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1995 Ls 400, P0340 came after installing a refurbished ECM.

Customer Question
1995 Ls 400, P0340...

1995 Ls 400, P0340 came after installing a refurbished ECM. Engine turns sputtering and hesitating. Fed some gas and revs up and down the dies. Code came up.

Mechanic's Assistant: Has the vehicle turned into a gas hog? And how does it start -- same as usual?

Initially spun ok, then would sputter and hesitate and pop like misfire and dies. Hard tries, slow as if battery dying, but new.

Mechanic's Assistant: Are you fixing your LS 400 yourself? What have you tried so far?

Yes. checked T-belt, plugs, changed igniter set. suspect bank 1 harness grounding by #1 cylinder/camshaft sprocket junction down to crankshaft pos. sensor - saw naked wires in that corner

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Lets start from there

Submitted: 11 months ago.Category: Lexus
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Customer reply replied 11 months ago
My car is a Lexus LS400, 1995.
Customer reply replied 11 months ago
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call.
Customer reply replied 11 months ago
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Customer reply replied 11 months ago
When can Speak to a mechanic or expect his/her response?
Answered in 44 minutes by:
9/22/2017
Lexus Mechanic: Matt, Engineer replied 11 months ago
Matt
Matt, Engineer
Category: Lexus
Satisfied Customers: 23,469
Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
Verified

Hello

to get the P0340 code means there's no cam position sensor signal back to the ECM so I'd 1st check the condition of the 'A' bank / driverside sensor connection and the wiring to it

with no cam signal the engine may struggle to start and have poor fuel consumption but it should otherwise run without it

so unless you find some wiring damage I don't think thats the issue with how its barely running at the moment

So it could be a lack of fuel pressure from the electrical pump at the tank.

1st thing to try is to remove the fuel filler cap and then flick the ignition on whilst listening for the brief ‘buzz’ of the pump

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,
Ideally measure the pressure at the injector rail (should usually be around 3Bar / 45psi +) and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.

You can also get this issue with contaminated fuel , if there’s water or dirt in the tank then either the petrol floats on top of the water or the filter sock on the pump is choked up – so if the other things check out then I’d consider pulling out the fuel pump and cleaning the filter sock

And one other thing to try is to loosen off the fuel filler cap, as there’s a 1 way valve built into the cap to let air into the tank and so prevent a vacuum from being created as the fuel leaves the tank to the engine
If this helps then replace the cap with a new item

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Lexus Mechanic: Matt, Engineer replied 10 months ago

Hi
do you still need help?
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