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Alan L's Avatar
 
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While you are doing warm pressure, you should check the boost pressure drop too, as Brian suggests. Warm or cold - all the same - but logical to check when you set up for the warm pressure. You put 7 psi into the WUR port attached to the throttle body, and watch the WUR fuel pressure drop. It should drop 7 psi too. For some weird reason it may be dropping waaay low - which would answer your question. This is probably not the issue since it is a mechanical mechanism and both WURs worked the same. But pay to check while you are in there.
Can do the warm pressure two ways - warm the car up then having everything ready to go, unhook your WUR and connect gauges and turn on again and measure pressure.
Or, can do from cold - hook gauges up and dummy in 12 v (alternative 12V battery) on to the socket pins on the WUR.
After 5- 10 mins you should have reached max pressure as the bimetallic finger does its thing - assuming it is working. (can leave car ignition off til need readings, then briefly depress air plate til pressure comes up to max). But this method does not guarantee your system is behaving like this - if you are not feeding 12v to the WUR then this won't happen in real life. So, if you go by method 2 , you also need to pull the plug off when the car is running and check you are getting 12v from the input plug for the WUR.
Alan
Old 07-15-2008, 09:16 PM
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UPDATE,, I was discussing this problem with Steve at Unwired Tools ( the guy is a CIS genius), said it sounds like a classic vacuum leak either in the hose or injectors.. suggested I tune it till it's on the hairy edge of running then hit various spots with carb cleaner.. VIOLA! it surged whenever I got near the left corner ( under the turbo manifold. So now it's a matter of finding the leak. I suspect a leaky injector.. How tough is it to pull the injectors on the turbo side of the engine???
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Old 07-21-2008, 09:04 AM
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You have to really take the intercooler and plenum off. Then you can get at it easily.
It could be a leaky injector block. That side is a bit harder to torque down - 18 ft lb from memory. But it would be worth re-torqueing it. 6 bolts/side - two per injector block. The worst one is behind the air plate chamber - on #3. You can't torque this unless you remove the system. But if you are lucky you can get a spanner on it and nip it a bit more if the others are soft.
The best way to find source is to pressurise the system. Then spray water (soapy) or feel around for any cold air - follow the hissing if you can. Thats how I found all my injector blocks to be leaking. There is a base gasket against the head.
Alan
Old 07-21-2008, 12:27 PM
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thanks Alan, i'll try that next,, How high do you pressurize the system ?
and where do you put the pressure in ?
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Old 07-21-2008, 12:42 PM
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It is a bit of a PITA - but so are leaks.
I did it via this pic - made up a unit.
But a simpler way - if you have the plenum off is to bung the intake butterfly and pressurise via another hole. I use a compressor.
What I'm really saying is that it is a bit of a guess that it is an injector seal - it could be several options down there. If you are going to have to do this much mucking around, hoping to find an injector leaking, you may as well go the distance and find all leaks - or find that it is not an injector after putting it all back together and having to do it again.
You can get your hand down that side with interccoler intact - at least to most places - to feel if leaking.
So it may be worth trying the approach as in pic first.
Personally, I doubt an injector would be leaking enough to cause problem unless it was completely loose - which is unlikely as it is held tight by the fuel line too. More likely the injector block/inlet manifold.
Regards
Alan
Old 07-21-2008, 01:15 PM
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Thanks!!! it will be next weekend before I venture into it again ,, but great info!
T
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"life"ll kill ya" Warren Zevon
Old 07-21-2008, 01:21 PM
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If you search for a link 'Where to start on a 930", that is me trying to sort my way thru these issues. Goran gives a good link there how to remove plenum - I can do it with eyes shut now (50 times at least) - but need to make sure you have the right hoses disconnected etc.
To strip down to intake manifold (removing plenum) really is no more than half hour.
Gives you plenty of working room. The trick then is to pressurise system to some useful degree to check the lower seals. This of course does not test integrity of plenum/intercooler seals - but easy working room to work on anything else.
If you want to test all seals - then you need to work something like my pic. But sounds like your leak is at lower end anyway. So, easier to remove all top stuff. Need large bung to block intake hole for pressure - about 90mm dia from memory.
Alan
Old 07-21-2008, 01:48 PM
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Alan, I just took a look and on the left side there were two or three nuts that were hand loose!!! I think I got to all 6 on the side of the leak.. just buttoned it up and will see if I can get full boost on a test run.. Hoping that this was it!!!
Todd
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Old 07-21-2008, 04:12 PM
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Sounds hopeful. Pay to tweek the RHS too.
If you get in there with a torque wrench, the specs are around 18 -20 ft lb from memory.
You won't be over tightening them at 18.
Could explain the lack of boost too. Don't forget the nut under the air plate box.
Alan
Old 07-22-2008, 05:48 PM
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A quick tightnening didn't seem to work.. Still rich and no boost. But couldn't get to them all from the top. This weekend I"ll pull the plenum and do it right!!!
Todd
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Old 07-22-2008, 05:54 PM
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If they are the nuts sitting in a slight recess in pairs on top of your manifold/injector blocks, and were hand tight, this has to be an issue. They wont stand 10 psi boost like that without major leaks. But you can't get at them all with plenum on.
Alan
Old 07-22-2008, 06:03 PM
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Quote:
Originally Posted by Alan L View Post
If they are the nuts sitting in a slight recess in pairs on top of your manifold/injector blocks, and were hand tight, this has to be an issue. They wont stand 10 psi boost like that without major leaks. But you can't get at them all with plenum on.
Alan
Actually Alan, hand loose would be more appropriate.. and I assumed I couldn't get them tight ( but I guy can hope right ?).. So I'll pull it and do it right this weekend.. So questions.. are there gaskets I need to replace or should I just tighten the nuts and be done with it ? Do the spacers warp or swell and need to be machined ??
I'll also make sure all the hoses/clamps are up to snuff..
Oh one more thing,, I notice my air pump belt is down to about three threads ( literally it's only 1/4 in wide now).. should I replace it or take it off totally ?
Wish I had an extra $700 I would love to throw on a digital WUR on this car as well since the other one is working out so well
Todd
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"life"ll kill ya" Warren Zevon
Old 07-22-2008, 07:56 PM
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My injector blocks/spacers were stuffed - cracked and chipped and sealed with silicone. Even nipped down I was getting boost leak there.
From memory they are about $60 each.
If you don't mind the work - you could potentially save $360 by just nipping them down. I think the torque figure was 21 ft lb - but I can't find it now. But if you do 18- 20 lb you will be safe.
If they still prove faulty you will simply have to pull all that crap off twice. Like I say - 1/2 hr. But if you need to replace injector blocks then need to remove manifold too - which includes the CIS air/fuel system. Only 3 bolts apart from fuel lines. But if don't need to, good luck.
There is a hose you should have a close look at with the plenum off - it joins a Y piece off your manifold - and back into the plenum. You let the manifold end off to remove plenum. Try and make sure all that area is sealing well - my Y piece was leaking. But if that hose leaks, as with others on intercooler etc - you have more leaks. But you can only really get at that hose with plenum off.
I don't have air pump - I guess you need one. But it makes the job more worthwhile to do as much as you can while you are there.
You need to disconnect the fuel /o boost trip switch wire (rear plenum), and the boost gauge wire (front plenum) plus the hose on Y piece - lower left plenum, plus the hose just behind the decel valve on plenum - the LH hose. Make sure it is lined up on the nipple when you put plenum back on - hard to get at otherwise. Prise on'off with screw driver. Need to remove big rubber elbow off plenum (plus rear connecting rubber to turbo intake). I marked my elbow F and R to save hours trying to put it on back to front. (after wasting hours trying to put it on back to front). Use a bit of WD 40 on the inside of it when reassembling - and on all rubber O rings.
When you put plenum back on make sure it is clear below lower bolt before bolting down - I found out hard way. Your ignition leads, vac hose and o- boost wire all feed thru down there. Don't trap them.
Other than that - pretty straight foward.
Alan
Old 07-22-2008, 08:18 PM
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Alan, I tightened everything up ( a number of possible culprits in the area).. Now a preliminary test drive show's its' still a bit rich - but I've not tuned it with AF/R yet.. However still only producing around .2 bar of boost.. I also tried the old carb cleaner around everything test and it seems solid,, starts right up and idles pretty well. So I'm still thinking there's a boost leak somewhere.. I took the hose off the inlet to the intercooler that goes right to the waste gate and I can hear the spring engage/disengage at what seemed pretty low pressure ( like 10 lbs).. how is the best way to see if it's holding pressure and not leaking ?? Or better question, what do you suggest next ?
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Old 07-26-2008, 06:29 PM
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A boost leak at idle will show up as a vac leak.
I think your best option is to try pressurising the system, and see where the gas is going.
If your waste gate is opening at 10 psi that is about right - 0.7-0.8 bar. So, how did you get 10 psi pressure for the waste gate.
I tested mine by removing it and pressurising it thru the same line you used - ie the one from the intercooler. Had a pressure gauge in line. You can see the valve begin to lift. That would be the simple way to eliminate that - pressurise it and see how much gas you loose before it hits boost pressure.
But this all suggests a big leak.
So, you could try pressurising via the inlet rubber elbow like my pic. This will take in the whole intake system. You have to flip the elbow around to do this, and make a up a piece like in pic - plastic plumbing hardware.
So, you could hit on the wastegate if you want to remove it and check it first (15 mins to remove), or try pressurising whole system.
Waste gate might be worth a shot. less time involved than option B.
If you try pressurising whole engine, you need spanner on the fan nut to rotate. There is some valve overlap so you will loose gas at exhaust if in wrong spot. There are pressure peaks/troughs. You may need to rotate say 30 deg to pick up a peak - no overlap.
Alan
Old 07-26-2008, 07:54 PM
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Ok so if I pull off the waste gate, what's the easiest way to check it ?
t
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Old 07-26-2008, 10:47 PM
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Apply some pressure to the inlet line - the one that hooks to your intercooler. There should be minimal bleed - none escaping via the outlet line , and minimal via the valve (you may loose a little via the valve guide clearance) until you hit your spring dump pressure. At which point, from memory if you remove the lower bit of the unit you can see the valve head. It should lift as you approach the spring pressure - eg 0.8, 1.0 bar - whatever.
If you are loosing gas before this point you have waste gate leakage. If you cannot pressurise it to 0.8 bar, then you have leakage. I'm assuming you have standard wategate.
Alan
Old 07-27-2008, 11:42 AM
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Apply some pressure to the inlet line - the one that hooks to your intercooler. There should be minimal bleed - none escaping via the outlet line , and minimal via the valve (you may loose a little via the valve guide clearance) until you hit your spring dump pressure. At which point, from memory if you remove the lower bit of the unit you can see the valve head. It should lift as you approach the spring pressure - eg 0.8, 1.0 bar - whatever.
If you are loosing gas before this point you have waste gate leakage. If you cannot pressurise it to 0.8 bar, then you have leakage. I'm assuming you have standard wategate.
Alan
Old 07-27-2008, 11:42 AM
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I"m heading out to buy a hockey puck,, my buddies tell me it's almost a perfect fit on the inlet .. I'll drill a hole in it and insert a fitting from my compressor.. I'll let you know.
T
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91 Spec Miata (yeah I race a chick car)
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Old 07-27-2008, 11:48 AM
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Todd, we don't have hockey pucks, so can't say. But since I am in there again, currently, this is how I pressurise the lower part of intake system. (I have a persistent tuning problem I can't rectify - have done this crap 50 times over now).
You can see I have blanked off all the hoses that connect from the intercooler/plenum - except the blue one that hooks to the decel valve. I use this to pressurise thru - but any of them will do - as long as you blank the rest.
I have to hold the cork bung in place - so hands are at a premium. Then I spray soapy water with my other hand. You only need 5-7 psi to find most leaks. Very small ones may show up at higehr pressures - but holding the bung in gets harder.
If you find the W/G is leaking - be careful pulling it apart. The spring is held in with more than 100lb pressure, and things will fly apart unless you restrain the can as you undo it.
Alan
Old 07-27-2008, 01:05 PM
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