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Discussion Starter #1
for the last couple of weeks or so my car has been really hard to start when it is cold . if it sits fir several hours, or over night it will not start for shit, it will turn over and over but will not start , then all the sudden it will sputter a bit and if you pump the accelorator it will start running . the funny thing is when the car warms up it will start very easy just like it should. and it will continue starting all day just like it should ,has anyone had this problem? any ideas what it may be?
 

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T88 YOU
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there are many possibilities as to what it could be, i would check the CTS first, try checking the resistance when it is cold (with the connector unplugged of course) and it should have very high resistance, in the killiohms, and when it warms up to operating temperature measure it again, it should be very low resistance.
 

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Discussion Starter #3
would that be a crank trigger sensor? i was thinking it could only be a few thing since it only does this when it has set fr a while. can you tell me where this thing is .
 

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What kind of battery are you running and how many cranking amps does it have??

I had this problem but my reason was the battery was too small to power up all my electronics so if it sat for a couple hours it would go, and especially overnight.
 

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Discussion Starter #5
93BlueTurbo said:
What kind of battery are you running and how many cranking amps does it have??

I had this problem but my reason was the battery was too small to power up all my electronics so if it sat for a couple hours it would go, and especially overnight.
man there is plenty of power there, the car cranks ,turns the motor over quickly , its just not starting . i have a red top optima and it has worked fine . its not really a problem with the car not having enough power.
 

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you could try doing the 12v mod and see if that helps. This will help you determine if it is fuel or ignition.
I personally wouln't bother going with a mirror under the pannel to the fuel pump ecu, just
go to the large wire bundle near the driver side rear shock tower and cut the large 12v switched power wire (i think blue with orange stripe but check mkiv.com)then slap a butt connecter between the switched 12v and the fuel pump + wire and see if that helps...
 

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Sounds to me like an o2 sensor , OR a coolant temperatore sensor.

the ECU relies on the coolant temperature sensor (i think on our cars) and the o2 sensor to know if the engine is cold or not when starting. When its cold, your a/f ratio requirements to keep an engine on are different, you could go as low as 4:1 or 1.5:1 because the gas is simpl not being burned. As the engine warms up it starts to lean out the mixture and then returns the car back to idle.

In your case, you stated the following, will crank a lot=battery pretty good, but you have to give it some gas= you're making the fuel mixture more rich. This leads me to think that your engine isn't sensing that its cold, because if it is, the fuel injectors would automatically inject more gas rather then you doing it with the pedal.

But I could be wrong.
 

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when you step on the accelerator you are actually allowing more air in to mix.

my car (93 gs300/aristo 2jzgte) has been doing this lately as well. I noticed the FP guage on my Sard regulator is not showing any fuel pressure when i first turn the key on.. no prime signal..cant hear the pump either. When i actually crank the key it jumps up and has to crank over a few times and then she sputters to life. Runs rough and smells really rich for a few seconds too.. I have a walbro 255, JDM 440s and the sard regulator at 45 psi.

I'm going to check the fuel pump ecu in the trunk and do the 12v mod i guess. :scratch:
 

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TommyR1 said:
In your case, you stated the following, will crank a lot=battery pretty good, but you have to give it some gas= you're making the fuel mixture more rich. This leads me to think that your engine isn't sensing that its cold, because if it is, the fuel injectors would automatically inject more gas rather then you doing it with the pedal.

But I could be wrong.
Because you are on the accelerator one should not assume that means you are richening the mixture. The issue to me sounds like no fuel, or maybe bad maf....
 

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Discussion Starter #10
DoriftWolf said:
when you step on the accelerator you are actually allowing more air in to mix.

my car (93 gs300/aristo 2jzgte) has been doing this lately as well. I noticed the FP guage on my Sard regulator is not showing any fuel pressure when i first turn the key on.. no prime signal..cant hear the pump either. When i actually crank the key it jumps up and has to crank over a few times and then she sputters to life. Runs rough and smells really rich for a few seconds too.. I have a walbro 255, JDM 440s and the sard regulator at 45 psi.

I'm going to check the fuel pump ecu in the trunk and do the 12v mod i guess. :scratch:
that sounds like what my car is doing exactly
 

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Discussion Starter #11
i think i fixed the problem, and it was the plugs on the CTS. i took them off and rewired the with new plugs off of another harness i have laying around. started up nicely , thanks for everyones help!!
 
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