JeepNasty93

Alrighty something is not right. My rig was fine but it's givin me trouble again. My fuel pressure is good, no leaky injectors, runs like a champ once started. It starts every time, it's just very slow to start, EXCEPT in the morning. In the morning it starts up fast like it should. But every time I try to start it after that, it's slow. then when it sits overnight it starts like no ones business. What gives? My timing is correct and everything. Anyone have a similar experience? I'm cornfused.

jordan96xj

Could be a number of things, but the first thing I would check would be your throttle body and whatever device controls your idle air (on the later XJs it is called an Idle Air Controller, but on earlier XJs I think it had a slightly different name). However, its job is to open a small port in the throttle body during startup and idle condition.

It often gets covered in gooey carbon over time, and that goo gets stickier when it is warm. So it is possible that yours is getting sticky when it is warm and not opening as it should. You can also try giving just a small amount of gas pedal while starting and see if it changes anything (this will also let just a little bit of air through the throttle body during startup).

Next up would be to clean-up all of your electrical connections and ground connections under the hood.

If neither of these help, then it could be something a little more involved like an ignition coil, crank position sensor, or fuel delivery problem related to thermal (heat).

JeepNasty93

awesome thanks for the quick reply. I'll check all of those right now.I'm not trying to stay awake tonight stressing about what the problem could be lol. I'll update as I troubleshoot

JeepNasty93

Okay so I let my iac valve dry over night (that thing was a mother to take out) and put it back in. it's still being crappy after the morning startup. I noticed something weird though. I've been messin with it all morning and noticed it starts up perfectly after I reset my ECU. After doing a little research, I've read that this is a symptom of a bad CPS. So looks like I'm gonna be replacing that to see if that'll help.

MtnGoat

My take is the engine is "flooded" when warm making for a long start to clear the cylinders. Overnight the fuel dissipates or drains into the crankcase.

Try adding a FP guage on the fuel rail. FP should bleed down after the engine is off after 30 minutes or so. If it bleeds down faster than that, check the FP regulator, or the injectors.

JeepNasty93

i checked the fuel pressure and it doesn't seem to change much if at all after half hour. And I pulled my fuel rail off with the injectors still attached and turned the key to the on position as well and no fuel seeped out onto the shop towel I had under it. I also tried the poor mans prime to see if maybe it was a fuel pump issue and it still cranks for about 5 seconds before start up. I changed the CPS just now on my break at work and that didn't fix the problem but at least I could check that off the troubleshoot list. Not sure where to go from here really. At this point I'm ALMOST willing to just live with it. It just makes me a little nervous when it sounds like it's almost about to die before it fires up at times.

JeepNasty93

Okay here is something I noticed, I adjusted the timing again just to make sure it was correct. (I've done this a few times btw. For good measure.) and noticed whenever I did, it would fire right up after. I'm so confused! Damn XJ... I hate her sometimes... to the point where I threaten to sell her, but I could never let her go haha.

JeepNasty93

If anyone happens to read this, I found out my hard starting was a MAP sensor issue. Which is odd because I thought a bad MAP sensor wouldve made my XJ run like crap. But I replaced it with a new MAP sensor from NAPA and she starts right up! I appreciate anyone that chimed in with suggestions!