Stumped by hard start
 

Alright. I am having a hard start issue sometimes. It generally seems like it mainly happens first thing in the morning or when the jeep has been shut off for more than 30mins-1hr. Normally cranks in 2-3 secs if I had to guess and when it acts up it can take upwards of 10 or more seconds. Also I sometimes get a stumble and crap idle and it clears out when it finally start. It is a 98 Model XJ.


So far I have replaced the pump, replaced the fuel pressure regulator that sits on top of the pump, took all that out and replaced with a drop in Bosch unit! everytime it seems to help it for awhile and then back to the same stuff. New upper fuel line, New CPS, new IACV, New CTS, plugs and wires seem to be in good condition as well as the cap and rotor, I have no exhaust leaks, I have upgraded the injectors to 4 hole bosch and they have never leaked down during inspection.


I am completely stumped ive tried so much stuff and still have the hard start. Any help is appreciated!

It's probably your heat injector shield, I have the same problem with rough starts after my engine is being started again usually for the second time within an hour or so. It's not the worst thing ever but it did cause my check engine light to come on. Luckily it's an $8 fix and shouldn't take more than 10 min to replace.

What's actually happening is your third injector is misfiring when you start up your jeep again, the shield is basically tin foil with insulation in the middle. You would be surprised to find out that replacing it actually does solve this problem.

mine usually does ok on restarts. il look into that

it seems like the injector heat soak is more prone to the 99+ models with the horse shoe intake. I had hood risers and its already pretty cold here in Virginia. Im highly doubting that is my problem.

Hey man it's an $8 fix and I heard from many people they've been surprised with the results, and even if that may not be the issue these shields are supposed to be replaced anyway so it can't hurt. I'm probably gonna buy myself one today to replace

do you have a picture? Ive never seen a heat shield on my manifold. why I was kinda thinking it was probably a 99up thing.

Cut the exhaust in front of the converter as a last option thinking it may be clogged. It does seem to start better and my shifts aren't as delayed and a lot smoother. However honeycomb is still intact and it doesn't sound like anything it loose in it!

It was an 0331 head only issue so 2000-2001 in xj's.

bump

Sounds like you're bleeding fuel pressure off. Have the rail tested after the jeep has sat for a while. My 97 would do the same thing and I was losing pressure at rail when I shut it off.