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94 5.9 Magnum build

4K views 7 replies 5 participants last post by  spun360 
#1 ·
I have a 92 Ramcharger originally 5.2 a518 4x4. My 5.2 failed when a lifter retainer came loose allowing those 2 lifters to rotate then the sideways rollers butchered the cam. I know, first gen, but.....

My new engine is a 94 5.9 Magnum from a 2500 pickup so I put it in the second gen forum, hope that's okay...first gen guys don't seem to know jack about Magnums.

This engine was just build by a local shop, all new internals except crank and rods pretty much. Stock bottom end, new EQ 2.02 heads, new Hughes cam HER0814ALN w/ matched springs and locks, Hughes plenum pan, cut 1/2" off kegger runners and smoothed casting, crappy Pacesetter shorty headers (cuz I already had them).

I'm using all the 5.2 PCM, harness throttle body and sensors but the 25lb 5.9 injectors.

First start up went very poorly, ran very rough and kept dying, would not idle.

Following night I pulled dist and saw intermediate shaft was off 1 tooth, corrected that. I'm not sure which way the distributor's tang belongs in the slot on the intermediate shaft, or how to tell its not 180* off, so I stabbed it in with the pigtail of the sync sensor to the rear with the sensor's marking eyeballed inline under the rotor tip.

It fired up and idled smooth for about a min, then stumbled and died. Took some pedal to restart, and occasionally some pedal to prevent it from dying again. I ran it at 1500rpm to bring it to temp and it ran smooth and sounded good except for a sputter now and then, then at idle it died. After a few restarts it would idle rough sometimes and just die others but mostly sounded fine revved above 1000.

I'm hearing impaired and have trouble identifying engine sounds especially over open headers, not sure if it was backfiring or not. I still have to spread the collector pipes to fit the headers.

I had no engine management problems before doing basically just a longblock swap so I'm thinking it must be an incompatibility between the 5.9/cam swap and 5.2 PCM.

Biggest question: Assuming that the 5.2 PCM is incompatible, would an OBD 1 5.9 PCM and required changes solve that problem?


Any input is appreciated, thank you.
 
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#2 ·
the 5.2 has the better cam in it.
the 5.9 just has more displacement.
the real trick is to install the 5.2 cam in the 5.9.
other than that the obdI should have no problems, unless something is off.
"fuel sync"
when installin the dizzy. the #1 cylinder needs to be in the TDC position. a mark on the crank dampener must correspond with the mark on the timing chain cover. verify this position by holding your thumb over the spark plug hole to create cylinder pressure insuring both valves are closed and not at the BDC position. once tdc is verified and marked, check the dizzy drive. the flat head slot should point to the front driver side corner of the intake manifold. install the dizzy drive with the rotor facing the #1 position on the cap.
AND after ALL that, its just a ROUGH in!
back pin the cam position sensor. run the truck. mine ran way off on the fuel sync. and it doesnt hurt it. YA! way off. when you turn the crank by hand you should get a sensor tick at +17 on the dampener degrees. +17* on the dampener is factory set as + or - 0 fuel sync. you may need degree tape on the dampener.
thats how to do it manually. or just pay the dealer ship $100 to put it on their fancy machine. also a snapon 2500 can do it. solus can do it. and a few others can do chrystlers fuel sync but most people have no idea what your asking about.
 
#4 ·
an update whether a good or bad one would be nice.
 
#5 ·
i realize there is no update on this. but being that he swapped the 5.9 injectors into it wouldn't it be over fueling? should need tuning to compensate for the extra fuel being dumped into the engine.
 
#6 ·
ah? believe the 5.2 and the 5.9 injectors are the same. its just the pcm is programmed for the 5.2 cam and the 5.9 is programmed for the mild cam and larger displacement. we are talking splitting hairs. and the injectors are not #25 either.
the 3 bar method "45lb of fuel" stipulates that the injectors are #22s yet our rams run at 49 and it does through the injectors off some.
on that note, "hemi says he can program a NA 408 on stock injectors" i personally wouldnt push an injector cycle that far.
perhaps try to swap back in the injectors from the 318 if you know they were good?
do you have any pcm scanner "92 5.9 RC RT" to view run time data on the short term fuel trims?
 
#7 ·
I'm very curious about this... Any updates???

Also, "spun360" stated that the 5.2 has a better cam... Can you throw a 5.2 cam in the 5.9 and end up with more displacement AND a better cam? Would you want the 5.2 computer or the 5.9 computer? Or would the tune need to be modified regardless? I'm sure it's been done, hasn't it?
 
#8 ·
the short answer is yes & yes!
to explain:
preferably i would want the sct tuner on the 5.9l pcm.
any who the junk yard dog swap can b done on a standard pcm. better to have the 360 computer either way. the lift on the cam increase is worth only .030 at the valve. like swapping in 1.7 ratio rockers.
 
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