Truck dies at initial start

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Rayallen577

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1998
Engine
5.9L magnum
i recently swapped a 5.9l 360 in place of my factory 5.2l

I installed a comp cams “RV” cam shaft installed new coil, plugs, wires, distributer cap and rotor, crank position sensor, as well as various other sensors...

I got a 5.9l ecu from a local pull apart yard as i had read on other fourms that the engine would run with the factory ecu to the 5.2 however would run lean, so I got the used ecu and the truck runs however sort of rough I have not attempted to drive it yet, I then replaced my fuel injectors and bought a new refurbished ecu and the truck sounds great at start up and perfectly healthy however even with playing with the throttle it immediately shuts off with the new ecu. But it with the used junk yard ecu it’ll sit and idle as long as you want it to just not as healthy as I would like for it to be. The only code it is pulling is a p1495 which is for evaporative emissions I purchased a new one but have yet to install it, the TPS and IAC were previously replaced as well as the battery and alternator. I’ve checked my fuses and swapped relays I’m not sure what it could be.


I just don’t understand how it could run off the old used ecu but not the new one however starts stronger and sounds healthy with it just shuts off afTer 2 seconds
 

dapepper9

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5 things that need to be answered:

1. What year is truck?
2. What year PCMs are you using?
3. Do you have any kind of tuning for the cam?
4. What PN is the cam?
5. Have you performed the Fuel Sync process?
 
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Rayallen577

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The truck is a 1998 Dodge Ram 1500 4x4 sport extended cab, I did not do any fuel compensation or a tune, and off hand don’t have the specs to the cam shaft, but where I’m dumb founded is that it’ll run with the junk yard 5.9l ecu but not stay running with the newly purchased remanned ecu however sounds much healthier with the new ecu just shuts off immediately and throws the p1495 code for Evap emissions the ecu I purchased did not state a year verification only a make model and engine displacement
 

dapepper9

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1. Fuel Sync is mechanically setting the engine to fuel schedule that is based on cam position. Download factory service manual from the site and find the distributor install procedures. That is where you'll find fuel sync. Very. Very. Important.

2. Find cam pn and post it. Don't bother with specs, pn will cover that plenty.

3. What year is the junkyard PCM? Year is critical when swapping PCMs as wiring and sensors changed throughout the years

4. Tuning is 100% required. To do it correctly you'll need a wideband 02 with an a/f ratio gauge. You'll also need to contact FlyinRyan at FRP, follow his recommendations on follow ons.

5. DO NOT spin the distributor attempting to adjust ignition timing. Common mistake people make with these. Distributor rotation is what sets your Fuel Sync, refer to install procedure in factory service manual
 

dapepper9

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For the record, a cam is not a cheap or worthwhile endeavor when dealing with a stock magnum. You'll likely be better off reinstalling the factory.
 
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Rayallen577

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When I get home I will post a photo of the box for the cam shaft I purchased, when I first had timed them engine I didn’t realize that the oil pump drive gear was in direct relation to the fuel timing of the engine and had to uninstall my intake manifold and take off the distributer assembly and lift and rotate the drive gear till it pointed towards the desired location from a downloaded schematics sheet. Prior to this I believe it was 180 degrees out of time and would back fire out of the exhaust but not start, then I replaced the crank position sensor and it would start but still back fire while running, now that I’ve re timed the drive gear to its proper location (I think) it does run however not as smoothly as I would wish for it to.

I knew it would need a custom tune from the get go however it is not yet to my standards to justify throwing a tune at it just yet.

I believe the Junk yard ecu was off of a 1997 I am not sure what year this engine came out of but I’m not sure that it Matters it was all plug and play and direct bolt on and I made sure it had the external balanced flex plate prior to install but yes I had concidered just putting the factory cam back in since it is rolle factory I bought a flat tappet with longer trick flow push rods to compensate height difference
 

dapepper9

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So for starters you downgraded by going flat tappet.

The timing you're talking about is fuel sync. Quick description is cylinder 1 at tdc of compression stroke should have distributor rotor pointing at cyl 1 plug wire on the cap.

Not going with a tune because it's not to your running standards, well we'll see if specs are something that'll do anything more than idle. Chances are idle is the best you can hope for.

Pcm needs to be a 98 or 99 for a 98 model year truck. Must match trans if the truck is auto. If the truck is manual there's work arounds
 
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Rayallen577

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Yes, I’ve done nothing more than pull it in and out of the garage the service manual showed it pointing towards cylinder 2 and being aligned with the square portion of the distributer where the cap mounts and secures to do it could potentially be 180 out

7F8BAA4D-F503-447F-B923-CCBA8CD402F4.jpeg
 

dapepper9

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Yeah at best it'll idle, too much duration to drive on stock tune.

You can pull the driverside valve cover and watch the valves move as you rotate the engine to be sure you're on the correct stroke. Also theres a mark on the pickup plate inside the distributor to align the rotor too.

I would start by verifying that and by using a 98-99 pcm. However, regarding the pcm, you'll need to figure out if you need a late 98 or early 98. They changed the neutral safety switch mid 98 as well as speed sensor i believe. Late 98 will match with 99. Early 98 will kinda be its own thing.
 

Shadow_Death

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Early 98 will kinda be its own thing.

Chrysler was notorious for crazy stuff like this in the 90s. I had a 92 Jeep Cherokee 4.0L I6 that you could take the distributor cap off, play spin the bottle with the rotor, put the cap back on, and fire it up every time. Apparently just that year they toyed with the idea of an electrical distributor instead of a oil pump driven one.

Also I've heard that better flowing heads will benefit these engines more than a cam as well.
 

dapepper9

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Also I've heard that better flowing heads will benefit these engines more than a cam as well.
Honestly that's true for about any old school pushrod v8. Guys cam stock engines all the time and think it's a 400hp engine but the reality is it probably only gained 20-30 at the crank. Small blocks anyways.

That stuff kinda changed when the hemis and LS engines came out with factory heads flowing more than ported Edelbrock heads for these engines. The cylinder head is one of the main reasons the new stuff makes the power that it does with a smaller displacement. That and they have better tighter clearances in places like the cylinder quench and higher compression.
 
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Rayallen577

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I’ve just take the intake manifold back off as well as distributer and am currently attempting to turn the gear so it’ll point to cylinder 1 it’s at TDC and the distributer appeared to be roughly 60 or so degrees out pointing to the firewall or cylinder 7 more so than 1, so I am attempting to turn the fuel sync gear to set it to its proper location and yes. I know I need a tune and had more than planned on getting one however not prior to it being mechanically sound.
 
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