Back fire after adding K&N?

[Brett]

First off, vehicle is a 1989 Cherokee, 4.0L with the AW4.


I've had this problem for quite sometime, even before I added the K&N yesterday, but now it's happening more. This usually happens at lower RPM's, between 1500 and 2000. Generally, if I recall correctly, it's at 1/4 to 1/2 throttle and suddenly I'll get a pop out of the throttle body. This is only when the engine is under load, never when I am just revving it. I did a search here and there doesn't seem to be anything conclusive.

FYI, I removed the air box and everything associated with it to do the K&N. Replaced it with a FIPK style intake. I did plug the single vacuum line that had been running from the intake manifold to the box. Is this a no no?

Dunno if this helps, but here's a pic of what I have now. Ignore the ricer breather on the valve cover please

 

[I Lean]

I'll bet it's no worse, you can just hear any/all sounds from the intake a lot more now.

 

[Fuller]

I'll bet it's no worse, you can just hear any/all sounds from the intake a lot more now.

don't you like that cool whistling noise when your cruising on the freeway

 

[Fuller]

Dunno if this helps, but here's a pic of what I have now. Ignore the ricer breather on the valve cover please

i actuallly thought that was a good idea, the rustys intake tube that i have has a nipple for that though.

 

[DOSS]

If you are getting a backfire start with the basics...
1. Check all of your vacume and make sure you don't have any leaks.
2. replace your plugs and do a normal tune up.
3. Run some Seafoam through the crank case and do the carbon removal method (just do what the bottle tells you to do)

If it continues from there let us know

 

[Brett]

If you are getting a backfire start with the basics...
1. Check all of your vacume and make sure you don't have any leaks.
2. replace your plugs and do a normal tune up.
3. Run some Seafoam through the crank case and do the carbon removal method (just do what the bottle tells you to do)

If it continues from there let us know

'


I'm going to pick up 20-30 feet of vacuum line and replace all the plastic lines, since they like to crack....have to wait till tomorrow or the weekend though.

Seafoam....I've heard of this....but what is it and what does it do?

 

[Brett]

I'll bet it's no worse, you can just hear any/all sounds from the intake a lot more now.

It's about as loud as before, but it seems to be happening more often now

 

[Brett]

i actuallly thought that was a good idea, the rustys intake tube that i have has a nipple for that though.

Yeah, I thought about maybe adding a bung onto the metal tube I used, but I decided I didn't want any oil going into the intake anymore

 

[Fuller]

what kind of metal is that?

 

[Fuller]

as per my 1990 jeep fsm

"intake backfire" lists the following

improper ing timing
faulty accelerator pump discharge
defective egr cto valve
defective tac vacuum motor or valve
lean air fuel mixture

most of these sound like there for the carb engines though

 

[Brett]

as per my 1990 jeep fsm

"intake backfire" lists the following

improper ing timing
faulty accelerator pump discharge
defective egr cto valve
defective tac vacuum motor or valve
lean air fuel mixture

most of these sound like there for the carb engines though

The metal on the adaparter from the filter to the intake? Aluminized exhaust tubing just sprayed with some silver paint. I suppose that it could be timing. The timing chain has probably never been changed. Off subject, but maybe related......Sometimes it feels like my Jeep suddenly has more power when it hits 3000 RPM's. Maybe the chain is stretched out?

 

[DOSS]

Sometimes it feels like my Jeep suddenly has more power when it hits 3000 RPM's

I doubt that it is a streched chain.. if it was that it would just run like crap in general ... 3000 RPM is when you are hitting the 4.0's tourqe range so it should feel like it has more power there

Seafoam is basicaly a lubricant that kicks madd butt. I have used it for the uses I stated and have had fenominal results.. heck I have unseased a slightly seased engine with it before

 

[Brett]

Sometimes it feels like my Jeep suddenly has more power when it hits 3000 RPM's

I doubt that it is a streched chain.. if it was that it would just run like crap in general ... 3000 RPM is when you are hitting the 4.0's tourqe range so it should feel like it has more power there

Seafoam is basicaly a lubricant that kicks madd butt. I have used it for the uses I stated and have had fenominal results.. heck I have unseased a slightly seased engine with it before

Max torque on mine is down around 2400 RPM's on my non-HO, so I don't think that it's that. I feels like the VTEC just kicked in, yo! It's weird...who knows.

I might have to give this Seafoam a try.....do you add it to your oil or something?

 

[Devel]

u can add seafoam to ur fuel or ur oil but if u add it to ur oil drive at most 50 miles then change your oil, the seafoam will brake down the oil and make the jeep run even worse

 

[92XJeeper]

Max torque on mine is down around 2400 RPM's on my non-HO, so I don't think that it's that. I feels like the VTEC just kicked in, yo! It's weird...who knows.

Yep, the non-HO motors have most torque at a lower RPM range than the HO motors. I would certainly look at the EGR to see if it has build up.

Another very simple thing: ensure the plug wires are connected properly. This will cause backfiring as well.

I might have to give this Seafoam a try.....do you add it to your oil or something?

It has directions right on the bottle and it depends on what part of the engine you want to clean out.

Pull a vacuum hose off the intake manifold (one that runs to the brake booster works great) and "suck" about 1/3 of the seafoam into the engine this way. I meter it in just enough to almost stall the engine. I then pour another 1/3 directly into the throttle body, pouring slowly at first, and then enough to stall the engine.

Let it sit for about 15-20 minutes. Then start the engine and watch the white smoke envelop your neighborhood. It will produce a lot of white smoke!

The last 1/3 I pour into the oil and run it for a day or two. Do this if you already plan to change the oil. Or you could pour it into the gas tank, but I highly recommend using BG44K for the fuel. It's a much better product in that regard.

Next time I use seafoam 1/2 will go into in via the brake booster vac line and the other half will go in through the throttle body.

 

[Brett]

This stuff sounds creepy! But, can't hurt to try

 

[spencurai]

I am willing to bet it is a vacuum issue. I have had those lines on my 99 cherokee crack just from staring at them the wrong way...I hate those damn things. I hit a pothole in delta once and it either broke the line or finished breaking one that cracked because my stupid heater controls wouldn't work anymore....a sure sign of vacuum leaks because they are vacuum actuated.

The crappy part was that it was near zero in Delta so the lines were so brittle I had to replace almost two feet of line with rubber hose from the parts store down there. I hate Chrysler lines forever!!

 

[waynehartwig]

I would definately check out your EGR valve.... Make sure you can see it open and the engine stutter when you apply vacuum, also make sure it will HOLD a vaccuum. Make sure the tube going from the exhaust manifold to the EGR valve is in good shape, and not off, broken, or bent.

 

[Brett]

I would definately check out your EGR valve.... Make sure you can see it open and the engine stutter when you apply vacuum, also make sure it will HOLD a vaccuum. Make sure the tube going from the exhaust manifold to the EGR valve is in good shape, and not off, broken, or bent.

Is the EGR the part that is on the edge of the intake manifold, has a line or two running into it? I think it would be directly behind the air intake in my pic.....?

 

[waynehartwig]

Is the EGR the part that is on the edge of the intake manifold, has a line or two running into it? I think it would be directly behind the air intake in my pic.....?

Possibly. I honestly don't know the location on a Jeep! But it will be on the intake manifold. It will have a steel tube from it to the exhaust manifold. It could have an electrical sensor on the end of it (which would pull a code if it didn't move when it is supposed to, or moved with it isn't supposed to). It could have more than one vacuum line hooked up to it, one for open and one for close.

Take a picture of what your thinking, and we can say yeah or neah....