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Another turbo boost issue


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Hello all, I would be very grateful for any assistance that you could provide.  I have a turbo boost problem with my '90 Esprit SE which has just appeared for the first time…I do not see any boost indications nor do I feel the normal significant acceleration that typically occurs at 2800 RPM…and I do not hear the turbine wind-up any more either.  Having read other threads from others experiencing turbine problems and the trouble-shooting recommendations that were provided, I have made the following observations:

- engine temp settles to a little over 80 C when at freeway speed but runs hot at slower speed (close to 100) which requires the fans to engage - I suspect this symptom is more a function of a degraded (inhibited air flow) radiator given that I have over 146,000 miles on her.

- engine behaves normally (minus the missing boost capability) both in actual driving and when idling although when trouble-shooting, I noted that the check engine light illuminated when reaching 4500 RPM (no actual load on engine - was in neutral and parked).

- after applying air pressure into the end of the pressure sensing hose at the point it connects to the turbine outlet, the wastegate control capsule did move to open the wastegate flap valve; however, the wastegate flap valve moved back to the closed position within a few seconds.  I didn't hear/notice any air leaks in the hoses.  I believe that the valve was supposed to maintain its open position rather than return to the closed position.

 

Questions:

- Would a degraded diaphragm in the capsule cause the above noted symptoms?

- If the diaphragm is the source of the problem, where can I buy a replacement and is there anything else I should get?…and are there any special procedures I should be aware of when replacing it.

- If it's not the diaphragm, what else should I look for?

 

Thanks…and I look forward to your assistance on this.

 

Romero

 

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Hello all,

 

    Here's updated observations once I removed the wastegate control valve capsule:

 

- the capsule appears to be working properly because when I took it to my bench and used a hand-pump with a better fitting, the capsule arm moved to an extended position and maintained that position until I allowed the air pressure to escape from the fitting.

 

- the hoses that connect to the wastegate control valve capsule and the pressurized air plenum did not leak either when put under 20 pounds of air pressure…the lines maintained the pressure each time - having applied the pressure from the different ends.

 

- one other observation that I forgot to mention earlier is that I did detect a very slight movement (barely above the 0) on the boost gauge when the engine initially reached normal operating temp (80 C) when I floored the accelerator (at 3000 RPM) - but it didn't translate to any discernible acceleration.  I repeated this a couple of times and noted that as I continued to drive, the boost gauge needle wouldn't move at all.

 

 

 

Thanks again for any ideas and/or assistance you may have to offer.

 

Romero

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You need to find out the cause of the CEL, either by Freescan/Espritmon or shorting pins A and B on the ALDL connector, turning the key to pos II and counting the flashes. If there's an error, you should still be getting boost but if it's related to boost, there's your problem.

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Hello Bibs,

 

    Thanks…I tried to download the Freescan (v.2.1.0) but was unsuccessful…I suspect that the Apple computer I'm using is not compatible.  Is there an Apple compatible variant available?

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When you say the boost needle doesn't move?  Not at all, or just won't go above the middle of the dial (~.65bar)?

 

It sounds like you aren't building boost at all, which means it is probably something other than the ECU reducing boost by venting the pressure from the boost frequency control valve (the solenoid that controls the wastegate).

 

It sounds like you have a restriction in the intake or more likely the exhaust.  Do you still have the Exhaust Back Pressure Valve (EBPV) below the catalytic converter?  That is a vacuum actuatef flap that closes off the exhaust below the cat to help it warm up faster when the engine is started cold. That often fails, or the vacuum hose leaks.  Check that fist of all.

 

Check your intake hose. 

 

If not the above, then your turbo may not be spinning.

Travis

Vulcan Grey 89SE

 

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Hello Bibs, Jim and Travis,

 

    Thank you for the suggestions.  I've ordered the connector wires and will conduct a scan after they are delivered.  Also, I checked all the air hoses that emanate from the turbo unit including the plenum connector and all are properly connected and have no rips/tears/holes.   The Exhaust back pressure valve has been disconnected from the vacuum line and the valve is wired to the "open" position.  With your suggestion, I had hoped that the wire had broken and the valve was the source of the problem; unfortunately, that wasn't the case…the valve is still locked open.  I'll take a look at the air intake system this weekend.  Regarding the "boost" gauge needle, it doesn't move…it stays pegged left at 0 with only the slightest little movement to the right (barely off the 0 line) as noted earlier.

 

    I recall in some of the other entries that inadequate fuel pressure caused others to have problems with their boost capability.  Do you think the symptoms that I'm experiencing could be caused by inadequate fuel line pressure?  If so, how should I go about testing for this possible cause?

 

    If my turbo rotor is froze, or spinning too slowly, how could I check for this?…and if this is the situation, do I have any options to salvage the turbo?

 

   Thanks again for your time and advice.

 

Romero

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If it's a standard SE turbo (oil bearings), when you spin the turbo, don't expect it to spin for ages. It will stop rather quickly. Just make sure it turns freely. Unfortunately, you can only see one end of the turbo wheel.

I had a problem with the wastegate (flapper) spindle collar migrating sideways so the wastegate didn't seat properly when closed. This allowed a lot of air to bypass the wastegate (not allowing pressure to build up). Here's a picture of it. Note how the flapper (disc) is hitting the casing

http://www.iinet.net.au/~b744er@ozemail.com.au/Lotus/TurboWastegate.jpg

Unfortunately, you can't see this side of the turbo without taking the exhaust off.

Cheers

Ian.

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If my turbo rotor is froze, or spinning too slowly, how could I check for this?…and if this is the situation, do I have any options to salvage the turbo?

Yes, if worse came to worst, you could have the turbo re-cored (new bearings and impellors). You could even have roller bearings fitted. It can get pretty expensive though.

Note: If you switch to roller bearings, you need a restrictor in the oil line. These type bearings only need a tiny amount of oil.

Edited by Qavion
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P.S. Just a thought.... fibre optic cameras are pretty cheap these days. I'm wondering if anyone has tried removing the oxygen sensor to look at the turbine blades and wastegate seating? (or isn't there enough bend in them?)

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If he's not building any boost whatsoever doesn't this indicate the turbo is entirely busted? Or can the wastegate dump so much air that the needle hardly registers anything? 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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In my situation, Vanya, I recall I had a small amount of boost at high rpms (and even with the wastegate not attached to the actuator, allowing the wastegate to flap in the "breeze").

I think the process of sleeve migration was fairly slow. If it's happened suddenly, then it does look like the turbine may be at fault :(

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Hello all,

 

    I took the air filter assembly off as well as the air trunk the connects to the turbo intake and noted no obstructions with the intake system although I noted the air filter probably needs replacement.  Additionally, I was able to turn the compressor end of the turbo rotor pretty easily with my fingers and noted that it rotated smoothly with no abnormal sounds (e.g. grinding or clanking).  I suppose that now leaves the exhaust system downstream from the turbo to be evaluated.  As I thought about this further, I realized that two other things occurred that may have a bearing on my situation:

  • four years ago, an injector malfunctioned which caused the engine to run very roughly.  I disabled the other associated injector so that I was able to limp home with the engine running a little smoother but I suspect that I wound-up with a muffler fire as the muffler was extremely hot - so hot that it caused the fiberglass of the rear bumper to heat-up and start melting to the point where I could smell fiberglass vapors.  After I replaced all 4 injectors, the car ran normally which included the routine boost acceleration from a properly functioning turbo.
  • two years ago, my Cat detached at the collar of the flange that attaches to the turbo during a "spirited" run.  I had it welded and then I cleaned-out the honeycombs in the Cat of debris and ensured good air movement though it using the discharge section of a vacuum cleaner before installing it.  The car performed perfectly as it had before until a month ago when the above noted behaviors occurred.

  As I think about it, the manner in which the exhaust gasses come out of the tail pipe seems different - not as forceful.  Does anyone have a suggestion on how I can test the exhaust system to see if the necessary flow capacity is present?  Also, how long should a Cat last?…the car is 25 years old and I've driven it as my everyday car all those years and have 146K+ miles…thanks.

 

Romero

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A quick search with Google revealed that cats should last about 100,000 miles, but can fail prematurely. If you have 146K on the clock, yours is probably due for replacement (at least from a pollution point of view). Running rich also seems to dramatically reduce lifespan.

 

Blockage may be due to other causes though.

 

I replaced my original with a lightweight high flow cat with custom fittings (which took the place of the cat and the EBP (Exhaust Back Pressure) Valve (Australian sourced).

Cheers

Ian.

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Hello Ian,

 

    Thanks for the feedback…I'm at the point of disassembling the exhaust system aft of the turbo…we'll see what's found….

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