VolumeToo

Hi everyone,

I've started a new thread on this, which I'll try to make more focussed and concise this time.

Right now my car is stuck on the driveway, and will crank but not fire. (It might eventually run for about a second, then die, with a lot of petrol fumes.)

What I do know is:

1. I have a code "P0135 Oxygen Sensor Heater Circuit (Bank 1 Sensor 1)".
2. The oil control valves are already suspect, and (according to the shop) were removed, cleaned, declared good and put back - along with an oil change from 10/40 to 5/30 about 6 months ago. (Symptoms at the time were bad idle with revs dropping alarmingly, misfire and 'check engine' in display only once. Starting was not a problem then, however.)
3. Starting issues seemed to coincide with when they changed the fuel in the UK to 10% ethanol (E10). It's still possible to buy "premium" E5, but you cannot trust the forecourts not to sell E10 through the E5 pumps and charge for E5.
4. Spark plugs are also about 6 months old, Denso SK20RII. (The old ones were quite wet / fouled.)
5. An emissions check in November (when starting was a problem) showed [fast idle] CO @ 0.01%, HC @ 44 ppm and lambda @ 1.007. (I don't understand these figures, but the guys at the shop said they were "amazing" and "better than a new car".)
6. The engine coolant temperature sensor measures 3.9k Ohms with outside temperature being about 12c (T-shirt tolerable).
7. On removing the air-intake, I could smell unburnt fuel
8. Recently completed a long trip at highway speeds where the car literally flew with no loss of power at all. (Therefore I am not suspecting the fuel pump at this time.) But since then the starting issue has got worse to the point of being unmanageable.
9. When the car does start, it's only with foot to the floor as if it's flooded. Or else, on a hot-start, it might shudder into life - not roar into life - if that makes sense.
10. ECU was meticulously re-capped by me, some 2 years ago, using only Rubycon ZLx and RX30-series capacitors - carefully chosen by scrutinizing the datasheets. I posted about it at the time. (Not wishing to boast, but PCB work is what I've been doing for a living for some 35 years, and I consider my soldering to be beyond reproach.)
11. Mileage is 160,000.

Any clues right now would be extremely welcome!

Thanks again,

Rich

CLLEXUSS

Well, you are guessing. You have to test. These tests are not terribly difficult. Test the fuel pressure. Engines are not terribly difficult to understand though they have a lot of things that can make them have problems. Basically the fundamentals are, compression, does your engine have decent compression in all cylinders, then there's timing, is it timed correctly via is there any issues with the timing belt or is that okay, you have to look at it. Then there's spark, are you getting spark on all cylinders, then there's fuel, are you getting proper fuel delivery pressure. So I would check all these fundamentals first, then start looking at a lot of the sensors, electrical, and everything else, etc

YODAONE

​​​​​​You tried spraying starter fluid into throttle body (not before MAF) to see if engine starts?

MIleage is 160,000 (you use term "mileage" but terms like "Petrol" suggest you are from Kilometer Country) then if original fuel pump, whether or not the cause, you are on borrowed time.
​​​​​​

VolumeToo

160,000 miles, not kilometers.

Not tried starter fluid as yet. But symptoms point to over-fuelling, if anything.

(What is the expected life of a fuel pump on these cars?)

Thanks...

VolumeToo

No, I am not guessing about anything

You say test fuel pressure like it's the easiest thing. With what? The high-pressure fuel system demands respect and I am very reluctant to start undoing banjo fittings on a whim.

Compression: Why would I suspect that? Likewise timing belt, when the problem has been intermittent for some months followed by a flawless hgh-speed run? (But bad OCVs could mean the timing is wrong for starting; that I will concede.)

I am well aware of what is needed to make an engine run, but doing even the basic checks you mention is difficult on these cars, by design. (Unless you have SSTs and whatever.)

(It would be useful to know, for example, the normal resistance of the coolant temperature sensor, which I did state.)

Thanks,

R

LeX2K

If you have too much fuel that means the injectors are dumping in too much or spark is weak. Or doesn't exist. Without testing injector pulse and spark, you are indeed guessing.

Yamae

Sorry for your trouble. Your words, (It might eventually run for about a second, then die, with a lot of petrol fumes) reminds me of a failing MAF or it's connection lines because "starts but die quickly" is one of typical symptoms of a bad MAF sensor. Is it possible for you to measure voltages of all 5 lines to the MAF sensor with the condition engine key ON position? You can find the pin assignments of a MAF here.

Other items like P0135 is nothing to do with the start up. The value temperature sensor measures 3.9k Ohms is a good value when cold. The situation of the closed system CO @ 0.01%, HC @ 44 ppm and lambda @ 1.007 is surely good. It is a smart idea to replace Nichicon's QAS capacitors before the leak starts.

VolumeToo

Thank you, Yamae.

I had not suspected the MAF, as as far as I knew a failing MAF caused a limitation of RPM - which I have not experienced. But I will do as you suggest.

Getting the probes into the connector might be tricky; I'll see if I can fabricate something. (No doubt there is a SST breakout cable!)

(Annoyingly, I am finding that connector clips are starting to break generally - if only they had put the clip on the part and not the loom - but that's another story!)

Regards,

R

VolumeToo

Update:

I did at least remove the MAF and measure its resistance, as per p.1350 of the 2000 LS400 manual. At room temperature it measured 2k3 between terminals THA/E2, which is within the acceptable range. (If I recall correctly, it measured 27k between VG and E2G, for what that's worth.) The wires (with elements?) looked clean, but I did give them a spray with Kontakt Tuner 600 (a gentle, low-residue electronic parts cleaner).

My new oil control valves arrived today from the UAE - a week early in fact - which I have now fitted. One of them in particular was very reluctant to come out - which makes it likely that it had never been removed - despite the mechanic's claim. (Old and new valves measured 7R2.)

On attempting to start the car after reassembly, it did crank a few times (albeit somewhat slowly) then stopped dead. Now it won't turn over at all.

Hoping that my 10,000-mile-old-starter isn't trashed, I now have to retrieve my battery charger from a relative whom I lent it to and has not had the courtesy to return it.

Happy days!

YODAONE

​​​​​Issues and solutions everywhere...
Any budget for mechanical assistance?

VolumeToo

I'm basically at that stage, yes.
Had the battery on charge the whole morning, now cranks at a reasonable speed, but stops dead after about the third revolution.
(Incidentally, the OCVs that I took out do seem to move freely enough when hooked up to a 9V battery.)
So until I can get the car to crank I can't really do any more tests, like check for spark.
I'm looking at getting it towed in.

aptoslexus

I'd do some more sniffing around the MAF sensor. You pretty much described the symptoms of a MAF sensor that has failed or isn't plugged in. Your battery also sounds like it's toast.

VolumeToo

Thanks, but MAF sensor appears fine. The sensing elements are clean and its resistance is in the correct range.

Yamae

This tells the story. A MAF sensor needs to be checked measuring the actual working voltages. The bridge circuit with a comparator can't be checked by the resistance.

VolumeToo

OK, perhaps I need to look at this a little more closely. (But one would expect the ECU to throw a code if the MAF was faulty - no?)