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Throttle Lag?

Mike Floutier

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I've read a lot on the site about "throttle lag" but I'm not sure if this is what I'm experiencing. Firstly this is an intermittent problem. Let me describe.

When it's working "normally" I can touch the throttle and the engine responds immediately powerfully and smoothly.

When it's working "abnormally" I have to press the throttle down about half-way before I get any response - thereafter it accelerates smoothly but obviously hits the floor at half power (ie only 1 gear kickdown).

The change from normal to abnormal (and back) occurs only when I take my foot of the accelerator - never when the pedal is depressed (which is a good thing!!).

I just have to be ready for the change (which happens frequently - many times in an hour's trip) and adapt my pedal style.

However, the frequency of this "switching" seems to be increasing so I'd like to sort it out if possible.

Does anyone have any ideas?

Many thanks


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Is this problem comparable to how your car initially runs when the outside temperature is very cold?

On the 98-up LS, a temperature sensor (in the transmission?) does not allow the electronic (drive-by-wire) throttle to operate normally until the transmission fluid (?) warms to a certain point.

I'm wondering if either this temperature sensor (wherever it is) or a component in the electronic throttle system is defective.

The following thread is for a 98 LS but it has a PDF for the throttle position sensor: http://us.lexusownersclub.com/forums/index...;hl=drive++wire

I may not be even close but you said you were looking for ideas.

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Thanks Jim and YES, any ideas are very welcome.

The problem doesn't relate in any way to the warmth of the engine or transmission - it does it all the time.

I've looked at the pedal position sensor and physically it looks in good condition - I'll look at the link you posted about the tps.

Another thing I'm going to try is disconnecting the battery and see how that affects things.

Anyway, many thanks and any other suggestions would be very welcome - I will let you know how it goes.

Kind regards,


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This sounds like the typical throttle by wire acceleration lag that exists in these cars and others with early-run electronic throttles. The issue is when taking your foot off the gas and then accelerating without coming to a stop, such as you would in traffic. Is that what you are describing?

I found that driving it in ECT PWR mode helps.

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Yes Steve, that's exactly when it happens - BUT

In my previous post I mentioned that I had looked at the pedal sensor. In fact what I did was to wiggle it to ensure it wasn't loose or anything AND then I removed the multi-plug and re-inserted it.

Since then I have just been for a two hour drive and I just realised that it didn't do it once whereas before it would have done it dozens of times.

I did wonder if it was just a loose connection so maybe it was - I'll keep an eye on things over the next few days but it is very promising not to mention very much nicer to drive!!



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  • 6 months later...

It seems that I might have a similar problem. At speeds of 120/130 km/h the engine seems to hold back when you lift off the gas pedal and than want to accelerate again. You have to really punch it to pick up speed again. Same thing happened on a roundabout at 20/30 km/h when it had to be really kicked to get some speed again. But it happens only every now and then.

Now I want to check the pedal position sensor and the connector / multiplug as described in this topic.

Can anyone point it out to me (pictures??) because my wife has to look at it since I'm in a wheelchair for the moment.


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