Ls400 Engine (Pinking ) ?

[PJ1888]

Hi there, my name is Pete and i have a 1997 LS400 ON 178,000 miles.Have had it about 2 years now and it runs like a dream. However since i have owned the car, under acceleration ( especially from cold )the engine sounds as though it is pinking but dissapears somewhat when warm,although not completely.It did not bother me too much then but as time goes by it is very annoying.I phoned a Lexus dealership about the problem and he said it was common on alot of 300s & 400s and that it was the fuel injectors, but it seems a very risky chance in spending out on them if it may be something else.I dont really know anyone with any knowledge of 400s so here i am hoping someone out there may be able to help.Many thanks, Pete.

[ROYT]

Hi there, my name is Pete and i have a 1997 LS400 ON 178,000 miles.Have had it about 2 years now and it runs like a dream. However since i have owned the car, under acceleration ( especially from cold )the engine sounds as though it is pinking but dissapears somewhat when warm,although not completely.It did not bother me too much then but as time goes by it is very annoying.I phoned a Lexus dealership about the problem and he said it was common on alot of 300s & 400s and that it was the fuel injectors, but it seems a very risky chance in spending out on them if it may be something else.I dont really know anyone with any knowledge of 400s so here i am hoping someone out there may be able to help.Many thanks, Pete.

I have only series two LS, but the first thing coming to mind is the knock sensor...

[ManicMark]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

[steve2006]

First thing is to read the engine codes to see if there are any stored ones,if it is pinking you could try a tank of "super unleaded" like BP Ultimate and run some injector cleaner through to see if it is pre ignition or something else.

As far as I know the knock sensor is there to prevent pinking by telling the ECU to retard the ignition if it is detected and if this could not be corrected I would have thought the EML would come on indicating a fault.

Referring to ManicMark's comment on the exhaust flanges what about the EGR pipe?

[Thunderchild]

It could be the cat causing the knock. If the core is lightly loose then it will rattle like pinking under acceleration. Had that on my Scorpio and confused me for ages before I worked it out.

Tc

[PJ1888]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

[steve2006]

If you meant to post something it ain't there :D

[PJ1888]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

[Ruud]

And again it's not there :)

[SteveLS400]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

Instead of clicking "Reply", scroll down to "Fast Reply" and type you response in there.

[PJ1888]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

Hi ManicMark.Many thanks for your reply and guess what,you were bang on the button.Popped down to the local exhaust centre today and the guy who checked it called me over to show me and it was exactly as you said.One of the cat joints is blowing slightly ( the other side does not look too good )and is very corroded but i think it is original ( 1997 ) . He did not want to undo it incase it broke so he put some sort of paste on it as a temporary measure and it made quite a difference so you were right.I think the long term answer is probably new cats unless there is another way but thanks for taking the time to help me .Once again,thankyou, Pete.

[SteveLS400]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

Hi ManicMark.Many thanks for your reply and guess what,you were bang on the button.Popped down to the local exhaust centre today and the guy who checked it called me over to show me and it was exactly as you said.One of the cat joints is blowing slightly ( the other side does not look too good )and is very corroded but i think it is original ( 1997 ) . He did not want to undo it incase it broke so he put some sort of paste on it as a temporary measure and it made quite a difference so you were right.I think the long term answer is probably new cats unless there is another way but thanks for taking the time to help me .Once again,thankyou, Pete.

No new cats. have a look at the search facility for "flanges" its those that you need and significantly cheaper than cats :winky:

[ManicMark]

Hi it might be a slight blow from the exhaust manifold down by the cats, that would explain why it goes when the engine is warm ( common problem & sounds like pinking)

Hi ManicMark.Many thanks for your reply and guess what,you were bang on the button.Popped down to the local exhaust centre today and the guy who checked it called me over to show me and it was exactly as you said.One of the cat joints is blowing slightly ( the other side does not look too good )and is very corroded but i think it is original ( 1997 ) . He did not want to undo it incase it broke so he put some sort of paste on it as a temporary measure and it made quite a difference so you were right.I think the long term answer is probably new cats unless there is another way but thanks for taking the time to help me .Once again,thankyou, Pete.

Hi Pete no probs thats what the forum is for we all learn from each other, as Steve says no need for new cats the flanges can be repaired or contact benfur on here for a good used pair.

[PJ1888]

Cheers Steve.As you can see i ain't used to using this yet but we will get there.How do i locate ( Flanges ) thanks.

[SteveLS400]

Cheers Steve.As you can see i ain't used to using this yet but we will get there.How do i locate ( Flanges ) thanks.

In this thread http://www.lexusownersclub.co.uk/forum/index.php?showtopic=71222&st=0&p=745376&hl=flanges&fromsearch=1entry745376 there's a post from me containing various links which should help you. Dont overlook the search facility - up on the right; its a massive resource.

[PJ1888]

Very helpful Steve thanks. Now have some options and will keep you posted. Pete.