I changed my headers a couple weeks back, and also replaced the spark plugs, but after this, my car has had rough starts if i start it up within a couple minutes of turning it off. I thought maybe it would be corrected after the tune but it still does the same thing. Only thing that I know I need to fix right now is all the egr gaskets need to be replaced(which I have absolutely no idea why that would even affect my starts but I figured I would mention it anyway). Also the spark plugs got wet after i took them out of the box, we set them on my friends truck and he eventually backed the truck out of the car port and forgot they were on there after it started raining. We cleaned them up as good as we could and the car still runs fine, just the warm starts are really rough, i usually have to hold the gas down for it to start we its rough like that. Has anyone run into this problem before? I didn't **** something expensive up did I? Any help is appreciated.

 

What kind of spark plugs are you using, and at what gap? If the plugs are anything but NGK or ACDelco, and/or the gap is larger than .050", that's a problem.

 

NGK TR55's and I gapped to .040

 

Fix the EGR gaskets and see if that helps. An exhaust leak can cause issues.

 

I plan on fixing the gaskets this weekend, been on 12s with no days off because of an exercise for over a week so I really haven't had the time yet. I'll see if that fixes it.

 

I know they are unrelated to the recent work but removing and cleaning both the MAF and IAC would be a good idea - especially since it's easy and very inexpensive.

 

Or you can take the EGR/AIR system off entirely if you don't have emissions. Takes about 20 mins tops....

Stock LS1 plug gap is .055" if your car isn't internally modded and you aren't running power adders.

 

My car came with Denso plugs from the factory and I ran Bosch single electrode plats for ~50k miles (half of which was while cammed) w/no probs so I don't think plug brands have that much to do with it.


While you were doing the headers, did you reconnect the O2 sensors? Did you get the front O2's back up front or could you have used the rear O2's? Are all your plug wires on good? Is this a local tune or mail order or hand held?

 

GM recommended gap is now .040"

 

^ I gapped mine at .055 and I still have them in there, and NEED to be changed.. .

ANyway.. Try this on a cold start: Turn the key to on (NOT start), wait for fuel pump to kick off, then turn it off then back to ON again.. Try this three times to bump the fuel pressure up.. THen try to start it.. If it works after that, replace the fuel filter.. It may just be a coincidence that you may need a fuel filter..

Did you replace the wires? Also, holding/pumping the gas doesn't do squat on an EFI car. Did you mess w/ the MAP sensor?? Just for curiosity.. Check the MAF sensor connections too.. Although the MAF would cause TERRIBLE drivability issues, same w/ the EGR if it were stuck open. If the gaskets on the EGR were bad, you will notice a slight drop in gas mileage.

 

The ONLY way I could get the car to start while it was still really warm (1-5minutes) was to hold the gas pedal all the way down until it cranked, then the idle would hang at about 2k-2.2k for 5-10 seconds before going back down to a 800 idle. But when i start the car 10-20 minutes after shutdown, I can crank it without using gas but it barely starts and if you try to rev the motor some, it acts like its a carbed car on a cold start, it hesitates to rev for a second or 2, this only lasts for 20 seconds or so. It is kinda weird, never seen a car do anything like this before. I am thinking its the fuel filter tho.

(cold starts start up just fine like nothing is wrong)

 

yes the sensors were reconnected but my buddy did that part and I doubt he payed attention which one came from where, yes plug wires are on good, hand held tune

 

^ Hypertech?? I've heard of some people having starting issues w/ the Hand held tuners.. Return it back to the stock tune and see how it acts.. IMO, Hand helds aren't that great unless pre-loaded w/ a specific tune.

 

Diablo Predator tune, and this was already happening before i tuned it

 

IIRC the rear O2's are a different part number than the front.