My resolution is to get the ***** back in my 318 Magnum 1994. I have replaced the plugs, wires, cap and rotor, coil, cleaned the IAC, ensured the Cat is not clogged, replaced the O2 sensor, and replaced the plenum gasket. Cleaning the IAC completely fixed my cold start stalling issue but the thing still has no *****. I mean, it's got decent torque in 1st or 2nd gear, better than my 3.9, but it's hard to say that it's any better than the 3.9 in 4th and 5th at 45 mph+. It is also running very rich, I don't even want to test my MPG but I'd be surprised if it were over 10 to be honest.

Now, this is a motor with 180k on it and compression is iffy on at least one cylinder (~105 psi) and kind of all over the place on the other 7. So I'm not expecting full factory HP out of it. But unless two cylinders were literally completely shut off, it should have noticeably more ***** than my old V6.

My thoughts of the next step (in order):
1) Inspect and clean all PCM harness contacts-shouda done this a while ago
2) Test MAP sensor-shoulda done this a while ago too. I'm really suspecting this might be it.
3) Replace timing chain and gears-well overdue if it hasn't been done before, but I'd like to eliminate all other possibilities first
4) Replace PCM???? I dunno where to go after this.

 

If the engine runs decent, then the PCM is working fine. If you have a scanner that can read live data, I would take a look at what your fuel trims are doing, and what the coolant temp sensor is telling the PCM.

What brand O2 sensor did you install? (I think you only have one?)

Low compression will certainly compromise power output.... Might consider doing a cylinder leakdown test, to see just where your compression is going. (probably everywhere.......)

 

Bosch sensor, it didn't make any change at all. Yeah I should do a leakdown test.

I know I'll lose power with low compression but I mean I've had way worse compression numbers than this on engines that weren't really perceptibly down on power...even 4 cylinder motors. I dunno, I really don't think compression is my [main] issue...I think (I know) my air fuel ratio is messed up but I don't know why.

Oh also I did replace the coolant temp sensor. The plastic on the old one was nearly separated from the metal and I thought for sure it was the problem. But nope.

 

My 94 B250 with 5.2 I ran up over 220K miles and never had any chain slap of any kind. Most of it was highway cruising but still with that amount of miles one would expect it to be worn, but no sound at all, so I'm not sure that you're going to find timing chain problems unless you can hear them.

I should never have parted with that, it was really reliable, bought with 70k and only sold it when the blower motor went out. Running on original OD AT too.

And Happy New Year too!!

Steve

 

Our trucks REALLY don't like the Bosch sensors...... there is just something about them that doesn't play nice with the dodge PCM. I have seen many folks have some odd issues, which went away after replacing their 'new' Bosch O2 sensor.......

On my 96 ram, with 180K on it, I had to pull the timing cover because it was leaking..... Figgered I might as well do the water pump, since it had to come off anyway. Once I had the timing cover off, I saw how sloppy the chain was, so, took a quick trip to the parts store, picked up an SA Gear double roller set, and installed that as well. I was absolutely amazed at the difference it made in perceived power.... probably the best 'mod' I did to that truck. Chain never made any noise.

 

Well, no; by the time it's slapping, it's WELL passed "stretched" and close to the "Jumps teeth for the hell of it".

The factory spec isn't for much deflection; on a 1988, the FSM calls for no more than 1/8" deflection when you apply 15 lb/ft (without heads) or 30 lb/ft (with heads and valve train) torque applied on the camshaft with the crank locked. It takes close to 1/2" deflection (from other reading) to slap the timing chain cover ...

For a Magnum, from the 1996 FSM, it says the same thing, BTW.

RwP

 

Happy New year.
So does anyone know how to replace that tiny rubber elbow for the MAP sensor? I was lucky and mine came off in one piece when I changed it out but only after I opened the new box did I find out that I had to salvage that part and reuse it. I wonder if mine has cracks and may be leaking air? I used a Japanese brand O2 sensor NTK or NGK which I think may be OE??
I'm interested to know if you find any solutions Tbugden. I have almost the same issue sans any compression testing with my 3.9 runs rich burning a lot more gas than I would expect. I got 19mpg first tank after I did the plenum and all the sensors in the intake TC and w pump and it went down quick after that. I get about 15 now.I have oil blow by that gets to teh air cleaner but like you I suspect the issue is something to do with air fuel mixture or other adjustment of the system.

 

I'll let you guys know what happens. Like I said, I have no way of knowing if the chain has been done but I will say there is no slapping. My old V6 was very slap happy but it really wasn't noticeably down on power--I replaced it and it felt basically the same.

 

I tested the MAP sensor today. It's good. Just for ****s I put the sensor from my 3.9 on it, no difference. When I took it out I decided to do a 0-60 run just to see if I really was as down on power as my butt dyno says I am. Well I didn't have the greatest launch but it wasn't too bad. It took me over 10 seconds to get to 50 mph...50. I stopped there, no reason to continue.

I checked my engine codes again, only have the two tranny codes (37 and 45) which is because the PCM is looking for the automatic transmission. My thought was that if it sees those faults that it could put the engine in limp mode so as not to wreck the transmission. But that seems unlikely as no one that I know of has reported any trouble running the automatic PCM on a manual truck (quite the opposite,in fact).

See, I got a chance to actually drive the auto Dakota this 318 came out of. While I didn't REALLY put my foot in it because the brakes weren't fit to stop a tricycle, it really seemed like it had full power when I was just testing to see if the tranny shifted as it should.

 

My fuel efficiency is nothing to write home about and I'd like to figure out what the problem is. Last three major trips, 16.x, 18.x and 17.x which to me with so much highway driving is ridiculous. These trips are 90% highway driving and not excessively fast driving either, speed limit all the way with this. I'm pretty light on the pedal anyway since I know the consumption is not good. I'm coming from driving a TDI car 100% of the time and my FE is always close to 50, and that's pretty much driving the way I want to.

I suspect my thermostat is not functioning properly, the heat has been mediocre to say the least, so since I suspect I also have a plenum leak too I'll be pulling and cleaning the TB and also pulling and resealing the plenum cover this weekend. I get occasional CE light but that's just EGR valve and it's rare when it happens so I haven't done anything yet.

Steve