| After installing a new battery, the problem is not solved. The problem again is that when cold, once the initial high idle cycle is done (air regulator closes), the car starts bringing down the idle. It will idle around 400-500 RPM and then die. I can drive the car around, with absolutely no driveability issues other than this idle. Even when warm, the idle will drop to 400-500 RPM, occassionally stalling, however, when cold, it pretty much stalls right out. I can see the vacuum going down as it approaches 750 RPM (about -20 in-Hg). After that, the vacuum really goes down as the idle is dropping until she stalls. So far, I have tried the following with no resolution: 1. Boost Leak test. I have a very very very small boost leak which shouldn't be causing this problem.
2. I have disconnected both clutch booster & brake booster right at the engine and plugged the holes to make sure that they aren't causing a vacuum leak. The certainly aren't the cause of this leak.
3. Cleaning throttle bodies.
4. Adjusting the Idle Air Screw - turning this screw does absolutely nothing to improving the idle. I have it backed out almost all the way and the idle doesn't rise. However, if I full screw it in, the car will stall right away. The connector has been cleaned many times and is fine. There is continuity between it and the ECU.
5. AAC Valve does appear to work. I can hear the solenoid ticking away. I have also done the WD40 trick to clean it and lube it.
6. Used another ECU. It didn't make a difference.
7. Checked fuel pressure. It is perfect as per the FSM.
8. Checked coolant temperature sensor. Nissan Datascan reads it and the temperature rises as engine temperature goes up. I even tried another coolant temp sensor that I have.
9. Power Balance test. Passed without an issue.
10. O2 test. I did this as per the FSM and it passed. A few notes (I believe that the car should be doing these things): 1. Disconnecting the coolant temp sensor while the engine is running makes it idle high and it won't stall.
2. Disconnecting the gray TPS connector also will make it idle high and it won't stall. A few things I am planning on trying tomorrow: 1. Install a different set of "known good" MAFs.
2. Check spark plugs and possible change them out for the PRF6B-11B's that I have kicking around somewhere. The current plugs in the engine (NGK Iridiums 7) have been in there for about 2 years without an issue. I look forward to hearing any good advice. After these last 2 things to try, I am completely stumped.
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