First and foremost, I'm aware I'm not FI. Unfortunately it feels like the only knowledgeable folks left on this board are the FI guys. Everyone else has moved onto other platforms except the guys with 10's of thousands invested leaving all the $13,000 "Z buyers".

Car: 2006 REVUP V2. 20,000km on motor. Stock bottom end. Fuel system never touched except for a fuel tap for pressure senders. Basic bolt on NA mods. Osiris Uprev Tune.

Problem: Towards the end of the last summer I was smelling unburnt fuel. Idle AFR (dual wideband) would also often spike. 14.5'ish, 13.5'ish, 14.5'ish back and forth.

Worklog: Determined fuel leak. Pooling on the rear right fuel rail mounting bolt. Couldn't tell exactly where it was leaking from so I removed upper/lower plenum to get at the fuel rails. Pictures of what I discovered below.

I'm having trouble piecing together scenarios of what is happening. I don't understand the dirt/grime around cylinder 4/6. I don't understand the oil on injector #6 nor why the injector holes seem pretty grimey.

I'm hoping some of the knowledgeable folks might really be able to shed some light here for me. Could really use the expertise I know exists here.

Injectors 1-5 looked like this.


Injector 6 looked like this.


Cylinders 1,3,5 obviouslly a lot cleaner


Cylinders 2,4,6. Why so grimey


This is where the fuel was pooling. Definitely not leaking from the fuel tap/regulator as I re-seated/replaced o-rings and it was dry. It's either injector #6 or a crack in the rail I can't visually see.

 

I guess I'll give my "theory". Not sure if it even makes sense though.

Injector #6 crapped out, dumping fuel, washed out cylinder #6 causing piston ring not to seat there for getting blow-by explaining the oil. But this is a theory from someone that knows very little compared to a lot of you guys.

 

Can you explain more of what the AFR was doing? You mention spiking - was it just one bank, both, or what? Was it doing it randomly or only under certain conditions? Also, what were you using to monitor all of it?

 

Thanks for chiming in. Appreciate it.

It seemed to be mostly at idle, although watching my guages while driving isn't the easiest but AFR seemed to be ok while on the throttle. I have two XD-16's mounted on my steering column.

My first thought with the idle "seek" was a vaccum leak. That's what it felt like. It wouldn't always do it, but did seem to be getting more frequent. It would basically idle fine, then you could feel it dip/bog and AFR would richen up to 13.4/13.5. Then it was like the ECU would correct and come back to 14.5.14.6. Rinse and repeat till I got back on the throttle. I should mention also, although rare I did see it spike to 15 is occasionaly too. After it bogged down to 13.5 it would try correct and hit 15 ish then come back down. Honestly trying to solve this based on the AFR could be hard.

Unfortunately, I can't recall if both banks were doing it. From memory though I want to say only one bank was.

 

Have you checked the oil lately? That looks like the last oil consumption engine we broke down.

 

13.5 isn't low enough to hurt anything, i idle and cruise ~13.4, so i don't cylinder wash is causing it. I may have missed this but do you have a rev-up? It could just be oil consumption and primarily on that cylinder. How did the corresponding spark plug look? Have you been losing oil?

EDIT: i see you have a Rev-up, id be willing to bet its oil consumption and its just alot worse on that cylinder

 

Okay. That's really interesting. I may or may not be having a very similar issue - a gremlin that has been plaguing me for over a year now where I'll have one bank spontaneously adding fuel and reading equivalently rich. It's intermittent like yours, and the other side will end up rising up a bit sometimes into a lean condition.

I've had the voltages on my injectors checked, but I never did the visual inspection like you've shown in your pictures... I'll probably do that this weekend and see if my situation looks like yours. Seeing how we have the same engine, I wouldn't be too surprised. Honestly, it would be a relief. And if/when I do get it checked at the dealer (it's a good dealership, though), I'll post back up on here with the results/information and see if it can't point you in the right direction on this whole thing.

In the meantime, any more information you can throw out would be great - any codes, for instance, that were subsequently thrown?

P.S. I just had my short block replaced last month for an oil consumption problem, and the problem is still there like it always was. So if it's the same thing going on, then oil consumption may be a symptom but not a cause.

 

To both of you guys, honestly since I got the REVUP V2 put in, I haven't been monitoring the oil level as much as I use to. I rely on the pressure guage and my usuall changes.

I swear to god, if this REVUP V2 is consuming as well I'm going to be pissed.

 

Please do. I'd love to hear if your injectors look the same. While it doesn't offer me a solution it would put us on the right track. I will be keeping this thread up to date as hopefully I'll get some good ideas from the folks around here.

 

Do a compression test

 

Can you show a picture of the valves and manifold? The oil is coming from the valve, valve stem, or manifold. Not many options. The fuel leak is probably from the O-ring around the nearest injector where it mounts into the rail.

 

Which would be caused by shot rings on that cylinder correct? I guess I'll have to put it back together and do a compression test also.

EDIT: Just saw your reply. You guys are too quick. Perhaps a stupid question but can I do a compression test with the upper/lower plenum off?

 

If you are smelling unburnt fuel, I would lean towards the o-rings on the injectors... It is a cheap and easy fix to test. It does look oily around that 6th o-ring so I would recommend a compression / leak down test.

 

Not sure if I can see an oil leak from what was posted.

 

Where the injector mounts on cylinder #6. That doesn't look like oil too you? Quite a bit blacker on the outside of the heads and the hole itself is pretty gunked up.

Really do appreciate the help.

 

What I found weird is the fuel was pooling on the bolt I highlighted. Seems a long way to go if it was leaking from Injector #6. But your right I'm replacing the o-rings either way since I have them out.

 

Yes you should be able to

 

Fuel Rail is back on to determine the leak and so I can do a compression test.

Fuel leak has been found. The rail has a crack where the bracket meets the rail. Right in where the weld is. It's not visible but it's definitely coming from there. Injector o-ring appears fine after all. This is just priming the fuel pump though without starting, I'm assuming it is the same.

The "sludge" around cylinder 4/6 on the outside is just dirt, obviouslly mixed with fuel. I cleaned it up with brake cleaner and it came off way to easy to be oil residue. So that's good.

What I'm still confused about is the oil on the injector tip, and my AFR seeking. But I'm getting there. Compression test tomorrow hopefully.

 

Glad you found 1 of the issues.

 

Quick update. Did a compression test today. Results were 150-152 across all cylinders. This was done COLD. Which means compression is tip top.

That is some good news.

I found an old thread on these boards of someone else who had oil just on injector six. Apparently there is a "passage" in the right side valve cover that easily gets gunked up causing a blockage and excessive blow-by. Sounds feasible to me so I'm going to replace the right side rocker/valve cover also.

At this point I'm just throwing parts at it in the possible areas.