Rough Starts

[TheRebel]

I assuming I have leaking injector by some of the descriptions I’ve read on other posts, but my situation sounds a little different from what others were experiencing. When I start my car in the morning I have to crank it for what seems longer than usual if I don’t crank it very long it will start but shakes really bad till it warms up. When it starts after cranking it longer, it still shakes and has a rough idle, but I don’t see any smoke. Once it warms up it is fine. I only seem to have these problems after the car has set for a few hours or overnight. I’ve replaced the fuel filter, but don’t know where to go next. I know the dealership won’t be able to recreate the problem unless they keep it all day or over night (and then it still won’t happen because that is my luck) so I’d rather have an idea of where to have them look so they can verify a faulty part and get a new one coming.

 

[Deliciousdaly]

do you use 91 octane? I had a problem like that where someone used my car for a week where they used 87 and then gave it back and my car had a hard time running, it was like it was going to stall out. I took it into the shop and they replaced some wire, but later on i found out it was because these cars have such a high compression ratio they wont work for anything less

 

[TheRebel]

I use 93 octane

 

[beaups]

check fuel pressure. could be failing pump, regulator, etc. if it cranks a long time before it kicks over I'd think fuel pressure

 

[TheRebel]

I couldn’t find my fuel pressure gauge, but I noticed something this morning that makes me think it might not be totally fuel related. It was a little chilly and when I started my car, it started fine and then the idle lowered really quickly (if I remember correctly it never has idled high for very long since I flashed the ECM with a different tune). When the idle dropped the car started stumbling like it was going to die so I gave it some gas and it idle up in proportion to how much I pushed on the gas pedal (it climbed RPMs smoothly). When I let off the idle went back down and it was stumbling again and I thought I heard a backfire. If I held the gas down to keep the idle up till the engine warmed up a little the car ran fine (just like a carb engine with no choke). Once at operating temp the car runs great as always (actually I think it was accelerating a little quicker this morning since the outside temp was cooler). Tonight I am going to flash the ECM back to stock and see if maybe the idle part of my performance tune needs to be adjusted.

 

[TheRebel]

Flashed the ECM back to stock last night. It was colder this morning and seemd like the car still took a little extra cranking, but when it did start the idle quality was much better. I'm still going to check the fuel pressure if I can find my gauge or borrow someone elses. What should the fuel pressure be with the key on and the engine not running, and what pressure should be present with the engine running? Also is the LS regulator adjustable? If not is there an aftermarket adjustable regulator? Just curious