Suspected OPDA, limp mode, CEL and code clearing?

[JKP]

Only use NTK or MOPAR O2s. Mopar is made by NTK.

Preferably Mopar crank sensor. Don't use store brand. Standard ignition is probably ok.

It is strange it started suddenly.

It would seem unlikely that all the injectors were leaky.

 

[williambmac]

Is P0300 the only code it is setting?
I'm not sure about your Autel capabilities but see if it has a misfire graphic screen so you can see which cylinders are misfiring.
Also, look in engine data and see what the crank/cam sensor rpms are. They should be steady with no dropout. If either is dropping out while running, you have an issue within that circuit.
Check your O2 sensor voltages.
What are your fuel trims at?

 

[JP_in_STL]

Is P0300 the only code it is setting?
I'm not sure about your Autel capabilities but see if it has a misfire graphic screen so you can see which cylinders are misfiring.
Also, look in engine data and see what the crank/cam sensor rpms are. They should be steady with no dropout. If either is dropping out while running, you have an issue within that circuit.
Check your O2 sensor voltages.
What are your fuel trims at?

Only code is the P0300. By looking at the plugs 4-6 look like it is running really rich. A buddy followed me and said it smelled pretty bad. So I will check my fuel trims - Neg indicates a bad O2? I picked up the 2 Upstream O2 this morning. They look fun to swap. :-(

I think the exhaust is louder? Possible Cat issue?

 

[JKP]

For the O2s you can use a sensor socket, but I have found a 7/8 or 22mm flare nut wrench works great.

If you have to, you can cut the wires on the old ones to use a box end or socket on them to get them out.

Hit the connectors with some WD40 and they will come apart easier.

Cats become an issue when they break up or melt and clog the exhaust. To the point it won't even run.

 

[JP_in_STL]

For the O2s you can use a sensor socket, but I have found a 7/8 or 22mm flare nut wrench works great.

If you have to, you can cut the wires on the old ones to use a box end or socket on them to get them out.

Hit the connectors with some WD40 and they will come apart easier.

Cats become an issue when they break up or melt and clog the exhaust. To the point it won't even run.

Ok, 2 new Walker Brand upstream O2 sensors installed. Was not bad for access and they came right out. Same issue, limp mode and a rough idle right after start. No immediate code set and I let it idle and come fully up to temp. No Codes, but a flashing CEL for Limp Mode.

I've gone though at least half of a tank in 80 miles so I think its getting plenty of fuel. Which makes me think it can't be a fuel pump or pressure issue since it is running so rich.

Did a Cam/Crank relearn so if the CPS was bad wouldn't it error on that.

To recap on parts replaced:
So I replaced the OPDA, new Dorman unit, and dialed it in with 0.7º sync.
New Champion Platinum Double Tips - old ones looked Rough
New O'Reilly House Brand Coil Rail
2 - Walker UpStream O2 Sensors

Still seeing a Flashing CEL at startup, poor performance, missing, rough idle, and will eventually throw a P0300.

 

[JKP]

Well it's in open loop until it warms up. So it only uses the coolant temp sensor, Intake air sensor, MAP sensor and TPS in open loop.

Did you check the MAP sensor reading?

 

[JP_in_STL]

MAP Sensor engine off reads: 745.8 mmHg = 29.37inHG and same Engine on. The current weather maps says 30.05inHg
Not sure if that is enough of a deviation to be concerned with?

I read up on checking Cats with a Laser Temp Gun, the rear is in line cooler inlet and about 50º higher outlet.
PreCat Bank1 Inlet: 460-480º Outlet: 460º
PreCat Bank2 Inlet: 315º Outlet: 405º

Did an Injector Kill Test, noticeably rougher running as 1-3 dropped. Seemed like 4-6 ran the same or slightly smoother when they cut out.

I've got an Autel MK808S and I can't find a cylinder misfire screen.

So this makes me think I blew the PreCat on Bank1.

 

[JKP]

If your MAP sensor reads the same with the key on engine off as it does with the engine running, you have a problem with the MAP sensor. Running at idle, AC off, the MAP should be around 18 in Hg less than atmospheric.

You can't use the weather reading unless you correct it for your alt. Weather pressure is adjusted to reflect you are at sea level.

You can subtract 0.1 in Hg for every 100 ft you are above sea level from the weather reading, or you can put a barometer app on your phone.

 

[JKP]

Your cyl 4 misfire is causing the cooler reading on the inlet in the rear cat and the gas burning in the cat increases it's outlet temp.

Edit: Looks like I got your mult cyl misfire confused with someone else's cyl 4 misfire.

 

[Danarch]

Do you know if the cats are good? My YJ would hit 3,000 rpm and that was it. Ended up finding out the cat was clogged.

 

[JP_in_STL]

If your MAP sensor reads the same with the key on engine off as it does with the engine running, you have a problem with the MAP sensor. Running at idle, AC off, the MAP should be around 18 in Hg less than atmospheric.

You can't use the weather reading unless you correct it for your alt. Weather pressure is adjusted to reflect you are at sea level.

You can subtract 0.1 in Hg for every 100 ft you are above sea level from the weather reading, or you can put a barometer app on your phone.

I'm about 700ft elevation so MAP reading of 746mm is 29.37in and the Weather Maps says 30in.
Which MAP reading am I looking for? Vac? Volts?
Map Vac Engine Off: 0 Idle: 380mm and if I blip the throttle is jumps to 580mm and then settles back down
Map Volts Engine Off: 4.41 and Idle: 2.0

 

[JKP]

Your MAP is correct with the engine off then. 30-.7 is 29.3. Close enough.

380 mm at idle would be 14.96 in HG. So you are only pulling 29.37-14.96=14.41 in HG vacuum. It should be pulling closer to 18 in Hg.

If the cats are plugged, one way to check is to pull the O2s out and see if it runs better as the holes will let the exh out.

 

[JP_in_STL]

Pulled the O2s out. Idle smooth. Revs smooth. Think that PreCat Bank 1 is the culprit. I got the pipe about 90% removed, but need a short sawzall blade to cut the rest of the way. I cut it close to the starter to leave plenty of length to match up to the rear cat.

Advance Auto has the MagnaFlow 50899 on sale currently for $700 and that's the best price I could find. Everyone else wants a grand if its stainless. I saw an aluminized Walker for $500.

Been an expensive week. OPDA did not need chNGED $150. The plugs def needed it, coil rail didn't hurt $150. The 2 upstream O2 were likely not needed, but likely a good idea considering the PreCat is shot $100. So about $1200 :-(

The $400 AUTEL MK808S was needed anyway, 3 rigs in the fleet and soon to be 4, all older.

 

[JP_in_STL]

Just a followup on the P0300 code. Bank1 PreCat was definitely bad. Got the pipes pulled off and the honeycomb had broken loose and shifted 90º so it was blocking the flow. AFE Brand got installed with a few hiccups. I found an "open box" for $400 and it took a bit to get everything lined up which might be why it was returned. Welds looked good, all stainless. I actually ordered a Magnaflow too, but it said after ordering that it would be 10-12 days. They both showed up this morning?? Comparing side by side they both looked of equal quality. I have an LJ so it took some extra measuring to get the pipe cut correctly. I was working alone so it took a few ratchet straps and some cussing, but I got it all put together this afternoon.

Fired right up and was OBVIOUSLY idling smooth. Took a run up the road for a few miles and came back with no codes or limp mode.