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Apr 16, 2017 18:14:28 GMT
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I've asked on FD:UK, but nobody replies. I bought the car in December 2015, did about 2000 miles in it, put it away in August of last year when the MOT ran out, and spent a bit of money and time getting it perfect; I replaced all the worn out suspension components, etc and gave it a proper service. The car ran nearly perfect, compression is fine, but very occasionally it would pop heavily and flame out. It did this in the Mersey Tunnel a couple of times, it sounds awesome and lighting up the tunnel with fire from the exhaust is pretty cool, but I just wanted it running 100%. I set about adjusting the TPS, and got it bob on, and then put everything back together. Since then it has had a horrible misfire under 3000 rpm. The car was run regularly and for a length of time every week during it's lay up, and the engine is in rude health. I'm not sure if this is related or if it was doing it before I changed the TPS setting, it's been such a long time I can't remember ... I checked ignition coils which are fine, replaced the O2 sensor, and checked the ignition leads - three are 5 KOhms which is spot on, but one is 10 kOhms. I will replace them anyway as they look like they look original. Would having twice the resistance of spec knock ignition out? The car kangaroos violently pulling away, but once over 3000 rpm it flies as if nothing is wrong. I'm missing the car massively and want to get it out for summer!!!  |
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Last Edit: Jun 26, 2017 14:33:15 GMT by DavidB
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luckyseven
Posted a lot
Owning sneering dismissive pedantry since 1970
Posts: 3,838
Club RR Member Number: 45
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Apr 16, 2017 18:20:07 GMT
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Stock twin turbo system? Could be any number of dodgy solenoids in the rat's nest. Or even a tiny vacc leak in one of the hoses. Is the MAP sensor securely plumbed in? Gives all kinds of horrible running problems in it's got a leak in the hose to the UIM
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Apr 16, 2017 18:23:13 GMT
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I was hoping you would turn up!  Checking the solenoids - I have a fault code for the Charge Relief Solenoid. I've had it all out, and it definitely doesn't open. All the vacuum hoses look fine, they're hard but not to a stage where they're going to crack. I'm going to change the lot anyway, it's a 98 car so it doesn't look too complex. Is the MAP sensor the Denso one labelled 'Boost Sensor' on the passenger side bulkhead? Everything is standard on the car apart from a 3.5" exhaust and sports cat. Standard twins setup. |
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Last Edit: Apr 16, 2017 18:23:28 GMT by DavidB
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Apr 16, 2017 18:40:02 GMT
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New plugs to start off with.
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luckyseven
Posted a lot
Owning sneering dismissive pedantry since 1970
Posts: 3,838
Club RR Member Number: 45
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Apr 16, 2017 19:02:00 GMT
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Is the MAP sensor the Denso one labelled 'Boost Sensor' on the passenger side bulkhead? Dunno how it's labelled on a later model, but yeah, it mounts on a funny little 45-degree bracket on the pass-side firewall. Has an electrical plug to the ECU loom and a short vacc line that goes to the manifold. That often blows itself off and then the ECU can't "see" how much pressure the manifold is getting so it massively overfuels. If it's got a leak it'll see mutant readings and overfuel sporadically... tends to idle like a dog but clear the more it revs. Backfires and coughs are another symptom |
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Ok, new plugs, new leads, checked and replaced all solenoids, replaced all vacuum lines, checked everywhere for leaks, checked TPS, double checked everything three times, and it runs completely horrible. Not revved high enough to check it, haven't got the balls.
I've taken both leading and trailing leads off the plugs and i can't tell if there's any difference, it runs so badly.
This car is surely going to bankrupt me financially and mentally.
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fad
Posted a lot
Posts: 1,781
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Walk away from it for a week or 5 until you miss working on it. Fresh head, fresh eyes, and you will see the glaringly obvious issue that it likely is.
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May 11, 2017 22:04:31 GMT
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This is how it sounds:
I know there is spark leaping from one of the trailing plugs (the lead wasn't on properly).
The strange GRRR noise after revving perplexes me.
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fad
Posted a lot
Posts: 1,781
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May 11, 2017 22:28:59 GMT
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Not a corner chipped off your rotor perchance?
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Not much help that. 7's/8's on compression test. |
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fad
Posted a lot
Posts: 1,781
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May 12, 2017 11:41:10 GMT
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Sorry. Not a rotary expert. Just thought if you were missing on low revs might be a possible cause. I'll shush. |
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luckyseven
Posted a lot
Owning sneering dismissive pedantry since 1970
Posts: 3,838
Club RR Member Number: 45
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May 12, 2017 17:28:49 GMT
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Hmmmm, it does sound a bit gnarly. What's the boost like? Does it build properly?
The "Bhoooooo" noise when you back off the throttle sounds a lot like its dumping boost in the wrong place at the wrong time, like the switchover flap is stuck between the twins and when the second turbo spins it's dumping boost straight into an open exhaust. That could be any number of things causing that.
Have to be honest, the rough running sounds like a classic MAP sensor problem especially if it clears up as you rev it. Are the plugs wet like its overfuelling? If it can't "see" boost pressure at the manifold it'll massively ovefuel to make it safe and that's why it runs better at revs because the overfuel ratio is less than at idle and it can dump the extra easier
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May 12, 2017 17:58:58 GMT
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No boost - doesn't go over 0 on the gauge!
I'll give the MAP sensor a go, bought more new plugs today.
Plugs are fueled up everytime I start it, never used to do this but it no longer starts so is constantly flooding. I've never had a cold or hot start issue, ever!
From the symptoms on the net about dodgy MAP sensors, it does sound identical ... Now where to get a similar MAP sensor on the weekend ... ? Is it worth raising any scrap cars just to test? I have a Saab Turbo one lying round.
Appreciate the help!
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Last Edit: May 12, 2017 20:14:21 GMT by DavidB
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May 13, 2017 11:47:10 GMT
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Fitted new plugs, went out on a scrappie raid, pulled one from a Daihatsu Turbo thing, bodged a temp connector and it appears to have cleared the choppy running, although it's probably too early to say.
Not sure if it's the plugs or the MAP sensor?
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luckyseven
Posted a lot
Owning sneering dismissive pedantry since 1970
Posts: 3,838
Club RR Member Number: 45
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May 13, 2017 12:10:07 GMT
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It's a start.
There's not much that goes wrong with the actual sensor... either they fail or they work. If the vacc line to the UIM is attached and not leaking it's probably OK. Check really carefully the vacc line doesn't have any cracks or splits though
The boost problem is likely to be a rat's nest issue.. either a split line or failing solenoid. I can't remember which one cos it's been ages since I had twins. I did have that problem once, way back, when the flap was sticking in the manifold assembly and allowing the secondary turbo boost to vent immediately. The sound is pretty distinctive.
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May 13, 2017 12:42:24 GMT
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That heaving sound has disappeared now - I think it may have been somehow related, the whole thing was so bogged down.
I think it's too early to say, I'll wait until I get another sensor before I run it again!
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May 14, 2017 21:57:56 GMT
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Righto, I've got both a working MAP sensor and TPS which was setup on the throttle body. The car still won't drive properly, same as two/three weeks ago, can not cope below 3000 rpm and there is a LOT of air coming through this pipe, to the point where it's scarily loud with it taken off:  There is a pipe coming off the airbox on the right (viewing from the front of the car) which is shooting out air constantly. Driving the car, it's just blue smoke from the exhaust, and even smoke from the engine bay. Is this somehow pressurising the turbos and pushing oil past the seals??? I only changed the frigging spark plugs. I don't think anything is broken, but something is really not right with this. |
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Last Edit: May 15, 2017 0:33:41 GMT by DavidB
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luckyseven
Posted a lot
Owning sneering dismissive pedantry since 1970
Posts: 3,838
Club RR Member Number: 45
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May 15, 2017 16:08:31 GMT
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Argh, I'm struggling to remember the stock twins set-up now. Is that pipe not part of the airpump malarkey? Does the open union on the airbox lead to a small separate chamber in the airbox lid with a little foam filter in it? That was part of the Mazda patented anti-moo setup.
Sounds mad (maybe it is) but when you disable the airpump it causes a weird air standing wave effect when you back off the throttle and it sounds just like a loud cow's moo crossed with a toilet flushing... in fact, a lot like the noise on your video. IIRC there should be a little round blow-off valve (Charge Relief Valve, is it? Can't remember... that might be the brown one just beneath your arrow there. There's a black similar one that's the blow-off valve) in that circuit. If that's knackered/the airpump's knackered/disabled/unplugged it might be causing weird air movements. Not sure why that would affect the idle though.
Might be worth putting that pic and latest info on FDUK for someone with more recent experience of mutant twin problems than me to offer an opinion
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Yeah, that pipe goes directly to the air pump. The pipe is just screaming air out, it comes from either under or actually in the ACV I think? I reckon a vacuum line is on wrong possibly, or possibly not, I really haven't got a clue.
There is a brown valve like the black BOV as well!
I don't think the idle/terrible running is related to this at all either, it wasn't doing this prior to the foolish 'checking the check spark plugs' ordeal which kicked all this off.
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Jun 24, 2017 10:55:57 GMT
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In the past couple of months I bought new solenoids to replace the non operating ones, new plugs and leads, working TPS and MAP sensor, vacuum hoses and new ignition coils and loads of other stuff, and also got the injectors rebuilt (three were shagged).
Nothing really improved it at all. When I was about to give up I redlined it a few times, a load of black smoke from the exhaust and then it ran fine. No smoke from the exhaust when hot and running a1.
I'm thinking the over fuelling may have blocked it up causing loads of random issues or possibly something else. Still a few more jobs to do, but four months of that ...
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