200SX s13, problems when engine warms up.

[acasmc]

all really point to leak in exh.pipe before sensor or at it itself. If you are 110% sure that this is not case, wiring or maaaybe ecu is your target. But rather drive without it then with that asshole in exhaust... Idle and const.speed issues should point turbo out of issue,isnt it?

everything is brand new. me and four other mechanics rechecked all hoses and piping for leaks. nothing was found.

i'm even considering remaping to remove o2 from ECU, if no other solution is to be found.

[pointz]

You dont need remap to remove lambda you need a pre-facelift engine bay loom, ecu and maf

[Jonny Wilkinson]

You dont need remap to remove lambda you need a pre-facelift engine bay loom, ecu and maf

You can write a custom map to ignore the inputs of the lambda.

[acasmc]

I have measured inputs today.

TPS sensor is ok. All values are within factory limits.

o2 sensor:

0,66v on idle, on throttle it goes down to 0,2v. It actually never goes up. Is that supose to be like that?

Left car in service, to remove injectors clean them and test them. Also fuel pump pressure is gong to be tested too.
Hopefully that will show the real problem.

[Jezz_S13]

lambda should oscillate pretty quickly between ~0.1v and 1v when it's in closed loop mode (cruising, fast idle)

lower the voltage = lean, higher = rich.
http://www.lambdasensor.com/main/mtesting.htm

The problem with a narrow band sensor is that you don't know how lean, as 0.2v is 14.3:1, which isn't really that lean.

[acasmc]

actually no fluctuation whatsoever. Just stuck at 0,66 and going down to ~0,2 on throttle press (about 2-3000rpm).

[acasmc]

UPDATE:

injectors cleaned and tested. no leaking, working fine, all good.

still the same. with o2 sensor undriveable, without it like a swiss watch!

any other ideas?

p.s. mechanic tried to remove CAS to check timing and belt. says screws came off easily, but couldn't remove CAS. Like it is bolted to engine???
is there any special procedure for removing CAS?

[pointz]

No procedure should just pull out if it wont remove the front cover with cas 5 hex bolts and 4 10mm bolts!

[acasmc]

One more question, excuse me if I'm boring.
Hypothetically speaking:
After exhaust change, turbo got higher boost level, during unrestricted flow.
That higher boost, required me to lower boost to avoid fuel cuts on full boost. Obviously I had to unscrew manual boost controler (which is connected to westgate) to lower it. Until I got about 15psi. Stage 1 chip requires manual boost controler to achive 15psi if I recall correctly. I have lowered it to 12psi just to be shure.
Is it possible that my doing on manual boost controller, fuked up air:fuel mixture and now that's causing the problem?
How to overcome that? Increase boost to required 15psi? Or lower it to 10psi?
Does my level of boost make any impact on idle fuel:air ratio?

[pointz]

I wouldnt run more than 12psi with t28 on a stage 1 chip that is written for t25.The chip removes fuel cut afaik.
Fuelling will be off with a t28 on a stage one as i said before! How much affect i cant tell you personally.

Why dont you just fit a h-dev stage 2 and report back if you have any issues.

[acasmc]

I'm planning on ordering one, after New Year. Little short on money at the moment.
Are there any prerequisites on stage 2 chip? Or I just solder it to the board, turn the key and drive...

[pointz]

If you have a stage 1 chip already your ecu may be socketted, if it is just carefully swap chips over and job done

[acasmc]

Thanks. That most definitely is the plan for near future.
In the mean time, gonna try to sort this out.

[Jonny Wilkinson]

TBH I don't know why anyone would just solder in a performance chip rather than soldering in a socket and plugging the performance chip into the socket. Its the same amount of effort and a socket costs less than a pound.

[acasmc]

I will definitely do like that. Since it would be much easier to replace it later.
Still, at the moment problem remains with this chip.
I have narrowed it to bad mixture. Now trying to figure it out, how to change that. Should I play with MBC, or there is another way of doing that?
Also does anyone knows, what air to fuel ratio should be on stage 1?

[pointz]

Search afr readings there is quite a few threads about it.

[acasmc]

ok. one more, before I start working.

can I excange ECU with friend of mine? he's driving 1991 200SX with Stage 2 chip. Just wanted to check before buying anything? what if his ECU is 39F02, or 44FXX (non o2), will that work, for the testing sake?

[pointz]

If you both have lamda sensor (facelift) then yes

[Jonny Wilkinson]

39f02 is OK. 44f is not

[acasmc]

Apparently I didn't get a hold on another ECU. :-(
But. Decided to go through testing modes. 1, 2, 3 and 5. Nothing there, except one tiny thing, that I have missed last time. According to manual, after doing Mode 3 testing, a proper way to finish is to went to Mode 4 and then turn off the ignition. Is it possible that missing that step previous times, made ECU work in some wrong mode the whole time?