weird cold start problem. need help - Tuner-Junction

Johnlude85 · #1 (**permalink**) April 24th, 2006, 10:58 PM

like the title says. i have a strange cold start issue. i cannot for the life of me figure out why. ill try to explain this the best i can.

this only happens after the car sits for 4 hours or more btw. ill use the first start of the day just as an example. i get in as usual, get all comfy in my nice 4th gen seats

, put the key in the hole and crank it over. well during this first start of the day, it takes about 4 times as long as it should to actually start. then it does start, and it seems to run really (not dangerously) rough. my rpms are at around 1300 - 1500...normal for cold start rpms, but it sounds like it misfires. well heres the thing, it doesent misfire, it just sounds like it does. no wacky idle, no popping/backfiring (other then the usual strange random popping my engine does). i cant figure out why its doing this. it has done it since the i got the engine in the car about 2 months ago, and im getting fed up with this problem, so now, ill take my questions here to you guys. it also seems to shake when it idles (which is another reason it feels kinda like a misfire). i can bring it up to about 2000-2500 rpms, and the shaking gets progressivle worse. but after a certain rpm (id say a little after 2300) the shaking goes away.

with high hopes to cure this problem, i have so far replaced:
the spark plugs - not the problem
the wires - not the problem
the entire distributor (came with new cap and rotor) - not the problem
the fuel filter - not the problem
i had a test pipe on there in place of my cat, so i now have an actual (new)catalytic converter - not the problem
the ecu is a chipped p28 from phearable so its not the computer

i have a code 22 for the vtec oil pressure switch, but that has nothing to do with it. i run 5w30 mobile 1 synthetc oil incase anyone is wondering. i run premium 93 octane incase any is wondering that too. and like a said before, it only happens when the car is cold. i can start it, itll run rough, let it warm up a little bit, shut it off, and start it up again and it runs and starts fine. fires on the 1st-2nd crank like it should. im shot for ideas here. can ANYONE please help me out, i dont want to hurt my engine with something as stupid as this.

im sorry the post is so long and greatly thank anyone for reading it.

jon ROCKS!!!! · #2 (**permalink**) April 24th, 2006, 11:02 PM

what is your fuel pressure at on start up?

Johnlude85 · #3 (**permalink**) April 24th, 2006, 11:09 PM

Quote:

Originally Posted by jon ROCKS!!!!

what is your fuel pressure at on start up?

thats a good question that i too was wondering. i dont have a gauge. would it make a difference though? wouldnt it run like that all the time, not just for the first 5 minutes of a cold start?

jon ROCKS!!!! · #4 (**permalink**) April 24th, 2006, 11:15 PM

Quote:

Originally Posted by Johnlude85

thats a good question that i too was wondering. i dont have a gauge. would it make a difference though? wouldnt it run like that all the time, not just for the first 5 minutes of a cold start?

could just be somthing weird with the fuel pump, that is where i would check first

Johnlude85 · #5 (**permalink**) April 24th, 2006, 11:18 PM

well till i get a chance to check, lets hear some other opinions guys. thanks jon btw. ill hafta get a fuel pressure gauge next time snap-on man comes to the shop lol

Johnlude85 · #6 (**permalink**) April 24th, 2006, 11:45 PM

i do have a valve tap, ill need to do a valve adjustment. could that possible have anything to do with it?

jon ROCKS!!!! · #7 (**permalink**) April 25th, 2006, 12:16 AM

Quote:

Originally Posted by Johnlude85

i do have a valve tap, ill need to do a valve adjustment. could that possible have anything to do with it?

doubtful

long cranking time is usually signs of a failing fuel pump, shitty spark, or some kind of sensor problem

Mustangeater · #8 (**permalink**) April 25th, 2006, 05:34 PM

run a compression test, a burnt valve can sometimes have that effect until the engine warms up and the vavle swells due to tempatures. I would check compression cold then start it and warm it up and check it warm, and deffinetly adjust your valves that could posibly be the problem remember heat swells metal i know that sounds dumb to keep repeating but strange things can happen like that.

Johnlude85 · #9 (**permalink**) April 25th, 2006, 06:34 PM

Quote:

Originally Posted by Mustangeater

run a compression test, a burnt valve can sometimes have that effect until the engine warms up and the vavle swells due to tempatures. I would check compression cold then start it and warm it up and check it warm, and deffinetly adjust your valves that could posibly be the problem remember heat swells metal i know that sounds dumb to keep repeating but strange things can happen like that.

well i did do a quick compression test not too long ago just out of curoisity. i did it cold, and forgot to do it with the throttle plate open, so the throttle body was closed. im not sure if there would be higher numbers or lower numbers with the tb open. but i got 185psi for #4, 185psi for #3, 185psi for #2, and 175psi for #1. so im 10 pounds short in culinder number 1. it is within factory specs so i dont see it being a problem, coulda just ben a carbon deposit or something simple like that.

Johnlude85 · #10 (**permalink**) April 26th, 2006, 08:48 PM

i ben thinking, i might have a bad coolant temp sensor. that could cause my symptoms ive ben having, but if i did have a bad ect, wouldnt i have a cel code for it or not necessarily?