Hello, thanks ahead of time for the input. Ive got a 2001 xj 4.0 4x4 220,000 miles. Im saying that 1 out of 40 engine cold starts it does this. Jump in turn key on, let pump prime, engage the starter and it turns over slow, like its at the top of a compression stroke. It turns over about 4 times, backfires once through the intake and starts. Then rough idle for about 30 seconds and eventually clears out. It runs fine pretty much all the time other than that. If im cruising highway speeds, i notice a slight jumping/ light misfire when trying to accelerate. Thanks again.
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2001 xj 4.0 4x4 slow crank sometimes and one backfire
- Thread starter Alec5y6
- Start date
- Location
- Minneapolis, MN
Typically those are symptoms of low battery voltage.
Load test the battery and alternator. Inspect, clean, and snug all the starting and charging wire connections. At +20 years of age, the battery terminal connectors or battery wires are likely due for replacement.
Load test the battery and alternator. Inspect, clean, and snug all the starting and charging wire connections. At +20 years of age, the battery terminal connectors or battery wires are likely due for replacement.
Unclewolverine
NAXJA Forum User
- Location
- Kansas
Could be a leaky injector, or related to heat soak. Are your injectors and fuel rail insulated? They are supposed to be on those.
I was wondering about that myself. I cant remember if the rail is insulated or not. Something tells me that i might have taken it off a while back when i did the valve cover. Im off work and home for the next 6 weeks recovering from a dirt bike accident so ive finally got plenty of time to mess with it.
RCP Phx
NAXJA Forum User
- Location
- Phoenix,Az
They didn't come from the factory with any "insulation".
Unclewolverine
NAXJA Forum User
- Location
- Kansas
No they didn't, it was a recall.
- Location
- Minneapolis, MN
Typical heat soak has no effect upon the cranking speed of the starter, unless the starter istself is overheated. Leaky injectors may cause a slow start, but unless they have partially filled the cylinder with liquid gas, they would not have any effect upon the cranking speed of the starter.
Testing the starter would be a good idea after eliminating low voltage as the root cause of the symptoms.
Testing the starter would be a good idea after eliminating low voltage as the root cause of the symptoms.
Alec5y6,
Backfire could indicate a timing issue/worn camshaft lobes. I'd pull the valve cover and look at the valve lifts while the warmed-up engine is idling. A valve that has a smaller lift indicates a worn cam lobe.
Likewise, the fuel injectors operate in a given sequence. The fuel injector wiring is color-coded and should be checked to insure each injector has the proper color-coded wire connected to it. That will check that the fuel injectors are operating/firing in the proper sequence.
Best regards,
CJR
Backfire could indicate a timing issue/worn camshaft lobes. I'd pull the valve cover and look at the valve lifts while the warmed-up engine is idling. A valve that has a smaller lift indicates a worn cam lobe.
Likewise, the fuel injectors operate in a given sequence. The fuel injector wiring is color-coded and should be checked to insure each injector has the proper color-coded wire connected to it. That will check that the fuel injectors are operating/firing in the proper sequence.
Best regards,
CJR
- Location
- Minneapolis, MN
When my 2000 is slow to start and will sometimes pop in the intake, I add a bottle of good quality fuel injection cleaner to the gas, and the symptoms clear up.
Timing issues or worn camshaft lobes are a possibility, but a very, very, remote possibility, and should only be considered after thorough, in-depth, and logical troubleshooting. One should always start trouble shooting and diagnostics with the basics, the common Jeep things, and the easy and cheap stuff.
Timing issues or worn camshaft lobes are a possibility, but a very, very, remote possibility, and should only be considered after thorough, in-depth, and logical troubleshooting. One should always start trouble shooting and diagnostics with the basics, the common Jeep things, and the easy and cheap stuff.
RCP Phx
NAXJA Forum User
- Location
- Phoenix,Az
Personally being a 2001 with the 0331 head I would go over every part in it! A valve cover gasket and a compression test (possibly even a lean down test) is cheap insurance for that motor.
