98 Q45 running rough, bucking and loss of power v3.0

[QCumber]

Ok, finally got the Q back to my shop after a couple of weeks of doing anything but putting myself under a car.

Ran fuel pressure tests and here is what I found out:

35 psi with vaccuum and 44 psi without vaccuum...nothing out of the ordinary...until I clamped off the intake and return to see if the pressure held on the injector rail...voila...

After weeks of monkeying around I have finally tracked my problem on this thing:

One (or more) of the injectors are leaking down.

The guys at my shop all want to put this additive and that booster in there to knock a possible carbon build-up around. I am not too enthused about doing that. I found some injectors at rock-auto (remanufactured GB's which I have in my R-Rover.

$300 shipped for all 8...looks like the way to go when I get my tax check

Getting the rail out looks like a good couple of hours worth of work so my gut instinct is to go ahead and replace them all at the same time.

[Mint Q45A]

Just in case.....

I was having what looked like "flooding" issues with my car, and suspected that there was some fuel leaking throught the injectors/ o-rings. Because of this I did a complete "leakdown" test. In the process I made some mistakes and had some "false" results. At one point I thought that I had confirmed my theory about the leaking injectos...but I was wrong...

Getting the fuel lines completely blocked/closed just by clamping them, proved to be quite challenging. It wasn't until I disconnected the return line and fully blocked it, and used a heavy-duty clamp on the feed line that I was able to get a good test....and the result: no leaks.

My result confirmed Q45 Tech's feedback: injectors typically do not leak....

Here is the link to the posting so that you can get some more info and see some pictures on how I did the test...

zerothread?id=298955

I just want to make sure you have good test results before you take the next steps...

Note: At one point I was so convinced there was a leak that I ordered three sets of o-rings.....
Modified by Mint Q45A at 8:40 PM 12/19/2007

[maxnix]

There is no such thing as "rebuilt" injectors. There are only new and used injectors.

It is very doubtful all 8 are bad.

If you pull the fuel rails, might as well do the full intake path cleaning.

Injectors seldom leak. Their O rings can be pinched upon insertion.

Have you used BG44K?

[QCumber]

Ordered a can of BG44K (ebay) still waiting for it.

I read the included post, and from experience I would agree, FI;s themselves seldom leak...the odds would point away from that. I will check the o rings when I pull the rail out.

Knock sensor started showing up on the p codes from the ecu. Not sure if this is a symptom or merely a endresult.

In other words, is my KS really fouled up and causing my flooding or is one or more injector causing my KS to trip?

More to come.

[Q45tech]

KS system just reduces ignition advance under load and don't affect idle.KS system is tested at each start and periodically...............for resistance and background noise levels of running engine.........either or both can set codes.

Historically KS sensors fail at a fairly perdictable rate every 10 years or so.It appears that the plastic housing can only take so many heat up cool down cycles before it cracks and changes resistance and microphonic sensitivity.

[QCumber]

I still don't get how this problem only shows up under the following circumstances:

On the first drive of the day, the car runs just fine (regardless how long or far I run it). The flooding problems don't start until you stop the car and then restart it.

As long as you let it sit for more than a few hours, the cycle of working just fine until first restart repeats itself again.

I would think that this points towards temperature or vaccuum but I have alerady checked out everything in both of those arenas.

[Mint Q45A]

Some additional feedback:As I mentioned, I was having some "flooding" issues, reason why I did the leakdown tests; fortunately after a few tries I was able to get good results and concluded that there were no fuel leaks - see previous post.

I recently replaced the two KS - since then, no more issues.

I am not sure how relevant this is: When doing the KS I noticed some oil accumulated inside the plenum. In trying to trace the source, I found out that when I cleaned the TB (a couple of months before) I had put the little wire-brush that goes inside the hose that comes from the plenum, where I think, is the wrong place - on the horizontal portion of the hose, right before the TB. I moved it to the vertical portion of the hose,as it comes from the plenum. I believe this will help trap any heavier particles (oil) before they make their way to the TB.....I maybe wrong though...

[Q451990]

I still don't get how this problem only shows up under the following circumstances:

On the first drive of the day, the car runs just fine (regardless how long or far I run it). The flooding problems don't start until you stop the car and then restart it.

As long as you let it sit for more than a few hours, the cycle of working just fine until first restart repeats itself again.

I would think that this points towards temperature or vaccuum but I have alerady checked out everything in both of those arenas.

The hot soak hard starting deal really does sound like an injector or flooding for some reason... maybe something as simple as a bad o-ring. When I replaced all of mine with rebuilt injectors in the late 90's, I had that issue. Repalced them again with new ones and it cured it. I don't think I would replace all of them unless you have to. Maybe you could send the entire rail assemblies to http://www.deatschwerks.com/catalog/ for a cleaning and bench testing? A lot of members have had good results with them.

The reason the flooding isn't evident after sitting for a long time is that the fuel seeps past the piston rings - diluting your oil... so I would go ahead and do an oil change ASAP.

Heath

[metaverse3]

I did have the injector flooding/hard start issue on a maxima about 5 years ago... The issue was the injector internal coil system failing and leaving the injector open allowing a flood condition.. It was washing down the walls of the cylinder (saw it with a bore scope)

I also tested the system on a bench with a controlled pressure system and witness the issue first hand..

Don't replace OEM with reman injectors (python reman) and do not replace 1 or 2 injectors individually.. Replace all 8 injectors and while you are at it, replace knock sensors/harness. Buy the OEM O-rings which are buna rated (if possible viton which is better) You are in to spend some money, but, it is worth it if you are intending to keep the car.

[QCumber]

I figured I was in for some dough. One of my customers just ordered 6 remanufactured FI's from rockauto.com and they looked in pitiful shape. A few hadn;t even been cleaned at all, they just looked like someone's core.

Deatschwerks might be the solution unless I can find another source for reasonably priced new injectors, best I can do with my shop discount so far is @ $135 a piece.

[maxnix]

That's a good price for OEM new. Check out Joe.

Still don't think all 8 are bad, but you must go through the steps and take the time to diagnose correctly.

A trip to Deatschwerks might identify the bad one or two which you can replace with new by having it or them dropped shipped to Deatschwerks and have them install it on the rail.
Modified by maxnix at 12:22 PM 12/31/2007

[texasoil]

I am a big supporter of Deatschwerks. Send the entire fuel rail system to them for cleaning ,testing done right. A leaking injector (yes they will occasionally leak on hot shutdown) may cause a wrecked engine if the fuel filled cylinder has piston just starting down--it may have enough momentum to bend the connecting rod or worse when it comes back up.