Rough idle on restart

[Heckler1963]

Hi guys I need help with something. I have a 2000 XJ and I'm having the rough idle on restart problem. I installed new manifold heat shield, wrapped fuel rail and all six injectors, installed new 4 hole injectors, and new spark plugs.Still have problem. Anyone have any ideas? Really could use some help. This problem is driving me nuts!

[denverd1]

Hi guys I need help with something. I have a 2000 XJ and I'm having the rough idle on restart problem. I installed new manifold heat shield, wrapped fuel rail and all six injectors, installed new 4 hole injectors, and new spark plugs.Still have problem. Anyone have any ideas? Really could use some help. This problem is driving me nuts!
messed with your sensors at all?


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[Heckler1963]

Have not messed with sensors.

[Charlie Foxtrot]

Sometimes it's just something simple. How do the plugs look? Have you checked for vacuum leaks?

[denverd1]

Battery voltage good and terminals clean is another

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[Heckler1963]

No vacuum leaks, plugs are new, 12.81 volts on battery 13.75 volt at idle, and just install new coil pack. Checked fuel pressure at idle and needle on gauge was jumping around and 1500 rpm gauge showed 45 psi.

[nickyg]

My first thought was voltage. I know when I need a jump start when I leave my lights on. (which I do a lot) It runs funky for about 15 minutes till the battery catches up.

Have you tried cleaning the throttle body and the idle air control valve?

[4.3LXJ]

That heat issue is common with hot restarts on the 4.0L, even with the heat shield. You are right, very annoying. Have you vented your hood?

[Heckler1963]

Throttle body is clean. No have not vented hood and really don't want to. I'm original owner and it's my daily driver.

[4.3LXJ]

The thing that causes that rough idle on start up is heat. It vaporizes the fuel in the rail and has no place to go until it can condense again, or out the injector nozzle. You can try to wrap some strips of tinfoil around the injectors and try to keep the engine heat from the fuel. The only other thing that can be done is convert the tank and injector rail back to the pre 2000 style so it has a return line to take that fuel away and back to the tank. A major pain and expense

[Heckler1963]

I bought a kit from DEI that has a new heat shield for manifold six heat wraps for fuel injectors and a wrap for fuel rail. Still have problem. I even opened hood after I stopped restarted ten minutes later and still had rough idle.

[4.3LXJ]

I know. It is the combination of the newer intake manifold, which does flow better and the single line fuel rail. But humor me, try the tinfoil trick. Only pennies and easily removed if it doesn't work or you don't like how it looks. It will work better if you crinkle it up tight and then cut into strips first. If it works you can always try a little Dynomat cut into strips later if you want. Aluminum tape available at builders supply in the HVAC section will work to hold both in place

[Heckler1963]

OK check engine light came on today. Codes P0300, P0303, and P0305 came up. got home from Autozone shut it off came out and restarted it 10 minutes later and it ran really rough and check engine light was flashing. Seems to be getting worse!!!

[4.3LXJ]

I am surprised they didn't come on before. Those are misfire codes for cylinder #3

[Heckler1963]

I've owned this truck since new it's never did this till the spring of 2016. Why would it not have any heat soak problems for the first 15 years? I don't buy it. Last week it was 15 degrees out when I got home park in my driveway shut it off and opened hood. 15 min later came out and it ran rough.