Timing

Tiny
VODKAKID
  • MEMBER
  • 1999 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
Timing wont stay set. Its always hunting.
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Monday, November 29th, 2010 AT 2:42 PM

18 Replies

Tiny
JDL
  • EXPERT
Take the belt off, can you feel any slack in the crank pulley? Does the rotor and crank pulley move at the same time? Ignition timing is controlled by pcm.
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-1
Monday, November 29th, 2010 AT 2:53 PM
Tiny
WRENCHTECH
  • EXPERT
It's supposed to. The computer is controlling it. The timing is not adjustable.
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Monday, November 29th, 2010 AT 2:53 PM
Tiny
VODKAKID
  • MEMBER
Theres no lash. I replaced the timing chain thinking what movement that was there would have taken care of it, replaced crank cam mapp plugs rotor and cap. Wires were new. It will start. It will jump to about 1600 rpm come down to 1000 then bounce 600 900 400 1000 500 900 stall and backfire sometimes. I know the pcm controls the timing but when I put it on tdc tdc. No fire.
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Monday, November 29th, 2010 AT 3:04 PM
Tiny
WRENCHTECH
  • EXPERT
I don't know why your looking at timing at all. You need to go back to basics and see what function is dropping out. You've probably got a bad crank sensor or something like that.
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Monday, November 29th, 2010 AT 3:11 PM
Tiny
VODKAKID
  • MEMBER
That was the first thing I did was go back to basics. I have spark I have fuel and great compression, so I moved to sensors. Replaced first
Crankshaft pos
cam pos. Because they dictate spark and when to fire, started truck ran ok. Then let sit for lunch. Went to start and no fire. Just kept cranking.

Just to be sure it wasnt I replaced the map sensor anyway.
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Monday, November 29th, 2010 AT 3:18 PM
Tiny
WRENCHTECH
  • EXPERT
Here are the basics. Cover all of them.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Monday, November 29th, 2010 AT 3:20 PM
Tiny
VODKAKID
  • MEMBER
I agree 100%. Have done these tests. I have good spark check.
I have tested all injectors.
Good compression and constant preasure at fule rail. Im inclined to give up I guess. I have done the tests. And replaced the parts. The engine still surges and stalls. Not knowing why it has no improvement. Could the pcm be the pronlem?
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Monday, November 29th, 2010 AT 3:29 PM
Tiny
WRENCHTECH
  • EXPERT
It just needs to be diagnosed correctly. A scan tool would be helpful.
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Monday, November 29th, 2010 AT 3:33 PM
Tiny
VODKAKID
  • MEMBER
Obd2 no codes.
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Monday, November 29th, 2010 AT 3:37 PM
Tiny
JDL
  • EXPERT
Did you clean the throttle body? Idle air? It runs ok off idle?
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Monday, November 29th, 2010 AT 3:42 PM
Tiny
VODKAKID
  • MEMBER
I did clean throttle body yes. And idle air was good as far as eyes could see, when it runs it runs rough. Playing with the distributor its runs better. But cant seem to get any sort of stedy idle. With more experiance with older trucks it just sounded to me like a timing issue. Im not use to a computer doing it.
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Monday, November 29th, 2010 AT 3:52 PM
Tiny
WRENCHTECH
  • EXPERT
Remove the EGR valve and see if it is stuck open.
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Monday, November 29th, 2010 AT 4:04 PM
Tiny
VODKAKID
  • MEMBER
Ok I will do that.
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Monday, November 29th, 2010 AT 4:08 PM
Tiny
JDL
  • EXPERT
Unplug the iac, does it effect the idle? Any time you replace a sensor, if nothing else, you can use a digital multimeter to check sensor wiring, ref voltage--ground--signal, where applicable, before replacing. At idle, the sensor signals should be steady, not jumping around. Also vacuum at the map sensor. Without something to point us in the right direction?
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Monday, November 29th, 2010 AT 4:34 PM
Tiny
VODKAKID
  • MEMBER
I worked on it today. Tis tuck is not equiped wiyh an EGR valve. So thats out.I checked my oil today, it was way high, by 4 quarts and smells like gas. Probaly because its been flooding its self. And it running today with my foot to the floor wouldnt get ofer 2k. Also to adding to that this engin ran puuurfect. When the exaust manifolds were off. Cat converter? I dont want to jump on an idea that could lead me down a dead end rd. Im getting a good amount of exaust out of the tail. But mainifolds are heating up FAST!
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Monday, November 29th, 2010 AT 11:05 PM
Tiny
WRENCHTECH
  • EXPERT
There are ways to diagnose and test things like this and it just takes some diagnostic equipment and some knowledge. You'd probably be way ahead of the game to let a professional diagnose it for you. Your just chasing all the wrong things.
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Monday, November 29th, 2010 AT 11:10 PM
Tiny
VODKAKID
  • MEMBER
I know your a expert and im not climing to be. I have to equipment to do these things, im a boat mechanic going on 8 years now. Its the computers and the hundreds of sensors. I know the nechanics and I know my way around a motor. Just need help finding the right sensor. What do you think?
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Monday, November 29th, 2010 AT 11:18 PM
Tiny
WRENCHTECH
  • EXPERT
Believe me, you are no where near trained enough to find this problem. Working on a computer car is an entirely different world and you don't have the required equipment to find your problem. You need to be able to read sensor data, understand exactly what it's telling you and how the sensors are interacting with each other.
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Monday, November 29th, 2010 AT 11:22 PM

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