silent running

OK here's the symptoms:

At idle and low revs while driving, it struggles to recover to the right idle speed, dipping down to 500 revs or even stalling when coming to a junction. Nowhere near as bad when warmed up properly, but still does it a little. Occasionally starts idling rough for no reason at all.

Engine very clicky on the offside, not injector noise, doesn't seem to go away when warm, very regular.

Have definitely got a split in my turbo hose which I have gummed up with silicone for the time being, have a new pipe on the way.

Every day shows at least one totally inexplicable, large knock spike (40-80 on Power FC readout) at some stage, always on overrun or at low revs/idle; never when on boost or driving hard.

Engine was rebuilt with STi heads by a bunch of now-bankrupt local 'Subaru specialists' about a year ago, one original WRX head had seized the cam and kept throwing the belt, in the end it had a pair of 'recon' STI 5 heads put on which seemed to sort the problem out. Whether it really was recon or just nicked off someone else's motor I don't know.

Diagnosis? What are the first things that spring to mind? I'm wasting virtually all my spare time trying to replace sensors, idle valves, etc, but tbh none of them show as problems on my Power FC and sensors are very expensive. I'm thinking I should rule out mechanical problems first; for example, a sticky or bent valve. I don't want it to be that because it's not something I'm confident I can fix myself, whereas for example an idle valve swap I can do in half an hour. Obviously the split inlet hose needs fixing, I know how vacuum leaks can make a car run weird. As far as I can tell there are no other vacuum leaks anywhere, but the car has always made a very quiet whiny/hissy noise that I can hear but it's impossible to locate.


Any help appreciated!

ReggieMY99

If its a version 5 id say your MAF sensor and/or lamda is knackered

fits om the description you give, also the knock acitivty although you say its not when on boost or high revs

hissing noice, you got a small leak somewhere, or its the turbo you can hear, more noticeable when decatted

test the maf by unplugging it when the car is running, if it stalls its probably ok, if surges down and comes up again in revs, its knackered get it replaced before it takes your engine out

jaytc2003

iTrader: (1)

clicky noise on the offside may be the boost solenoid. The rough running does sound like an air leak. I would fix what you know is definately wrong first and then take it from there. If you have a problem with something already then it could be masking a problem with something else if you see what I mean, so its best to fix what you know needs fixing

silent running

Cheers for the replies. It's a V4 'F' MAF. Lambda I did only a few months ago with a new Subaru part. Perhaps once I get the inlet pipe off I'll find another leak somewhere. I'll try the MAF again, but I'm pretty sure last time I tested it, the engine stalled straight away when I unplugged it.

As far as the clicky noise goes, sorry, I meant nearside. So I'll get the inlet pipe replaced and go from there, at least then I'll know THAT air leak has been fixed. Once I've done that I'll do a compression test anyway to see what's what. If only it wasn't such a hassle getting at the plugs!

j900ase

Easy way to find air leaks is to spray area with brake cleaner, engine note will change or stall when it sucks in air.

I dont know that much about classics, but sounds like you have air leak, possibly inlet manifold. Allthough air leaks usally make idle higher, it could be your ecu is trying to correct and dropping duty cycle to iscv and adding fuel to compensate.

If you fit vac gauge on car and it fluctuates wildly at idle this can indicate sticking valve.

I would not spend any money or take apart till id diagnosed the fault, diving in fitting parts ***** nilly usally costs more and makes job longer.

Re. compression test thats a good start as is vac readings at idle and over run.

Jase.

scoobynutta555

Is the car standard, have you a VTA dump valve?

silent running

My vacuum/boost gauge doesn't show anything to wacky. It stays pretty steady most of the time and I've got plenty of vacuum showing, when it hunts around, the vacuum hunts with it, but it's hard to say whether that's a cause or an effect. Has a standard dump valve. I'll do the compression test asap and go from there.

jasonius

iTrader: (1)

Clicking, possible noisy injector..? Just a thought..

j900ase

Thats some good news, unlikly to be sticking valve or broken spring.
Have you got figures on idle and over run?

Jase.

silent running

Idles around 17 in HG, overrun goes well over to 21-22 inches. What that is in metric I don't know! The thing is it only really plays up when it's cold. When it's warmed up it starts and runs pretty much fine most of the time.

ZEN Performance

The clicking is the purge control valve, it will cycle on the PFC when it's in closed loop fuel control.

The poor running is almost certainly linked to the split turbo hose, which will et unmetered air in the engine, making it run lean, and with increased ignition timing. Do not do anything else until this problem is 100% fixed.

silent running

That's my first job this weekend. Still mulling over whether to remove the inlet manifold or not.

j900ase

As Paul (Zen) said fix know air leak 1st, then spray area with brake cleaner or carb cleaner if you still have problem. Any air leak will become very apparent.

Like i said before dont go doin things just because it "might be", better to know and spend less time/money.

Jase.

j900ase

Also your vac figures are about on the money, which is good.

Jase.

silent running

So probably best to get the manifold off and have a good poke around. Still worth doing the compression test first though, as surely an air leak in the inlet pipework won't make any difference to it.

Any tips on how to do it? I'm not so keen on the idea of getting the engine up to temp then attempting a spark plug job. With the engine cold, it's just time consuming, but with it hot, that could be a real pain in the ****, there's little enough room to work anyway and having to keep my hands from burning at the same time...

j900ase

No DONT take manifold off.

1st Renew leaking pipe.

Then if still no good, With engine running spray brake cleaner around pipes, joints and inlet gasket area. Not forgetting boost solinoid pipes, fuel pressure vac lines etc.

Any air leak will show as stalling or engine note change.

If that ok whilst WARM remove plugs and check compression, dont forget to disconnect coil primary (so you dont get nasty shock) and hold throttle fully open to fill cyl with max amount of air.

Write down cyl pressures and post them/check with manual, i dont know figure but any more than 10% diff is not good.

Jase.

ZEN Performance

It can be difficult to change the inlet pipe without taking the inlet manifold off.

j900ase

Yes you are correct as per usual. I was assuming he would be replacing with silicon pipe as most people do.

I should know better cause assumption is the "mother of all f@@k ups".

silent running

It is a silicone pipe, the Hong Kong variety. But seeing as I've just gone and ordered a couple of inlet manifold gaskets anyway, I might as well do the job as a bit of 'fun'.

donnas roo

hi there going back to your rough running at idle, it could well be the coolant sensor for the ecu, you say it gets worse when the engine warms up then it sounds like it could be over fueling. the air leak could also tie in with with the erratic idle i would check the pipe from your map sensor to manifold. hope that this is of any use to you

silent running

I've got so many little things wrong, I'm losing track of what I've written. But the running is much much worse when cold. When it warms up it settles to a decent idle most of the time. Today for some reason it went perfectly all day, not a single problem. Last night I spent some time whacking a bolt out of the slam panel - perhaps that's done something to fix the idle?!

Anyway, I finally managed to do the compression test...and by the time I'd managed to get everything disconnected, removed or pushed to one side the engine was nowhere near running temp any more. The rocker covers were just slightly too hot to touch for any length of time though.

I can't remember which cylinder is numbered as which, but this is what I got:
n/s/rear 171/174/163
n/s/front 174/166/171
o/s/front 158/155
o/s/rear 162/162

Each time I turned the engine over for 5-10 seconds. I did notice the starter was sounding slower towards the end, perhaps this explains the lower readings, but the o/s front cylinder was noticeably lower than the rest even though it was done third. So what's the verdict on these figures? They are all within the right range AFAIK, both on the gauge and on my Subaru workshop manual figures, but the difference I'm not so sure about, especially the lower one. Would a valve problem show up as a small difference or a large one?

The other problem (they just keep on coming!) is that I found the offside rocker cover had a sheared bolt top left, nearest the turbo. What do I do about that? For the time being, I've bodged some silicone back round it because oil is leaking out of the bolt hole - the rubber seal is thrashed and all in tatters.

Then finally I took a picture of the plugs as well. Looks like one wasn't in as far as the others by the marks on it. I'll try and see how to upload a picture.

silent running

Any comments on the compressions?

samcowrx

Something else to consider is to make sure your battery is up to scratch because if that is running under voltage it could cause other probs

silent running

Thought of that...it's been charging at 13.9 to 14.6 volts the whole time, and first thing in the morning it's still showing 12.2- 12.4 volts on the battery before turning it over. Soon as the engine's running it goes straight to over 14 volts. So I've pretty much ruled that out. It never has any real trouble starting or anything.

ZEN Performance

compression numbers are good, I suspect if you did it again with less cranking they would be more consistent. It's not unusual to get a variance from one side of the engine to the other due to slight discrepancies in cam timing.

j900ase

Plug not screwed in far enough could cause a problem, because plug can not get rid of heat as well. This could be the problem, but i think not the one you have. I would fit new plugs any way as this could cause another problem later.

Post some pics of plugs if you can, colour and condition can go a long way to diagnosis of fault.

silent running

So here are the pictures, I've finally worked out how to get them hosted I think.

silent running

You can see in the top picture where the knackered bolt was, that rubbery thing coming out of the hole is what I have no idea about, is it part of the gasket or part of the bolt housing or what?

In the lower picture you've got the four plugs laid out as they would be from the driver's seat...sorry I can never remember what the cylinder numbering is. Anyway, the bottom left one is the nearside rear cylinder which wasn't screwed in properly from the looks of it. All the rest were a fairly even colour, black and a thin layer of caked on soot up the thread, tan colour on the insulator.

You can also see the knackered rocker cover bolt, with the weird rubbery mess attached to it still. At the moment it's just bodged back in and covered in silicone to keep more oil from leaking out.

Anticipating that I'll need to have the rocker cover off at least, and possibly the inner cam cover to get at the snapped off bolt, I've ordered a new rocker cover gasket, two plug gaskets, and six bolt thingies the Subaru parts desk said I'd need as well, I can't remember what they were now. And obviously the new bolt.

What a pain in the ****. Any tips? If I get the rocker cover off and find I can't get a pair of pliers on the snapped bolt, is it basically either lift the engine and drill it out, or weld a bolt onto the end of it so I can get hold of it? Does it even matter that much as long as I can bodge up the hole on the outside of the rocker cover?

ZEN Performance

The rubbery thing on the bolt is the evidence of the fact the bold was sheared when the engine was installed and fixed in place with silicone sealant.

silent running

Bloody crooks eh? Doesn't surprise me at all though. Any idea how likely it is that I'll only need to take the rocker cover off to fix this? Or will I need to go deeper?