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99 Crank Position Sensor on 318

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Old 08-23-2008, 10:54 AM
cessnajfb cessnajfb is offline
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Default 99 Crank Position Sensor on 318

99 Dodge Ram 1500 with 318

Searching the internet I found a post that said my crank position sensor is on the bell housing adjacent to the rear of my passenger side exhaust manifold. I can't see it.

Does anyone know if this is where it is and what the best way to get at it is?
I also read that it was mounted with two 1/4 inch hex drive screws - can anyone confirm?

Thanks,

Frank
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Old 08-23-2008, 11:04 AM
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Yes,

It is a blind job, because you can't see what you're doing.

The sensor is behind the passenger side valve cover and exhaust manifold. It's a PITA to get to. If you crawl under your truck and locate the oil filter and then look up toward the exhaust manifold on the passenger side, you'll notice a little steel flange bracket with 2 bolts holding it down. That's the little bugger right there. Here's a thread on how to get to it if you are having problems:

http://www.dodgeforum.com/forum/showthread.php?t=130645
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Old 08-23-2008, 11:27 AM
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I found the best way to attack it was from the top, but its a tight fit even to get your hand in there. Its a PITA to get to is all.
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Old 08-23-2008, 11:45 AM
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Thanks guys, I plan on attacking it tonight. I'll let you know how it goes. Frank
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Old 08-24-2008, 08:38 AM
cessnajfb cessnajfb is offline
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Like you said, it was a PITA. I looked from underneath first to see where it was and then from the top was able to feel it and get the 1/4 hex into the bolts and remove it with no problem. To get the wire connector apart I had to pull the removed sensor over to the harness where I could pull both directions on the wiring. Inserting the new sensor back into the rubber grommet was also a PITA and I didn't think I'd ever get the second bolt started. I drove it to work this morning. I'm going to get Auto Zone to test the old one - if it tests good I guess I won't know if the problem (truck dies while going down the hiway) is fixed until I drive it for a while. Thanks for all of your help, Frank

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Thanks guys, I plan on attacking it tonight. I'll let you know how it goes. Frank
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Old 08-24-2008, 09:01 AM
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The Crank Sensor is just a magnet that records the ticks in the flex plate to set the timing. Either it works or it doesn't, and it should be read by the PCM at startup as well. Check your voltage on the pre-cat O2 sensor to see if it's sweeping funny. If it's bad, it'll lean out the engine to a stall. running lean constantly isn't a good thing either.
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Old 08-24-2008, 10:44 AM
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I'm not being defensive here I just want to explain how I got to where I am. The truck was dying while my daughter was driving it, the first two times, by the time she got to the side of the road it started back up. The third time it wouldn't start and we had it towed to a shop where it showed no diagnostic codes but started back up and wouldn't die for them. I then drove the truck 4 hours home and then 60 miles round trip for two days and then it died on me at 60mph on the next day. The shop told me that the crank position sensor on this truck has a history of failing (temporarily) and not leaving any codes. (I had an 88 318 that the distributor pickup plate did the same thing on) That being said that's why I did a trial and error replacement of the crank position sensor ($75).

The pre-cat 02 is the pre catalytic converter oxygen sensor? Are there two, one on each exhaust downstream of the manifolds? What kind of voltage should I expect to see from the sensors - what does sweeping funny mean?

Thanks much for replying, Frank



Quote:
Originally Posted by aim4squirrels View Post
The Crank Sensor is just a magnet that records the ticks in the flex plate to set the timing. Either it works or it doesn't, and it should be read by the PCM at startup as well. Check your voltage on the pre-cat O2 sensor to see if it's sweeping funny. If it's bad, it'll lean out the engine to a stall. running lean constantly isn't a good thing either.
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Old 08-24-2008, 02:32 PM
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Check your wiring harness to your PCM. I've heard of guys trucks dying (especially while running a jet chip) because the wiring harness would work it's way a little loose and temporarily lose connection from vibration. You may have already checked it, I just thought I'd mention it since it's easy and free to check.
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Old 08-24-2008, 02:44 PM
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I'll check it. Thanks, Frank



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Originally Posted by Ramdamit98 View Post
Check your wiring harness to your PCM. I've heard of guys trucks dying (especially while running a jet chip) because the wiring harness would work it's way a little loose and temporarily lose connection from vibration. You may have already checked it, I just thought I'd mention it since it's easy and free to check.
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Old 08-24-2008, 03:30 PM
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Quote:
Originally Posted by cessnajfb View Post

The pre-cat 02 is the pre catalytic converter oxygen sensor? Are there two, one on each exhaust downstream of the manifolds? What kind of voltage should I expect to see from the sensors - what does sweeping funny mean?

Thanks much for replying, Frank
No offense taken, it's possible the crank sensor isn't working, there might be a short in the wires that run around the back end of the engine, I'm just throwing out other possibilities for you to check.


there are 2 sensors in the truck, unless it's a California emissions Truck then it has 4. The Post cat sensor just tells the PCM that the cat is in good working order. The Pre cat sensor leans and enriches the fuel mixture.
This link should tell you more than what you want to know about O2 sensors:
http://mr2.com/TEXT/O2_Sensor.html

It could also be a failing ignition coil that's giving up after it's been put under load for an extended time. Or, I've read that fuel pumps can sometimes go slowly if they are partially blocked.
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Old 08-24-2008, 07:44 PM
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Ok, before leaving work today (32 miles from home) I check the PCM wire harness connections and left for home. About 10 miles down the road at 35mph it died. 5 minutes later I started it and drove the rest of the way home. At home, I located the pre-cat and post-cat 02 sensors. Both have 4 wires coming out of them. Their wires go into a harness and run between the motor and firewall to where I couldn't tell. I read the link on testing 02 sensors, I think I'll nee a little more step by step, any assistance on how to test these sensors would be appreciated. What are my odds that its a failing coil as mentioned above? Thanks, Frank
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Old 08-24-2008, 08:52 PM
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Also, no one has mentioned the possibility of my problem being the distributor pickup plate (coil). A faulty one in my 1988 Ramcharger (318) led me down this same path - I'd be driving down the freeway and the vehicle would be instantly dead - no sputtering - no diagnostics. My shop tech didn't think it could be this. I'd like to hear from someone before I spend $50 on this possibility. Anyway, the coil is my next try - I'll post after I install and try it out. Frank
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Old 08-25-2008, 08:18 AM
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Quote:
Originally Posted by cessnajfb View Post
I'm not being defensive here I just want to explain how I got to where I am. The truck was dying while my daughter was driving it, the first two times, by the time she got to the side of the road it started back up. The third time it wouldn't start and we had it towed to a shop where it showed no diagnostic codes but started back up and wouldn't die for them. I then drove the truck 4 hours home and then 60 miles round trip for two days and then it died on me at 60mph on the next day. Frank
That sounds like the typical Ram fuel pump problem.
As the fuel pump electric motor gets old
and the suction filter below the pump get mostly clogged with crud
either the pump begins 'cavitating' and you lose fuel pressure
and the engine sputters and dies
or
the temperature sensitive circuit breaker embedded in electric motor winding
opens up from overheat
and your fuel pressure falls to zero

either way the engine either runs extremely rough or completely dies,
but no code is set in the PCM computer memory
because these Magnum engines don't have a sensor for fuel pressure

if you end up changing the fuel pump assembly
consider tilting up the cargo box from the driver's side
as it is easier than dropping the tank,
and remove the 'roll over valve' from its rubber bung
very carefully and gently
because most replacement fuel pump assemblies expect you
to re-use this part

good luck
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Old 08-25-2008, 08:31 AM
cessnajfb cessnajfb is offline
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Thanks Hank,
Both times it has died on me (two drive days in a row) I have been driving at a constant speed (60mph and 35mph) and when it died it died instantly - no sputtering. I'm going to go ahead and replace the coil tonight and drive it to work on Tuesday. I guess I'll try the fuel pump if it's not the coil.

Thanks,

Frank

Quote:
Originally Posted by HankL View Post
That sounds like the typical Ram fuel pump problem.
As the fuel pump electric motor gets old
and the suction filter below the pump get mostly clogged with crud
either the pump begins 'cavitating' and you lose fuel pressure
and the engine sputters and dies
or
the temperature sensitive circuit breaker embedded in electric motor winding
opens up from overheat
and your fuel pressure falls to zero

either way the engine either runs extremely rough or completely dies,
but no code is set in the PCM computer memory
because these Magnum engines don't have a sensor for fuel pressure

if you end up changing the fuel pump assembly
consider tilting up the cargo box from the driver's side
as it is easier than dropping the tank,
and remove the 'roll over valve' from its rubber bung
very carefully and gently
because most replacement fuel pump assemblies expect you
to re-use this part

good luck
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Old 08-25-2008, 07:55 PM
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Wait! Don't just replace random parts! I'm just suggesting what it could be, not what it is. You'll have to test to be sure, unless you just want to rebuild the whole engine to be sure. Coils can be tested for spark with a spark tester, you need not replace until you're sure.

You can also check fuel line pressure via the schrader valve on the fuel rail. you can rev the engine while checking to see if it fluctuates. Rail pressure should be 45-49 psi (the closer to 49 the better).
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Old 08-26-2008, 09:11 AM
cessnajfb cessnajfb is offline
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Thanks, can I check the fuel pressure with a regular tire pressure gage?

By the way, I replaced the coil and the distributor pickup plate (camshaft position sensor) last night - if it fixes it I don't care which is bad. I drove it to work this morning (32mi) with no problem. This afternoon might be the test since it has died both times for me on the way home (each incident within 5 miles of each other).

This should be the end of my trial and error efforts. Auto Zone quoted a PCM at $350 - I assume a fuel pump assembly is about the same.

Thanks,

Frank


Quote:
Originally Posted by aim4squirrels View Post
Wait! Don't just replace random parts! I'm just suggesting what it could be, not what it is. You'll have to test to be sure, unless you just want to rebuild the whole engine to be sure. Coils can be tested for spark with a spark tester, you need not replace until you're sure.

You can also check fuel line pressure via the schrader valve on the fuel rail. you can rev the engine while checking to see if it fluctuates. Rail pressure should be 45-49 psi (the closer to 49 the better).
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Old 08-26-2008, 09:16 PM
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Died again today but different. Installed so far are crankshaft position sensor, camshaft position sensor, and ignition coil. Made it to work (32mi) just fine this morning. Started to leave at 4pm 95deg farenheit - I started it and let it run about 2 minutes and started out of the parking and it died after about 20feet but this time the gages didn't all go dead and all the lights like check eng and airbags didn't come on. It started right up and I drove it 32 miles home with no problem. Hopefully the parking lot stall was a fluke.

I'm going to drive it again tomorrow and will probably stop at Auto Zone to see if the have a pressure gage that will fit on the fuel rail pressure test valve.

Frank
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Old 09-15-2008, 09:58 PM
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did you ever figure out your problem?
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Old 09-16-2008, 06:13 PM
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Quote:
Originally Posted by dakotas ram View Post
did you ever figure out your problem?
I'm not sure. My wife found a lot of threads on the internet where people had the exact same problem as us. Some solved it by removing the plug (rectangular with lots of wires - next to the battery on our 99 ram 1500) from the computer and scraping all of the male connection plugs, blowing out and pluging back in (has a phillips screw in the top middle of the plug). My old mechanic told me that he had fixed similar yr model dodges several times by cleaning the contacts at this plug. I drove it today (the high outdoor temp was 85F) to work and back with no probem. I guess time and miles will tell. Thanks for inquiring. Frank
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Old 01-17-2014, 10:06 AM
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Default 1994 dodge ram 1500 engine studder and misfire

I have a 1994 dodge ram 1500 and I gave full tune up and engine still studders and has new plugs wires cap and rotor I was told the crank sensor was weak is this common?
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Old 01-17-2014, 10:06 AM
 
 
 
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