Cleanshots

iTrader: (2)

car war working perfect did timing belt like 5 months ago ran flawless, did k&n air filter a month before the issues came up..

ok so drove to the next town on free way got off freeway was sitting at the light for about a minute the idle dropped to like 300-400 and ran rough obviously.. but when i looked down when it got rough no check engine light. car dies. wont start. fires up. like VROOM then just turns off...
got car home. checked the ecu and its the oem replacement for that recall they had so someone in its life changed the ecu.

with timing belt it also got new plugs
new wires
new rotors
new caps
new waterpump of course
.
.
things i replaced after problem came up.
new fuel filter
new fuel pump
different maf/afm
new alternator
timing is good.

no difference... um it wont run with the throttle a little open either. soo the idle air control valve isnt the issue either.

sooo what the hell can it be? any idea someone have this issue then solve it? help plzzz.

here is a quick video.

zyzygy

Had a similar issue with my 96; only difference is that I had a new fuel pump relay with me, once I changed it car runs great.

steve2006

Sounds more fuel related than spark, lift the hood,locate the engine bay diagnostic socket and open the lid.
Place a jumper wire from B+ terminal to FP terminal and then try and start car.
If it starts and continues to run then check the supply to the fuel pump ( including relay as mentioned above).
Don't leave the jumper wire connected after testing it is for diagnostic purposes only!

4hunnit

Having identical issue on the same year and model. Have a new alternator, pump, and filter as well. I'm working on diagnosing the ECU and IAC right meow. There's a thread here that goes over the ECU problem in these cars, it has to do with the capacitors.

4hunnit

https://www.clublexus.com/forums/ls4...capacitor.html
Before getting into this, I would check an OBDII test, if you're getting reading errors or connection errors, then it's probably the ECU

Yamae

When those capacitors are in bad conditions, it is the often case that the ECU can't generate the error codes properly. You sometimes can't get any code or you get some unusual codes that are not related to the symptom.

If you have a good multimeter and a film capacitor, I suggest you to measure the ripple voltage as is shown here to know the condition of the ECU simply, quickly and easily.

I also suggest you to check the fuel pressure if the ripple is limited.

If you are not ready to do above items, it would be a smart idea to replace those capacitors as a preventive measure. Judging from the age of your car, it is one of items that you'd better to replace like you do a spark plug change.

Many people are reporting that the car runs much better than before after replacing capacitors although they were feeling no so bad. It is natural that increased ripples give sensors a dirty DC and signals from sensors contain abnormal voltage swings and those confuse the processor to work properly. When capacitors are too bad, even the processors can't work and the ECU can't generate codes.

4hunnit

Yamae, I posted some pics of the inside of my ECU here https://www.clublexus.com/forums/ls4...-start-up.html. Everything lookds great though, no sign of anykind of age/wear/corrosion. Followed the lines, and checked all the other solders. No burns, no cuts, no interference. Is there really any way to test an ECU? Or would it be best to try that multimeter trial and go from there?

Yamae

Capacitors can't be checked by your eyes as you can't check a hard disk drive just looking at. You need to check the capacitance and the ESR. The ripple test can check those simply.

4hunnit

Got my problem fixed. Wasn't the ECM.. was between the Main Engine Relay, the IAC, and also had a loose chord in my ignition coil. Replaced all three at the same time so I'm unsure of which it was. Excited that my ECU was perfectly fine!

sha4000

iTrader: (1)

Well good for you but check back in to let us know if it's still running good in a couple of days.

Cleanshots

iTrader: (2)

ecu is good, so you saying the coils might be bad? i dont wanna just throw parts at this car. bump please help.. should i even check the ripple? it reads fine ecu is working fine, and its the good part number.

RA40

iTrader: (6)

Check the ripple on your ECU regardless and it is a good measure to replace the caps in the ECU. The cap EOL is 10-14 years so it going to need to be done. Better to do it before it leaks and damages the PCB.

There is also the ECT sensor and the variety of vacuum lines that are dried out and possibly cracking. Check the battery cable for signs of corrosion.

cobalt91

What tests have you done? How does the spark look? How much fuel pressure? Hows the compression and timing? Are the wire harnesses damaged? ECU should be the last thing you check.

Shmee

iTrader: (3)

^^^^
Agreed