IAC valve

[mickdole]

got problem with stalling but with a twist, at higher revs and speeds if i go to accelerate sometimes the engine dies like fuel starvation.Could IAC valve cause this effect? or is there 2 problems and where is the valve situated please.

[greekmix]

Mick,

I dont belive the IAC can cause this fault at high revs. however make sute its adjusted to .065 volts in freescan.

You are welcome to get a log also and provide this to the forum for the experts to analise.

This fault can be caused by a number of fault condition so lets start with the log first.

I hope someone else can provide you with more details.

Good luck

[mickdole]

also having probs getting freescan to work with excel and vista

[Bibs]

I dont belive the IAC can cause this fault at high revs. however make sute its adjusted to .065 volts in freescan.

You're thinking of the TPS, the IACV doesn't get adjusted in Freescan, you can just reset it and view it's reading value.

[Qavion]

Welcome to "the club" !!!.... I have a similar, if not identical, problem... Look for the message thread below entitled "Running out of ideas" ... Hope it doesn't scare you

http://www.lotusespritforum.com/forums/ind...showtopic=19937

The IAC is very easy to change. It's mounted on the forward upper left hand side of the engine (just at the rear of the chargecooler). Two screws and a quick disconnect plug... and it seems no adjustment is necessary prior to fitment. Part Number "A910E6942F".

Clean the pintle mating surfaces before you put the new one in.

The manual says turn off your engine for 10(?) seconds prior to disconnecting the plug.

If Freescan is not pinpointing anything, go for the easy things first

Good luck!

Cheers.

Ian

Edited October 26, 2008 by Qavion

[DanR]

The Lotus manual does specify checking the IAC is correctly set from the factory. The specs are 20mm (+/- 2).

From the manual here are the details:

ToRemove

1. Release the electrical connector, remove the two retaining screws and

withdraw the valve from the manifold.

2. Rexrove the mating spigot '0' ring and discard.

Note: As the IX valve is an electrical corqonent, it must not be soaked in any

Gid cleaner or solvent, or damage may result.

Ib Replace

The IX valve used on the Esprit Turbo has a dual taper pintle. Check that

any replacement valve has the correct part number and pintle shape. The IAC valve

plunger position is preset at the factory, and should require no adjustnxant

before fitting. However, to check that no mal-adjustment has occurred in transit,

it is advisable to check the plunger extension before fitmant, in order to speed

the 'learning' process. If necessary, move the plunger in or out until the

specified extension is achieved, as shm in the diagram.

1 . Fit a new IX valve '0' ring and lubricate with engine oil.

2. Clean the IAC valve sealing surfaces on the manifold and fit the valve in

position. Fit and tighten the two retaining screws to 3.4 Nn (30 lbf.in).

3. Refit electrical connector, start engine and allow to reach operating

teqerature.

Important: No physical adjustment of the IX valve assenbly is required

after installation. The IAC valve 'learns' its correct position via the ECM when

the car is driven normally above 20 mph. See section EBlH.2 - 0.

lWH.3 -N DIRECT IGNITION

The JEM uses information from the MAP and coolant sensors in addition to rpn

to calculate spark advance as follows:

. Im MAP Output Voltage = More spark advance

. Cold engine = More spark advance

. High MAP Output Voltage = Less spark advance

. Hot engine = Less spark advance

[Qavion]

The IAC valve

plunger position is preset at the factory, and should require no adjustnment

before fitting. However, to check that no mal-adjustment has occurred in transit,

it is advisable to check the plunger extension before fitment, in order to speed

the 'learning' process. If necessary, move the plunger in or out until the

specified extension is achieved, as shm in the diagram.

Unfortunately, Danny, the IAC valve (Lotus P/N and Lotus packaging) came from the factory un-adjusted...and there is a potential to break the pintle shaft if you try to adjust it (on my first attempt, the shaft disengaged from the body). The old one (fitted to the car) has a metal shaft and didn't even allow manual adjustment (this has been confirmed by other Lotus Forum members). SJSportscars (the people who sold me the IAC) also said that adjustment is not necessary.

I'm wondering how much longer it takes for the car to learn without adjustment (seconds? minutes? hours?).

Cheers.

Ian

[lotus4s]

got problem with stalling but with a twist, at higher revs and speeds if i go to accelerate sometimes the engine dies like fuel starvation.Could IAC valve cause this effect? or is there 2 problems and where is the valve situated please.

I doubt the IAC is causing this problem. Problems with the IAC are usually evidenced by rough idle and stalling at idle. Check the simple things first like fuel filter and fuel pressure.