Mk4 LS400 won't rev past 5k

Daveyboy20 · February 19, 2018

Hi guys - new owner here; bought my LS400 yesterday. I'm loving it, but just encountered a disapointing problem. It drives beautifully, and pulls really well too, but i tried kickdown and when the revs hit around 5k it stuttered and bounced and wouldn't go past it. It said check engine on the dash, but as soon as i stopped accelerating the message dissapeared. I tried acceleraring more gently without kickdown, and sure enough, the same thing happens at around 5k.

The car has 118k on it, is in lovely condition and has recently had a cambelt, waterpump and service.

runsgrateasanut · February 19, 2018

I will be most interested to read members opinion on this situation. I don't think I've ever reached 5k revs but when I get to the point of Overdrive kicking in and expecting a smooth drop in revs I do get a splutter and seemingly no change. For this reason the Capacitors are to be changed when the damp weather improves which on my much earlier car may be the reason??

royoftherovers · February 19, 2018

31 minutes ago, Daveyboy20 said:

Hi guys - new owner here; bought my LS400 yesterday. I'm loving it, but just encountered a disapointing problem. It drives beautifully, and pulls really well too, but i tried kickdown and when the revs hit around 5k it stuttered and bounced and wouldn't go past it. It said check engine on the dash, but as soon as i stopped accelerating the message dissapeared. I tried acceleraring more gently without kickdown, and sure enough, the same thing happens at around 5k.

The car has 118k on it, is in lovely condition and has recently had a cambelt, waterpump and service.

5000 rpm, suggest to me that you have bought the wrong car for the wrong purpose Davey.

cruisermark · February 19, 2018

This probably does not help the OP,s problem - but im sure when just surfing around I read a selling advery which stated this problem.

I dont think I have every achieved 5K revs in my 430 lol

Daveyboy20 · February 19, 2018

I'm not planning on redlining it all the time! I just like to know a car is capable of what it is capable of... There's clearly an issue - kickdown is effectively useless as it splutters and coughs when the revs hit 5k. It's sublime in all other driving conditions. In fact it makes my 2003 XJ8 feel like an MGB! It's so comfortable and rides so well. It pulls strongly and runs very smoothly. Does anyone have an idea of what it might be? I'd like to get it just right.

ste42 · February 19, 2018

try it with the air filter box partly open could need a new air filter or maf sensor

runsgrateasanut · February 19, 2018

Throttle body might need a clean but as I said earlier Capacitors a possibly clue. You may want to go on to the clublexus site and look at thread "all my crazy Lexus issues solved" which suggests Lexus over twelve years old should check its Capacitors. OK it suggests also that if the Car won't rev out to beyond, or less than 2000 rpm, that this could be the cause. Your car is twenty years young, so.............

Daveyboy20 · February 19, 2018

Cheers guys, as mentioned it runs beautifully in all other situations. Idles perfectly, drives spot on, pulls like a train to about 5k then coughs and a message 'check engine' comes on. .. but only whilst it's coughing. As soon as you back off, the message goes. What are the capacitors?

C Andrew Green · February 19, 2018

Is a 1998 LS OBD II? If so get a Mini VCI dongle with Techstream and try to read the (hopefully) stored codes might give you a clue. Also possibly investigate the EGR valve and it's plumbing.

Andrew

Malc · February 19, 2018

hmm.......... I guess I'm lucky, I'm told the capacitors on my rev counter aren't often connecting properly in certain heat/weather climes and I have to live with irrational but sometimes spot-on rev counter readings. Therefore i don't bother to notice the reading often these days..... last year when the rev counter was all ok i did once or twice redline her to 6000 revs ........... didn't seem a problem and quite honestly I never thought i would ever do that. It's a bit scary tbh .............. I think she performs impeccably at 0 - 60 in the statutory 6.9 seconds and i don't doubt would readily reach 155 mph ............. but us old buggers rarely have the need to go that quick or fast .......... except when pulling away at the traffic lights alongside go-faster Audis or boy racers

Malc

sorry i digress a little

steve2006 · February 19, 2018

First thing with any fault diagnosis is to read the fault codes and go from there, even though the EML has extinguished there should still be a stored code.

The possibilities without codes is huge ranging from faulty MAFs, TPS, Engine ECU capacitors or a fuel starvation situation.

JohnDavis · February 19, 2018

An easy thing to try - remove, clean and check that the rotor arms (at the front of the cams in the distributors) fit on their mounts with no movement at all.

Daveyboy20 · February 20, 2018

Thanks for the advice fellas - and can i just say I'm really impressed how many of you have offered help to a newbie to the forum. I'm a member on a ridiculous amount of forums, as I've had a ridiculous amount of cars, and this seems to be a good one! Anyway, absolutely loving my LS400 so far, seems to be a truly wonderful machine!

runsgrateasanut · February 21, 2018

On 19/02/2018 at 5:07 PM, Daveyboy20 said:

Cheers guys, as mentioned it runs beautifully in all other situations. Idles perfectly, drives spot on, pulls like a train to about 5k then coughs and a message 'check engine' comes on. .. but only whilst it's coughing. As soon as you back off, the message goes. What are the capacitors?

Check out the thread I mentioned on the other forum clublexus. Its the ECU and you can see what can happen and the fault list. Could be you have none of the problems associated with the main ECU. Fingers crossed.

Daveyboy20 · February 21, 2018

Will do - cheers mate. I've just bought an air filter for it, as a 'probably could do with one anyway and it might fix the problem - measure. Absolutely loving driving this big beast around. I've come from a Lincoln Town Car, an 03 XJ8 and a 01 XJR... and the Lexus feels like an amalgamation of them all. It's without a doubt more comfy than the XJ8 - it's not as quick as the XJR - it's as comfy as the Lincoln, but actually handles.... it's awesome.

JohnDavis · February 22, 2018

I've had Silver Spirit - XJ-S - Bristol and others but since I tried an LS that's the only car I want (apart from my lovely old Volvo 760 Estate - dog and work car)

Connor2x4 · February 23, 2018

Had a similar problem in a toyota celica gen 7 which wouldn't rev past 5k either. Someone had the same problem which was solved by a new camshaft sensor. Changed it on that to no avail, had it looked over by a garage to find the water pump had been leaking onto the crank sensor. Changed that and it was fine.

If the usual check this and clean that doesn't work, I'd advise checking those points there.

Sent from my SM-G920F using Tapatalk

ColinBarber · February 23, 2018

On 19/02/2018 at 5:21 PM, C Andrew Green said:

Is a 1998 LS OBD II? If so get a Mini VCI dongle with Techstream and try to read the (hopefully) stored codes might give you a clue. Also possibly investigate the EGR valve and it's plumbing.

Andrew

I don't think so, not the UK models. 1998-1999 GS models certainly weren't.

JohnDavis · February 25, 2018

Malc - 3000 revs will dispose of the GTI lads!

Daveyboy20 · February 27, 2018

Well the more I use it, the better it gets. Seems to rev to 5800 before choking now. A few times it's not done it at all. I'm thinking it's had limited use and never been pushed. Current theory is the VVTi is a bit 'sticky' and giving it some use is freeing it up. I'm going to give it a couple of oil changes to try and clean out any crud that could be contributing to it.

Malc1 · February 28, 2018

just remembering that my Mk3 red lines at 6000 revs on the dial, not 5000 ........ is the Mk4 different ?

Malc

Daveyboy20 · February 28, 2018

It's not that the redline is low; it gets to 5800 and misfires with a check engine light. The light goes away as soon as I back off.

ColinBarber · February 28, 2018

Does sound like it could be a camshaft or crankshaft sensor not giving out a very good signal which can't be interrupted by the ECU above a certain frequency. May need an oscilloscope to diagnose the issue.

Dale_V · March 2, 2018

it sounds like fuel starvation, I read a similar topic a while back

and btw, once its sorted, don't feel guilty about redlining it, mine gets redlined on pretty much every trip and has done for 8 years.

royoftherovers · March 2, 2018

36 minutes ago, Dale_V said:

it sounds like fuel starvation, I read a similar topic a while back

and btw, once its sorted, don't feel guilty about redlining it, mine gets redlined on pretty much every trip and has done for 8 years.

What sort of speed would one be doing on a trip when "red lining" it ?