enash99

I am working on a 1997 LS400, it began running very rough and the check engine light came on, I pulled the codes, and received the following,
Multiple misfire,
misfire on cycl 2,
misfire on cycl 4,
misfire on cycl 6,
misfire on cycl 8,
I have replaced the plugs and the passenger side coil pack, now I still get a code that comes up for Cycl 4 mis fire, and when it idles its fine, but you can feel a little miss in the idle, but soon as you put it under a load the check engine light flashes like its in limp mode and there is no power at all, I have been told to check the Cats by taking out the O2 sensors and seeing if the power comes back then that will tell me the cats are bad, but im thinking there is something else very wrong here maybe even ECU, why would the entire right side of the engine have a misfire, when that part of the engine runs on both of the coil packs, and changing the plugs didnt help, does anyone have any ideas on what i can try or what i can test for, im really confused at what to do next, I have an OBDII reader so i can post codes if needed.. any help is very appreciated..

thank you
edit: i was told this car had a timing belt replaced a month ago is it possible that the car has jumping timing maybe?

Moarpower

Yes it's possible the timing belt isn't correctly fitted as the right bank is out. Other things could be cam sensor or oil control valve. Lastly it could also be an Ecu issue but look elsewhere first.

Continuing to drive it will melt the cats if there is no spark at the the correct time as unburnt fuel builds up in the cat cells. You can try unplugging the upstream o2 sensor and see what happens, no need to remove it.

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Losiracer2

when the mechanic that did my timing belt messed up the timing, it didn't throw any CELs but after 3k it would just bog and not go anywhere. I'd probably say that you have a sensor that's not functioning vs. timing being off a few teeth

enash99

Other than looking for a code, is there a clear cut way to test the egr and cam sensor, I was speaking with someone who said they think it’s the ECU, with a capacitor problem that these are know to have? Any ideas on this? If so am I able to buy an ECU from any 95-97 and have it work on the car? What about an earlier ECU? I’m thinking it has to be obdII at least

Moarpower

Don't go straight for the Ecu. No an earlier won't work. The Ecus often have failing caps but the problems they exhibit are so vast and yours seems more simple.

​​​​​​You can test the resistance of the cam sensors. There are a few tutorials on this site for doing this. Also head on over to lexls.com. There are many tutorials posted there.

​​​​​​Expect maintenance to need doing. It's an older car and all sensors and valves have a service life.

Check the timing. Check the ocv and check the cam and o2 sensors. Make sure the cam sensor plug is connected, people often disconnect these when doing a timing belt. People also often crush the wire when putting things back together if they aren't careful
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enash99

Thank You, With the more information i have as to which sensors to test that might cause this issue, then i can look for the resistance for them and test, But with out knowing which sensors cause this issue, im kind of chasing the dragon, I will be working on this tomorrow, and I thought i should also just pull the ECU from behind the glove box and open it up to see if there is any noticeable damage to any capacitors, i also am aware tho that they can be bad even if they look good, i have a multi-meter, so i'm going to look up about testing each capacitor as well maybe..

Moarpower

Other serviceable parts on that bank would be the caps and rotors. Your issue is bank specific so this may not apply and the caps and rotors are shared between the banks firing order.

enash99

honestly the coil packs and plugs were my first thought, but then i realized that the banks are split between both coil packs i had hoped plugs would fix it, but neither has...

billydpowe

iTrader: (1)

go here and read AND understand:

All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)

Moarpower

Pulling out the ecu is a good place to start. Be sure to check both PCB's if your year model has 2 like the earlier ones. Before you pay for someone to fix the ECU, check the sensors and connections. I have started a few threads here with issues related to misfires and every time been told it was the ecu..Not once was the ecu the issue. Even after fixing my ecu with new caps, problems persisted and mine was a 1990. Now in saying that, the ecu may inf act be your issue, however, I am just sharing MY PERSONAL experience. I suggest replacing the caps either way as soon as you can as a preventative measure.

Someone had similar issue to yours recently, however it was on the other bank. Unfortunately they have not updated with a solution, however people said it was the OCV

https://www.clublexus.com/forums/ls-...-misfires.html

Yamae

A 97 doesn't have any OCV. OCVs are introduced for 98 models and after.
I'd check the skipped timing first. Of course those QAS capacitors in the ECU are not in good conditions any more after the 20 years of usage and you'd better replace them quickly if not replaced.

timmy0tool

iTrader: (7)

i would do the simple stuff and check the cap/rotors next. look at the contacts and make sure all sensors are connected properly and not pinched off.

how many miles are on the car?

aptoslexus

Check Crankshaft position sensor.