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This was posted by Jimmy Da Testa the other day...rather than try to tell you how to look...I am going to let you read Jim's write up as it is more logical than most of the stuff I write and cuts to the chase. Read point # 3. (the second # 3) LOL By the way, most parts places have a noid light for about 7 bucks...
<<<<<<Hmm...are you the guy that IM'd me about a noid light blinking but no start?
OK, to diagnose ANY car, you need to find what you have and dont have. The way *I* usually go about it (which might not be right to some people, but its methodical and consistant so I stick to it.
1) Note the check engine light (if EFI). If its not on, STOP and find out why. Listen to how it cranks. I can pick out compression problems doing this. If you are in tune to your car, you can too. Listen to the starter as each cyl comes up on compression stoke. You'll hear the starter slow down a little at that point. You bight hear deerdeerdeerdeer, where a dead cyl m ight sound like deerdeeeeedeerdeer (great sound effects huh?)
2)Depending how accessible the intake is, I'll shoot 3 or 4 seconds of carb cleaner into the plenum. Either thru the throttle body, or the brake booster vacuum port. If its a lack of fuel problem, the car may start, it may simply kick. If it does either, its time to look to fuel system (usually, although enrighening can bring out a low sec output problem too, so dont take my suggestion of fuel as law)
3) If the car kicked, I'll put a FP gauge on it. If fuel pressure isnt in spec, now you need to see why. Fuel pump, filter, resticted line, bad reg, low batt voltage, bad relay, blown fuse etc. If FP is in spec, its time to hook up a noid light and verify our injectors are getting pulsed. If youre not getting a pulse you will want to hook up a scanner and look for RPM during crank. If you are getting RPM signal, check for spark. If you're getting spark and no fuel, although there is a commanded PW (see below) you probably have a bad ECM. How fast it cranks isnt as important as the fact you get a RPM signal. Next you'll look at Coolant temp to see if it coincides with ambient )if the car is cold), and verify TPS isnt shorted to Vref which will put the car in clear flood and cut off fuel. If these all look OK, you'll want to take a look at commanded PW.
3) If the car didnt kick, I'll yank a plug wire and see if I got spark. If I got no spark, then I'll check also for inj pulse using a noid light. If I have neither its usually due to a dead crank sensor. If I have no spark, but I have injector pulse, its usually a module.
See, its pretty cut and dry when you go back to basics of what the car needs. Air, fuel, spark, and compression. If any are missing, the car wont run. The hard part I guess is finding out what you DONT have, then finding out why. I guess I take my experience for granted, maybe it is difficult. Kinda like Me trying to learn or diagnose a Linux problem (Right Jeremy?)
Turn the key on. Look and see if the SES light is on.
If yes, listen for the "3 second" fuel pump prime.
With the key still on, bump the starter. Do NOT crank, just bump it. The fuel pump should prime for three seconds everytime.
If it does NOT prime, probably the cranksensor. MOST the time No spark/no injector pulse/no fuel pump prime (by bumping the starter) is cranksensor.
If you have a aftermarket tach crank the engine to see if the tach is reading. If the needle is moving it IS getting a ref pulse from the cranksensor. If no movement it is not (again usually cranksensor).
This will work with stock tachs also, but they are not accurate and hard to read this way.
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A broken timing chain wont crank normally...see thats where listening to your car comes in.
You need to find out if you got no spark/inj pulse. Like Steve said, get a noid light and keep it in the toolbox.
Typically:
No start - no spark, has inj pulse -> Module
No start - has spark no inj pulse -> ECM / cam sensor prob
No start - no spark OR inj pulse - crank sensor or module
Oh, and if the module is dead, I suggest putting a coil pack on it as well as most of the module failure are caused by an overheating or arcing coil.
A broken timing chain wont crank normally...see thats where listening to your car comes in.
You need to find out if you got no spark/inj pulse. Like Steve said, get a noid light and keep it in the toolbox.
Typically:
No start - no spark, has inj pulse -> Module
No start - has spark no inj pulse -> ECM / cam sensor prob
No start - no spark OR inj pulse - crank sensor or module
Oh, and if the module is dead, I suggest putting a coil pack on it as well as most of the module failure are caused by an overheating or arcing coil.
Turn the key on. Look and see if the SES light is on.
If yes, listen for the "3 second" fuel pump prime.
With the key still on, bump the starter. Do NOT crank, just bump it. The fuel pump should prime for three seconds everytime.
If it does NOT prime, probably the cranksensor. MOST the time No spark/no injector pulse/no fuel pump prime (by bumping the starter) is cranksensor.
If you have a aftermarket tach crank the engine to see if the tach is reading. If the needle is moving it IS getting a ref pulse from the cranksensor. If no movement it is not (again usually cranksensor).
This will work with stock tachs also, but they are not accurate and hard to read this way.
