It starts up rough and uneven, like a plug wire is off when left overnight only.

takes 30 seconds of shaking to smooth out.

Then runs flawless all day!
(start and drive)

Every morning, back to horrible.

Fuel pump??
(On start up only, possible??)

Thanks!
Love the car since new!

 

Could be an injector that has some buildup that makes a bad fuel pattern when cold and when warmed pattern improved to allow complete burn. I would Try a can of BG Platinum 44k in tour gas at the next fill-up. IMHO.

 

I would also suspect an injector issue.
Any chance you could hook the car up to SDD and check for codes?
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A tire store said fuel pump and their are 2 or 3, One in the tank. He is not sure which one yet.

Could it be a fuel pump for 30 second on start up?

 

The tire store is correct there are 3 fuel pumps. The tank pump is relatively low pressure and either works or not. The other 2 are mechanically driven off a small "cam" shaft located on the lower right side of the block and are the high pressure pumps. and we have seen almost no failures. I still would try the BG 44k fuel injector cleaner before anything.

 

I ordered 2 cans.

 

Yes do that first. But again a fuel pump issue should have a code. Can you hook up SDD and see if anything is there?
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My 2013XJ is doing the same thing. Rough start up...then smooths out after a minute or so. Its at my mechanic, he read the codes (there were like 30+ codes) and suspects high pressure fuel pump.

I had an injector replaced about 8 months ago (and one of the O2 sensors). Im think this maybe related to that, but not sure.

Im not sure how much this pump is yet, but thought Id search this forum for some answers.

 

He said $900 for the part. (In tank)
But easy install.

 

The in tank pump assembly is relatively easy to replace. But it is not a high pressure pump. I still recommend that you run at least one tank of gas treated with BG 44K IMHO

 

The in tank pump/sender unit (C2D37814)
has a msrp of $545.00. Was that $900.00 a typo? Not trying to throw anyone under the bus, but just saying . . .

 

@KingRT, in addition to the fuel system additive, remember to always use a quality fuel as well.

How many miles are on the vehicle and when did the cold misfire(s) begin?

If the MIL begins to flash, do not drive the vehicle as catalyst damage is the result.

 

No typo.
This why I posted.
I will look into it.
Thanks!

Code reader came today and I cleared the codes and it started fine today.

Waiting for gas additives.

 

What codes did it show?

 

67000 miles.
misfire 1weel.

 

Rock Auto doesn't appear to have the low pressure pump, but two of the high pressure pumps available right now.
Bosch high pressure fuel pump for $163, or the Delphi pump for $395.
I don't know why they don't currently offer the low pressure pump.
Their injector prices are pretty good too.

...but as most have said above, the BG-44 will likely/hopefully clear it up to acceptable performance. Dirty injectors & I maybe carbon build-up on the back of intake valves, maybe even throttle body could degrade the smooth idle.
So is the BG-44k Platinum the best recommendation from those who have used it? (I've used mostly the Lucas fuel products.)

 

Don't know but I did just run a can thru my XJR that did not have any problems/symptoms. I thought it might be a good preventive thing to do since it's been recommended so much on this forum.
I did not notice any differences at all.
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I did just call BG, and spoke with a repp afor a while, and the BG-44k Platinum is their best retail product for pour-in injector cleaner.

 

It’s in.
Purchased 2 cans.
So 2 tank fills.

Thanks!

 

I ran 2 cans and tank fulls through, and still started rough.

The mechanic said it was a vacuum line going to the Mass Air Flow sensor.
No Charge.

We will see on morning start up.