sbtots

Hello All,
I'm a new member, great forum indeed.
I'm having missing during idling, loss of power especially uphill and low fuel economy along with hesitation when the gas pedal is depressed. The car revs fine in park. 1999 RX300 3.0v6 AWD. No CEL is display but the bulb is intact, (lights up when I disconnect the plug from the coils).

I suspect fuel pump but was wondering about the coils as the symptoms are alike.
Thanks in advance or any assistance provided.

lserlohn

It seems that coils failing is common on this model, according to a Lexus Master Certified, but should have codes coming up. Waiting answers from other experts in this forums.

sbtots

That's what I suspected too so I thought I'll ask the many experts on this site. Like yourself I'm eagerly awaiting there replies. Thanks .

hypervish

Welcome to Club Lexus.

Bad coils usually give CEL's.
I wouldn't go as far to say that coils failing on these cars is common.

Lexmex

I wish I were down there to help you out, I loved my visit to Jamaica in 2007 and it was a pleasure to see so many Toyota Harriers and Lexus RX300s, https://www.clublexus.com/forums/rx-...er-emblem.html

Best thing to do first is disconnect the battery cables and then reattach them. Then run minimally about 15 minutes and preferably try to get out on a highway or a long road you can get above 100 km/h or so for a few seconds.

You can get such hesitation as you describe, but that's more symptomatic of possibly something clogged in the fuel injectors. Some fuel injector cleaner would help there. Also curious to know how any kilometers you have on the vehicle and when spark plugs were last changed out?

Also check out our DIYs related to MAF cleaning and IACV cleaning in the DIY thread at the top of this forum. Especially if the MAF is dirty, that can lead to some pinging and hesitation and that would not necessarily cause a CEL.

https://www.clublexus.com/forums/rx-...x300-diys.html
https://www.clublexus.com/forums/rx-...-cleaning.html
https://www.clublexus.com/forums/rx3...-write-up.html
https://www.clublexus.com/forums/rx-...out-yours.html (see the photos in this thread)

What kind of fuel economy are you getting (mpg or km/l)?

sbtots

Thanks Hyper and Lex next time you are in Jamaica we could link up and if possible I'll show you around. There are quite a number of Harriers and RXs. I have about 243743 km on the clock. I've disconnected the negative cable, did the MAF and IACV cleaning, swapped the horn relay with the EFI one and was able to get about 1/4 turn on the ground bolt on the left of the engine. Thanks for the great DIY! I'll be changing the tranfer, diff and trans oil and filter on Friday follwing that other great DIY.

The misfire on idle basically disappeared on start up will drive her today and see if there is power. The spark plugs were changed about 18,000 KM ago, genuine Toyota ones. I've checked and regap the front ones yesterday (was'nt off by much). They were clean and in excellent condition. I've changed fuel filter with the spark plugs but hesitation continues.
Thanks again guys/gals.

Lexmex

The hesitation could still be an issue with the injectors being clogged up and some fuel injector cleaner could help there. The only other issue that happens is sometimes with lower octane gas there can be a hesitation, but not sure what octane you are using there.

I'd also try to get a reading on what voltage you have on your battery. As batteries get older (I've seen it firsthand myself), you can get a hesitation that won't be triggered by the a CEL or bad coil, but merely a low voltage in the system.

Other possibility is a leak somewhere in the exhaust piping that can give some issues in the low range.

sbtots

You may be on to something Lex as my battery seems to be on its way out to the extent where the clock is reset when I attempted to start. I tightened the terminals but she still start a little lazy. In Jamaica we only have 87 and 90 octane at the pumps and thats with 10% ethanal, other wise there is C16 (116 octance for racing and I've heard of a 103 octane for small aircraft.
I don't think I have a exhaust leak though.

Lexmex

It resets to 1:00 a.m. Common sign of battery on the way out.

That high octane won't do much of anything without a tuned engine. In Mexico City, a lot of friends running at my track would get maybe .1 second faster in the 1/4 mile, that's a statistically significant number if your are consistent in running times, but those boosters favor a vehicle modified to accept those high octane numbers.

I am not a fan of ethanol in any amount, because I have seen reduction in gas mileage with it (Florida is a 10% ethanol state), but I will take the gas we have here over the higher sulfur gas I had back in Mexico. Highest there was a 92 octane with an 87 regular.

BTW, where are you in Jamaica?

sbtots

Not a fan of ethanol myself but that is all thats available here at the pump. I've used the 90 octance but get about 100-150 km less per tank than the 87. I will put in a bottle of injector cleaner today and try to get the injectors tested and cleaned next month or so.
Oh, I'm live near the old capital Spanish Town but frequent Kingston, May Pen, Treasure Beach and Ocho Rios. Have families in Montego Bay as well.