Misfire P0310 P0301 P0300 on Stock ish 2001 GTS

[MH60M]

SOLVED! Do a Smoke Test! This issue was caused by Bad Intake manifold gaskets in a hidden area.

UPDATED: 8-12-19

So, I’m at a loss......P0310, P0301, and P0300 misfire codes at cruising speeds. It doesn’t do it at idle. Car is a 2001 GTS w/headers, HF cats, catback. I’ve been troubleshooting this for years and not driving it much because of it.
I’ve replaced these parts one at a time to try and isolate the issue. I’ve also checked other items.

Replaced:
Spark Plugs w/gen3 Champions
Wires with “Quality Wires”
Coils With Demon Coils
Fuel Injectors w/good used set
Fuel Filter
Cam Sensor
2001 PCM
MAP Sensor
o2 Sensors to NTK...OEM
Replaced Vac Line from Air Filter box to Intake/Valve Covers



Checked:
Fuel pressure at idle
Fuel pressure at cruise and WOT
Compression of all Cyl
Leak-down of #1
Valve springs-Visual
Vac System-Visual
Evap System-Visual
Battery Voltage
Grounds-Visual
Removed Battery to Ground Wire, Cleaned and Re-Installed
Ground/Reset PCM and reset adaptives via Doug Levin procedure

[ACR-ISH]

So, I’m at a loss......P0310, P0301, and P0300

What are the exact codes, each one? Is each one for a different cylinder? If so, what do they have in common?

[MH60M]

Cyl #10 misfire and cyl #1 misfire totally unrelated. Po300 is just multiple misfires.

[dave6666]

Get rid of the crap wires and demon coils just on principal. Check your fuel pressure under the same conditions you are having the issue. Fuel pressure at idle with an issue at speed is a meaningless test. Have you tried another injector harness? Cleaned the contacts on the one you have? Checked supply voltage and continuity to the PCM on the injector harness to all the injectors and coils? Checked the grounds on the injectors at the harness to PCM reference and the same on the coils too?

[pokeyl]

Dose the car misfire or is it just a code. One reason Dodge went to the new computer in 08 was for better misfire detection, and to meat new EPA misfire rules.
My car gives misfire codes but runs perfect. P0300 and sometimes P0303.
I changed plugs wires, injectors, coils, NO change.
I just reset the fail and press on.
Sometimes it will be 6 month without a code. Other times it is each drive.

Hope this helps!

[mackzilla]

I too had these codes once and replaced many of the same parts + more trying to resolve the issue.

I ended finding my problem was map sensor voltage, so I changed the sensor to no avail. Upon further investigation, my map had been spliced into for a vec kit at one time. When removed, the wires were poorly deleted and were shorting.

Check map voltage.

[MH60M]

Get rid of the crap wires and demon coils just on principal. Check your fuel pressure under the same conditions you are having the issue. Fuel pressure at idle with an issue at speed is a meaningless test. Have you tried another injector harness? Cleaned the contacts on the one you have? Checked supply voltage and continuity to the PCM on the injector harness to all the injectors and coils? Checked the grounds on the injectors at the harness to PCM reference and the same on the coils too?

Objection noted on the wires and coils. Yeah, I remember your fuel pressure gauge taped to the windshield. Sounds like I need to go buy a real multimeter.

Dose the car misfire or is it just a code. One reason Dodge went to the new computer in 08 was for better misfire detection, and to meat new EPA misfire rules.
My car gives misfire codes but runs perfect. P0300 and sometimes P0303.
I changed plugs wires, injectors, coils, NO change.
I just reset the fail and press on.
Sometimes it will be 6 month without a code. Other times it is each drive.

Hope this helps!

I'd do that if it wasn't repeating every 3 minutes. The code scanner is almost a permanent fixture in my car.

I too had these codes once and replaced many of the same parts + more trying to resolve the issue.

I ended finding my problem was map sensor voltage, so I changed the sensor to no avail. Upon further investigation, my map had been spliced into for a vec kit at one time. When removed, the wires were poorly deleted and were shorting.

Check map voltage.

I could totally see this being a possible problem, I'll have to get a good multimeter and do some work. Someone PM'd me that I should replace the MAP sensor.

[Old School]

Crankshaft position sensor.

[ACR-ISH]

Crankshaft position sensor.

2nd! ^^^^

[ellowviper]

Deleted....

[dave6666]

Objection noted on the wires and coils.

Here's my issues with those plug wires and the aftermarket coils.

Wires - 1) I've melted more than one set. I mean almost falling off the plug melted them. 2) I found out who is making them and the markup / profit margin. It is rather stunning what he makes every time someone buys a set of them.

Coils - 1) Never seen a scientific dyno comparison to stock coils so as far as I'm concerned there is no data showing they increase hp. Well, other than their pep boy-ish sales pitch. 2) To make a hotter spark requires more current. That works the driver circuits in the PCM harder. What have you done to shore them up? Your PCM coil driver circuits? It's like the huge amp / crappy speaker thing. 3) They don't even fit the car without modification from what I've read. Insert lol here.

IMO parts like those are just another case of people thinking the engineers that designed our cars were dumbasses. Whereas in contrast, the factory parts do actually work quite well.

Lastly, yes, I know there are heat shields / boots / sleeves for the plug wires. I'm not a dumbass either. Just an ass.

[MH60M]

Over the weekend I removed the Belanger headers/high flow cat converters, and went back to stock 2001 headers w/spiral flow mufflers. A couple of 2001-2002 guys said they had misfire problems with Headers+ Catback.

It's much quieter, but I still have the #1 and #10 misfire. I did notice that my O2 sensors are Bosch and not the OEM NTKs.

Crank sensors are sold out everywhere....except the gougers. Anyone have a good source?

New MAP sensor should be delivered today.

[Old School]

Crank sensors are sold out everywhere....except the gougers. Anyone have a good source?

I remember seeing the V10 truck (not Viper engine) ones could be made to work.

[MH60M]

I remember seeing the V10 truck (not Viper engine) ones could be made to work.

Interesting, I'll look into that. That might have been the great cam sensor depression, when we were making just about anything work.

[Dan Cragin]

Get rid of those Bosch 02's and make sure you are running the correct long reach plugs.

2000-2001 Engine controllers have very sensitive miss fire and O2 heater monitors. Small things can trigger a code.

When we do a cam change and headers on these models we need to modify those monitors to work properly.

[ellowviper]

I had deleted my earlier comments but to build on Dan's comment....01/02 PCMs were more sensitive to misfire CELS...in fact, when I did my aluminum flywheel I started to get misfire CELS. I was told by a reputable tuner that the 01/02 PCM would set a CEL simply due to the engine reving faster than the PCM was expecting....such as power-adders that would contribute to that scenario. Aluminum flywheel did for me. SO I ultimately used my SCT Pro Racer software to change the misfire sensitivity and after many 10's of thousands of miles, no issue with misfires. Doesn't sound like your situation, but as DAn says...you just never know. Oh..I love my Demon coils...able to run a .035 gap at 16 PSI boost AND Water/Meth injection no problem!!

[MH60M]

Get rid of those Bosch 02's and make sure you are running the correct long reach plugs.

2000-2001 Engine controllers have very sensitive miss fire and O2 heater monitors. Small things can trigger a code.

When we do a cam change and headers on these models we need to modify those monitors to work properly.

Yep, I'm using OEM Gen3 Champion Plugs.........Should be fine?
Sunday I swapped out my Belanger headers and HF cats for the stock headers and no cats....No change, and feels slower!
Yesterday I changed the MAP sensor....No change.
Last night I installed OEM NTK o2 Sensors....No change...Actually got another misfire on cyl#2 as well.

I had deleted my earlier comments but to build on Dan's comment....01/02 PCMs were more sensitive to misfire CELS...in fact, when I did my aluminum flywheel I started to get misfire CELS. I was told by a reputable tuner that the 01/02 PCM would set a CEL simply due to the engine reving faster than the PCM was expecting....such as power-adders that would contribute to that scenario. Aluminum flywheel did for me. SO I ultimately used my SCT Pro Racer software to change the misfire sensitivity and after many 10's of thousands of miles, no issue with misfires. Doesn't sound like your situation, but as DAn says...you just never know. Oh..I love my Demon coils...able to run a .035 gap at 16 PSI boost AND Water/Meth injection no problem!!

Should I borrow a 1997/1998 PCM and try it out?

[Martyb]

As Ellow said, aluminum flywheel will and did cause this same issue on my 01. He sent me a file and got me fixed right up with SCT(thanks again Ellow!). You didn’t mentioned if the car has a lightweight flywheel or not.

[MH60M]

As Ellow said, aluminum flywheel will and did cause this same issue on my 01. He sent me a file and got me fixed right up with SCT(thanks again Ellow!). You didn’t mentioned if the car has a lightweight flywheel or not.

It has a stock flywheel. File?........I have an SCT Tuner!

[Martyb]

I don’t have the tuner and file as I sold the car, but Eric had told us what to change in terms of misfire sensitivity. I just don’t remember what rpm settings as I’m getting up there in age!

[ellowviper]

Man....THAT must have been a while ago since I don't recall our discussions!! Must be my post-Afghanistan PTSD. Regardless, any tuner you work with can change misfire sensitivity, 02 heater warm-up parameters, rear 02 sensor on/off...and so forth. Can't change everything with SCT, but enough to motor on down the road with most mods.

[MH60M]

I used an infared thermometer and found cyl#10 not firing or intermittently firing. I'm replacing the injector and checking the signal from the PCM.

Can a stuck lifter or collapsed lifter do this? I haven't checked for a broken valve spring on this cyl yet.

Engine seems to run well at start-up and idle....then I get misfire codes when cruising at normal operating temp.

Anyone else have any thoughts?

[Mbccenter]

I used an infared thermometer and found cyl#10 not firing or intermittently firing. I'm replacing the injector and checking the signal from the PCM.

Can a stuck lifter or collapsed lifter do this? I haven't checked for a broken valve spring on this cyl yet.

Engine seems to run well at start-up and idle....then I get misfire codes when cruising at normal operating temp.

Anyone else have any thoughts?

Stuck lifter would do that but should make noise. I have some brand new injectors laying around if you need.

[Crimson135]

I used an infared thermometer and found cyl#10 not firing or intermittently firing. I'm replacing the injector and checking the signal from the PCM.

Can a stuck lifter or collapsed lifter do this? I haven't checked for a broken valve spring on this cyl yet.

Engine seems to run well at start-up and idle....then I get misfire codes when cruising at normal operating temp.

Anyone else have any thoughts?

Did you ever get my PM?

Also, I was able to buy the OE branded fuel injector from AutoZone for around $60. They had it in stock!

[MH60M]

Stuck lifter would do that but should make noise. I have some brand new injectors laying around if you need.

Thanks for the offer, but there were a few New In Box OEM ones on ebay a few weeks back for $30ea.....I bought the last two. I'll keep you in mind If It's an injector issue and I need to replace them all.

Did you ever get my PM?

Also, I was able to buy the OE branded fuel injector from AutoZone for around $60. They had it in stock!

Yes I just saw/read it!..... I replaced the PCM with a new build 2001-2002 MOPAR PCM. The injector drivers should be ready to rock!