OK, so I have three problems:

1- The car will not fire on the initial startup.
2- When coming off of the throttle and using the clutch, it drops to 500 or so RPM and surges between 500 and 1000 RPM then settles in at 750RPM (where it should be). I will add that the higher I am in the RPM range, the worse it is.
3- At standard highway speeds, when holding the throttle barely open (enough to maintain speed, not accelerating), it wants to sporatically "hiccup". I've even had one occasion, in fifth gear, where I press the throttle down more and it hesitates for a second or two then moves out. This has happened only once.

I've got a Blackwing with the hole in the radiator shroud. I've got a "icebox" but it's not installed at this moment.

The first one could be the check valve in the fuel pump OR a fuel pump regulator. I've had the fuel filter changed in the last month.

The second, I've run Techron through the motor, and cleaned the throttle body. I've also checked for air leaks behind the MAF. Could 2 and 3 be issues with the Throttle Position Sensor?

 

Hmm let's see here.

For 1), have you checked fuel pressure? You can buy a fuel pressure gauge that will simply plug into the fuel rail (it's a schrader valve, you just unscrew the plastic cap like you would a tire valve stem). They're pretty cheap. If you're not seeing proper fuel pressure when you put the key "on", then you have a fuel pump/regulator problem.

Fuel pump/regulator problem could easily cause #2 and #3 as well. How bad is #2? Honestly, both of my LS1 cars will dip in RPM after I throw in the clutch, and will surge a little bit. Depends on how bad it is.

If you determine that it's not a fuel pressure problem, I'd check into the MAF and the O2 sensors next. Either one can cause stumbling/surging/hard start problems. You can easily swap out a MAF (even from a friend's car?). Hell, unplug your MAF and try to start the car. It will run in SD mode - it should start but maybe run rough. If it starts the first time then you at least have a better idea.

Dope

 

For 1), have you checked fuel pressure? You can buy a fuel pressure gauge that will simply plug into the fuel rail (it's a schrader valve, you just unscrew the plastic cap like you would a tire valve stem). They're pretty cheap. If you're not seeing proper fuel pressure when you put the key "on", then you have a fuel pump/regulator problem.

Fuel pump/regulator problem could easily cause #2 and #3 as well. How bad is #2? Honestly, both of my LS1 cars will dip in RPM after I throw in the clutch, and will surge a little bit. Depends on how bad it is.

If you determine that it's not a fuel pressure problem, I'd check into the MAF and the O2 sensors next. Either one can cause stumbling/surging/hard start problems. You can easily swap out a MAF (even from a friend's car?). Hell, unplug your MAF and try to start the car. It will run in SD mode - it should start but maybe run rough. If it starts the first time then you at least have a better idea.

Dope[/QUOTE]

#2 is bad. The higher in the RPM range, the lower it will fall when it comes down, sometime down to 300-400 RPM. In some rare instances, it will stay there, not stalling, but stumbling. Then, it will "hunt" between about 500 and 1000. At some times, it will find 750 immediately, then drop off to 500, then surge to 1000.

 

may have some unmetered air getting in..might have a loose clamp connection as well

 

I've checked and rechecked all of the clamps. I don't see where I could get any unmetered air in, unless there is a connection that I'm not aware of.

 

I had a friend who is a professional mechanic (not your typical shade tree guy) and he did a scan of the computer. The only thing he thought that may be out of wack is when the car is idling, the throttle percentage was at 7%. If he hit the brake, while idling (and nothing else), it would jump to 15%. Tap the accelerator and it would go back down to 7%.

Is this normal?

 

What about an idle relearn. When you had the last work done on your car was the battery disconnected?

If power is disconnected to the PCM, then the manual indicates you need to perform and idle relearn to establish the right parameters.

Off the top of my head, I believe the procedure for a Manual transmission is you start the car and let it idle until the engine temp is above ~180*F, let it idle for 5 minutes with no other loads on the engine, then shut it off for 30 seconds.

 

OK, I did an idle relearn last night. NO change. The next thing I want to check is the MAF.

 

Anybody?