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Discussion Starter #21
paul cawson said:
If you can borrow the coils, plugs, AFMs and ignition amp off another GTR you know to be running OK. Also check the injectors by pulling their plugs off at idle one at a time.
Gonna show my ignorance here, but how will pulling the injector's plug off whilst idling help? What am I looking for? I'm guessing that I'll just have a miss then?
 

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Sorry for not posting back quicker. The vacuum reading on my car at idle is approx 5 - 5.5 mm/Hg. (My needle sits between -7 and the middle mark with no number) Your 3 mm/Hg sounds a bit low..........:confused: I dont run hairy cams etc like your motor, but i am sure this would not effect the idle. This grey smoke you are getting sounds worrying. Could be a duff injector. Take them off and get someone to do a flow test on them if you are suspicious of them. Are they uprated/bigger injectors?

Cornhoolio
 

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Jim27 said:
Gonna show my ignorance here, but how will pulling the injector's plug off whilst idling help? What am I looking for? I'm guessing that I'll just have a miss then?
I thought you rough idle could be a misfire? so if you pulled off the plug and nothing changed that could be why.Is it just that the revs are rising and falling on tickover.
 

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Discussion Starter #24
The grey smoke has stopped - mixture of condensation in the exhaust and bad mixture due to me (dufus that I am) forgetting to reconnect the crankcase breather to the intake system, leaving a nice big air leak through the unconnected intake connection. Sorted now though.

So - today...

I stripped the intake off again trying to get to the rear turbo - nope. Not happening. There's just no way I can see that I can undo the lower bolt, even when using a ball-joint ratchet - there just isn't the room between turbo 1's exhaust housing and turbo 2's inlet elbow. Have decided to leave it for the moment. The front turbo spins free and easy and the 'chuffing' noise is coming from both intakes, not just the rear one (see below)...

Well, John (car32) popped over today and we had a chat and a look/listen.

It's always helpful to have an extra brain/pair of ears added to the mix (especially when my own are somewhat limited ;)).

We didn't manage to get a compression test done but once we had everything back together Paul cast his slightly more experienced ear over the old girl as she was ticking over. With the new (clean!) air filters in place you can quite clearly hear the Darth Vader *chufff* (pause) *_chuff_* (pause) *chufff* (pause) *_chuff_* coming back through the intake from the turbos, one at a time.

The injectors all seem to be ok (yes they are bigger ones than standard - 550cc) as there's no change in injector noise when the idle goes lumpy (cheers John for teaching me how to listen to an injector through a screwdriver! ;) :D

So the idle's lumpy and there is a definite misfire.

Looking at the big single GReddy atmospheric BOV I've got, it's a bit on the manky side so there's every possibility that it's leaking a bit. I've got a pair of Blits atmos BOVs as well as the factory recirc ones in the attic so the next job will be to retrofit the factory BOVs and swap the plugs for a tested set that are a known quantity. That's the theory at the moment - air leak through the old BOV to give the lumpy idle and the revving up and down on coast down (in neutral) to traffic lights, and the misfire is probably due to a badly gapped plug.

We may be completely wrong but it's an avenyue to pursue that won't cost anything more than a little time so I'm all in favour :)

Then, of course, we had a cuppa and stood around nattering about cars like a couple of old housewives :D:D

...and just for John:

 

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Cornhoolio said:
Sorry for not posting back quicker. The vacuum reading on my car at idle is approx 5 - 5.5 mm/Hg. (My needle sits between -7 and the middle mark with no number) Your 3 mm/Hg sounds a bit low..........:confused: I dont run hairy cams etc like your motor, but i am sure this would not effect the idle.
Actually, changing the cams *does* affect your idle vacuum. I noticed a drop idle vacuum when I went from stock cams to Tomei 260 cams.

I've not driven my car at all over the winter (don't want to get salt on it) so I have really vague memories of what the figures actually are - I think it was something like -450mm Hg on stock cams and about 300 - 350 on the Tomei ones.
 

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Discussion Starter #26
That sounds pretty similar to my own - running circa -3 to -3.3 on the factory vac gauge at idle with 264/264 HKS cams.
 

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Discussion Starter #29
Right - just spent half the evening removing bumper, unfastening the big GReddy single atmos BOV that came on the car from Japan (yes, it was horribly corroded and full of sh1t) and have fitted a pair of standard recirc BOVs. Bumper's back on and I've just about regained some feeling in my fingers (love the cold weather :D).

I haven't fired the old girl up yet as a) it's quite late now, and b) I don't think there's enough charge left in that sh1tty Jap battery to crank her over properly. Will wait until I've got the spare plugs in too.

One thing I want to check, though, is this: if my PFC was mapped with an atmospheric BOV, will the recirc BOVs result in more air being retained in the intake than the map expects, possibly leading to lean running?
 

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Discussion Starter #30
Fired the old girl up this evening for a few minutes. The misfire is still there, but the idle seems better with the factory recirc BOVs on :D

Looking on the PFC Hand Commander has raised another question though...

AFM1 0.95v
AFM2 1.35v
O2 1 0.08v
O2 2 1.00v

Those are the AFM & O2 sensor readings (approx). The difference between AFM1 & AFM2 is fairly constant, as is the difference between O2 sensor 1 and O2 sensor 2. Any idea what this could mean? I guess that this is more suited to the 'Electrical' section so I'll post seperately there :)

From cold she starts up and idles around 900rpm. After a minute or so the revs rise to 1,200rpm and sit there unless you blip the throttle, when they drop back down to 900ish and then after 20-30 seconds sitting at 900 they rise up again to 1,200 and hold there. Again - anyone got any ideas why this might be the case?
 

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The difference between the AFM voltages should be no more than around 10-15%, so that is a little high. I assume both are moving a little? Was this the max difference?

The O2 voltages should be moving rapidly around the 0.1V point.

If the rear one is sat at 1V steady it is likely it is fried (internal short circuit). The rear sensor may be being flooded in fuel but this would read around 0.9ish volts and still show some movement when you blip the throttle.

Its possible the rear lambda is dead, the PFC would then run rich causing the increased idle speed. At cold start the lambda sensor is not used and so initial idle may be OK, followed by poor running as the sensor comes into the loop.

What happens if you disable the O2 feedback on the handcontroller? (Forth option down)
 

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Discussion Starter #32
I disconnected the two grey O2 plugs in the engine bay (above the turbos) rather than fiddle with the PFC settings, and there was no appreciable change. However that was with what we suspect was a leaking atmos BOV so it was all shot to sh1t anyway.

I'll try it again now that I've got the recircs fitted and see if it makes any difference. Cheers for the input ExScoobyT :D Will let you know what happens :)
 

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Keep us posted Jim.

It's good to see that you are making progress, even when it sounds like you have got multiple problems on the go.:confused:

PS I looked at an old photo of my cars clocks with the engine on idle, and it's the same as what you are getting now, about -3ish.

Matt.
 

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Discussion Starter #34
Nice one Matt :) Nice to know that at least the vacuum is right! :D

Things on the 'to do' list now are to run her up to warm then disconnect the O2 electrical plugs (in the engine bay) and see if it does anything. Then it's to swap the spark plugs for a known good set. I'll also swap the AFMs round and see if the AFM reading swap - if so then there's obviously a dirty or faulty AFM as well :)
 

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If you disconnect the HEGO`s it will still show a fault if the O2 feedback setting is on. Turn the setting off (untick the forth option under, I think, the settings menu on the handcontroller - will take you 5secs!)

If one of the sensors is reading 1V steady it is **cked!
 

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Discussion Starter #36
Fair enough - so I'm assuming that once warmed up, if I turn the O2 feedback off on the PFC then the idle should stabilise completely (if it IS a fried O2 sensor)?
 

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Discussion Starter #38
:( Ran her up to temp this evening. After a few minutes of idle at 960ish she rose up to 12-1300rpm and sat there. I noticed that both the O2 voltages were fine (hovering between 0.9v and 1.3v) until the idle rpm rose, then O2 1 dropped to around 0.04v (ish) again. Went into the ETC. menu and found the O2 feedback ON/OFF control. As I can't read Japanese I'm not 100% whether it was already n or off, so changed it to the opposite symbol to the one that it showed initially. Went back to MONITOR and no change to idle. Turned engine off and started her up again - no change to idle. Up to 1300ish and drop back down to 960ish when you touch the throttle, then creeps back up to 1,300ish over a few seconds or so...

Also noted that at start-up both AFM readings are about the same. Once the idle rises though no.1 drops as per my original description...

Any more ideas, guys? :(
 

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Discussion Starter #39
Whipped the plugs out tonight checking for any damage to the electrode insulator (wanted to rule it out).

The plugs are NGK 9's - the code on the plug is R7234-9. Am guessing that this means they're NGK iridiums, heat grade 9...?

Not too great on diagnosing spark plug conditions so am posting a photo of each one - can someone 'in the know' let me know what these plugs tell me about how the engine's running? T :)

Cylinder 1:


Cylinder 2:


Cylinder 3:


Cylinder 4:


Cylinder 5:


Cylinder 6:


Better shot of plug from cylinder 6:


So - do those look like healthy plugs?


Also, whilst snooping around my coils and plugs I took a moment to look up inside the big rubber suckers that fit over the plugs, protruding from the bottom of each coil. I can see a small metal tip inside each one (that obviously presses on the top of the spark plug) like this one from cylinder 3:



All the others are just like that apart from cylinder 6, which seems to be missing the metal tip:



Will this make any difference???

Also wanted to check the gap at 0.8mm but dammit - I can't find my gap feeler :mad: The dog's probably eaten it... I've left the plugs out of the engine overnight and have pushed a scrunched up piece of kitchen towel into the plug hole on each cylinder - will that be ok until I refit the plugs tomorrow night?
 

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All the coils should look like that last pic you posted, that is the spring inside the coil that makes the electrical connection to the spark plug.

BTW you need to use the macro function on the camera when doing close ups so that the object is in focus and not the floor. :D Looks like a flower symbol on my Fuji.
 
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