Backfiring up front
#1
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Year: 1987
Model: Cherokee
Engine: 4.0
Backfiring up front
When I give a little more than normal gas or at WOT it kinda starts to give up, and then backfire up front. I am pretty sure that I have an exhaust leak. I was checking the manifold last night and I could wiggle it a little as well as missing the fwd most bolt. And I have a feeling that the gasket is definitely bad. So is that a good starting point, or should I check sensors or somewhere else. Work has picked up and it is dark by 5 PM now, so thats why I am trying to take shortcuts on the trouble shooting. Thanks.
It's a 4.0 auto.
It's a 4.0 auto.
#2
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OK ya I'd start with the manifold gasket. But I'd also check you plug wires make sure all plugs are firing all the time.. Those would be your best places to start..
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Year: 01
Model: Cherokee
Engine: 4.0L I6
do you get any codes? maybe get a code reader and see if you can narrow it down that way. i know my XJ has the cylinder 3 misfire problem sometimes, as do most other 00 and 01's.
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Year: 1987
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What is a easy way to check the plugs. I was messing with the vac lines and noticed with the MAP line disconnected the idle went down to normal ranges. And I am also having a whole lot more stumbling right now. I am also leaning heavily to putting the old airbox back in. Would a bad IAT cause this as well. It was oil soaked and I cleaned it and put it back in.
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Year: 1987
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A little update. I snagged some injectors from a 4.0 explorer today(red top). And after installing them i can accelerate without any backfire. But it does backfire if I really give it gas, but I can accelerate in any normal driving conditions and I got it up to 60 no problem. I am still going to do the gasket but I think I will wait now till I get a new exhaust manifold.
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#9
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Year: 94 XJ
Model: Cherokee
Engine: 4.0L
Probably where the factory locked it in at. Timing is most often controlled by the computer. Even in 87.
I would lean more to the manifold gasket. When air is allowed into the leading end of the exhaust system, backfiring can occur.
Might I suggest getting the manifold changed while you have it off, as they are prone to cracking. Often, welding up the crack is only a stop-gap as they almost always re-crack. Trust me, this is something you do not want to do more than ONCE. eBay is the best place to find them. The seller I bought my TWO from usually has them for $89.95 Buy It Now. That price includes shipping. They come with both the gasket for the head and the pipe.
Why TWO?? I have a '91 Laredo and a '94 Sport.
Here's a link to his eBay store (Manifold catagory)
http://stores.ebay.com/DoctorAutoPar...QQftidZ2QQtZkm
Just scroll down past the Mazdas
I would lean more to the manifold gasket. When air is allowed into the leading end of the exhaust system, backfiring can occur.
Might I suggest getting the manifold changed while you have it off, as they are prone to cracking. Often, welding up the crack is only a stop-gap as they almost always re-crack. Trust me, this is something you do not want to do more than ONCE. eBay is the best place to find them. The seller I bought my TWO from usually has them for $89.95 Buy It Now. That price includes shipping. They come with both the gasket for the head and the pipe.
Why TWO?? I have a '91 Laredo and a '94 Sport.
Here's a link to his eBay store (Manifold catagory)
http://stores.ebay.com/DoctorAutoPar...QQftidZ2QQtZkm
Just scroll down past the Mazdas
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Year: 94 XJ
Model: Cherokee
Engine: 4.0L
Like I said, I have installed 2 of these...never want to do that again.
Not a real pain...just takes time.
Even better if you are doing a "full-system"
Helpful note: When installing a manifold w/o a new system behind it...
Hang manifold loosely by the front and rear studs, do not tighten.
Makes easier to line-up the system and get the flare connection bolts started.
Once started...go to town.
2nd Helpful Note: Start nuts and washers that will be "under" intake by a few threads. These bolt the intake and exhaust to head together (Washer crosses bosses in both manifolds) When you are THERE, you will see what I mean. Then carefully slip the intake down with it tilted slightly to drivers side. There are two locator pins that stick out from head that the intake needs to sit on/over. Once the intake is nestled behind the mounting washers...tilt to passenger's side until intake sets over locators. Install rest of hardware and torque everything down.
Not a real pain...just takes time.
Even better if you are doing a "full-system"
Helpful note: When installing a manifold w/o a new system behind it...
Hang manifold loosely by the front and rear studs, do not tighten.
Makes easier to line-up the system and get the flare connection bolts started.
Once started...go to town.
2nd Helpful Note: Start nuts and washers that will be "under" intake by a few threads. These bolt the intake and exhaust to head together (Washer crosses bosses in both manifolds) When you are THERE, you will see what I mean. Then carefully slip the intake down with it tilted slightly to drivers side. There are two locator pins that stick out from head that the intake needs to sit on/over. Once the intake is nestled behind the mounting washers...tilt to passenger's side until intake sets over locators. Install rest of hardware and torque everything down.
#12
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Year: 1987
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Probably where the factory locked it in at. Timing is most often controlled by the computer. Even in 87.
I would lean more to the manifold gasket. When air is allowed into the leading end of the exhaust system, backfiring can occur.
Might I suggest getting the manifold changed while you have it off, as they are prone to cracking. Often, welding up the crack is only a stop-gap as they almost always re-crack. Trust me, this is something you do not want to do more than ONCE. eBay is the best place to find them. The seller I bought my TWO from usually has them for $89.95 Buy It Now. That price includes shipping. They come with both the gasket for the head and the pipe.
Why TWO?? I have a '91 Laredo and a '94 Sport.
Here's a link to his eBay store (Manifold catagory)
http://stores.ebay.com/DoctorAutoPar...QQftidZ2QQtZkm
Just scroll down past the Mazdas
I would lean more to the manifold gasket. When air is allowed into the leading end of the exhaust system, backfiring can occur.
Might I suggest getting the manifold changed while you have it off, as they are prone to cracking. Often, welding up the crack is only a stop-gap as they almost always re-crack. Trust me, this is something you do not want to do more than ONCE. eBay is the best place to find them. The seller I bought my TWO from usually has them for $89.95 Buy It Now. That price includes shipping. They come with both the gasket for the head and the pipe.
Why TWO?? I have a '91 Laredo and a '94 Sport.
Here's a link to his eBay store (Manifold catagory)
http://stores.ebay.com/DoctorAutoPar...QQftidZ2QQtZkm
Just scroll down past the Mazdas
#14
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Year: 1987
Model: Cherokee
Engine: 4.0
Well I was still having the problems as well as stalling after driving for awhile. So I pulled out the fuel pump and the hose on the from the pump to the line was barely hanging on. And it was pretty deteriorated, so after switching that and a new strainer it started within 2 seconds. And the pressure was so high the regulator started leaking. I guess I crushed some of the o rings when I did the injectors but there never was enough pressure to leak. So the backfire is gone i think it was pulling air into the fuel rail with weak pressure and causing the problem. I hope this helps anybody else.