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Random stalling


redshift

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Over the last week or so, the car has developed the occasional habit of stalling when pulling up to a stop.

Maybe around 1 in 10 journeys does it do this. In every other aspect all is normal but sometimes coming to a stop will result in the revs jumping between 500 - 700 then cutting out.

Sounds IAC related but a couple of hours after doing it yesterday, I drove home and all was perfect again.

If (sorry, when) the TVR does this I'd pull the stepper motor from the idle control and clean it up. Unfortunately it looks like the Esprit has a completely integrated stepper motor/valve device.

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Does indeed sound like the IAC valve is struggling to react/catch the idle. It probably needs a clean out - unfortunately it is a bit of a pain to get to.

You can remove the IAC valve without having to fully remove the plenum, but it is a bit tricky. Procedure is like this:

- loosen the clips on the silicone couplings on the throttle body elbows

- remove all plenum bolts

- disconnect vaccuum connections on the rear (engine front) of the plenum

- disconnect fuel pressure regulator hose to plenum

- disconnect IAC valve wiring

You should now be free to rotate the plenum upwards to gain access to the IAC valve. Just prop the plenum up to have clear access.

In this way, you don´t have to mess about with depressurising the fuel lines to and disconnecting the secondary injector feeds.

Also useful if you need to check/replace the coil packs and don´t want to take the plenum off fully.

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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I was reading the service manual for all the things to disconnect just to get the plenum off :cry:

Probably better to replace it if its such a pain to get to.

Nice to know that it could be accessible without undoing everything though.

Was thinking about maybe re-newing the EGR pipe under there at the same time? The other part of the EGR has already been replaced a few years back as it was leaking and I don't imagine that the extra heat of a leak under under the plenum would be good for these electromechanical parts if that one should fail too?

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No - you don´t want an EGR leak....

If you are planning to replace the EGR pipe, then you may find that you need to remove the plenum fully, since it is at the other ´pivotal´ end of the assy. Access will be very cramped at that end. :thumbdown:

I never use EGR on any of my engines and do have a selection of EGR pipes from low mileage engines if you want. I can bag them up and send them over?

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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I use neither the EGR nor SAI.

It is a tiny bit more involved as you need to block off both the gallery in the cylinder head and the EGR manifold on the throttle body stack. It gets a lot of unnecessary clutter out of the way and with fewer parts to fail in the future.

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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OK, it looks like the EGR pipe is bolted to a flange on the LHS manifold and then into the throttle body unit with a join mid-way.

Would it be too much to hope that there are blanking plates available for non-EGR cars?

I can't see any reason why this would effect the regulatory emissions performance? No doubt the ECU isn't going to notice that the EGR valve is not having any effect.

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Hahahahha... yes... there is a blanking plate for the exhaust manifold, but you would need to tap and blank off the EGR manifold in the throttle body stack.

You can remove the whole EGR system - the EGR valve is also removed.

Are you considering removing the SAI at the same time?

The engine should still meet the emissions test and there will be no CEL associated with the removal.

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Well it doesn´t aide performance and as many owners have found, the pipes have a nasty habit of breaking over time. It is all emission related stuff that is not helpful on a performance oriented engine.

The V8 is not intercooled as standard, so anything that is inceasing the in cylinder temperature is not very welcome. Having the EGR and SAI removed also makes installation of chargecoolers on a V8 much easier to organise. :whistle:

I´m the same with the crank ventalation - I do not feed these fumes back into my intake.

Cheers,

Mike S

Edited by mike_sekinger

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Had a think about this last night.

I think I would like to take you up on the offer of an EGR tube if thats possible Mike?

But what I am planning is to put a blanking plate on the manifold in between the manifold and the EGR pipe so the system is effectively sealed. Should there be any problem with emissions it would be a very quick fix to undo and remove the plate and all is back to normal.

You mentioned SAI? Is this the what the vacuum pump is for? Not really sure I understand what that circuit does.

Its already been an expensive start to the year what with the A service and then the turbo coolant hose going and replacing that and the oil feeds.... not much change out of 3000 euro by the time all the siezed and broken manifold studs and bolts were done :shock:

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Hi Pete,

No problem. I can bag-up all of the EGR pipes that I have. I can either send them to you, or you can do a drive-by and collect. Totally up to you.

The Secondary Air Injection is just another control function that works together with the catalyst to reduce the CO and HC emissions. The air pump is supplying air into the exhaust ports via a gallery on the cylinder head. To delete this function, you need to tap and blank off the gallery in the cylinder head and then all of the hardware can be removed.

If you are leaving the EGR physically in place, then I´d leave the SAI as well, although I´ve never considered removing only one before.

Let me know what you want to do about postage or pick-up?

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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That would be great if you could pop them in the post as I can't see having any free time for dropping by in the near future. Will PM the address and send a cheque by return for the wine cellar fund.

OK for the SAI, if thats pumping air into the system for efficient combustion purposes then I'm not really worried. It was just the idea of eliminating adding hot exhaust gases to the intake of a non chargecooled engine.

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Will do Pete.

Hope you can start to use the car for pleasure purposes before too long.

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Interesting what Redshift says- I have I assume a problem caused by the same componant (I always assumed it was the idle control valve) where the tickover revs do not fall below 2500 rpm. To temporarily solve this I have just disconnected the wiring- the engine now ticks over a bit lumpily once warm at about 600 rpm and the revs drop sharply to this rather than the slow reduction that used to happen even before it started sticking at 2500 rpm.

Mike's explanation on how to get to it is very useful to me- plus I was assuming that it would need replacement rather than dismantling and cleaning out.

Rgds

Bob G

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From what I've read, the standard IAC problem is that is sticks open and that gives the high idle.

Mine just seems to be sticky around the fully closed position as the problem is only there once up to temperature.

I have also seen comments that cleaning it may not last that long. What would be a 10 minute job on the TVR looks like several hours on the Esprit.

It would be nice to have a mechanical base idle setting on the throttle bodies themselves so that stalling didn't occur.

Just re-read your comment Bob where you say the revs drop quite sharply without the IAC connected?

Thinking about it, I've had the feeling that the revs were 'hanging up' on gear changes. Maybe that's IAC related too?

Did you engine automatically idle on its own with the IAC disconnected, or did you have to adjust something?

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:sleeping: Yes definitely think the IAC used to cause a slow reduction in revs when throttle shut- this might have been built in to assist gear changes- revs don't drop too much when your foot is off the throttle and clutch down. Revs fall sharply when it's disconnected

No I didn't adjust anything- engine only ticks over once warm and can't be left for any time as it just stops! One can drive normally though but not a stable situation. I know I going to have to get a new one- as you say not worth just trying to fit the old and have it last 10 minutes because so difficult to get to!

I also get a sort of misfire after a period of heavy throttle use- which I think is also related to the IAC being disconnected though not certain about that point. Engine settles down with no misfire if one is gentle for a few miles... :(

It will be interesting to see whether on my engine also, there are a load of pipes corroded under the plenum chamber.

Sorry don't know how to add emoticons

Cheers B

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  • 2 weeks later...

Well here is the offending article.

Not only is it sticking and very dirty, but the barrel is also badly scored, as though its been trying to operate and failing.

No point in even trying to clean this up. And if you knew just what is required to get this out :scared:

So whats involved?

If you're much over 6ft and 80kg and not a contortionist then you can stop reading now :wacko:

Remove the boot floor and start with disconnecting:

- Battery

- EGR pipe join at the bracket

- Large and small vacuum pipes from the front of the plenum

- Small vacuum pipe under the front LHS side of the plenum

- Black plastic pipe with quickfit connector to valve at centre of bulkhead

- Vacuum pipe to throttle body RHS

- Throttle cable (theres a locking pin on the end ball)

The the electrics

- MAP sensor plug centre rear of plenum

- Throttle potentiometer

- L/R secondary injector plug on rear corners of plenum

Now unscrew:

- P clip holding the transverse metal tube to the underside of the throttle cable frame

- Both hose clamps on each inlet duct between turbo manifolds and tracts to the throttle bodies

- Hose clip on the blue silicone tube to the IAC on the RHS turbo manifold

Now, if like me, the car hasn't been started for a fortnight there probably wont be any pressure in the fuel rails. The pressure relief/drain is under the black plastic cap (like a tyre valve cap) on the front of the RHS fuel rail near the bulkhead. Pressing the centre pin confirmed that there was no residual pressure.

If the care has been run recently then disconnect the fuel pump supply and run the engine until it starves out. Then check the fuel rail pressure as above.

The fuel supply to the secondary injectors is via the black tubes with quickfit connectors that slide onto the rear of the fuel rails. Each quickfit connector has a red button on each side. You need to press both in together and then pull it off the fuel rail. Whilst catching any residual fuel with a cloth.

Unscrew the 14 bolts holding the plenum in place (10mm heads)

Now comes the tricky bit :shock:

post-1528-0-09058800-1300693688_thumb.jp

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The next part is best done with hindsight.

So this is what you will be "feeling" for under the plenum:

zxs86w.jpg

Between the throttle bodies and the IAC valve is the EGR valve. There is a connector on the end of the EGR valve, tucked up tight near the plenum underside. And there is another connector on a very short flying lead on the LHS of the EGR valve.

So gently lift the plenum cover from the front so that it more or less rotates at the main inlet hoses. Now get your arms underneath the plenum and find these two connectors and disconnect them. After 4 fruitless attempts start looking for Mike Sekinger's phone number :help:

Stop for coffee, reassess and finally success!

Final connector is on the end of the IAC at the front.

Carefully remove plenum while trying not to get EGR pipe trapped on the way ouy and you will be rewarded with this on your lap:

biv7m1.jpg

Now its just undo the two clamps on the blue silicone hose to the IAC and the bolts holding the retaining strap.

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Oops, forgot to mention the breather pipe from the RHS camcover that needs disconnecting too :whistle:

Re-assembly (as they say) is just the reverse order except:

- Disconnecting the EGR temp sensor was actually quite easy because you could follow the wire with your hand until you came to the in-line plug. Now try and find that trailing socket blind.

- Whoever designed the under plenum wiring harness should be taken outside and shot, now.

I made up an EGR blanking plate in 2,5mm aluminium using the end flange of the pipe as a template. This goes between the two sections of EGR pipe at the join.

Just as well Mike sent me the EGR pipes as the old one connected to the valve, whilst looking OK, actually split in the corrugated section while removing the plenum.

And to confirm, as Mike said, blanking off the EGR has caused no warning lights or error codes.

Still trying to work out what the metal tube is that runs across the rear of the engine from the RHS of the block to a valve on the LHS? Looks like an air valve from where its connected?

In any case, looking at all the corroded bits with the boot out has made me start my shopping list for later this year.

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Well done for performing the transplant. :thumbsup:

The other metal tube is for the Secondary Air Injection. There is an air pump in the rear LH arch area of the rear luggage compartment.

All we need now is some more good weather in which to enjoy the cars.

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Aha! So that's the SAI then.

Well its b******y annoying, seriously obstructs other maintenance and its very corroded too.

Maybe the SAI can be deleted too.

Weather here is blue sky and 18°+ for the rest of the week.

Guess who's coming out to play tomorrow :thumbsup:

Thanks for the parts and the advice Mike.

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Hi Pete,

To remove the SAI, it is easiest simply to tap the SAI gallery in the RH cylinder head and fit a blanking plug.

I agree completely about the clutter. Having all of that stuff out of the way makes a lot of space in a very cramped part of the engine compartment.

Enjoy yourself.

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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