It can, but then you have to sit around waiting for it to learn to do that. If he is already at rich it means it's tried and that's where it's at for now. Adjusting the fuel pressure lets you do that and immediately see the difference until the fuel trims start to move. Sounds like it's close to pegged, so it gives one another means to adjust beyond waiting around for a computer.

Again, a leak is most likely, but this will still let you tinker in a new way for adjustment.

 

Alright, so it's been a couple weeks, but we got back to work on it earlier this evening. Installed the good intake pipe, then discovered that cylinder 1 was not firing. I felt the injector, and it didn't feel like it was working. I double checked with a noid light, and it's certainly firing. We swapped that injector out anyway with a spare, but that made no difference. I pulled the coil connector to confirm that cylinder 1 is definitely the culprit.
I also replaced the cracked PCV hose, so that is no longer a concern.
I'm going to check compression on cylinder 1 just to be certain that that's not an issue, but I'm beginning to suspect the flywheel alignment is a problem. BUT, would that cause cylinder 1 to not fire? Would that affect ignition timing, causing the misfire?

 

Yes the ECM bases ignition timing off of the data sent from the crank position sensor.

 

Ok, that makes sense then. Wonderful... may be a flywheel position issue. How the hell did he manage to do that? lol

 

There's an alignment dowel on the back of the crankshaft that's supposed to line up with a hole in the flywheel but sometimes that dowel falls out, or some flywheels can be installed in any orientation. Hard to say really, I would definitely do the compression test at least on that cylinder to rule out something major though.

Out of the 6 different potential orientations of the flywheel, 1 is correct, 3 won't work at all, and the remaining 2 will make the engine run VERY VERY rough if it runs at all. I think I've seen 5 of the 6 positions with my own eyes lol. For some reason it's a mistake a lot of people here in town have made. Every single time it was because the dowel had fallen out.

The dowel is Nissan part number 11022-AD200, you don't technically need it though if you're careful.

 

Interesting. I'm definitely going to start by checking the compression on cyl 1, and we'll see where it goes from there.
I've seen some interesting stuff screwed up before. For example, when I put the clutch disk in my Subaru backwards... don't know how I managed that!

 

Well he pulled the trans, and lo and behold, the flywheel is in the correct position. I was pretty sure that would be the problem, but I guess not! Back to the drawing board. That is, once the car is put back together...

 

Like I said before, I would consider adjusting fuel pressure to bring it around for now. Unless you can program the car with different size injectors to get the fuel richness down to a better range.

 

I am VERY happy to finally post the solution to this!

He had replaced the injectors with a freshly rebuilt set of JECS injectors, but that made absolutely no difference (to my surprise, honestly... I've never seen a car with a year-to-year injector change just accept the others no problem). At that point, he sent it over to a guy who was a former Infiniti master tech and now owns his own shop. He took a look at it, swapped around the cylinder 4 and 6 coil connectors that had at some point been reversed, and advised that he replace all 6 coils and the cam sensor on bank 2 (which is interesting considering the 25% fuel trim was on bank 1).
He drove the car to my shop, and went and got a Hitachi cam sensor (it was a generic junk sensor that had been installed). Absolutely no difference. After some fooling around, I took another look and discovered the bolt missing for the #1 coil... interesting. Put a bolt in, no change. That led me to unplug it, that made no difference. Same with cylinder 3. So I pulled the connector over to cylinder 3 from 1, and it picked up that cylinder. Plugged in 3, and it smoothed out perfectly. No more popping, and the fuel trims normalized. Still a tad lean, but I think it needs some fresh gas. The car has been sitting for a LONG time.

How the guy missed that when he was "diagnosing" the problem, I have no clue. Can't fault him too much, I somehow missed it too, but when there are so many hands on one car, it can seriously complicate things.

Two lessons here... 1- take your time to diagnose problems, and don't let anybody else swap things around the test theories, then forget to put them back (eg. swapping coil wires, which is exactly how cylinders 4 and 6 were reversed, then forgotten). And 2- MAKE SURE YOU REPLACE COIL/INJECTOR CONNECTORS IN THEIR CORRECT LOCATIONS. Just because the harness seems like it doesn't quite reach, doesn't mean the whole harness hadn't been rotated/moved/twisted the wrong way to where it looks like it's correct.

Alrighty... onto the next project!

 

The car overheated 1 hot summer day in south florida on the highway. The Water Pump had to be changed. While they were in there they did the Timing belt/chain.

Then Transmission fluid covered the driveway and the radiator had to be replaced. It wasn't the radiator,it was the welding point that branches the transmission line to the radiator that was cracked.

Idle was so rough and rpm at 1000-1100. It was so rough, it was visibly shaking at redlights.

I did the coils, spark plugs, and cleaned the throttle bodies. Car idle was significantly better but fluctuated around 750 rpm at idle. PLus the check engine light is solid, and blinks after approx 30 mph.

I did the idle relearn. It helped the idle somewhat, but once car engine is turned off, idle returns to a 750 fluctuating rpm.

It's the end of August 2023 and since March 2023, the car has only had approx 60 gallons of fuel. I've added Lucas fuel treatment every time I put in 10 gallons or so.

I understand this car is 2008 and has been in Tropical Storm and Hurricane elements since its original purchase. With that said, this car has a huge amount of water and rust damage. Accumulation of small leaves and other plant/tree debris under the wipers and around the trunk hinges. Battery and Brake compartments both rusted. UNderneath is very rusted. The front "struts or springs" are fully orange covered rust.

I use a cheap ODBII reader by MOTOPOWER, i bought off Amazon. I had multiple cylinder random misfire codes before new coils and spark plugs. Now just have 1 P0300 $07e8??


Had Firestone do a full diagnostic. They put a new spark plug and coil into cylinder 1. And received the same P0300 and P0171.

They said the next thing they would do, is to change the fuel injector. Quoted me a piece of around $1500. Just for 1 fuel injector. I don't have my own garage or way to get underneath the car.

Am I missing something?

 

It sounds like Firestone was just firing the parts cannon... if you already changed the coils and plugs, odds are that they're not the problem. I'd also be willing to bet your injectors are all fine. A random misfire code doesn't usually point to a specific cylinder.
P0171 is pointing to a lean condition on bank 1. View the short and long term fuel trims for both banks. Make sure you don't have any vacuum leaks, you may need to smoke test it to find them. Start with the easy stuff, vacuum hoses and intake ducts.

A compression test couldn't hurt either. It's entirely possible that a cylinder head warped from overheating the engine before. I wouldn't worry too much at this point, but regardless, you need to methodically diagnose this rather than throwing parts at it. Contemplating potential issues isn't going to tell you anything. Kinda sounds like that's what Firestone was doing.