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Problems under heavy throttle

C

CodyJames

NAXJA Forum User
Location
Olathe, KS
Well my XJ has many problems. BUt stiil drivable. When it idles is studders alot. Like it mis fires every 5-9 seconds. This is not a heat soak issue because it does this when its cold or hot.. I know what heat soak is. I get it alot. Well the big problem is anytime I give it say 85-90 throttle it messes up. It kinda misses or somthing. Its cold and I have a pipe running from the cat back with no muffler if that has any cause or effect. It makes a little "pa....pa" sound? I can feel it slow the acceleration process.

First gear sounds like this if I get on it hard.
VVVVRRRRROOOOO pa...pa...OOOMMMM
 
First rule of fight club--never talk about fight club!

First rule of NAXJA--if you don't share the BASICS, like year, engine, transmission, etc., you won't get much help here.
 
Skreed said:
This might be the problem I having...Could you trying making your post a bit more intelligible?
Click to expand...


Well the engine studders so to say. Its will idle fine, and then it will make almost like a hissing sound llike air is entering somewhere every few seconds. Another problem is when I give it about 95% throttle the motor makes a pa..pa sound. Sounds like air is being sucked into something.
 
Could be a number of things.

It becomes harder to fire the fuel mixture as the RPMs increase. Anything marginal can work at idle, but as the engine load increases things can get wonky.

Ok, distributorless and coil paks. Pull the spark plugs and check the gap. BTW, you should be running NGK V-Fires in yours. Make sure you torque the plugs to specs--over tightening plugs causes the gap to distort.

No cap, rotor, or plug wires to worry about, but how do the coil paks look? They can develop small cracks from heat/stress and start shorting to ground. Wait for night, open the hood, start the engine and have someone hold it about 2000-2500 RPMs, and then use a kitchen sprayer bottle to mist around the coil paks and plugs to see if you got any stray spark.

You say you suffer a lot from heat soak--maybe yours goes a little beyond and you have one or more injectors not performing at their best. Try running BG44K through the fuel system.

Good luck.
 
No thats different from what I have, but anyway, you can also try a spark tester between the plug and coil pack. I found a bad coil pack on a bmw that way. Make sure the spark is bright and has sharp snaps.
 
joe_peters said:
Could be a number of things.

It becomes harder to fire the fuel mixture as the RPMs increase. Anything marginal can work at idle, but as the engine load increases things can get wonky.

Ok, distributorless and coil paks. Pull the spark plugs and check the gap. BTW, you should be running NGK V-Fires in yours. Make sure you torque the plugs to specs--over tightening plugs causes the gap to distort.

No cap, rotor, or plug wires to worry about, but how do the coil paks look? They can develop small cracks from heat/stress and start shorting to ground. Wait for night, open the hood, start the engine and have someone hold it about 2000-2500 RPMs, and then use a kitchen sprayer bottle to mist around the coil paks and plugs to see if you got any stray spark.

You say you suffer a lot from heat soak--maybe yours goes a little beyond and you have one or more injectors not performing at their best. Try running BG44K through the fuel system.

Good luck.
Click to expand...


I am going backpacking tomorrow so I will have to try this later in the week. I have heard as many cons as pros to BG44K but I think I will give it ago. I seafoamed it. Fun as heck to watch but it did not smooth my idle or help and any way I can hear or feel. Could there be any sensors I should clean? As you might have read in my early post. These problems are a post "terrible over heat". I dont think my head is cracked but now I got these other problems
 
CodyJames said:
I am going backpacking tomorrow so I will have to try this later in the week. I have heard as many cons as pros to BG44K but I think I will give it ago. I seafoamed it. Fun as heck to watch but it did not smooth my idle or help and any way I can hear or feel. Could there be any sensors I should clean? As you might have read in my early post. These problems are a post "terrible over heat". I dont think my head is cracked but now I got these other problems
Click to expand...

Been using BG 44K for over 15 years and never heard anything negative. What did you hear?
 
perhaps it has something to do with overheating your jeep so badly that you had no coolant left?
 
Skreed said:
Why would that cause any problems? :laugh:
Click to expand...
I'm not sure, but engines tend to not like treatment like that :roflmao:
 
Clogged exhaust system, broken catalyst perhaps causing excess back pressure.
 
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