Since i put my motor back together it has been behaving abnormally. When I give it throttle, it revs up, then slows down, revs up and slows down, while i'm giving it the same throttle the whole time. Then sometimes it'll die shortly after I start it while it's idling, but i gave it a different IAC (not new, just different than the previous IAC) so that problem may be absolved.
MAP is all connected. On a cold start it idles at 1500 and then goes to 900, which is normal. I have no idea how to verify fuel pressure. I forgot to mention in my first post, there's is black junk coming out of the tailpipe. Here's a pic:
Is it possible that this is caused by too far advanced timing?
Something else I forgot to mention, it was fine last night. Idled good, smooth, reliable. The difference between last night and this morning is that I put the thermostat back in. I highly doubt the thermostat is causing this, but I like to keep an open mind.
[This message has been edited by MordacP (edited 10-12-2007).]
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03:32 PM
CC Rider Member
Posts: 2037 From: Cameron Park, Ca Registered: May 2001
How long have you had it running once you got the motor back together? Could the ECM be resetting itself after all the work you did? Did you adjust the IAC before installing? Any codes since the work being done?
What work did you do to the motor?
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04:03 PM
MordacP Member
Posts: 1300 From: Clovis, California, US Registered: Sep 2007
How does one adjust the IAC and why? I changed the head gasket. I have been running it less than 24 hours. These spontaneous problems do make it seem like the computer is figuring stuff out. The service engine soon light isn't on. Or do i have to jump those two terminals in order to see codes?
What about the black stuff?
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04:22 PM
MordacP Member
Posts: 1300 From: Clovis, California, US Registered: Sep 2007
It would make sense to me that it's a fuel pressure problem. That black stuff could be unburned fuel, and the unresponsive throttle would also make sense. So, how do i check the fuel pressure?
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04:25 PM
BobadooFunk Member
Posts: 5436 From: Pittsburgh PA Registered: Jun 2003
The black stuff is soot left from running rich normally. Then when you start up the water that forms in the exhaust from shor runs picks some of it up and spits it out when you start the car.
If you have bee running the engine without the stat it will run richer for longer since it does not heat up as fast.
As far as setting the IAC as long as it was not out very far when you installed it, (like an inch or less) you should be ok. Just as long as it was not out far enough to get smashed inthe the seat when you screwed it in. If you have not driven the car very much or not fast enough the iac has not set itself yet.
But it's a good idea to always check your fuel pressure first to eliminate that.
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08:20 PM
Oct 14th, 2007
MordacP Member
Posts: 1300 From: Clovis, California, US Registered: Sep 2007
I got a fuel pressure tester and performed the check. It went up to about 47-ish PSI when the igition was turned on and the pump ran, then QUICKLY (in a few seconds) dropped at least 10 PSI to 35-ish. The drop slowed down after that but continued to drop down to 10PSI. SI this normal behavior? I will give the results when I start the motor when my stupid battery (which is new and has died several times) is done charging. Good thing I have a warranty.
The 10 PSI you report is much lower than is typical with fuel injection, and in fact only a few PSI higher than what you'd expect with a carbureted system.
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06:37 PM
MordacP Member
Posts: 1300 From: Clovis, California, US Registered: Sep 2007
Yeah, but that was after the pump stopped running. So it might be okay. I have also got a compression checker, so if anyone following this thread will tell what the compression is supposed to be after so many seconds of cranking, that would be swell. I looked in the haynes manual, and couldn't find it.
The strange thing about this fuel pump test is that i ran the pump a few more times, and the pressure kept within the range you mentioned. The pressure only fell the very first time I turned the key.
I cranked my motor for 5 seconds (counting 1-one-thousand, two-one-thousand.......) and the compression tester reads 140 lbs. Is this normal?
I also found a severed spark plug wire, this may be the cause of my woes.
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08:32 PM
MordacP Member
Posts: 1300 From: Clovis, California, US Registered: Sep 2007