difran25

i have a 1999 trans am 30th that wont start in cold weather. im not talking about freezing temps. anything below about 50 degrees the car wont fire. it will turn over fine and just not fire. new plugs and new wires. fuel pump is fine. anyone ever hear of this? when the weather is nicer out the car starts right up with no problem at all. it doesnt make any sense why the cooler temps would not allow for start up. thanks

Old Geezer

iTrader: (3)

Maybe try the correct forum???
Tune/diagnostics might be a good start.............

Mac 2002 SS

iTrader: (6)

have you ever changed the starter on your car ? that could be the problem.

difran25

The car is from texas his whole life i just got it to NY. I have not replaced the starter. you think the cooler weather would have an effect on the starter even if it is turning over.?

M1SERY

sounds like ur ect sensor is out of limits, this is how i would check it 1st thing in the morning after the car has set all night ,put ur scan tool on it and check the sensor data dont start the car, has to be done while its cool out side early in the morning, look at the ect reading and the iat sensor reading they should about the same no more than a couple of degrees different in the two sensors, of course use some common sense when looking at them ,you know 3 maybe ok but 5 degrees may indicate a bad ect sensor .

if it shows a big difference and you suspect a bad sensor there is a test where you pull the sensor out and put it in water and change the condition of the water temp, and read the resistance, compare those reading to the reading that u would get off any shop key for that test and this will verify if the sensor is bad. or if it shows good u may have a corrision build up in the wire or a plug ect.
ps. if you what to do a little check without a meter to verify the wiring, one way is to unplug the sensor after the first test the look at the scan
tool data ect it should read something like -40 degrees thinking its on the north poll,and then take a jumper wire and jump the plug and the data should read 240 or some thing like that , thinking its on the sun , if ur reading is any one of these too reading before u unplug or jump the plug it will indicate an open (-40) or short to ground (240)
good luck my friend

difran25

thanks for the great advice. where is that sensor located?

Remnant-of-VII

It's on the driver side cylinder head, to the left of the exhaust manifold.

mchicia1

iTrader: (5)

Is this car tuned? Idle and startup have many tables based purely on ECT.

difran25

i dont know if the car was ever tuned. i just got it. but the car starts and idles great, just in cooler temps it does not. im going to replace the coolant sensor its 15$ and try that. i did reasearch on the sensor and it does say it will crank and not fire if its screwy

SSellers

The system in my '69 uses the same ECT sensor. I had one go bad and would not read lower than 60 degrees even in a cup of icewater but read fine above 60. The colder the ECT reads, the more cranking fuel is used. Wish I had replaced it first instead of spending so much time tuning it to start in freezing temps since it just screwed up my hot starts.

difran25

i replaced the ect sensor yesterday. this morning was cold and i went to start it. still wont fire. i drove the car yesterday after i chaged it and it ran great. is there another sensor that would hold the engine from firing? i thought this would fix it but there must be something thats telling it not to start. it sounds like a sensor but what else would hold it out?

mchicia1

iTrader: (5)

It sounds like the car was idle tuned but they never addressed the colder ECT base running airflow cells. It doesn't have enough airflow in the colder cells most likely.

Are you able to pedal it at all and get it to fire?

difran25

ill try to see if i can pedel it. where do i take it to get it tuned so it will start in cooler weather? for them to do that wouldnt it have to be cooler outside when they do it?

mchicia1

iTrader: (5)

Ok if you can crack the throttle and get it to start, it is an airflow issue.

You need to find someone who has hptuners or efiLive. Yes, the best scenario would be to get it tuned in that cooler weather so you can reproduce the issue to the tuner.

Mac 2002 SS

iTrader: (6)

lol...naw,not at all,man! I just said it could be your starter thats bad cause it seems your car will fire and run just fine every other time you try to start it and then when you turn the car off,it won't start for you. I had the same problem about two weeks ago. Pull the starter out and had it tested and it was shot!! Put a new starter in and she fires right up without any problems. It was just a suggestion .

difran25

cooler this morning wouldnt fire. i pedeled it. after about the 8th try with the pedel it fired. so im not really sure if it was just luck or the throttle body opening helped.

Mac 2002 SS

iTrader: (6)

Is your car starting without any problems now ?

garygnu

unplug and replug all your sensors.you mite have moisture in your connections.check for the moisture seals in all wire connections .check the crank sensor .

mchicia1

iTrader: (5)

If it started by pedaling, then your issue is either too much fuel or not enough startup airflow or the base airflow tables are fucked.

You need a tuner to fix this. If you were close to me, I'd help you out. I am in eastern PA.

difran25

Thanks for the info. No the car still doesn't fire up in cooler temps. Only problem is it is getting to warm out side now where I shouldn't see this again until fall. Not a bad thing but this is so annoing.