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kingbucktoo
P Plater
54 Posts
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 Posted - 02 Nov 2011 : 9:08:59 PM
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Has anyone found a good description on how the ECU works on the net??
Just tryimg to problem solve V8 mis firing.
Don't have access to a TECH1 but I downloaded a program from the net, made the interface cable. I connected this to the ALDL plug and data started to stream out.
The motor was close to operating temp. 89 degrees C
The one thing I saw was the EST Operational Flag was going on and off. Also the closed loop status for the ECU was not set, occassionally it was being set but then it was in open loop mode again.
Can someone confirm for me that the EST flag should be ON and the motor should also be in closeloop mode when the motor temp is at 90 C
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VNGRPA
Fully Licenced
426 Posts
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Posted - 02 Nov 2011 : 11:09:01 PM
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is it misfiring at idle speed mate
in the Gregory's repair manual it says
ENGINE MECHANICAL TROUBLE SHOOTING
ENGINE MISFIRES AT IDLING SPEED
NOTE= most causes of engine misfire can be traced to faults in the fuel or ignition systems, if reference to the fuel and engine management or electrical systems sections trouble shooting does not locate the fault check the following fault and remedies
1) air leak at the inlet manifold gasket: check for air leaks by running oil around the manifold joints if a air leak id detected tighten the bolts if that doesn't work replace the gasket
2)blown head gasket: check compression
3)burnt valves or seats in heads: check compression
4)weak or broken valve springs: remove the rocker covers and check the condition of the valve springs
5)broken piston rings: check the compression and renew the piston rings as necessary
hope that helps a bit i'm not shore about the EST flag to be honest i don't even know what that is after reading the book |
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VNGRPA
Fully Licenced
426 Posts
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Posted - 02 Nov 2011 : 11:11:08 PM
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| VNSVLE might know but as hes pretty clued on |
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kingbucktoo
P Plater
54 Posts
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Posted - 03 Nov 2011 : 12:29:04 AM
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The motor starts ok when cold, as the motor starts to back off the revs say down to ~700 rpm it will misfire/ hiccup / miss a beat!! but no back fire. eventually stall. When Engine is running it is smooth like it has aways been.
If you raise the revs with throttle say up to 2000 to 3000rpm it will give a miss maybe after two to three minutes then run sweet, then hiccup again.
Yes the Engine check light starts to flicker on then off, but when you look at the fault codes it is flashing 12 everything OK.
I pretty sure the mechanics of the motor are fine, but I'll check them. (Oh what fun I'm going to have to remove spark plugs from a V8) When the motor is running its not vibrating like if its one cylinder down and it sounds Ok.
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VNSVLE
Forum Moderator
1316 Posts
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Posted - 03 Nov 2011 : 01:59:45 AM
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Sorry buddy cant help you out with your inquires unfortuneately
I would recommend having a chat with the people on this site - http://www.delcohacking.net/forums/index.php?sid=35d22fda90f5467a75dfbc8aa0219dfa
You could also shoot delcowizzid a message or email he will be able to help you out with your questions
Let us know the outcome whatever it may be buddy.
Cheers |
What's the difference between understeer and oversteer?
Understeer is when the driver is scared.
Oversteer is when the passenger is scared. |
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Mechknight73
National Driver
1001 Posts
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Posted - 03 Nov 2011 : 12:45:22 PM
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| Misfiring at idle, the way you describe it is often caused by a vacuum leak. EFI engines are very sensitive to it, but even carburettor engines will play up with it. The worse the leak, them more trouble it will have. The main reason being that it confuses the ECU about just how much air is getting into the cylinders. It's something basic you can eliminate from the diagnostic progress before you miss it and it drives you bonkers |
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ECU question
