Lexus Specialist Required

[Mark W]

Not a happy chappie......after only 2 weeks of buying my GS430 (2000 model) in a private sale, engine mgmt light came on.

Luckily in RAC so had it recovered to my local Lexus Dealer (Wolverhampton)

Fault codes were stating "TOO RICH - Bank 1" and "TOO RICH - Bank 2" (RAC connected their diagnosis at scene)

Dealer just called asking if Ive been driving through any water recently - Which I havent - although there has been a lot a rain recently but Ive not been driving through anything you could consider deep.

Then said theres low compression on the 4th cylinder.....(Only 90 instead of 170 on all the others) and suspects its a bent piston.....wants £420 just to strip down and take a look.

Anyone know of any Lexus specialists around the Stafford/Wolverhampton area they could recommend as I dont particularly want to pay £105/hr x 4hrs labour charge just to investigate and see if indeed its a bent piston.

Also, I'm no expert on mechanics.....anyone know why he would ask this given the cars symptoms?

[Steve ( West Mids )]

Try Lexus Hanley, they are very competitive on prices. Or PM "Chris S".

[IanCornwall]

Sorry but pistons don't bend, they may crack, or rings break or wear, or, a bore crack which on a standard Lexus or almost any other new car is rare unless you have avoided oil and filter changes or have trashed the hell out of the car

or run it through rubbish with no air filter and sucked in garbage

Did the garage tell you if they had done a compression test wet and dry ?

A dry test can show a drop in compression but that is only part of the test

If a cylinder shows a drop then they should put some engine oil in the cylinder through the spark plug hole and restest

If the compression rises it is because the oil has sealed the piston / bore gap temporarily, if the compression stays down then the fault has to be above the piston head such as a bent or sticking valve, a head crack (rare) or a cylinder head gasket

In any case the only real answer is to take the head off and have a look

[IanCornwall]

Just had a thought,,, the analysis showed overrich on both cylinder banks ??

and u have a 430 V8

a piston even blown completely or a head gasket or a valve on one bank would not affect the other bank, i would be tempted to look at an electrical or fueling fault first that is common to both sides

[Mark W]

Just had a thought,,, the analysis showed overrich on both cylinder banks ??

and u have a 430 V8

a piston even blown completely or a head gasket or a valve on one bank would not affect the other bank, i would be tempted to look at an electrical or fueling fault first that is common to both sides

Thanks for your comments Chris.....very helpful certainly as I know nothing about engines so dont know what questions to ask.

Yes its a V8

Definately showed as Bank 1 and 2 - I saw it with my own eyes on the screen.

Lexus told me they had done a compression test - not sure wet or dry and dont know what either is (told you I knew nothing ;o) and all were around 170 but cylinder 4 was at 90.

Only had the car a fortnight but service history shows regular servicing at either lexus dealers or lexus specialist.

If it is a piston - Lexus Wolverhampton have quoted +2K labour only + parts.

To be honest, during the recovery process, I was involved with 3 different "mechanics" - 2 of which did not work for RAC - and they all thought it was an electrical/sensor problem.

Dont really want to fork out around £420 quid getting the engine stripped down and another £480 to put back together if it is an electrical issue.

[MacRS200]

I assume that the numbers given for the compression test are PSI, just did a quick check and the GS430 has a compression ratio of 10.5:1 so I would expect figures nearer 150 and not 170. OK 90PSI is low but if they got 170PSI on the other cylinders I smell some BS here, did they actually do a compression test at all.

Also I agree with Ian, I don't think that low compression on one cylinder would not cause a "Too Rich" error on one bank never mind both.

[Mark W]

I'm thinking it may be worth getting a second opinion on it.

Is it safe to drive without causing any (more) serious damage? RAC stated due to being rich it could overheat my CatConv.....even catch fire?????

Wouldnt use for normal driving - just to get it to another garage (ive seen very good comments ref Lexus Hanley)

[IanCornwall]

I have always the utmost respect for the vast majority of garages, as the vast majority seem to know what they are on about

But something doesn't seem quite right here as Mac says 10.5 to 1 compression would only give a maximum of 156 psi and that is on a brand new engine with zero wear if you are lucky, the only way to get more than that is to up the compression falsely by oil filling the cylinders during the test

Ask the garage to put their compression findings in writing, if they are genuine then they will do that no problem along with an estimate for the exploratory work and then also ask why the fault codes were showing on both banks

the chances of both banks suddenly blowing a piston without blowing the engine up completely is nil as it would cause a catastrophic failure to do that on a modern engine such as the Lexus

As far as I can understand each bank richness is measured by the O2 sensor in the exhaust, a blown piston, head gasket or similar simply cannot affect the other bank as they are not connected physically

I reckon an ecu fault or a wire falling off the sensor is to blame, it has to be a common link between the 2 sides and that only indicates electronic failure

[Mark W]

Thanks Ian/Mac for all your help.....I feel a little more armed when I go in tomorrow. Ive found a local garage only a mile away from the lexus dealer that has loads of positive reviews on an independent website - specialise in Bentleys/Rolls Royce and Range Rovers - so used to dealing with large engines.

Ive dropped them a note (well informed thanks to you guys) and asked if he can look at it for me....

Cheers again.. ;)

[Mark W]

Thanks to forum memebers support youve saved me more than 2 grand.....collected car from Lex Wolverhampton on Tuesday...conflicting ppwk from them (one said low compression cylinder 4, the other cylinder 8) also now stated my MAF sensor faulty, and coolant found in the faulty cylinder (not sure which one, 4 or 8) and rough idle (which i didnt notice) prob due to bent piston.

When i collected car, noticed no engine mgmt light on and car ran fine. (it never felt like it had run dodgy in the first place to me though)

Took to specialist......called me today stating engine near perfect - no loss of compression anywhere - no missfire or rough idle ....they also confirmed Ians an Macs comments ref max compression at that ratio...cheers guys...

Anyway....result !!! My car back and still 2 grand better off than if i had trusted the dealer!

[88b]

From the other post and this one it sounds like this "stealer" needs to be avoided. Did it look like they had a lot of work on ? wonder if they were fishing for work.

Glad you got your car back and didn't get ripped off.

[Scorps01]

Pays to ask questions on a forum such as this.

With a diagnosed fault like this the average person would just go ahead and get the work done, in reality the dealers know this and how could you inspect that the faulty pistons were shot?

Glad you got it sorted B)

[IanCornwall]

Glad all worked out fine in the end Mark

Hope it keeps running sweet

[Mark W]

Came home last night and it bucketed it down with rain....so much everyone had to stop on the dual carriageway as you just couldn't see where you were going......also rained all night and car isnt garaged....got in car this morning, drove a few miles and engine mgmt light came on again.

Listened carefully to the engine and it does sound a little like its misfiring a little, although I didnt notice any difference in performance

This sort of proves the theory that water is getting where it shouldnt (somewhere by the spark plugs) when the car is driven in heavy rain.

I'm going to have a good look around the engine tomorrow to see if I can suss out where the water is getting in.

I was quite shocked when I opened the bonnet just how much water ran out from under the front grille.....is that normal?

But my main question is - will the Engine mgmt light automatically go out if I fix the problem or do I need to reset myself?

Had a Vectra in a previous life and the ECU in this would clear the error after several successful starts and no more problems - Is the Lexus the same or will I need to get it reset (or perform some tasks to reset it myself)?

[Mike_B]

Water pours out of my front grille when I lift it, even if it's just after a wash. Goes all over the engine when you lift it up - daft bit of design really.

I guess the engine light will go out if it thinks the problem is cleared, but will retain it in memory so at service time when they plug the computer in it will give a history of faults it's noticed.

Have you tried giving the plugs a good spraying with WD40? The whole engine in fact, it won't do any harm. I do it to my bike engine all the time and it keeps it a) clean and B) waterproof. WD40 is primarily made for displacing water, not as a lubricant. And no, it won't catch fire when it gets hot, just make a nice smell...

[newport]

Yes rain water pours out of the grill when I lift the bonnet up and can go on the engine if lifted up fast, Ive had no more rain water problems since I park the car nose faceing up my hill, I have a look everytime it rains, so yea im out there all the time

I have seen water sitting on the bonnet seal at the back (fire wall) so I think that is where it comes in, my old mk 1 let water in the boot alot (seals again).

[Mark W]

Thanks guys.....just bought myself a large can of WD40 and will give it a go.

Going to have to suss out where the water is getting in and fix it somehow...otherwise not going to be able to drive the car in the rain....which given this summer is going to be a slight problem

Glad to see you've had no more probs Newport.

Update: No use....good dousing with WD40 and reset ECU....light out but still misfiring so looks like back to the garage.

I'm wondering if its ruined the spark plug on the 1 cylinder...as when the garage replaced them last time they showed me the old plugs and the one from the misfiring cylinder didnt look too healthy...