Help With LS400T

[Lextreme II]

The car is running now, but the engine would die when i put in gear. The car idle ok but for some reasons, it just die with gear. However, the car seem to runs find after 2500 rpm. What could be the problem. ISC is replaced, motor is new. Possible ECU?

 

[Peewee]

Any codes being thrown?
Does it die instantly?
Is the idle perfectly smooth, the right rpm?
You have stock ecu with piggyback? still using the AFM/MAF? Any intake leaks after MAF?
What happens if you put it in ear with your foot off the brake, and the parkbrake down. Does it stall still? or does it creep forward slowly?
Can you disable the piggyback and see if it still does it while running the stock ecu only?

Just a few q's to help.

 

[Lextreme II]

Any codes being thrown?
Does it die instantly?
Is the idle perfectly smooth, the right rpm?
You have stock ecu with piggyback? still using the AFM/MAF? Any intake leaks after MAF?
What happens if you put it in ear with your foot off the brake, and the parkbrake down. Does it stall still? or does it creep forward slowly?
Can you disable the piggyback and see if it still does it while running the stock ecu only?

Just a few q's to help.

Does it die instantly?
No but it idle very rough and un-responsive and then die. However, if i keep rpm high then its ok.

Is the idle perfectly smooth, the right rpm?
Idle pretty smooth during Park, but rough and un-responsive during D

You have stock ecu with piggyback? still using the AFM/MAF?
Yes, still using MAF with piggyback

Any intake leaks after MAF?
Negative

What happens if you put it in ear with your foot off the brake, and the parkbrake down. Does it stall still? or does it creep forward slowly?
Good question i think it because un-responsive and rattle and then die

Can you disable the piggyback and see if it still does it while running the stock ecu only?
I wont run because the injectors are too big. This problem occurred before the new motor. I think its possible the ECU that control the transmission part.

 

[Peewee]

Hmmm, thats a curly one indeed.

Do you have someone nearby you can swap ECU's with?
Put your ECU in his, see if it does it in his car?

 

[Zuffen]

Lex,

Are you sure it's not running too rich on the idle.

It could be that it can idle with the rich mixture without the load of the trans and dies with the extra load of the trans.

As you're running big injectors it could be simply overfueling the engine.

Normally a rich mix will make the engine hunt a little or sound like it has a big cam.

Can you check the fuel mixture at idle.

I figure if it runs after 2,500rpm the engine is either close to stroic at this point or just revving hard enough to keep going.

You see a similar problem with old Webber carburated engines. they are set too rich and will only run well at higher revs.

 

[Peewee]

It would have to be very rich to cause it to die.

I was running an AFR greater than 9:1 at idle and it was running fine (besides the black smoke)
Couple this with the extra fuel I put in for a cold start, and you have even more fuel, yet it still ran fine.

But, its definately something to look at.


Like I suggested in your other thread Lex, put a wideband o2 sensor on it, see what happens to the AFR's when it dies.

 

[Lextreme II]

Its possible that i am running too rich, but the problem occurred out the blue. No tuning or change of setting.

This what i speculate:

1. ECU - Transmission portion
2. Transmission Sensor/s
3. Transmission itself.

Update: I just talked to my friend who is a transmission specialist and he stated its possible the Lock-Up Solenoid.

 

[Zuffen]

Lex,

As you've been working on the fuel system and now have a problem it would be too coincidental to have a transmission solenoid fail.

I think you can get distracted going down the transmission track when you haven't looked at all your options on the fuel system.

My advice is do what Peewee said with the fuel ratios. If that doesn't turn up anything re-check all the piggyback settings.

 

[Lextreme II]

The reason why i said that is because it happened by itself. Even when i was running rich at idle, the car still runs fine. However, for some unknown reasons it just happen without any ecu changes.