Question about Check Engine light

AbnMike

Well-known member
Apr 6, 2016
1,218
117
Western Slope, CO
Does it appear as soon as there is a problem? Or is there a lag?

Meaning, if a "cylinder misfire" code pops up does it mean it happened right at that moment, or some time in the past? Yesterday morning I had a "P1316 #E8 Misfire Excessive Emissions Fault" I have new plugs and wires. I did nothing but clear the code, and it hasn't reappeared. Is it an old code? Why doesn't it appear every time the motor runs if something is incorrect?
 

AbnMike

Well-known member
Apr 6, 2016
1,218
117
Western Slope, CO
This makes me think I have a bad injector - poor MPG, new plugs and wires, no air leaks that I can identify, and after sitting a couple days threw the excessive emissions fault...maybe leaking into the cylinder?

right track? off base?
 

p m

Administrator
Staff member
Apr 19, 2004
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La Jolla, CA
www.3rj.org
Try hooking up the pressure gauge to the fuel rail, and observe how the pressure holds (or doesn't) when someone shuts the engine off.
One of the reasons for a quick drop in fuel pressure is a leaky injector; if you then unscrew the spark plugs, you may find one or a few that smells more of raw gasoline than the others.
 

edthediscoman

Well-known member
Nov 4, 2005
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Rivertucky, Ca
You could verify fuel by putting a gauge on the fuel rail. Starting car and then shutting off. Watching if there is any bleed. I seem to remember the D2 has a check valve on the fuel system to prevent draining back to the tank.
 

AbnMike

Well-known member
Apr 6, 2016
1,218
117
Western Slope, CO
Fuel pressure test:

40 initially, then settled at 37. Turned key off and held.

So apparently not leaking. Bonus: no codes for past few days.