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Lift off -> stall prob, an update


Ian C

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Originally posted by dude

I think Ians allready tried the O2 sensor !!!:thumbs:

 

Dude:flame Dev

 

The symptons of over rich are there - but also talks about

 

Sparks

Grounding - what is the volt reading?

 

Did you take the afc out and try without (sorry lost the will to live going back over what you have and haven't etc!):thumbs:

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*you've* lost the will to live? Lol :)

 

I'll try another O2 sensor, and I'll check that voltage. I keep disconnecting the AFC every now and again in vain hope but it never changes anything.

 

I've also gone round with a fairly beefy wire connected to the battery negative, trying to give a super-earth to various places.

 

My O2 sensor reads a steady .94v btw, so it's either wrongly reporting rich and thus leaning out the mix or it's rightly reporting rich but the ECU isn't doing/can't do anything about it. Disconnecting it logs a fault code but doesn't change the behaviour of the engine.

 

Dude - I'll have a closer look at that pulsation dampener and see if it's likely to be causing that click but I don't think it is. It's sooo strong between injectors 3 and 4 it's gotta be from there unless it's some bizarre harmonic.

 

-Ian

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Guest Terry S
Originally posted by Ian C

That clicking noise is strongest around injectors 3 & 4 on the fuel rail. There is nothing else for it now but to strip it out and visually inspect the rail and injectors. That's a job for tomorrow. However I would like to check my fuel pressure, how can I do that?

 

-Ian

 

You'll need to plumb in a gauge. If you have the stock FPR it means cutting a hose and teeing in. If not the FPR probably has a port which you can screw a gauge into.

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from what i can see on the wiring diagrams,the idle valve has 4 coils in it each controlled by SCR (switch in laymans terms)within the ecu thus giving 16 possible valve positions 1 , 1+ 2,1+3,1+4, 2,2+3, etc ,all controlled by the ecu SCR,s providing earths,the valve is supplied with constant positive.this must give quite a selection of idles available to the ecu based on input sensors(coolant temp,intake temp,air con,etc),but I cant see this affecting the mixture (rich running),as that must be dependent on the injectors,duration/pulse width,fuel pressure/flow, as you have swapped the ecu and sensors without success,:( thats why I suggested the fuel enrichment during cranking ,permanently being supplied . could the clicking be coming fron the injectors? as on the jag you can hear them during cranking(fatter injector pulse). The cranking signal to ecu comes from the start relay,this could be isolated by pulling the 7.5 amp fuse -(starter),after the engine has started,its also possible to get a back feed from the immobiliser circuit to the ecu if the immobiliser is tits up,could you disconnect this? if not you would have to remove the pin at the ecu to isolate.hth

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Ooh, Jag, that "pulling the fuse while running" sounds nice and easy, I can try that :thumbs:

 

The Idle control valve is stepper motor based, not preset-position binary logic, I think the six wires are three for each direction, a +ve, gnd, and signal.

 

Thinking about it getting at the injectors, as I've done it before, it's not such a shit job and it should take a couple of hours if that, so I'm gonna have it all out and visually check of everything tonight.

 

-Ian

 

Edited to say - the terminal STA (77 on B) wire?

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Yeah, I'm learning a lot :rolleyes:

 

I yanked the fuel rail just now, would you believe you can take it out without unbolting the intake manifold or throttle body? :D

 

Nothing obvious wrong with it but I cleaned all the injectors, o-rings, brackets, etc. and I've put them back in my spare (and better condition) fuel rail. It's in position but there is about an hour's work to bolt everything back together.

 

I tried Brian's O2 sensor again before doing this, and his igniter pack, didn't make any difference. Most of the engine is now running of Brian's write-off's sensors :eek: I was going to sent the injectors to CW to get them flow tested and cleaned but then I remembered I had a couple of other people looking at the car early next week and they'd soon diagnose why it wouldn't run if the injectors were missing :innocent:

 

I wish I could nail down the symptoms to a cause. I think the next thing after this is an end-to-end resistance check from sensors to ECU plug but even then if it's the connection between the ECU and it's plug, like so many other problems have been so far, it wouldn't highlight it :(

 

Oh, and there is still nothing that could cause that loud click on the fuel rail :looney: I've swapped back my newer FPR onto this better condition rail as well, so maybe that might stop the click.

 

Failing that, anyone know a good priest for an exorcism?

 

-Ian

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Originally posted by dude

Yup ugly looking thing fuel hose either side of it , ive got a by pass hose you can borrow to try if you want :thumbs: :thumbs:

 

Dude:flame Dev

 

Is that an up-on-ramps job to fit? I can't see me getting at it from above :) I can feel the click in it, and it's the only plausible culprit. I need more info on this dampener, what does it do, how does it do it, when, and why - any assistance would be great :)

 

-Ian

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Righto, I've got my Fields harness and I've plumbed it in so I can multimeter from it's plug end to various sensors ect throughout the engine, and once I fired the car up it ran at high revs again. Stopped, started, no change. Yet again jiggled the wiring loom around, it started and ran at 500rpm (badly). Switched off, jiggled again, fired it up, 1500rpm. Moved the loom plug within the fields' socket, and the engine went iffy and the Apexi units reset themselves.

 

So, I think I still have more than one bad connection at my wiring loom ECU plug:

 

http://www.ian.chisholm.clara.net/pix/elecdiag.gif

 

Dodgy bit highlighted in blue. Now, with this causing me grief, again, just because I unplugged it, says to me that there is something deeply wrong in that lot of connections. Including one or more that causes my liftoff stall problems and yet fails to log a fault code, and especially doesn't get fixed no matter how much plugging/unplugging I do, or compressing of contacts, or whatever.

 

Thankfully now the Field harness is emulating the loom's connection to the ECU in a way that I can multimeter test the connections via the field's plug side. So that's a job for tomorrow.

 

Grr, sunny weather, fcuked car :mad:

 

It's getting to the point where I'll just cut my bastard loom plug off and splice in Brian's spare one. Matt H made the foolish comment that it would be a long but do-able job :sly:

 

-Ian

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Can't you just swap Brians loom in? (I'm assuming he has the whole lot, not just the plug!). I know you have to unthread it from the engine but that's no more tedious than all the other stripping down of bits you've done. That way you can isolate the problem before you start hacking wires . . .

 

Or, splice in the ECU end of your fields harness, that way if it all goes tits up then you've still got one intact loom to fall back on!

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Alas, Brian had a bit of a strop when he hacked his hand open trying to get the loom out of the firewall, and there was an angle grinder nearby, so let's just say that isn't an option :)

 

I'm not going to hack up my brand new fields harness :eek: the whole point of it is that I can unplug it and wire in modifications on my desk in good light, which won't be an option if I cut the end off and solder it in! And I don't *have* an 'intact' loom anyway, as the plug on the end is shite :D

 

-Ian

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Right, I had a mobile tuner bloke around today and he monitored the emissions. It's running very rich, it's not shutting off the injectors on overrun, and we could also get the idle speed to vary by tweaking ECU wires. Everything checked out mechanically - sensor readings, fuel pressure, the lot.

 

Pin 24 on plug 10, EFI Main Relay was (and still is) loose. The voltage loom side went from 11v to 0v and the engine tried to die (and the Apexi units reset), whereas the field harness side it stayed at 11v. That's just an example, I've had about ten different and widely dispersed pins go visibly tits up, and who knows how many more are freaking out my ECU with marginal/intermittent connections?! Time for drastic surgery I think.

 

-Ian

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due to the erratic nature of your problems,and all sensors check out,plus no fault codes,can I suggest a screen problem,spurious signals can be picked on the sensitive circuits if the screening is broken,at either end of the sensor wire,Iwould check the oxy sensor first,followed by the crankshaft position sensor,youll have to check each end of the sensor cable screen to earth plus screen to screen end to end for continuity, thats the easy bit:) ,if the screen continuity is missing you will have to find the chafe/break along the cable length thats no fun:( bet you wish you had carbs,and points,and coil:D

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Dunno Jagman, I reckon it's the plug, seeing as I can flex the plug in it's socket and kill the engine and/or change the idle behaviour to one of 4 states :D

 

I wish I could hook a USB cable up to the ECU and see what it is seeing, but that's not gonna happen :(

 

-Ian

 

Edited to say but, that screen thang is a very good point. However, the O2 sensor is reporting all the correct voltages (0.9v usually because it's running so rich all the time) but also you can hear the engine drop into closed loop once it reaches 0.45v so the ECU is seeing the values correctly... Just that something is making it overfuel regardless.

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  • 10 months later...

I can losely answer that.

 

The outcome was that

a) the stock j-spec ECU can't cope with 550cc injectors in closed loop mode.

b) The S-AFC he was using wasn't adjusting the fueling (ie broken) like it said it was.

 

Replaced the S-AFC with an eManage and it was fine.

 

Is your problem with a UK spec or a J-spec? A UK spec with an aftermarket atmospheric bov may well stall...because of the MAF found on the UK and VVTi models. I'll explain further IF that's relevant.

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Thx Alex, This is on a J spec with safc. I can dial out the rich condition at cold (-30%) but have to return to original settings (-8%) when warm.

Have checked most of what Ian checked except for air temp sensor-Where is that? Still think its to do with the ICV not opening fully.

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I'd start a new thread on that one - tis a different issue. I've had similar behaviour from my VVTi 1998 spec car. I've not yet gotten to the bottom of it. But I know my throttle does have an issue with it and on the VVTi the idle is controled by the throttle butterfly (there is no IACV).

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