1998 Dodge Ram 1500, 360, V8, 197K miles

Truck lost power on road, limped home, reader says multiple misfires P003,P004,P005,P007.
check engine light on and sometimes blinking.

Checked fuel pressure reads 41 psi when key turned on, bleed gas from injector manifold to bottle looked good and clean. Not running good or long enough to check pressure while running. When I bleed down manifold (gauge has push button) I lose pressure and need to turn ignition key off then on to restore 41 psi. Is that normal?

I think the gas is OK spark plugs wet when removed after crank so was compression gague fitting.

Compression check: Checked two cyls 4 & 3 - 150 lbs of compression. Didnt check all because 3&4 setting codes and checked ok. (will check 5&7 @ later date) Dont think its compression related.

Changed plugs all but 5&7, their too tight to mess with right now dont want to further complicate matters with broken plug...

Checked spark by using old plug and grounding base with jumper - weak *** spark, doesnt seem steady either. Barley jumps gap yellow white.

Changed Coil, Dist Cap (was crudy), Rotor and Ignition Pick-up.
Spark still weak!

Changed plug wire on coil to dist. (have new set will put remainder on soon)
Spark still weak!

Checked coil voltage while ignition key is turned on shows 12.1 vdc then goes to zero.
Toggling the key will bring the 12vdc back momentarily, is this normal?
Swapped new coil for old
Spark still weak!

Swapped ASD relay with fog light 2 relay (relays all look the same, Are they?)
Engine started but didnt run good, (need to keep TB open to start and run)
Spark still weak!

When engine runs it doesn't sound good at all, sound like big vacuum leak, could a sensor be causing this ?

The TB, IAC, MAF & TPS are dirty, should I remove and clean? I see 3 sensors on TB not sure what i'm looking at:
Is the one in front of the TB the mass air flow sensor?
in back the IAC and driver side TPS?

Wouldnt the PCM set a code if these sensors were bad?

This is the reason my boat has points and carbs makes life simple.

Is there anything else that controlls spark - looking for a hot *** spark!

thanks for any comments or suggestions

 

the flat looking sensor in front of TB MAF, the one one the driver side is TB the one in the back is IAC. I know the IAC valve can make the truck run shi%ty if it's dirty which is probably the hissing sound you hear. As far as the spark maybe some of the moer experienced members can help. When you removed the old cap and rotor did you wiggle the dist? If it has too much play this will also cause multiple misfires. Check plug in at coil to make sure wires are good and that it's seated correctly. I had to use 2 zip ties when I replaced mine because the locking tab would'nt completely seat and it would come loose.

 

Will remove and clean the IAC tomorrow. My 12v coil connector is good, should be OK there.
I will also check for distributor shaft play, i think its tight. BTW I love where they put the distributor... real nice, think I f@#%&* my knee up getting to it.

Thanks

Looking forward to the part where I get to drive the be och.

 

there are a couple more important sensors, but i don't know if they would create a weak spark or not. one is cam position sensor and its located --- guess where ---- yes, inside the distributor. then there is the crank position sensor, its a toss up as to which one is harder to get to. crank pos is on back of the block, passenger side, top, and it sticks down inside the bell housing. its just to the inside of the oil filter.

 

I'll just throw some stuff out:

He replaced the pick up sensor (cam position sensor.)
Crank sensor going bad usually results in a no fire at all, but it's possible it's failing.
Did you check the battery for a good, solid charge?
Alternator pooping out?
Relays do have different amperage ratings, be careful blindly swapping.
Dodge used a MAP sensor, not MAF (manifold absolute pressure). It does have a vac tube leading to it that can crack at the MAP connection. It's the sensor on front of the TB
If you have to hold the TB open to get it to run, it's probably the IAC or TPS. IAC shouldn't cause power loss while driving. TPS might.
Double check wiring harness connections to PCM and ensure they are tight.

 

I couldn't see in the distributor, but took a picture of it. With the ignition pick up removed I didn't see any other sensors or wires. Is the ignition pick up also the cam sensor? If not, do u need to remove the distributor to access the cam sensor? I should mention that last week I didnt know much about a 98-360 ignition and as of now I still don't know much, trying to get to a point where I know a little and can guess the rest.

I guess I could turn the key off and make a shed out of it.

 

The cam sensor is the pick up sensor, it's the flat plate that sits between the disty and the cap. DON'T take the disty off or you'll probably have to take it to the dealership to have the sync set. You can't tune these engines by twisting the Disty like in the old days.

Take the TB off and give it a good cleaning, especially where the IAC port is on the back.

If I recall correctly, the ignition system on these trucks are the coldest of the big three. Some of the guys that have really souped up these trucks recommend that you upgrade the ignition system, others say it doesn't matter.

 

Have patience. I know how frustrating it can be. I bought my truck with 145K. Thought I got a great deal at $2,800, seeing it only needed tires. 2 months later the transmission went. 1 week after that the starter went. 1 week later the IAC fails. 1 week later I started getting miss fires. Replaced the plugs, wires, cap, rotor, MAF, and TPS. Then I noticed oil in the intake. Pulled the plenum to replace the gasket and found the PO broke an intake bolt in the head. While it was apart I ordered headers, cat, and exhaust. Broke a stud in the head for the exhaust manifold. Ended up pulling the heads to get the bolts out. Get it back together and the oil pressure sensor is bad. Now the truck is back together and running great.

 

Should I remove and reseat the PCM plugs (I think there are 3) or is that a bad thing to do?
They look fully inserted.

The relays all had the same numbers so I assumed they were the same, I take a closer look tomorrow.

Thanks for the disty tip. By "cold" do you mean not a hot spark?

Any tips on cleaning the TB sensors?


Thanks to all for the help

 

I would pick up a couple cans of throttle body cleaner, and a new throttle body gasket. Then pull the throttle body and clean the whole thing. There is a thread somewhere on hear on how to clean it.