Bgilly

Greetings all! Short time Lurker, first time poster.

2 weeks ago I inherited a 1996 LS400 with 338,011 miles on the original engine (new transmission installed at a Lexus dealer 3 years and 75,000 miles ago) It was previously driven by a family friend, the second owner from 90,000 miles (retired pilot who drove it on 2,000 mile round-trips across the country once a month to visit family) It was given to me for free and I'm working with a $500 budget to turn it into a daily driver for the wife.

Here is the rub-
P0300, 0302, 0306, 0172 (random misfire, cylinders 2&6 misfire detected and system too rich bank 1)
Car was running excellently in June when it was inspected and registered. Made a trip from DFW (Texas) to Kansas mid-July. Arrived just fine and was parked in a driveway for 2 days. PO needed to move it out to the curb to let someone out of the garage and shortly after starting, the car started misfiring. CEL on, Trac flashing then CEl flashing as well. Drove it 20 feet and turned it off. It sat another day and was driven back to DFW with zero issues. After arriving back in TX it started misfiring randomly on short trips around town, usually a few minutes/miles into the drive. The frequency of misfiring trips increased to the point it was almost every time it was run. Family friend decided it was time to get something new and give it to a loving home for a third life (me). So it was driven 30 miles to me with no issues, go figure.

Finding of my initial test drive:
Fried up after about 3 seconds, then ran smooth a quiet. CEL on solid no Trac light. My first Lexus and WOW! What a treat thing thing must have been to depend on for 338k miles. So many features and almost all of them work as intended (only thing that stopped working-recently- is the memory position steering wheel and driver's seat) Drove it for about a mile, back roads up to 30mph and no signs of issues. Very impressed with the smooth ride, tight steering and quiet operation. Paused at a stop sign and accelerated onto a highway- misfires started. CEL flash, trac flash sluggish acceleration up to 55mph. Lots of white/grey smoke. Limped a mile to the local auto parts store and picked up new plugs, air filter and a few tools -$112. Noted a very rich smell- slight smoke and fluid dripping from behind the cats, where the pipes come back to the middle of the car. Started up after 4 or so seconds and limped home 3/4 mile, started misfiring and smoking just over halfway.

Initial hood open checkout-
Who let the previous mechanic touch this thing??? Immediately saw a vacuum leak after the MAF and 5 mis-matched looney tunes wtf vacuum lines (will upload photos if I can figure out how). Ok, that definitely isn't helping things.... Otherwise engine bay looks awesome for the age/miles. Oil, coolant, and PS fluid are all full and the right colors and smells, except PS which is either old or not ATF.... Pulled the old plugs out, which were Densos 5 years and 125,000 miles old. Replaced with new Double Plats. Threw out very dirty air filter and replaced with new. Put it all back together and it started up much faster than before, not really surprised by that. Idled smooth, but stinky for a good minute (rich, gas smell like a go-kart track). Took it out for a drive and misfires started as soon as we started rolling, smoke started about 1/4 mile later. Parked it and started reading this forum.

Plan of action-
ECU Capacitors- Ordered recommended types from Digikey, awaiting shipping arrival
Compression Test- Borrowed gauge from buddy who is a Lexus mechanic at a very reputable dealer
Vacuum Leaks- To be addressed after first 2 items are addressed and assuming Comp test doesn't sink the battleship
Drain/Fills- All fluids replaced with manufacturer spec
Brakes- OMG the squealing...

Results of First Compression Test- Fail
User error, was my first attempt at this on any vehicle. I undid all of the air intake, left the plugs in and pulled the Fuel Pump Relay in the engine bay. (Working off of various generic compression test how-to's) Assumed it would fire and then die when it lost fuel... well 3 minutes of running and that never happened, dang thing kept chugging along. Gave me a chance to watch and listen to it run/misfire. Fired up smooth and quiet, 30 seconds in started smelling/seeing/feeling misses. Soft 'poof poof' sounds of misses and very slight dark smoke from passenger side exhaust aligning with time of the misses.


So......
1. How is a Comp test competently done? Pull the EFI relay?
2. What do you think of the proposed plan of action?
3. What am I missing?
4. General feelings on the likely hood of success within my budget? ($380 left)

Thanks in advance! Pictures to come!

Bgilly

RA40

iTrader: (6)

Getting the ECU taken care of is one part. Then step by step for the other symptoms. All those cracked or stiff hoses will effect the engine, getting the vacuum leaks managed is another for this car.

Looking at the pic one of the fittings has broken off. My thread on this:
https://www.clublexus.com/forums/ls-...e-fitting.html

For a compression test, disconnect the coil wire to the 2 distributors. Screw the gauge into the spark plug cylinder and crank car, repeat for each cylinder.

Off the top there are likely a good handful+ of parts but go step by step and see how the engine responds with each fix. Very easy to spend lots of $$ on this car so depends what your goals are.
Squealing brakes, definitely check pad thickness and replace as necessary.
Fluid replacement as mentioned-good.
ECU checked
vacuum lines
...

Bgilly

Yeah, it appears the fitting that broke was snapped because the ACV delete was done and the mech had gorilla hands, or the delete was done in response to snapping the fitting- maybe at the time of the last spark plug change....

The EVAP hose from the charcoal canister is one of the rubber snakes in that bunch. Not sure if that affects anything in that system...

Also noted that there is nothing in the slot for the 40A H/CTRL relay. What does that control?

dicer

O2 sensors, maybe normal tune up stuff, temp sensor replace, where is timing belt at miles etc.? Transmission drain and fill. Check front suspension.

Bgilly

Yes, all of these are on the radar if I can get the misfires solved. As far as timing belt..... no clue. PO had some indy mech whom he paid cash and there are not documents or receipts to refer to. I assume Aisin for a Tbelt kit? That's what all my Subarus run on. Seems to be the only remaining good-quality, non-Chinese supplier

Bgilly

Capacitors arrived from Digikey today. Hoping to knock out the Comp Test after work today and then pull the ECU

Bgilly

Compression Test Results-
This was my first time doing this type of test and I was in a rush, so it wasn't a textbook job. It was done on a cold engine and 6 cylinders in, I realized I did not have the Throttle blocked fully open... So I don't know how much that skews the results, but for what it's worth all cylinders were tested under the same conditions.

1- 215
2- 220
3- 230
4- 190
5- 230
6- 130 (dry) 150 (wet)
7- 228
8- 218

So some takeaways-
Bank 1 215,230,230,228 Very similar results (avg. 226)
Bank 2 220,190,152,218 (avg. 195)

The two bank 2 cylinders closest to the bank 1 avg were 2&8 and were within 8psi of the avg.
The two bank 2 cylinders furthest away from bank 1 avg. were 4&6, which are next door neighbors....

Misfires were detected on cylinders 2&6. 6 had lowest compression tested and 2 was in line with the 6 good cylinders. Cylinder 4 (no misfires detected) had the second lowest compression...

I'm guessing 6 has a piston ring going out, but what about 2 & 4? 2 has misfires, but good compression and 4 has lower compression but no misfires.

Any coincidence that the two lowest in compression are next to each other? Could it be a failure to a part common to both (head gasket?)?

Thanks for listening!

Bgilly

Bump. Looking for some input- thank you

RA40

iTrader: (6)

Signs of coolant in oil or oil in coolant? Get the ECU caps taken care and as dicer mentioned above.
The compression in #6 is low but for intended uses, leave it. Fixing that goes well above the $500 plan.

Ignition wires:

ECT the suggested is the Toyota version but the third party ones are in the $25 range.

Bank 1 O2 sensors: 2X

Bgilly

Thank you! No signs of mixing fluids, both are the expected color and consistency. I'm planning on also snagging some caps and rotors from a member here. They were bought for a 93, are they compatible for the 96 year? My colleague just finished moving last weekend and he's a computer technician, so the ECU should be revamped by next weekend.

jaaa

Hope all goes well with your 96. Took me some time to sort mine out, but well worth it in the end.

Bgilly

New Denso ignition wires installed, no change.

timmy0tool

iTrader: (7)

first step when a misfire is found, change the spark plugs associated with the cylinder! cheap and easy check.

lextout