P0171 - CEL Troubleshooting (1 Viewer)

[2001LC]

Two cans of 44k in one tank of gas, helps free up spark plugs. I've had to repeat as much as 3 times, to free up plugs. Penetrating oil, like Seafoam in spark tube can be beneficial also. Seafoam then ends up in cylinder and helps free up rings along with valves & piston carbon.

Number one cause of plugs freezing in head, Anti-seize used on threads. Carbon build-up is second and not near as bad.

Yeah definitely not throwing parts at it. Stuff that I would consider "normal maintenance" is getting handled, like the plugs. Every... single... one... has given me grief coming out, finally had to get out my 24" ratcheting breaker bar to get them out better/easier. Still working them slowly though. Problem is that it is large enough that I cannot get to the last two cylinders #7 & #8, so gotta figure that out.

Had one coilpack last night that had cracks along the body of the coil so I replaced since I had the two Densos that I purchased. Put new one on Cylinder #1 to see if that resolved that code, and not dice thus far. Replaced the cracked on #6 for good measure. Going to the buddies place after work tonight to do some more troubleshooting. This morning on the way to work she threw a P0300, P0301, P0305, P0307 but no P0171. Think she was throwing codes just because I had been spraying around the intake to see if I possibly missed a vacuum leak last night. CEL started blinking as I left the house but light didnt stay on, and when I tried to read codes nothing was there... Wasn't until a few lights later that it did same thing again and light stayed on that time which is how I got the codes. Funny thing is that in all of this, when I am monitoring through Techstream, cylinder #6 is the ONLY ONE that doesn't have misfires.

We will see what we can come up with. Unfortunately my EZ Out didn't work last night for getting the sheared bolt out. Gonna talk with him to see what can be done, really hoping that I don't have to remove the valve cover to get it out, I know he said he has a good set of lefthand bits so maybe his stuff will be more successful.

I did drive her to work this morning and while she did the normal stumbling/rough idle at the first couple lights, by the time I got to work she was running rather smooth. So who knows. Maybe something like the Crank Position Sensor, Camshaft Position Sensor, Fuel Pump, Fuel Filter or something else is causing issues. The two things that have me really questioning what is going on is the Fuel Trims and the one O2 Sensor that is constantly at 99.15% (Bank1Sensor2)

Just to confirm that I am not going crazy... Drivers side of the engine is Odd Number for cylinders (1, 3, 5, 7) and Passenger side is Even Number (2, 4, 6, 8) correct? Which would make Bank 1 passenger side and Bank 2 side, correct?

BK 1 is ods and on DS. BK 2 is even and on PS

 

[FlammableFishie]

Drivers side of the engine is Odd Number for cylinders (1, 3, 5, 7) and Passenger side is Even Number (2, 4, 6, 8) correct?

Correct.

Which would make Bank 1 passenger side and Bank 2 side, correct?

Flip flop. Bank 1 includes cylinder 1, meaning driver's side is bank 1.

 

[gregnash]

Two cans of 44k in one tank of gas, helps free up spark plugs. I've had to repeat as much as 3 times, to free up plugs. Penetrating oil, like Seafoam in spark tube can be beneficial also. Seafoam then ends up in cylinder and helps free up rings along with valves & piston carbon.

Number one cause of plugs freezing in head, Anti-seize used on threads. Carbon build-up is second and not near as bad.


BK 1 is odds and on DS. BK 2 is even and on PS

Ok thanks for that...
I have the two cans of 44k in a full tank of Techron currently. I did spray some PB Blaster in spark plug tube last night when I pulled the coil pack to inspect. 7 & 8 are in just such awkward locations that I have a hard time getting to them but I am sure I will, even if it means that I have to buy another ratcheting breaker bar that is 3/8" instead of the 1/2" I have (too long with an adapter).

 

[gregnash]

Just ran to Starbucks to grab something and system threw P0300, P0301, P0305 and P0307 codes again, but no P0171.
So now we have a moving code... LOL.

 

[gregnash]

Ok so on the way home for lunch (about 15 minute drive through town) I popped P0171 code alone, no P03xx codes.
Been slow at work today so was looking up multiple misfire stuff and saw another post by @2001LC that said to test fuel delivery by pinching off the return line while idling and that if the idle increased with the return line pinched off then it was indicative of a fuel delivery issue (likely either pump or filter).

So sitting in the driveway I pinched off the line and sure enough idle increased. Still going to buddies tonight after work to do some more troubleshooting but this is giving me more canon fodder pointing to fuel pump.

 

[BnvS]

Ok so on the way home for lunch (about 15 minute drive through town) I popped P0171 code alone, no P03xx codes.
Been slow at work today so was looking up multiple misfire stuff and saw another post by @2001LC that said to test fuel delivery by pinching off the return line while idling and that if the idle increased with the return line pinched off then it was indicative of a fuel delivery issue (likely either pump or filter).

So sitting in the driveway I pinched off the line and sure enough idle increased. Still going to buddies tonight after work to do some more troubleshooting but this is giving me more canon fodder pointing to fuel pump.

@gregnash .... Fuel pump ... told you so.

BTW if you dont mind can you take a pic of where the return fuel line is located? I kinda have an idea of where it is located for the car, but having a pic is worth a 1000 words.

 

[gregnash]

@gregnash .... Fuel pump ... told you so.

BTW if you dont mind can you take a pic of where the return fuel line is located? I kinda have an idea of where it is located for the car, but having a pic is worth a 1000 words.

This is @2001LC post I am referring too...

Urgent advice needed on rough running/misfire!

Got a code reader and I had a cylinder 6 misfire. Replaced the coil and it runs great but still needs extra cranks when warm.

forum.ih8mud.com

return line is pointed out.

 

[gregnash]

Ok just got back from my buddies house. Truck decided that she didn't want to start when I left work, cranked hard but didn't catch a few times then finally did. When I got to his house he pulled up his techstream and looked at everything and agreed with latest that it seems to be pump.

So ordered new Denso kit (950-0107) from RockAuto that should be here next week, also grabbed new tank seal for the pump and a fuel filter from Joey (Wits' End). Hopefully everything will be here first thing next week so I can get this handled.

We were also able to get the last two plugs out so all plugs are changed.

 

[gregnash]

CHECK YOUR INJECTOR INSULATORS!!!!

Reading through some threads and saw there were a couple guys (literally only a couple) that had same issue (P0171 or stumble/rough idle/stutter with no CEL) and found that their injector o-rings/grommet/insulator were going bad on certain cylinders. I know I had checked them when I was spraying around looking for a vacuum leak but wondering if the driving around today (have been riding my bike) heated up the insulator enough to let things breathe more than before when I was just letting it get to operating temp.

#8 and #5 are definitely leaking as a shot of carb cleaner at them had them immediately idle up. Tried to check the rest and seemed like #1 might be leaking a bit but not near as bad as those two. I saw a post about removing the fuel rails as one piece, now to find that again (can't remember who wrote it but apparently didn't save) so I can handle this ASAP.

So question is, OE grommet/o-ring/insulator or LAPS?

Found the post I was looking for....

Replacing Fuel Injectors

Of course things always happen on holiday weekends when it's pouring down rain. Long day of chasing codes on my '98 LC. The fun started with my rig loosing power and running rough followed by the check engine light. Ran diagnostics and I got the dreaded P0301 code—thanks to IH8mud threads/FAQs...

forum.ih8mud.com

 

[yngmrostrvile]

Ok just got back from my buddies house. Truck decided that she didn't want to start when I left work, cranked hard but didn't catch a few times then finally did. When I got to his house he pulled up his techstream and looked at everything and agreed with latest that it seems to be pump.

So ordered new Denso kit (950-0107) from RockAuto that should be here next week, also grabbed new tank seal for the pump and a fuel filter from Joey (Wits' End). Hopefully everything will be here first thing next week so I can get this handled.

We were also able to get the last two plugs out so all plugs are changed.

I dont know how down your boss is but this sounds like the perfect opportunity to install a long range fuel tank

 

[gregnash]

I dont know how down your boss is but this sounds like the perfect opportunity to install a long range fuel tank

I'm my own boss!!!
Wish I could justify that to myself but not at this point in time!

 

[gregnash]

OE stuff is on order from Partsouq, so should be here early next week.

 

[gregnash]

Alright tomorrow is the day. Got parts on Wednesday but had other stuff going on. Buddy and I are going to handle this and while I am there I will check to make sure that intake bolts are all nice and snug. Will use @JunkCrzr89 little write-up to pull the fuel rail and injectors as one piece and replace all the rubber, even got new crush washers for the banjos.

So knock on wood this handles this issue. If this doesn't then I am going to be at a loss for what is throwing the code unless there is a massive leak I am just completely missing elsewhere.

 

[JunkCrzr89]

Alright tomorrow is the day. Got parts on Wednesday but had other stuff going on. Buddy and I are going to handle this and while I am there I will check to make sure that intake bolts are all nice and snug. Will use @JunkCrzr89 little write-up to pull the fuel rail and injectors as one piece and replace all the rubber, even got new crush washers for the banjos.

So knock on wood this handles this issue. If this doesn't then I am going to be at a loss for what is throwing the code unless there is a massive leak I am just completely missing elsewhere.

 

[gregnash]

Well on to more testing...
Replaced all the insulators, grommets and o-rings for the injectors along with crush washers for the banjo bolts. Pretty much all the insulators were done, two of them were absolutely gnarly (#5 especially).

But still popping the P0171 code with the stumble, stutter and misfire codes coming up.
Untitled by Greg Fisicaro, on Flickr
Untitled by Greg Fisicaro, on Flickr
Untitled by Greg Fisicaro, on Flickr
Untitled by Greg Fisicaro, on Flickr

So going to the techs house on Monday evening to see if we can diagnose further. So far I have replace multiple coil packs, all spark plugs, injector seals, fuel filter, fuel pump, MAF and one O2 sensor. There are no vacuum leaks to speak of and unless there is something going on with the Cam or Crank position sensors that isn't throwing the code of one of the other O2 sensors is not throwing a code, then I am at a loss. Tech suggested next step be a leak down and compression test to rule out <badword>. Timing belt, water pump and t-stat were done toward the beginning of the year and the timing was found to be 1 tooth off then, so don't know why that would affect things. Other than that only other major work that has been done is the power steering pump that failed after the P0171 code initially started popping up.

 

[jerryb]

what has been done with bank 1 sensor 2?

 

[gregnash]

what has been done with bank 1 sensor 2?

Bank 1 downstream sensor has not been touched. No definitive O2 sensor code.

Oh and we did check the intake bolts and everything was still nice and tight.

 

[Mauser]

Bank 1 downstream sensor has not been touched. No definitive O2 sensor code.

Oh and we did check the intake bolts and everything was still nice and tight.

I chased the same code for months on my 98 LX. I pulled the throttle body to clean it and noticed the dirt inside the intake manifold so I bought gaskets, pulled it off, and cleaned it good. After reinstallation the code was gone.

 

[gregnash]

Looks like @ClassyJalopy and @Mauser are the winners.
Got it over to buddies place, went through things we had done and agreed that injector seals and everything were toast for sure. New coil packs were needed. MAF is good maintenance replacement item. Heard the rough idle and he could actually hear a vacuum leak. This was not something that I had heard yesterday so don't know if it just took him pointing it out (buddy that helped me replace the injector stuff didn't hear either) or if it was being masked by the back injector insulators and now that those are replaced, the next thing down the line that was leaking just go that much worse.

Sure enough intake on bank 1 is leaking badly now. Checked bolts and everything is tight to the head. Poking around he thought the gasket looked like factory meaning that shop that did the starter either didn't replace like they told me or ordered wrong part and then just slapped some FIPG on the old gasket and did that. So going to be ordering parts from local dealership tomorrow in hopes that I can have them on Tuesday then replace everything Wednesday.

So will now be replacing Intake Gaskets, Throttle Body Gasket and Banjo Crush washers.

 

[ClassyJalopy]

Glad you have it figured out! It took me roughly 2 hours in 10⁰F weather to replace the intake seals along with fuel injectors grommets, cushions etc.