Yikes!

[sonnydas]

Hi everyone. Im new to this forum and was hoping someone could point me in the right direction. (Level of techincal expertise... 7/10)

I have a 93 SC400. it has 177K miles. In the last 3 weeks I have changed a leaky power steering pump and related vacuum hoses to manifold, rebuilt the alternator, changed all plugs and air filter. I tested all my plug wires with my multitester (resistance was within parameters as specified for OEM wires per lexls.coms website.) I have also checked the heater circuit resistance on all 4 O2 sensors (black wires) and were found to be at 6.3 K ohms as outlined in lexls.com...

The car has always... and even today... starts perfectly both hot and cold. But from standstill I get a lot of knocking/pinging and the car 'bucks' while driving. At idle when warm the engine RPM (under load) periodically drops below 500 and unless I tap on the throttle it wants to stall.

Until the power steering pump change 3 weeks ago... I have NEVER had issues with the car. Routine maintenance of course... but no issues that have stumped me. Until now.

Please advise! Thanks! :cries:

[Cure]

Hi everyone. Im new to this forum and was hoping someone could point me in the right direction. (Level of techincal expertise... 7/10)

I have a 93 SC400. it has 177K miles. In the last 3 weeks I have changed a leaky power steering pump and related vacuum hoses to manifold, rebuilt the alternator, changed all plugs and air filter. I tested all my plug wires with my multitester (resistance was within parameters as specified for OEM wires per lexls.coms website.) I have also checked the heater circuit resistance on all 4 O2 sensors (black wires) and were found to be at 6.3 K ohms as outlined in lexls.com...

The car has always... and even today... starts perfectly both hot and cold. But from standstill I get a lot of knocking/pinging and the car 'bucks' while driving. At idle when warm the engine RPM (under load) periodically drops below 500 and unless I tap on the throttle it wants to stall.

Until the power steering pump change 3 weeks ago... I have NEVER had issues with the car. Routine maintenance of course... but no issues that have stumped me. Until now.

Please advise! Thanks! :cries:

←

I have the same problem as the car gets older. It was very severe this past winter, given the cold, dense air. I think it was like adding an intercooler, cause I had some serious power, along with some serious bucking at 60-80km regardless of rpm. I changed the distributor caps and it helped a little, but what made the biggest difference was a fuel injector cleaner. Try a bottle of this product:

http://www.lucasoil.com/products/display_p...atid=2&loc=show

It's supposed to be a fuel injector cleaner/upper engine lubracant. The smallest bottle cost me ($6 Canadian) and its almost completely stopped bucking since then. It might be as simple as that... Let me know if you get the same results, cause it just warmed up here and I believe that has something to do with it as well. I use 89 octane BTW.

The first time it started bucking I replaced the oxygen sensors and that helped a great deal as well. (220,000 kilometers on car). The ride is much smoother since then and the low rpm chocking has gone away (2-3 years now). It's a bit-ch to change them yourself, unless you've got an entire day and the proper equipment. If so check out the following site. (I mention oxygen sensors cause I now get about $5 more milage out of every tank since then and a far smoother ride, so well worth the cost).

http://oxygensensors.com/

Let me know how you make out, especially with the fuel treatment cause I'm very curious. Good Luck!

Regards,

Cure

[Shadow]

check out the following site.  (I mention oxygen sensors cause I now get about $5 more milage out of every tank since then and a far smoother ride, so well worth the cost).

http://oxygensensors.com/

Did you replace with OEM or universal O2 sensors?

[Cure]

check out the following site.  (I mention oxygen sensors cause I now get about $5 more milage out of every tank since then and a far smoother ride, so well worth the cost).

http://oxygensensors.com/

Did you replace with OEM or universal O2 sensors?

←

Sorry, I should have mentioned this. I had the same question when I first ordered:

OEM - Comes with a NEW plastic clip.

Universal - Comes with a kit for splicing/claming your old plastic clip onto the new sensor. However, you can solder them on as well. If you're handy then go this route and save the $50 on the plastic clip.

When it comes down to it, I use aftermarket parts. I don't think this particular item has all that much technology, to warrant a purchase from Lexus. Which by the way is $250 CND at my dealership.

The universal will also come in handy for replacing the "REAR o2 sensor", which otherwise requires the carpeting to be ripped up for access.

Note: Buy an oxygen sensor wrench as well. Heat up the exhaust by driving around for a while; this way you won't stip the screws. Put the car up on ramps and give it a good crank. Should come off. If you do strip it, you can fix the hole by using a regular sparkplug tap. (If anyone wants, I can give you the exact measurements for the tap.)

Hope that helps.

Rob