Just like delivering a babyđ
Paul, Can I get you to send me an off-list email? Go to my website and find the link to send me an e-mail.
Gracias, SD
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just replied, in a PM.
Well damn. Thatâs what Iâve learned about this car, do not celebrate too early! ;(
Started her up today after sitting overnight. Sheâs misfiring again consistently on A bank, 4A, and ECU is enriching fuel again. The car ran great yesterday, two test runs, no misfire, although towards the end of the day yesterday, i DID start noticing mild random misfire on A bank, but thought nothing of it.
I checked intake manifold torque, they all needed a tiny grunt to get back to 18 ftlbs. But no help.
About the only other thing i did while the manifolds were off, i poured a few ounces of seafoam down each intake port. May try that again and see if it temporarily helps?
A bit lost now, i guess compression check is next? Or could the injector still be at fault?
Intermittent faults. My favorite.
There is one thing to keep in mind: You can rule out any fault that couldnât be intermittent.
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One more possibility marked off the list. Was not the intake gaskets causing the miss although they may have contributed to some not ideal runningâŚair/fuel ratios off. Dr. House would call that progress. Is the sucking/hiss noise gone ? I donât think itsâ an injector with crud in the filter. That would be full time, not intermittent. Iâm beginning to think its time to have a the engine scanned on a laptop, or use an o-scope. It is beginning to appear more like an intermittent electrical fault, which means it needs testing while it is misfiring. Something like a corroded connection or frayed wire, and I do remember you testing the spark as good, and the injector clicking before the gasket replacement. SD Faircloth
Nor is it a mechanical issue. Any of those mechanical parts would be a full time fault. Skip the compression test. SD
Continuing my thought process from aboveâŚIf you continue the DIY avenue, go back and redo a spark plug test with a store bought plug in spark tester, and buy a Noid light to test for a continuous signal to the injector. Youâll need to run both test, one after the other while A4 is not firing. Running the engine before the test to confirm the miss is there, and after the tests to confirm the same. SD
Thanks for the feedback.
Before I look into buying a noid test, what is the difference between me seeing a consistent flashing light, and me using my stethoscope to hear a consistent clicking? (which I get) Remember, I also swapped fuel injector sockets with 5A injector, and the misfire was still at 4A.
Is there any possibility of the spark plug not having a good ground? I previously tested the wire and am getting a good spark from the cap.
And the car âseemsâ to run fine, smooth and powerful at higher RPMs, plenty of power. When I pulled the plug on 4A, it looked OK. Hard to tell if it looked lean. Not sure if that means it only misfires at idle, or if I just canât detect a misfire at higher RPM.
I know youâre the expert here, but could a slight clog causing a bad spray pattern affect idle? Could having the injector dry for two weeks temporarily changed anything?
I had that fuel rail rotating all over the place upside down, right side up, etc, while I painted the fuel rail, could some crud have moved around while dry, and then slowly found itâs way back to affecting the spray?
Not necessarily. A broken valve spring near the end of a coil can cause intermittent problems if it it screwing in and out of the broken piece. That causes more or less valve seat pressure.
Find someone who can do in cylinder running compression testing with a digital pressure transducer. That will quickly determine if you have a cylinder issue.
Also scoping the ignition train can rule out ignition issues. Fast and easy with a distributor based ignition.
Scoping the injector pulses is also easy. You can see if you are getting drop outs that you canât catch with a stethoscope or noid.
Now days there is no reason for a DIYer to not have a scope. Go to the Logical Canuck channel on YouTube; he has a whole series of tutorials on using the HScope app for Android with inexpensive two channel USB scopes. You can have a scope for well under $100, if you have an Android phone or tablet, that can do anything professional shop Picoscopes can do, and sometimes more.
I donât remember if youâve changed ignition components anytime recently. Remember that new often doesnât equal good.
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Looks like I should invest in one of those oscilliscopesâŚyes, I can use it with my android phone.
Thinking back to my test run Tuesday after intake manifolds were put back on, it idled smooth with no misfire. Went for a short 5 mile drive. Still smooth. Went for a 20 mile drive. Came back, and I started to note an intermittent mild misfire on A bank. Let the car sit overnight. Next day, instantly noticed a steady popping misfire on A bank. And itâs still consistent.
And here I am again.
Iâm still thinking about that oil I saw on the intake valve on 4A when manifold was off. Perhaps accumulating as I drove, and especially sitting overnight. Is it a big no-no to add the valve stem seal oil additive to this engine? Remember, I poured seafoam down intake ports while manifolds were off, it sat in there for a good week. But I never see blue smoke out of exhaust, nor am i losing oil. Same with coolant level, stead as a rock. (thinking head gasket)
And Iâm running 10/40 Valvoline Synthetic oil. Good oil pressure.
Took a look today, did a lot of wiggling, and other checks. I cannot see any telltale signs of electrical fault, for now.
What i did find, is some dark grey oily substance again in the A bank air intake housing, all along the bottom. Filter looks fine.
There is a tiny bit of oil near pcv on B bank, but it looks more like oil. A bank is thin and grey with bits of spec.
Could exhaust be getting into 4A intake valve and pushing it up thru intake manifold? Someone mentioned worn valve springs? Or is this simply a byproduct of the steady misfire?
Will a vacuum reading determine valve spring?
I do remember Kirby saying I can eliminate non-intermittent things, so hopefully valve seat drop or valve spring breakage are not so? Could a sticky intake valve cause all this? Could the pouring of seafoam down the intake valve have helped it for 1 day?
Greg, A quick reply as I am covered up. A magnet will tell you whether those particles are metal and that will give you some info. If the springs were acting up, wouldnât you have a backfire thru the exhaust or the throttle body, depending on which valve. A compression test would tell you whether all of that stuff is tight. Kirbysâ non-intermittent said the right way is your problem IS intermittent. Two negatives make a positive sort of thing. The valve spring thing came up from another poster (jal5678), indicating it may cause an intermittent issueâŚwhich I did not completely understand. You may be getting trash from the PCV valve or those deteriorating hoses. SD
Thanks, i may just bite the bullet and send the injector off to youâŚi posted above that it could still be to blame?
Just for the hell of it, i swapped in a new NGK spark plug, but no difference.
Yes. Not sure why itâd be sticky, though.
I dunno how that would unstick it.
That crud youâre seeing is in the air filter housing? Which side of the filter?
Whatâs your air pump doing?
On the intake manifold side of the air filter.
Air pump was removed back in 2018.
Iâm also thinking about the injector harness like several have stated, i hear the injector clicking, the noid light will tell me more (Iâve ordered a noid light), but for all i know itâs clicking at the wrong time? That would definitely cause a misfire? No way to test that out? I did have to remove entire harness while doing the intake manifold, could have knocked something. I know some of you have rebuilt the harness, i may try it.
Just sticking my nose in here, on the AJ6 engines the injectors pulse twice for each cylinder, one when the valve is open and the second when the valve is closed, by that reckoning a mis-timed injection shouldnât affect the idle/running. Comments SD?
Why? How would a fault in the injector harness result in that crud in the air filter housing?
You do know that the entire bank fires at once, right? Timing simply could not matter less.
The injectors on each bank are connected in groups of three, and the groups of three are connected together into a single group for the entire bank within the ECU itself. That means that anything affecting the entire bank would have to be at the ECU, and anything affecting 3 injectors could be in the wiring between ECU and injectors. Anything affecting only one injector would have to be right there in the injector harness, or the injector itself. But you swapped the 4 and 5 connectors, which rules out the harness.
I think you need to concentrate on the crud in the air filter housing. That stuff ainât right, and finding the source is called for â whether it solves the miss or not.
ah yes, i remember the groups of three, but forgot itâs all at once. For some reason, I thought since it was grouped in threes, then each bank had two timings.
Yeah, iâll try and see if i can make any headway on that crud. One idea, is to block the pcv pipe to the A bank, in case itâs finding itâs way through there, although it would be showing up on the B bank too.
Will also use my endoscope camera to take a peek inside manifold.
Canât have anything to do with my air pump holes, right? I resealed all of them. If one came loose, iâd just have noise.