OK here is the problem in a nut shell.

I have a 1997 3.8 I have just changed the head gaskets on the car. These problems were there before I changed the head gaskets.

Problem number 1 the car will not hold fuel pressure without the pump running., I have changed the pressure regulator and it is still doing the same thing.

Problem number 2 the car is idleing rough and low and throwing a random multiple missfire code.
I have changed all of the sensors on the car with the exception of the MAF and the TPS. there are no vacume leaks that I can find. the wires and plugs look good. I have changed the coils and the ignition module.

I am at my wits end with this car. I don't know where to go from here. I am litterally about to just sell it.

ANY ideas on this?

 

Injector leaking? Leaking injector would cause rgh idle and cause the system to drop pressure.

Wire look good? I have never seen a wire that I could tell was bad by looking. Unless it was sitting for years. When you say all sensors does that mean the Crank and cam sensor?

 

Look good in other words no burns or cracks. No I have not done the crank and cam sensors. If it were an injector leaking shouldn't I see that on the plug? and would it run rough other times other than idle? Thanks Gorn..

 

If it was a small leak the biggest problem it would cause is ruff idle. Many times when a wire fails it just builds up to much resistance. Normally this will cause the coil to fail. If not fixed coils will keep failing over time.

Spark plug can be funny if you had just let the car idle for a while I would expect you would see some sign of too much fuel but if you where just driving it and shut it off the fuel leak might not have shown real bad. With a drip like this the faster you drive the the less the leak effects it. You can just pull out the whole rail and turn the key on and see if you have a leak.

 

Looks like I am pulling the rail off tomarrow. thanks Again Gorn..

 

Fuel pressure not holding with pump off is usually caused by:
Bad check valve in fuel pump
Bad pressure regulator
Leaky injector
External fuel leak

Random multiple misfire can be caused by:
Ignition system problem (wires, plugs, coils, etc..)
Lean fuel mixture (low fuel pressure, bad maf, bad O2 sensors)

Have fun.

 

^ I agree with Gorn about checking the injectors (this has happened to me)

To check for bad plug wires, plugs, or coils I like to use a timing light - connect the light up to each wire, one at a time, and if the spark isn't being fired for any reason the light won't flash. Any problem with the ignition will show erratic flashing. Makes tracking down the culprit a little bit easier. There might be a better tool for this besides a timing light but it has worked for me.

 

Or something like this

http://www.harborfreightusa.com/usa/...bCategoryName=

The nice part about using the tester is that it adds some load to the spark. This will show not only does the plug fire but it will fire under load.