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3.8 Liter Hard Starting and Erractic Idle Hard starting when weather is cold and motor is cold. Rate Topic: -----

#1 User is offline   JMAC 

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Posted 23 October 2009 - 05:58 AM

Hey Guys,
I have a 1997 Firebird. 3.8 liter engine. Since the weather here has turned cool I am having a hard time with my car starting in the mornings. Once it starts it idles a little erractic but not severe. The weather here is back and forth right now. When it is warm in the mornings the car starts fine and seems to idle okay. The problem only showed up once the cooler weather got here. I was thinking a cold start switch bad or maybe a temperture sensor. Does that apply to this application? The computer isn't throwing any codes at all. Once you drive it and stop at like a store or anything it cranks fine, hence once the motor has warmed up. Any ideas will be greatly appreciated.

thanks in advance,

JMAC
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Posted 23 October 2009 - 07:34 AM

Sounds like it could be the engine coolant temp sensor, might want to test that first.
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#3 User is offline   whitdog54 

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Posted 26 October 2009 - 05:50 AM

any SES codes?

This post has been edited by whitdog54: 26 October 2009 - 05:50 AM

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#4 User is offline   JMAC 

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Posted 26 October 2009 - 08:04 AM

View Postwhitdog54, on 26 October 2009 - 05:50 AM, said:

any SES codes? No codes are showing up. It was cool out this morning so just to check it again I went out and cranked it. Turned the key once, motor turned over but would not start. Released the key, turned the key again and the motor started right up. Let it idle, and it idled a little bit erractic until the motor warmed up and then it idled okay. Haven't replaced the temp sensor yet but probably will give that a try. Any other suggestions would be appreciated.

thanks,

JMAC

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Posted 26 October 2009 - 10:35 AM

Check the fuel pressure.
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#6 User is offline   whitdog54 

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Posted 27 October 2009 - 05:30 AM

Yea, was just going to say maybe bad fuel pump. Do you hear a whine when you turn the key to on position? Might want to check your fuel filter too.
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#7 User is offline   Scotts 98 

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Posted 27 October 2009 - 07:34 PM

Don't forget the fuel pressure regulator.
:twocents:
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#8 User is offline   JMAC 

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Posted 28 October 2009 - 05:02 AM

View Postscott-leanne, on 27 October 2009 - 07:34 PM, said:

Don't forget the fuel pressure regulator.
http://www.firebirdnation.com/forums/public/style_emoticons/default/twocents.gif Checked fuel pressure.....it checks fine. Haven't thought about the requlator and will give that a look. This morning the weather is warmer and the car started right up without a problem. Making me lean back towards the temperture sensor?

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#9 User is offline   Scotts 98 

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Posted 28 October 2009 - 03:47 PM

Check this post out...

http://www.firebirdn...l=&fromsearch=1

I did not want to retype it all.

:12EMOTICHEERS:

This post has been edited by scott-leanne: 28 October 2009 - 07:31 PM

1968 Dodge SuperBee
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#10 User is offline   whitdog54 

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Posted 29 October 2009 - 04:32 AM

is it my computer, or do you keep pquating people, but then do not have a response. Do you have any ses codes?
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#11 User is offline   Scotts 98 

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Posted 29 October 2009 - 12:04 PM

View Postwhitdog54, on 29 October 2009 - 04:32 AM, said:

is it my computer, or do you keep pquating people, but then do not have a response. Do you have any ses codes?


What does this mean??? "is it my computer, or do you keep pquating people, but then do not have a response"

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#12 User is offline   JMAC 

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Posted 29 October 2009 - 04:30 PM

View Postscott-leanne, on 29 October 2009 - 12:04 PM, said:

What does this mean??? "is it my computer, or do you keep pquating people, but then do not have a response"

http://www.firebirdnation.com/forums/public/style_emoticons/default/B%29.gif
Thanks for the heads up on the posting about the regulator. I checked my requlator today and there is no fuel leakage into it. The vacuum line that goes to it is dry all the way through. I couldn't find a trace of fuel in it at all. I checked it for difference in pressure as you work the throttle back and forth. The vacuum does change as you increase and decrease the throttle. So thinking the regulator is okay but still not positive. I did go ahead and change out the temperture sensor, air filter, fuel filter and replaced a couple of fraile vacuum lines just in case. I will wait till in the morning to see if any of this helped. The car usually has to sit about 5 or 6 hours before it will duplicate the problem. If is only sits 2 or 3 hours then it starts fine. That is what is puzzling about the situation.
Whitdog, I am not sure if you are getting my postings are what is going on there. But no, there are no codes showing up at all. I have had it checked for that and there are no codes stored nor has the check engine light came on. I wish it would throw a code so that would point me in the right direction. I am really hoping by some small chance that is is the temperture sensor. Nothing else really is just making sense with this. Thanks for the help.

JMAC
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#13 User is offline   Scotts 98 

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Posted 29 October 2009 - 06:20 PM

Let us know...
Oh, your regulator is good. All it does is... create a higher pressure of fuel for your injectors when you hit it. When the vacuum drops, the pressure in the injector rails goes up. You can see this with a fuel pressure gauge.
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#14 User is offline   JMAC 

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Posted 31 October 2009 - 05:21 AM

View Postscott-leanne, on 29 October 2009 - 06:20 PM, said:

Let us know...
Oh, your regulator is good. All it does is... create a higher pressure of fuel for your injectors when you hit it. When the vacuum drops, the pressure in the injector rails goes up. You can see this with a fuel pressure gauge.
http://www.firebirdnation.com/forums/public/style_emoticons/default/B%29.gif
Update. I changed the fuel filter, the air cleaner filter, put in new temp sensor unit. Car starts better and on the first try. However, instead of starting right up like it use to, it takes about 2 to 3 seconds of the motor turning over before it cranks. This could be normal? Seems like the car use to crank right up as soon as you turned the key to start it. The car now idles fine and runs good. Just let me know what you guys think and if you have similar reactions out of your car when it is cooler outside. Thanks again for all the help.

JMAC
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Posted 31 October 2009 - 11:58 AM

When you say the fuel pressure tested fine, can you tell us what the pressure tested at, and how long it held the pressure after the fuel pump cycled off?
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#16 User is offline   JMAC 

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Posted 31 October 2009 - 08:36 PM

View PostBob, on 31 October 2009 - 11:58 AM, said:

When you say the fuel pressure tested fine, can you tell us what the pressure tested at, and how long it held the pressure after the fuel pump cycled off?
Bob, that is a good question. I had a local shop check it for me. He said it was in the limits. If I remember correctly I think he said it was around 50 PSI. He let it sit there with the guage hooked up for about 5 minutes or so and said it was okay. That is all I am going by. I may buy a guage myself and check it. The car is starting fine but it is after you turn the motor over once and turn the key back and then try it again. Meaning it is starting fine on the second try. It will start and run on the first try but it takes about 3 or 4 seconds of the motor turning over before it will crank and run. I am thinking of in the morning turning the key on and off twice (cycling the pump twice) before actually trying to start the car and see if it will start right up. What should the fuel pressure do, so that I will know? I know the pump is running because you can hear it make a humming noise for a few seconds when you first turn the key on. After the car starts you can then hear the pump running all the time. One thing I have checked is to release all the fuel pressure through the schrader valve and then turn the key on again. After doing this, I went back to the schrader valve and there was fuel pressure there again or at least fuel would spew out again once I pushed the schrader valve in. Let me know what you think and if the pressure he told me is correct. Or any other checks you know I could do will be appreciated. I will let you know how the car starts with me trying to turn the key twice before starting the car, then starting once the pump has cycled twice before starting.

thanks again
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Posted 01 November 2009 - 12:05 AM

The pressure should be between 41 and 47 psi and should hold after the pump cycles off. Although there may be fuel coming out of the schrader valve, that doesn't mean the pressure is correct, so that is definitely something I would look into. When was the last time the car was tuned up? Have you checked for vacuum leaks?
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#18 User is offline   JMAC 

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Posted 01 November 2009 - 10:24 AM

Hey Bob,
I am going to check the pressure again. I was thinking about doing another tune up. I did a complete tuneup on it about 10,000 miles ago. This morning, I did cycle the fuel pump three times before trying to turn the motor over to crank the car. The car seemed to start a little better. It cranked in about 1 or 2 seconds instead of taking 3 or 4 seconds. I let it set every hour and tried starting it again and it did about the same, starting within 1 or 2 seconds. The last time I let the car warm up and then turned it off. Then I cranked it over again and it started as soon as I turned the key to the run/crank position. The fuel pump seems fine. You can hear it energize everytime you turn the key on. I am going to check the fuel pressure again and make sure it holds steady. I am starting to lean towards maybe it needs a tuneup. I had to replace the ignition module about 12,000 miles ago but when it was bad the car wouldn't start at all. Once I replaced it, the car cranked extremely well, better than it ever had. I am starting to wonder if the module is going bad again. Anyway, I will keep you guys updated once I find what the problem may be. Thanks again for all the help.

JMAC
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#19 User is offline   JMAC 

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Posted 05 November 2009 - 02:40 PM

View PostJMAC, on 01 November 2009 - 10:24 AM, said:

Hey Bob,
I am going to check the pressure again. I was thinking about doing another tune up. I did a complete tuneup on it about 10,000 miles ago. This morning, I did cycle the fuel pump three times before trying to turn the motor over to crank the car. The car seemed to start a little better. It cranked in about 1 or 2 seconds instead of taking 3 or 4 seconds. I let it set every hour and tried starting it again and it did about the same, starting within 1 or 2 seconds. The last time I let the car warm up and then turned it off. Then I cranked it over again and it started as soon as I turned the key to the run/crank position. The fuel pump seems fine. You can hear it energize everytime you turn the key on. I am going to check the fuel pressure again and make sure it holds steady. I am starting to lean towards maybe it needs a tuneup. I had to replace the ignition module about 12,000 miles ago but when it was bad the car wouldn't start at all. Once I replaced it, the car cranked extremely well, better than it ever had. I am starting to wonder if the module is going bad again. Anyway, I will keep you guys updated once I find what the problem may be. Thanks again for all the help.

JMAC



UPDATE: I put new plugs and wires in car. Still the same result. I finally and went and bought a pressure guage so I could check the fuel pressure. When you turn the key on, the pressure goes to around 48 to 50 PSI. After letting it sit for about 15 or 20 minutes, the pressure drops to like 35 to 38 PSI. If you let it set for a couple hours it goes down to like 15 psi. So is this normal? If not, does this mean the fuel pump is going bad, the relay is bad or the regulator? When you first turn the key on the fuel pump does energize so I am ruling out the relay to the pump. However I am not sure. It still does the same thing. You first turn the motor over the first time for 5 or 6 seconds it won't start. You turn the key back and turn the motor over the second time and it starts right up. Almost like it isn't getting enough fuel the first time. I did replace the fuel filter already. Sombody local had told me that he has seen the igniton box (under the coil packs) going bad and causes this. Once the car starts it runs fine and idles fine now. It doesn't stall or anything. Just hard to start the first initial turn over and then after it sits 2 or 3 hours it is the same again. Any more ideas would be appreciated.

thanks,
JMAC
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#20 User is offline   Scotts 98 

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Posted 05 November 2009 - 06:49 PM

Where did you buy the ignition module? I remember replacing one on one of my other cars a while ago. I bought it from NAPA and the car did not like to start. I bought one from a chevy/gm dealer and the car started like new and ran better. Also, I replaced an Idle bypass valve on a different car with one from autozone and it made the care surge on the highway with the cruse set, it never did this before. I replaced it with an OEM one and its fine. Bottom line is, some stuff like plugs, wires, filters, regulators are fine from autozone and napa but I've noticed when I replace electronic control stuff, O2's, tps, cps, maf... I have better luck with OEM overall. It costs more sometimes but not allways.
Let us know...
Your bird should start like mine, turn the key to start and bang, right up!
It sounds like your fuel injectors are ok and not leaking down, the fuel pressure for a 97 bird 3800 is... key on not running; 41 to 47psi. Engine running; pressure should decrease by 3 to 10 psi.
This info is out of a Haynes manual, if you don't have one, get one or get a chiltons. They are inexpensive and at most autoparts stores.

Hey, didn't someone say something about the crankshaft position sensor?
Sometimes when I can't find something you have to think what would make it not start right up? Have you checked the EGR Valve to make sure its not causing a vaccum leak? It should be closed at idle, (will not let air through).
Scott
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