Hmmm, yes it's a mystery.
I'm still pretty sure it's not a vacuum leak. Covering the IACV hole in the throttle body causes the car to significantly bog down, although not die. Also, the power loss is throughout the RPM range, not just at idle.
I'm leaning away from ignition coil and ICM because it starts up nice an quickly. And as you mentioned, these fail rich, not lean. Although I have heard they are more likely to fail after warm up.
Here's another symptom. I noticed if I have the car in neutral, and rev up to, say 2000 RPMs, the RPMs start to decline, 1900, 1800, 1700. I have to press the gas more to get it to go back up to 2000. They won't keep declining, 2000 might go down to 1600 and stop there. Shouldn't the RPMs hold steady at a given opening of the throttle? I have a feeling this symptom might be more telling than previous symptoms.
I'm not sure if this matters, but the problem usually occurs when the engine is around 190 degrees. This might be why the engine runs great for 10 minutes.
I'll check the timing today and get back to you.
Also, when applying electrical load, the RPMs surge, or are SLOW to respond. Example, at 800 RPMs, turning on the headlights, half a second delay, then RPMs go up to 1000, then after a couple seconds settle back at 800. Weak IACV? Maybe this three second RPM jump and settle is normal.
- Intermitant loss of power
- High MPGs (lean running)
- erratic idle (settles anywhere from 600 to 1000 randomly)
- RPMs slowly lower at set throttle position
I've read that lean running can be Weak Coil, MAP, TPS, Air Intake Temp Sensor, Vacuum Leak and other stuff we've already ruled out.
Would a faulty IACV cause this problem?
Some notes on the brake booster. I am getting intermitant solid and soft pedal. This keeps pointing to a vacuum leak. When I tested the vacuum, previously, I hooked it to the brake vacuum line. So, I may have eliminated the source of the problem when I tested the pressure. I'll cover the IACV hole and try the propane technique one last time tonight.
Just for troubleshooting sake, what if we pretend the problems have nothing to do with the car warming up. As I'm noticing the cold performance seems to be getting worse as well.
Can I clean out the MAP sensor by soaking it in electrical cleaner?
Thanks again. I'm about to go parts shotgun on this because it's so frustrating.
Monday, April 27th, 2009 AT 5:19 PM