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Fuel pressure low when cold


TadsQuest
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I have searched and searched but found nothing with similar symptoms. When the engine is cold and I start it, the idle is low and tries to stall on me unless I keep feathering or steadily give it gas. Then if I try to drive it, its very lean, no power, and tries to stall under load.

 

Once it is warmed up everything is fine, tons of power and idles great.

 

Idk if its the CTS or what but I can't find anything else.

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I have searched and searched but found nothing with similar symptoms. When the engine is cold and I start it, the idle is low and tries to stall on me unless I keep feathering or steadily give it gas. Then if I try to drive it, its very lean, no power, and tries to stall under load.

 

Once it is warmed up everything is fine, tons of power and idles great.

 

Idk if its the CTS or what but I can't find anything else.

 

What is your Fuel Pressure reading at a Idle?

 

Bill

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You might as well change your topic title to my car won't idle and I don't know why. Maybe your spark plugs are the wrong type. Maybe you have dead lifters and inconsistent and low compression. I can swap a couple vacuum hoses and cause a car to ldle like crap but there's nothing wrong with it.
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Yes,you just need to estimate the coolant temp. test it with the engine cold. The manual should give both ohm and voltage specks.

 

Here's the specs on the CTS (per coolant temps):

 

32 degrees-5.9 ohms

68 degrees-2.5 ohms

104 degrees-1.1 ohms

176 degrees-0.3 ohms

 

Here is another way to do it. Disconnect the CTS plug. Go to Radio Shack and buy a 300 ohm resistor (a couple of bucks). Hook the ends of the resistor up to the plug (the 300 ohm resistor will fool the ECU into believing that the coolant is at 176 degrees, which is operating temp.). Does the car Idle fine? If so, the CTS needs replacing.

 

Bill

Edited by Caliber308
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The problem is, i need the plug to think its not at operating temp, so it will tell the ecu to give it more gas.

 

It is already getting TOO MUCH FUEL!!!!! That is why it runs like CRAP. When these cars are cold they run rich with the Throttle Body Set up we have. If the ECU sees 300 ohms from the CTS, it will lean the car out. Why do you think your car runs fine at operating temps, or runs better when you leave it parked in the sun? Because it is not getting drowned with fuel like it is at initial start up in your case. The only reason your car keeps running cold when you give it some gas is this: "You are clearing out some fuel so it won't die". Pull out your Spark Plugs after it runs for 5 minutes cold. They should be fuel soaked (Black).....And that is a overly rich condition that caused the Spark Plugs to look like it, not a lean one

 

Bill

Edited by Caliber308
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Alright so I hooked a 300ohm resistor to the CTS plug and it didnt help, it didn't change it at all. Also I checked the plugs and they were completely dry, not black, and did not smell like gas. Any other ideas would be helpful. Thanks again.

 

Also the bog i'm talking about under load is the boost gauge (stock) going up to zero but low RPMs, as if I was going up a hill.

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I got it fixed it was the CTS, thanks!

 

Glad to hear that.Maybe you didn't have the 300 ohm resistor hook up properly to the CTS plug? I had the same problem years ago, and the 300 ohm resistor told me it was a bad CTS.

 

Glad you got it fixed,

Bill

Edited by Caliber308
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