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benjamincalleja

89 carb turbo rough running cold

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hey guys, my domestic 89 carb turbo starts perfectly but until warm the whole car jerks about when driving quite violently sometimes?  Totally fine when warm, very smooth but also idles at 1200-1400rpm?  if you start the car and dont drive it anywhere it will idle at 900-1000rpm all day but as soon as you drive anywhere the idle wont settle back down to 1000rpm?

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Did the 89 carb turbo have a throttle jack? Could it be the linkage is sticking? 


Vanya Stanisavljevic '91 Esprit SE | '91 Elan SE | '97 XK8

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i had a look it was stuck so its idling ok now and correctly jacks up idle speed with aircon on etc but i still have the issue where:

1)  cold starting results in the car jerking about violently when driving - the driveline jerks about shunting me back and forth until it warms up, after which it suddenly is totally fine and smooth.  Symptoms are thus:

  •  The car starts eventually without choke but will start and result in a violent lumpy idle for 5 mins until it reaches 50/60 degrees coolant temp at which point it snaps to a kitten smooth idle.  Driving it like this, cold without choke, is violent with shunting. 
  •   Starting it with choke from cold results in instant starting but also with violent shunting until coolant temp 50/60 degrees, at which point it snaps to kitten smooth idle.

So basically, no matter how i start the car, if the coolant temp is below about 60 degrees the driveline shunts me back and forth.  above 60 ish the car is perfect in every way. ??

 

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This sounds very much like your vacuum advance is causing problems.  When the car has warmed up the green valve (between the carbs just below the inlet manifold) switches the vacuum feed to the distributor from high (vac pump) vac to low (manifold) vac.  Trace the high vac line (the one which is furthest away from the engine) to where you can get better access to it, and block it off/clamp it.  See if that fixes it.

If it does, your vac capsule may be failing.  Has it always done this or started recently?

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hi neil, thanks will do - it has always done the jerky shunting on cold and ive had it five years.  the car drives perfectly when warm?   ill check and see.  Steve Taylor at Lotus Marques said this, do you concur? 

 

Hi Ben

I am currently visiting the UK and return to Oz on 10/7/2016

Unfortunately you have not mentioned the year of manufacture - maybe its
1988

If you have a turbo Esprit with Dellorto carbs then you car will be a
private import (exactly the same as Vinko's)

 From what you describe this appears to be a cold start ignition problem

I recommend you grab your workshop manual and check all the small rubber
hose connections on the distributor and inlet manifold

Next check the ignition timing per the section in the workshop manual here -

http://lotusmarques.com/info/technical/30-lotus-esprit/936-lotus-esprit-87-hc-ignition-timing-part-2

If the rubber hoses are connected correctly and the distributor plus
static ignition timing is correct, the idle rpm should be at about 1500
- 1800 rpm

The high idle should drop down to 950 rpm when the TIV valve located in
the inlet manifold operates at about 75 degrees

NOTE - an increase in idle speed is achieved via the idle jack located
on the front carburettor when the air-conditioning unit is turned on

Please check your workshop manual as I dont have mine with me:-)

Kind regards, Steve

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Steve isn't wrong; it's a cold ignition problem.  It's certainly worth checking all the vac lines to match spec, but i doubt your static timing is wrong if all is fine when you're up to temperature.

But I do think you'll solve it by ensuring the distributor only gets the manifold pressure.  Reason is I have the same problem since i got the distributor rebuilt, and I'm sure it's because the vac capsule delivers too much advance.  Problem went away when i blocked off the high vac feed to the distributor.

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I'm struggling to think of the 89 carb' turbo system but if it's as I think, then 50-60 degrees is when it starts to use vac advance, below that it's disabled by a thermal switch in the inlet manifold, in which case, at the temperature range you have a problem the vac advance shouldn't be happening and therefore wouldn't be the capsule itself.

My suggestion is: Disable the vac advance (take pipe off, sand plug the hose with a screw) check that the car now starts and run well until it gets warm, at which point you'd then get a new symptom (poor running when warm), if this does give better cold running then look to the problem being that thermal switch. 

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Andy, that's almost it, but the dizzy gets vac pump vacuum when cold before the thermal switch changes it to manifold vacuum; hence the three pipes out the switch.  It's supposed to need more advance when cold to speed up idle and warmup, but I found I was getting too much and it was causing much like what Ben is describing.

On my car i get manifold vacuum all the time and have no problems.

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If your still having issues the best thing i can recommend is to check if you have the restrictor fitted inline of the pipe to the distributor if not you may be over pressuring the advance timing i think it should be 20º its only for increased driveablity untill warm, if you by pass the pipe from the TIV valve  to the 4 way adaptor as pictured. Then it will only run at 10º BTDC should make the car drive less iffy.

Good luck. 

Screenshot_20160801-220100.png

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