Dodge Grand Caravan with about 90k miles. CEL code p0152 (O2 sensor too ric). A couple days ago it misfired on startup, but ran smooth after restarting. Got codes p0300 (misfire) and p0152 (O2 sensor) and reset. Now CEL is back but just showing p0152.
This looks plugs and/or at least one coil. Will definitely replace plugs, because that's cheap, easy, and beneficial. My limited experience says it's more than just a fouled plug and is probably a bad coil, but I don't know how to diagnose which one.
Should I do just the plugs and see if that fixes it?
Try to identify and replace a single coil?
Just go ahead and replace all 6 coils?
I'm leaning in favor of the last option just to get the job done with the least hassle possible. At $40/ea, coils aren't exactly cheap though.
Edit: or buy Bosch or NGK coils off Rockauto at around $20/ea?
If it were a coil or plug I would expect a code for a single cylinder misfire.
Any other stored or pending codes? I wonder if you have an injector hanging open? That should still affect a single hole but it could give a startup misfire and a rich code.
Fix the vacuum leak first.
The MPV was short of 100k miles when the first coil went bad. It was during a drive in the rain, it resulted in a dead miss is one cylinder, and it set a code that identified the specific cylinder. Because the plugs and coils on the rear-facing bank of a Duratec V6 in a Mazda MPV cannot be reached without pulling the intake manifold, I chose to replace all three on that bank. I bought them at the local FLAPS, paid very near $100 each for Chinese cheapies, and did the job.
The next one probably failed around 120k miles and since it was easy to get to, I did just that one. Curiously, it and the remaining two OE coils all failed after/during a rain. Around that time, I had access to another vehicle, and a I found that Rockauto was selling the OEM NipponDenso coils for about $48 each. I ordered up three of them, and kept the 2 extras until the last of them failed, which they did. This was the event that signaled the end of my sourcing parts from the local FLAPS. I can get better quality at half the price if I've got a couple of days to wait for them.
I suspect it's not a coil.
Ranger50 said:
Fix the vacuum leak first.
This is solid advice, bust out the smoke machine and look for air leaks.
Ranger50 said:
Fix the vacuum leak first.
Except the code is backwards from an air leak. Unless it's bleeding off air post measurement.
In reply to alfadriver :
It's a Chrysler.. still speed density. It's maxed the enrichment adaptive.
Unless it's plugged the cat.
Or contaminated the oxygen sensor with antifreeze.
Ranger50 said:
In reply to alfadriver :
It's a Chrysler.. still speed density. It's maxed the enrichment adaptive.
Unless it's plugged the cat.
So it would be over measuring MAP to be too rich. Or it could be leaky fuel injectors- with age and stuff on them, they could be dribbling fuel.
In reply to alfadriver :
The standard joke I had when working at the various Chrysler dealerships was, "If they could just make a gasket, rubber hose, or bearing last past warranty, it would be great.".
Even as E36 M3ty as Chryslers are, their misfire calcs are surprisingly berkeleying accurate. So at this time, I wouldn't exactly believe a leaking injector to be at fault. Intake gaskets either upper or lower in a heartbeat. They still put in spark plugs needing 30k mile changes...
P0152 and misfire could be caused by a dead DOWNSTREAM sensor, or exhaust leak upstream of it, so it reads lean and the computer cranks up the fuel trim trying to make the O2 happy, which causes the upstream to stay pegged rich and can cause a rich misfire.
The failure algorithms assume that the downstream sensor is in better shape than the upstream, which sees more heat and therefore ages faster. Any disparity between upstream and downstream usually sets a code for the upstream, as a result.
The fun part about diagnosing by code read and pray is that you're assuming that the code algorithm is valid.
Or if it's a 3.6 it could be a wiped cam lobe... saw three of these last month. This usually has a righteous tick/knock long before it misfires, though.
Codes only get you so far. A true scan tool is needed to see which cyl is mis firing, what the o2 is reading etc. Of course scan tools are $$$$$ compared to simple code readers. Then there is figureing out how to use the thing , run proper diagnostics and so on.
Gearheadotaku (Forum Supporter) said:
Codes only get you so far. A true scan tool is needed to see which cyl is mis firing, what the o2 is reading etc. Of course scan tools are $$$$$ compared to simple code readers. Then there is figureing out how to use the thing , run proper diagnostics and so on.
$400 buys a scan tool that can do 90-95% of what the factory OEM scan tools can do. While that isn't exactly cheap, it's definitely doable for most diy'ers....
What year is it? I wouldn't call myself a Chrysler tech necessarily but I am a Stellantis guy being a Alfa/Fiat tech. I'll pull up the workflow for that dtc in dealerconnect and post it so you can see what Chrysler wants you to look at. My money is on air leaks without seeing it because every jerp, challenger, van, etc with a v6 that comes thru our dealership seems to have had one at some point lol.
Already fixed the problem. It ended up being an O2 sensor, which was actually the cheapest and easiest possible fix.
All good now.
