10-2013, 09:21 PM   #1
gunner608
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Change exhaust manifold now missing, chugging and shaking

I have a 1994 ZJ with 4.0 I had a crack exhaust manifold so decided to change it out with a brand new one. I'm actually a nurse wanna be mechanic so I'm not that skilled of a mechanic but more of a weekend warrior but I have came pretty far in the past couple of years but do enjoy learning. Anyways, i replaced the exhaust manifold, with that i did clean the fuel rail and also clean the injector with some sort of homemade system i seen on you tube with a push button switch 5ml syringe and some carb cleaner and did replace all the o-rings. I also replace the valve cover gasket as it was leaking along with new valve cover grommets and CCV valve on the back and blow by elbow on the front. I got the exhaust and intake all back on and everything back together and started it up. Thing was running horrible, I dont know if you wanna call it missing, sputtering, chugging. To me it sounds like it is missing and chugging with maybe a little bit of a back fire here and there nothing major but just little back fire here and there, when you barley step on the gas you can feel the whole jeep vibrate, get her out on the road and it chugs under acceleration. I replaced spark plugs, Cap, Rotor. Also replaced 02 sensor with an NTK. I did have my buddy read for codes and it was the 02 sensor, now that i have replace the 02 sensor the CEL is not on. I'm going to have him read it again probably tomorrow with the new 02 sensor just to see if any other codes will pop up. I've checked for vacuum leaks with carb cleaner, also did some ohms testing on the injectors and got 15-16 on all 6 of them. Before I did the exhaust the jeep ran well it did shake every once in a while going down the highway not sure if engine related or tie rods or what that could of have been. I think tomorrow I'm going to clean the throttle body and IAC. I'm just kind of stumped because the exhaust manifold went pretty simple and i don't see how i could of messed something up so bad. I feel as though it could be fuel related or vacuum related as I kind of had to unhook that stuff to get the exhaust manifold in and out. Anyone had these kind of issues. Ive been reading some stuff and could it be TPS, Crankshaft position sensor, coolant temp sensor? Would a code reader pick these up? Can you ohms test these sensor? Oh and my gas mileage is in the ****ter, before all this with a cracked manifold i could 18-20mpg hwy now I'm only getting 13-15mpg with new plugs, wire, rotor, 02 sensor, ccv valve. There was one thing I was unsure off when I was putting back together and that is when I pulled the air box out there was a little black hose just kind of underneath there, does not look like it plugs into anything but on the side of the air box there are little like tube holders that the tubing fits into just perfect so i just kind of loop it on the air box. Sorry if my explanations are poor. What else can I try?

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Unread 04-11-2013, 12:47 AM   #2
jeepkid945
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I would test fuel pressure first. Possible that you crossed any plug wires? The firing order is stamped into the intake manifold. Cylinder 1is closest to the radiator.
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Unread 04-11-2013, 08:55 AM   #3
dylantheheeler
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Check firing order, and while your there make sure you didn't cross any fuel injector plugs.
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Unread 04-11-2013, 09:42 AM   #4
Scopez
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The black hose you saw is a front differential breather tube.
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Unread 04-11-2013, 10:29 AM   #5
zjosh93
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Also check to make sure you didn't pinch any wires between the intake and the block when you bolted it back up. At the worst it'll short the sensor and have a big vacuum leak.

The two hoses on my 93 4.0 that run behind the airbox and between the fender and airbox go to the evap canister I believe. One is about 3/8" the other 1/8", both hard plastic except where they broke and I replaced them with rubber hose. The larger goes into the upper part of the air box the other to a fitting on the intake. IMS the same fitting the fuel pressure regulator vacuum line attaches to.

My air box also has the clips on the engine side but there has never been a hose that goes there.

The breather tube is the 1/2" tube that runs from the upper air box to the valve cover. Doesn't sound like what you are describing.

How is the hose to your MAP sensor?
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Unread 04-11-2013, 11:03 AM   #6
Scopez
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Quote:
Originally Posted by zjosh93 View Post
Also check to make sure you didn't pinch any wires between the intake and the block when you bolted it back up. At the worst it'll short the sensor and have a big vacuum leak.

The two hoses on my 93 4.0 that run behind the airbox and between the fender and airbox go to the evap canister I believe. One is about 3/8" the other 1/8", both hard plastic except where they broke and I replaced them with rubber hose. The larger goes into the upper part of the air box the other to a fitting on the intake. IMS the same fitting the fuel pressure regulator vacuum line attaches to.

My air box also has the clips on the engine side but there has never been a hose that goes there.

The breather tube is the 1/2" tube that runs from the upper air box to the valve cover. Doesn't sound like what you are describing.

How is the hose to your MAP sensor?
Clearly its the Differential breather hose, as I've already stated. Correct me if I'm wrong though. I practically took the whole front end off my Jeep about a month ago and replaced the motor. So I'm pretty fond of the whole engine bay, 5.2L that is.

I put my airbox back in yesterday and I put the breather tube exactly where you put it.
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Unread 04-11-2013, 11:07 AM   #7
zjosh93
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Ha! Yeah, you're probably right. Went back and reread your post, missed the "differential" part of that. Thought you were talking about the CCV breather. Mine's 2wd so obviously no front differential breather.
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Unread 04-11-2013, 06:19 PM   #8
jnowak
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1-5-3-6-2-4 firing order
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Unread 04-11-2013, 06:54 PM   #9
buttersjeep90
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I to have a 4.0 mines a 97, anyways I did my intake/exhaust gaskey and mine did that weird running thing, my buddy told me to cycle the key a few times to prime the fuel system seeing as I had to disconnect the fuel line from fuel rail to take intake off. And after cycling the key 5 times it started up and ran great, maybe it could be something as simple as that in ur case, you never know. Make sure all of ur wires are plugged in all the way and check for fuel pressure at the rail, I'm pretty sure you should have a test port on the fuel rail, atleast mine does I know of. I'm no export myself either, I've learned as stuffs gone wrong and needed fixing. It's fun though how we live out jeeps but we get mad at them sometimes. I love it.
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Unread 04-11-2013, 07:25 PM   #10
Uniblurb
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When I replaced the manifold on my 96 4.0 the black hose from the intake to the brake booster was in the way so I just spun it around out of the way. Sure enough when I put everything back together I ended up with a vacuum leak at the rubber brake booster grommet when I turned it back to where it was before and it was spitting & sputtering. Put a thick layer of ultra black gasket maker on the outside of the grommet/metal of the booster and my problems were solved. Believe the exact same thing happened to ZeeJay1997 when he was replacing the manifold at the same time I was and same fix. Good luck.
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Unread 04-11-2013, 07:55 PM   #11
gunner608
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Thanks for all your responses guys. I'm from Wisconsin and we've had some cold crappy weather so I've only been able to do a little here and there aside from working too. This morning before i went to work I took the IAC off and cleaned it all up nice with some throttle body and carb cleaner, also cleaned the the throttle body as well. Ohh I was also reading through some other forms and and seen info on cleaning the intake with poring Sea foam into the brake booster line, so did about a half a can of that as well. When I tore it apart I was pretty organized and used masking tape and labeled my injectors 1-6 so i wouldn't mess it up when it came to plugging them back in but mistakes can happen. Anyone know like the color of the wires on the injector clips to which injector, trying to read through my repair manual and im not to good with it but i can seem to find that sort of info, so just wondering how can I make sure i hooked up the right clips to the right injector been trying to research that and all i come up with are forms about switch injectors from one hole to 4 hole injectors which was interesting stuff as well. So tonight I was doing some research which seems like all I do now that my beast isn't running and fishing coming up around the corner I need my girl running to pull the boat. I found a thread on how to read codes turning the key on and off. I got codes 12, 13, 14 which are related to map sensor but I know I unplugged the map sensor when it was running this morning and the check engine light did come on at that time so I'm sure there just stored from this morning's episodes but I unhooked the battery for tonight and I held the power and negative together and I'm going to try the ignition on then headlights on headlights off and then ignition off to see if it will clear the adaptive memory. I do not have a fuel pressure tester but i know i do have a port on my rail and i found some stuff in my manual at what PSI I should be at. "39 PSI at idle then disconnect vacuum line and fuel pressure should raise to 39 PSI if fuel pressure does not rise 8-10 PSI after vacuum line is removed then replace regulator." I'm going to buy a fuel pressure tester tomorrow or rent one or somehow get my hands on one and test that out. Im also going to recheck to make sure my spark plug wires are good as i directly disconnected and connected one at a time i find it hard i would of messed it up but I'm going to double check have to do a little research into that. I thought i almost found the problem this morning when i was messing around, i would unhooking my vacuum lines and checking for suction when i came across the nipple that hooks up the ccv valve had no suction at all so i unscrewed the nipple out and idle went high so I shut her down and the thing was completely blocked off so i cleaned it all out and reinstalled and i now had suction, but jeep still running like crap. I recorded a video of what my tail pipe sounds like so if you guys want to here it, check out my YouTube link because I don't really know how to explain it but this is after everything I did to it this morning. But in summary, I am going to check fuel pressure at the rail, recheck to make sure spark plugs are in correct firing order which is on intake manifold, I'm also going to do a propane test around my manifold gasket to check again for vacuum leaks also will re-connect battery let it run for wild and recheck to see if it pops map sensor codes again since I'm positive they only registered because I unplugged it while it was running this morning, Also going to check and make sure I didn't pinch any wired between the manifold and block. Again thank you for you feedback it is greatly appreciated and let me know if there is anything else I can check

youtube link:

Hopefully someone can tell me what that sounds like becuase it sounds like something aint right.
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Unread 04-12-2013, 03:24 PM   #12
ratmonkey
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you've got at least two cylinders not firing. remove injector plugs one by one. the ones that don't make the motor run significantly worse when you pull them are the ones you have crossed.
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Unread 04-12-2013, 04:10 PM   #13
zjosh93
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Not disagreeing with you ratmonkey but I would be very surprised if switched injector wires were the problem. The only ones that are easily switched are 1 and 2 or 5 and 6. The rest are too far apart for the wires to easily reach.

In fact, I just went out to mine and switched the 1 and 2, no noticeable idle change. Switched 5 and 6, no noticeable idle change. Remember that the first multi-point fuel injection systems were batch fire and they ran just fine. As long as the injector squirts the right amount of fuel it'll be alright. If it squirts at the wrong time the fuel just puddles against the back of the intake and warms up then atomizes as the intake valve opens.

Even with two injectors unplugged mine didn't sound as bad as the OP's.
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Unread 04-12-2013, 04:48 PM   #14
ratmonkey
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Quote:
Originally Posted by zjosh93 View Post
Not disagreeing with you ratmonkey but I would be very surprised if switched injector wires were the problem. The only ones that are easily switched are 1 and 2 or 5 and 6. The rest are too far apart for the wires to easily reach.

In fact, I just went out to mine and switched the 1 and 2, no noticeable idle change. Switched 5 and 6, no noticeable idle change. Remember that the first multi-point fuel injection systems were batch fire and they ran just fine. As long as the injector squirts the right amount of fuel it'll be alright. If it squirts at the wrong time the fuel just puddles against the back of the intake and warms up then atomizes as the intake valve opens.

Even with two injectors unplugged mine didn't sound as bad as the OP's.
my v8 will. the 2.5l with one bad injector will sound like that.

still. that sound is from at least 2 cylinders not firing at all, or worse, overlap on the exhaust stroke...

there's a major misfire. and the only things he should have disconnected that would cause it are the injectors.
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Unread 04-13-2013, 11:41 AM   #15
jnowak
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I recently had what kinda sounds like this. Got a map code replaced map. Ran good for two days than went stupid again. While messing around with it I wiggled the map sensor wires. Could make the engine change just by just wiggling the wires. Noticed the wires insulation where melted together. Started separating the wires and pulled one in half. The wires had corroded inside the insulation. Couple spliced in new wires been running for three months no problem.
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