I have a 97 5.2l. I keep getting random cylinder misfires with all cylinders missing and never feel the truck missing or acting poor on performance. Here is alist of what all i have done. New plenum gaskets, new NGK plugs, new msd wires, new cam sensor, new crankshaft sensor, new water coolant temp sensor, new distributor cap and rotor button, new msd 40,000 volt coil, 3 year old bosch oxygen sensors. Im at a loss. I am about to spend 200+ on maybe a msd ignition to try to bump up the crapy low voltage dodge ignition. Any help is appreciated. I did take the truck to dodge dealer and they hooked it to their main computer and found no missing, timing, or fuel delivery problems. I am thinking about getting new o2 sensors and was wondering who makes them for mopar? I heard they were the same as NTK.

 

I would like to help you out here. I had gone through the very same thing a while back and, I had found, in part, the root of the problem was MSD ignition wires. Let me explain. I had installed not only ONE set but TWO sets to where, I was so frustrated with this condition that, I finally got around to running some bench tests on the MSDs and, lo and behold, the root of the problem was bad ignition wires.

Upon performing an continuity test, one wire was completely open. I also found erratic OHM readings across the entire set to which, only when stressed, would induce an OPEN condition thus, creating an intermittent misfire condition. Upon flex testing of the MSD wires, they would open right up. What I found after opening them up (removal of the cheap insulating jacket material yielded tiny breaks in the fine wire that they use to wrap around the core. Whether they wound it too tight, the core material expanded, or, the wire is of low quality thus, being brittle - I don't know.

But, as soon as I got them things out of my engine bay and installed a set of Mags- I've NEVER had an issue since.


Ignition wiring ROUTING:

If the wires are induction cross firing due to being too close to one another and possessing poor dielectric properties, the high voltage will arc / jump over to an adjacent wire thus, firing off the cylinder prematurely thus, inducing a misfire condition.

Now, moving away from ignition wires, we can look at your condition and, we note that there's multiple misfires across the board. We can then ask the question of, what would induce this condition to occur. Well, one answer to that question is a fault at the coil level either, at the PRIMARY side or, at the SECONDARY side of the coil.

If it's at the input side, it could be one of two things and, they are:

1. Source issue or

2. Ground issue

SOURCE ISSUE: You can verify this quite easily by simply back-probing the INPUT side of the coil at B+ GN/OR while grounding the DMM to the headlamp FRAME GROUND. SPEC says you should read ~12-14 volts respectively.

GROUND ISSUE: The black wire is GROUND and, it ties INTO THE PCM connector / harness to where, the PCM switches this ground ON / OFF by means of internal means to PULSE the coil. To verify, REMOVE NEG BAT LEAD, wait one to three minutes and disconnect the middle connector at PCM. I believe (based on memory) that this one is the one that handles all the grounds. Perform a CONTINUITY TEST or, OHM TEST. Verify it is ~1 OHM of resistance or buzz out.

If all that CHECKS OUT- now, it's time to test the SECONDARY side by running another simple OHM test across Primary and Secondary and note reading on DMM. Refer to MSD specs.

IF THE COIL checks out, time to move onto another system. Now, when asking the question, what would cause misfire across multiple cyls, well, the common component that would affect all could be as simple as improper heat range of plugs used. I am listing the simplest to most complex here.

If that checks out, (refer to OEM spec for heat range, plug length and proper metallurgy of plug. DO NOT USE PLATINUM in these engines. Copper (Cu) and Iridium will work fine. V-powers (NGKs) are excellent plugs providing the correct model is selected or sold to you.

Next up, another common component that's been well known to induce misfires across the board is a failing O2 sensor. This, when bad, will put out voltage to which, the PCM uses to LEAN OUT the A/F ratio and, if and when it's too lean, it will induce a misfire condition due to insufficient fuel to burn.

Next up, another component to induce the same symptoms is the FUEL PUMP. If the psi is insufficient, this too, will lean out the A/F ratio thus, inducing misfires across the board.

Next: VAC LEAK at either the injector level (bottoms) due to incorrect bore size at intake level and undersized o-rings on lowers. Had this happen as well at one time. To check, get a long rubber hose and place the end into the injector at intake level. Place other end into your ear- listen for hiss. To fix, get better o-rings and, get the right size for the bore size in intake.

Next fuel injectors. I had NUMEROUS issues in this area in particular for quite sometime years back and, it literally took me a WHILE to find this but, what ends up happening is, the connectors AT THE INJECTORS become very sloppy or, if you use another type of injector (REMAN) that has thinner blade contacts, this can result in a mismatch between the thickness of the injector blade contact and the harness connector resulting in intermittent connection thus, creating a misfire condition due to no / low fuel mix being injected into the combustion chamber.

I also had deteriorating fuel rails which, rust kept flaking off and plugging random injectors thus driving me mad until I designed and built a whole new fuel delivery system that alleviates the problems associated with OEM - cold rolled steel junk fuel rails and cheap fittings. The rust plugs the injectors thus, again, leaning out the mix thus, misfire city.

NOTE: a CEL / CK ENGINE / ODB code will result BUT<NOT ALWAYS! Check the connectors for a good, tight fit and verify the interference fit of the contacts to connector interface as well as making sure all 8 safety clips are in place and not missing.

Next up: valve train related failure. If the valves are not fully seated, upon the compression stroke, the A/F mix is expelled thus, a no burn condition will be detected. If, the valve guide seals are leaking, misfire. If, the head has a dry crack / compression leak will result thus, misfire.

Next up: spent rings: excessive blow by / oil fouling up the plugs thus, a no fire condition / misfire occurs. But, they would have to be really in bad shape to affect all cyls.

Next: low compression at the CYL level. This speaks for itself- too low compression, yields a no-burn condition thus, inducing a misfire condition.

Gotta run but, check the simple stuff first.

CM

 

wow! Thank you for your input. Its much appreciated and you sound very professional at your diagnosis. My next question is did you ever actually feel your truck missing? I dont under stand while i would be misfiring if i cant feel it. At idle i will cost and not even apply acceleration and actually try to feel it missing with no actual mis detected. I have spider-webbed the ignition wires so cross-firing is not a problem. You mention a weak fuel pump psi. I forgot to mention the fuel pump was replaced in 2009 and was bought directly from chrysler(mopar). I did this just for the psi rating. Most aftermarket pumps were at lower psi than the stock therfore, i wanted oem. I would invistigate internal component further but like stated i DO NOt feel the truck missing or performing poor on performance. My dad has worked on several vehicles over the years and he has driven my truck. Also a dodge certified tech drove it and felt no missing whatsoever. If you dont mind me asking what exact msd wires did you have the problems with? I am running the msd street fire wires but am considering a different brand now you surprised me with this info. My cheapest route now is to change o2 sensors to an oem type since i beleive thats the main source the computer checks and sees for a misfire. I have a custom exhaust with a high-flow converter so the sensors could be contaiminated or trying to play out. I would blame my exhaust but its 3 years old and this problem has only came up within the past year.

 

I would definitely replace the Bosch o2 sensor. You can get the NTK at rock auto. And when you did the plenum did you check or have the cat checked out? Also, did you just replace the plenum gasket or did you do the hughes or aps upgrade?

 

While you seem to already have the right approach regarding AM parts, it is true - all sensors and all pumps should be replaced with OEM parts. Why? Like I've stated many times before, after-market parts are parts that either did not meet OEM specs and were sold off to brokers who, in turn sell them to 3rd part chain stores or, are sub-standard parts that were made Taiwan and Mexico and S. America sweat shops pumping out bogus parts that, are not fully tested to meet OEM specs thus, when placing one of these non-compliant components into a vehicle, a problem arises.

Go with NTK for O2 sensors.


Now, let's answer your questions:

MISFIRE; feeling it. Depending on the TYPE of misfire, there are times where, one will NOT FEEL the misfire. Let me explain that. I was working with an older guy on a very old Henry J and, it ran mint but, it had low power. It turned out it had a dead cylinder. Now, when going through and pulling plugs, it just happened to work out that, on the particular cylinder that was dead, it made no difference in how the engine felt.

EDIT: forgot to answer your question regarding, if I felt it on mine. YES AND NO is the answer. I use a test run up to the high desert. In So Cal, I run from LA to China Lake and, during my test runs, the CEL would come on, but, I couldn't feel it ALL the times. YES- sometimes, I could very much feel it and, it would shake or, lose power. In my case, sometimes it would flip out and, sometimes, it ran fine but, the darn engine light came on all the time under loading conditions only. ON flat ground, even WOT at >90 MPH- no CEL was seen. But, 100% under loading- the lamp was burning.

Now, if you were to go around on your Dodge and remove one plug wire at a time, you would feel the change initially if the system is healthy. Same can be said when removing one injector connector at a time when rooting out bad injectors by feel and sound.

Moving on: I have a question regarding the spacing of boots at ignition wires.

Q: What is the spacing between the boots at the head level? Are they angled away or towards each other?

Q: What type of routing AT THE CAP did you follow?

Here's the TSB method: http://autorepair.about.com/cs/faqs/l/bl654h.htm

Disregard if you already are wiring it this way. The routing at the cap is particularly important so, pay attention to the routing at that level.

Also, don't cross the wires at the boots as illustrated. The boots are to be splayed out / rotated away from one another across the board in my experience. But, the rest of that procedure checks out.

As to WHICH MSD WIRES: I ran their so-called, top of the line, Super Conductor model and, it was most likely 8.5MM- I don't recall the size. Again, in my experience and, upon opening them up, they are LOADED with design flaws and cheap materials. The ends are particularly problematic. The way they stamp those out creates a lot of open areas thus, creating weak areas that flex. The material that they chose was very thin and not robust thus, the ends had little structural support near the crimp area. There was another major issue with crumpling but, I can't quite recall just what that was at the moment. Anyway, I don't like their wires and, from quickly reading their electronics forum (ignition system products), I got the impression that their electronics (now made in China) are also problematic. It's ok to make stuff overseas so long as you control the processes and materials used.

Moving onto the next topic: Diagnosing your problem 100%.

There is a sure way to examine, down to the firing line, exactly what is going on and, at what time during the ignition cycle it is occurring. For this test, I would have to steer you into the dealership to have them place the vehicle on a dyno, put it under load at 1500, 2000, 2500, 3000, all the way up to WOT and watch on the scope what is going on.

Like I said, the plug may be firing but, the mix is not igniting. It's either one of two things: no spark / no ignition source OR, A/F related issue to which, this stems out into possible root cause failure modes previously mentioned.

Again, look into testing the simplest of things first. Never assume that a new component is working. I've had DEAD injectors right out of the box despite being new builds. FYI- trust nothing, test everything! LOL

CM

 

The cat is brand new and good. I have true duals with a dual inlet dual outlet cat and its flowing fine. As far as the plenum i bought the replacement gaskets and not a new intake.

 

The spacing of the boots at the head is good. The boots are all inserted till they "click" and lock into place. They are indeed angeled away from each other and the wires like i said are spider webbed out with zip ties so they are not touching/crossfiring.

 

Let me also ask you if you trust taylor wires? I am thinking about ordering new NTK oxygen sensorsalong with some new 8mm spiro-wound taylor wires.They are supposed to exceed oem style wires. (even tho msd claimed the samething)

 

If it's spiro-wound, it's got the same problems associated with that design in general however, in no way are those on the same low level that MSDs are.

Test for test, real-world conditions, on a dyno, on the same test bed during the same day- we ran MSDs and, the HP was below predicted amount. A change was mandated to remove MSDs and replace them with Taylor wires. The results showed a difference in HP - 12 HP in fact.

Now, this should not be confused as a positive gain in HP in the engine but, what that proved to us was that MSDs were lossy thus, not providing all the voltage to the plug for some unknown reason. So, I've seen LOTS of folks running Taylors and, I'll tell you another thing that is a positive for those guys- not only do they have a very good design for their boot, they (last time I spoke to someone at Taylor) were making their own wire and using their own designed materials vs. using off-the-shelf wire for the core wire. This is something that is uncommon. You see ONE company making the wire overseas along with ONE or TWO others who, also make the insulators and supplying the entire industry.

So, in the end, what we have is one or two suppliers making the same junk that goes into just about every ignition wire under the sun. As I learned, Taylor was one of the companies that was using materials that they designed and made or, had someone else make to their specs.

But, in general, the technology (spiro-wound) is not the most robust construction method and, again, I would not use them myself. I've heard many tell me to use Moroso's over Taylors and, while certainly more costly, it's the same design as well and, in case you're wondering-yes, I've run those too at one point.

I don't recommend anything other than www.magnecor.com using SS core wire. After running many brands of sprio-wound ignition wires, I just can't see recommending spiros after running Mags - sorry.

CM

 

your plenum probably blew out again. replacing just the gaskets wont do ****. you need to get a kit from APS or Hughes Engines. The Hughes kit comes with a 1/4in Aluminum plate, gasket, new bolts, and a cool sticker, with directions for torque specs.

The intake is aluminum, the Belly pan is steel. at hotter temps they expand differently allowing leaks. Also the bolts from the factory were made a tad bit to long, so they are not able to torque to spec....


Might want to re-do the plenum.