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Slow Cherokee

T

Truckedup

NAXJA Forum User
Location
Western NY state
I have three XJ's, two 99's and one 97. All three are 4.0 5 speeds. All have about 150,000 miles.One of them compared to the others is noticably slower when accelerating at near or full throttle.The engine idles smooth,no surging or hesitating and will rev to redline but just slower. Last year I put in the 4 hole injectors and it accelerated briskly.
Other than a catalytic convertor starting to plug up,is there any other components I can check out?
 
Does the slower one have a higher (lower numerically)
gear ratio?

Other than gears, then yes I'd look at the exhaust.
 
All the same gears... It does have bigger tires but felt no slower than my other XJ's last year....
 
then sea foam the intake, then replace plugs, wires, cap and rotor, fuel filter, air filter, injector cleaner(lots of it) in the tank, then I personally would replace o2 and TPS. Also, clean all your grounds. Then make sure battery connections are not corroded and clean them. Test for clogged cat too. If its an automatic, adjust the TV cable as well . Start there and get back to us.
 
I had a similar issue and it ended up being fuel pressure related. Had fine pressure at idle and partial throttle. But dropped off at wot and lost power to about 80% of what it should be.
 
Fuel delivery was / is my first thought. Check pressure & volume.

Steps...
Pressure at idle should be 49 psi, give or take 5 psi, at idle.
To check volume,
Disconnect your fuel rail from the line. Put the line into a measured bottle, hopefully one that won't dissolve in gas.
A good fuel pump will deliver at least 1/4 liter of fuel in 7 seconds.
If capacity is lower than specification but the pump is running, check for a kinked/damaged fuel line somewhere
If both fuel pressure and capacity are low, replace fuel pump module assembly. Refer to Fuel Pump Module Removal/Installation.
 
blondejoncherokee said:
then sea foam the intake, then replace plugs, wires, cap and rotor, fuel filter, air filter, injector cleaner(lots of it) in the tank, then I personally would replace o2 and TPS. Also, clean all your grounds. Then make sure battery connections are not corroded and clean them. Test for clogged cat too. If its an automatic, adjust the TV cable as well . Start there and get back to us.
Click to expand...
It got new plugs etc and an O2 sensor 6 months ago .The intake is quite clean when looking through the throttle body.I don't like the idea of pouring Sea Foam into an intake as routine maintenance. Where does the stuff go after it's dissolved ?
I'll hook up a gauge and drive it to check pressure...
 
Seafoam will burn with the fuel when it makes it's way into the cylinder. I typically use Berryman's B12, as it is basically the same and less expensive.
Why would the company recommend using in your fuel tank and such aside from using it in your intake, if it was bad/damaging to your engine?
 
Johnnie Walker said:
Why would the company recommend using in your fuel tank and such aside from using it in your intake, if it was bad/damaging to your engine?
Click to expand...

...To be perfectly honest I have tried Seafoam in several vehicles and noticed no difference other than a cloud of smoke and my wallet was 8 bucks lighter. Perhaps my engines are not dirty inside for some reason...
 
I don't believe in Seafoam or any of those fancy little bottles. You'd think they do something since there are so many of them, but they're not subject to any regulation.

You can spray water into your intake to clean it, it will vaporize and steam clean your pistons and cylinders, and it's a proven, measurable effect, just look at a cylinder that's had a slow coolant leak.

To those that swear by it to "clean injectors", what makes you think your injector is "dirty"? Have you pulled them and inspected them? They have constant filtered fuel going through them, you're sure to have a lot more carbon buildup on your intake as a result of your EGR system than dirty fuel.
 
photondisruptor said:
I don't believe in Seafoam or any of those fancy little bottles. You'd think they do something since there are so many of them, but they're not subject to any regulation.

You can spray water into your intake to clean it, it will vaporize and steam clean your pistons and cylinders, and it's a proven, measurable effect, just look at a cylinder that's had a slow coolant leak.

To those that swear by it to "clean injectors", what makes you think your injector is "dirty"? Have you pulled them and inspected them? They have constant filtered fuel going through them, you're sure to have a lot more carbon buildup on your intake as a result of your EGR system than dirty fuel.
Click to expand...

Well said, I don't get the sea foam bandwagon, you can see exactly whats in the seafoam and nothing about its is magical beyond being a light oil that smokes so you feel like something is accomplished. hasta

Sorry to not offer the OP any other advice beyond agreeing with what photondisruptor. I would look at an exhaust or fuel issue though.
 
My buddy/mechanic told me if i want my engine to run better run 2 qts of ATF and 3 qts oil for 20 mins then change the oil
 
ATF has much heavier detergents than engine oil; if you have crap in your engine, ATF will probably break it up so it gets caught in the filter.
It probably won't run any better, though.
Sea Foam or similar products will clean things up but as to whether it makes a notable difference in a practical sense is harder to say.
Now, all that aside, any updates on the Slow Cherokee?
 
yossarian19 said:
Now, all that aside, any updates on the Slow Cherokee?
Click to expand...

No...Since it runs smooth and seems fine during normal driving I haven't messed with it more.And I've been busy on motorcycle stuff.
But I'm rigging up a gauge to hook up to the injector rail so I can check fuel pressure while on the road...
 
After a drive, check to see if the catalytic converter
seems unusually hot. When they get partially clogged,
they get very hot.
 
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