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Discussion Starter #1
The check engine light came on shortly after start-up yesterday.Looking in the engine bay i found a white/semi clear hose had broken off wherever it connects to. At first touch it felt loose, I pulled gently and it slid from under the intake manifold.
The hose runs at the fire wall and has a check valve, then it extends to the center of the engine, under the intake.
The broken end of the hose appears burnt.

It seems to me the only way to find the connecting point is to remove the intake manifold. Is that a correct assumption?
How hard of a job is that? Where can I find procedure to move the intake? Is it just a matter or removing the bolts on top and disconnecting the two switches on the rear end of the intake?

Looking at the diagrams (44.05, item 30), the hose appears to be the one connecting the evaporative/charcoal canister to the manifold/plenum.
Thank you for any advise you can provide.
1265139
 

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Hi Raul,

Unfortunately, you will have to remove the intake plenum to get to that hose. The hose runs up to the EGR manifold area, so it's nearly impossible to reach. You might be able to get away with just loosening the intake and pulling up on the end nearest the front of the car, but you risk damaging the gaskets underneath, which you might also want to purchase before you start this job.

There are several dreaded clear hoses for the evaporative system (most of them near the tank filler, so you will have more of them on '97 vs. the other V8s that only have one fuel filler), and you will eventually need to replace all of them. Make sure you use black, fuel-rated hose and you'll probably never have to do it again.

The procedure in the workshop manual for removing the plenum is so clear, I won't repeat it here. I typically disconnect the EGR pipe near the LH valve cover, and the hose you are replacing at the check valve, and leave them hanging.

In short, from memory:

  • Read the workshop manual procedure
  • Disconnect the vacuum hoses to the plenum
  • Reach under and disconnect the fuel pressure regulator black hose
  • Loosen the large intake hose clamps and shove the hoses aside.
  • Disconnect the secondary injector plugs and the push the quick release for the fuel hoses that run to them (yes, fuel will spill here, so be ready to catch it)
  • Disconnect the MAP sensor plug.
  • Remove the plenum bolts and raise the end nearest the front of the car. There should be some slack in the wiring, but you must carefully reach under and disconnect 3 plugs. This is the trickiest part if you've never done it before. It's not difficult, but if you don't know where to squeeze, you can tug on the wiring and damage it. I found it best to lift up, look underneath it, and get a mental game plan before doing it by feel.
There are likely some other details in the manual that I have missed, but that's generally it.

Good luck,

Jake
 

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My car sneezes
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Like Jake said, plenum needs to come off. If this hose has rotted, chances are many more are rotting. Remove the side panels to inspect the rest of the evap system. For replacement hoses, you can order tygon fuel hose from McMaster-Carr.

Removing a plenum is not the easiest job on the Esprit. When reinstalling, be careful not to damage the gasket or crush wires. Also, slipping the chargepipes over the TB is a bit of a challenge. Resist the urge to pry with a sharp object. Seen so many torn boots from previous repairs.
 

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X2 on using Tygon tubing from McMaster. It bends SO much easier than modern fuel hose, which has thick walls.
 

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Tygon tubing is good stuff but I'd be careful about using it in this application. Generally it's for laboratory or food and beverage industry use, but there are different grades such as F-4040-A Fuel & Lubricant Tubing.


However this one is only temperature rated -35°F to 165°F. My concern would be that area under the intake manifold might experience high temps around this range pretty consistently or may even exceed it causing the tygon to break down over time.

This was just a quick look so there may be other grades I'm not aware of.
 

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My car sneezes
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Tygon tubing is good stuff but I'd be careful about using it in this application. Generally it's for laboratory or food and beverage industry use, but there are different grades such as F-4040-A Fuel & Lubricant Tubing.


However this one is only temperature rated -35°F to 165°F. My concern would be that area under the intake manifold might experience high temps around this range pretty consistently or may even exceed it causing the tygon to break down over time.

This was just a quick look so there may be other grades I'm not aware of.
... and maybe that’s one of the reasons Lotus switched to hard nylon tubing for the later cars when the evap system was redesigned.
 

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If you loosen the plenum you can lift it enough to get your hand underneath and replace the hose. If you want to remove the plenum you still have to lift it enough to get your hand under and unplug the EGR. You can reuse the gaskets but it is always best to replace. Be VERY careful not to catch or pinch ANY wires when you put the plenum back or you will get codes. Might as well replace all the hoses you can, especially the ones on the hot motor. Verify proper throttle movement after you reinstall.
David Teitelbaum
 

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... and maybe that’s one of the reasons Lotus switched to hard nylon tubing for the later cars when the evap system was redesigned.
That would be a very good reason. The later cars seem to use the same hard tubing for the evap line and the actual fuel lines.

Downside (if there is one) is that they have pushbutton connectors. As usual the double-edged sword is that they are very simple to disconnect/reconnect as I learned when working on the evap purge solenoid (see pic). But if a hose fails, which hopefully won't happen -- somebody pinch me, I may be dreaming -- it could mean replacing the hose/connector assy with a Lotus OEM part, which may not even be available now.

Anyway this isn't really relevant to the 1997 as it's probably not practical to swap over to the later setup, but food for thought when you select replacement hoses.
1265158
 

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Discussion Starter #9
Thank you all for the advice and recommendations. I have been reading through section ED to understand what is required.
There is mention (if removing the plenum) that the EGR pipe (page 16) must be disconnected. There appears to be an "O" ring at the connecting flanges. Is that correct?
My car also has a problem with the turbo boost gauge. The gauge does not register pressure. According to the instructions, there should be a red hose connecting to the boost control valve (page 18). Perhaps this hose is also broken and not carrying pressure to the transducer (near the ECU) and therefore no reading at the gauge. (?)

I will try loosening the plenum to see if I can lift it enough to connect the translucent hose, as suggested by Mr. Teitelbaum. However, I think I may end up taking it apart to check and replace the hoses in that area.

It seems to me that I will have to remove the trunk floor as well. Is this correct?

I appreciate your help.
Thank you!
RG
 

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The EGR connections are less of an "o-ring" and more of a "compression seal". They are metal gaskets that you can usually reuse if they aren't damaged. I think you will find that trying to lift the plenum to get to the hose is just causing a lot of frustration. If you are to the point where you can lift it, you've only got 3 plugs left to remove it.

Good advice from everyone about pinching wires, though. It's way easier to pinch wire and hoses than it seems.

Jake
 

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Removing the floor gives you a lot more room to work on things. There are a bunch of "While you are in there" kinds of things too. Change spark plugs, air filters, check or change the fluid in the gearbox, flush the clutch cylinders, wash the header tank, general clean-up.
David Teitelbaum
 

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Discussion Starter #12
David, you mentioned earlier that the plenum may be lifted enough to get a hand under it and connect the hose.
I guess all bolts would be removed for this and the rubber connectors to the turbos loosened up.
Is all this work performed from the sides of the car or standing in the trunk space after removing the floor?
How high can the plenum be lifted without disconnecting everything? a couple of inches?
Thank you for your advice.

Jake, GMendoza, and others: thank you for your replies and insight.
RG
 

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All of the connections and bolts have to be removed. You can lift and tilt the front of the plenum enough to get you hand underneath to either do the hose or undo the connectors and remove the plenum. As mentioned it is tricky to know just where to squeeze the connectors so you can undo them without seeing them. It all has to be done by feel.
David Teitelbaum
 
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