My e30 318is s52 swap thread

[BigD]

Don't plug things in or take them out without killing all power to them first!!

:stupid:

[MIKe30]

Matt, if i were to swap chips without disconnecting the battery would the ECU not adapt to the new chip properly?just a weird thought.

I know you asked matt, but i have to chime in because I do this at work all the time (with fire alarm equip and know i shouldn't). Don't plug things in or take them out without killing all power to them first!!


Perhaps it has no effect on car ecu's but it made me :nice: because i find myself doing it sometimes (but on equip that i dont care if it blows up :mrgreen:). As a general rule of thumb, you kill power to electronics before working on them.

Hope you get things sorted though, i'll be keeping an eye on this thread to see what happens! good luck bud.

[windsor318is]

matt thanks for your expertice, im going to steal my moms 92 ECU switch chips, and give it a try just for the hell of it. once the mechanic installs the exhaust, im going to do my feared compression check.

bigD, i bought the motor from a RMP customer, they removed it and also did a comp test before i bought it, they also confirmed it was a strong motor before it was pulled out for a swap to a s52 that the customer had purchased at a great price with a blower already installed on it.im confident that its nothing mechanical like Matt suggested, but you never no,

so i take it i should swap o2s just to be sure??? can i try the m42 unit or modify the plug end on the factory s52 o2?? id prefer not to buy a new s50 o2 and have it make no difference.

Matt, if i were to swap chips without disconnecting the battery would the ECU not adapt to the new chip properly?just a weird thought.

[BigD]

Adaptation is a big deal. It can be the difference between a car that runs well and a car that doesn't. The ECU runs its "stock" mixture all the time (provided the MAF is working, and it has backup tables if the MAF fails) but it uses the O2 sensor feedback to fine tune the mix all the time, also.

The purpose of adaptation is to let the motor learn around issues that come up like vacuum leaks, fuel pressure or injector problems, and the programming of the chip not exactly matching the performance of the motor. So, it does the learning at part throttle and idle (when the target is ALWAYS 14.5-14.7) then it applies the adaptation globally (because WOT fueling will be effected by vac leaks or fuel system issues also).

In his case, the adaptation is not pulling fuel out... it's just not adding it back in. But I don't think that's the real issue. M50 motors will idle happily up to 17:1, they just fall on their faces under load if they stay that lean. I think there is some mechanical issue with the motor, fuel system, electronics.... not sure exactly.

I appreciate you taking the time to write that out, thanks dude!

[tjcm3]

You may want to do a leak-down and/or compression test if you haven't already. Considering the amount of troubleshooting you've already done it may be time to verify that the motor is mechanically sound.

[matt]

Adaptation is a big deal. It can be the difference between a car that runs well and a car that doesn't. The ECU runs its "stock" mixture all the time (provided the MAF is working, and it has backup tables if the MAF fails) but it uses the O2 sensor feedback to fine tune the mix all the time, also.

The purpose of adaptation is to let the motor learn around issues that come up like vacuum leaks, fuel pressure or injector problems, and the programming of the chip not exactly matching the performance of the motor. So, it does the learning at part throttle and idle (when the target is ALWAYS 14.5-14.7) then it applies the adaptation globally (because WOT fueling will be effected by vac leaks or fuel system issues also).

In his case, the adaptation is not pulling fuel out... it's just not adding it back in. But I don't think that's the real issue. M50 motors will idle happily up to 17:1, they just fall on their faces under load if they stay that lean. I think there is some mechanical issue with the motor, fuel system, electronics.... not sure exactly.

[BigD]

Cool, my understanding of the way the ECU uses the O2 sensor is wrong then. I was always told that a dead or dying O2 sensor results in the ECU running it's stock mixture which is on the rich side. I've had bad O2 sensors on several cars, including my E30 when it was an eta. Some dead some not quite, never had one motor go lean, always running well and guzzling fuel like a bitch. But then none were engine swaps with the ECU learning from scratch.

Rich or lean isn't more power, I mean a little each way. But a little rich would be, especially when you goose it - and when you do goose it you should feel it because a lean engine will bog, whereas a rich one will actually clear up (if only for a little while but still).

By the way, I gotta ask, are you really saying that the "adaptation" is so significant that it can lean out the motor to the point of being as weak as he describes? I always figured this "adaptation" is a very very minor adjustment one way or the other, which is only really visible on the emissions report.

[matt]

If you have a working O2 sensor, it won't stay lean for long. It will adapt back to stoich. So, I would say you have an issue with either your narrow band O2 sensor or your meter is wrong. No/bad O2 sensor can cause all sorts of running issues. More importantly, it will prevent your motor from fixing its own issues by learning around problems (like vacuum leaks or non-stock fuel pressure)

With a bad O2 it would be running in or equivalent of open loop mode - which is always rich. So if anything you'd have more power than normal, just shit fuel economy. So you confirmed that you have proper fuel pressure at the rail now?

No no no.

Don't think of these ECUs as having "open loop" or "closed loop" modes. It doesn't work that way. At WOT, the ECU is ignoring the O2 sensor, yes... but it is STILL USING the adaptation data it obtained at idle and part throttle. Adaptation data is collected at idle and light load but applied globally. And it is not always richer, in fact I would say that most of the time the O2 sensor is actually adding fuel globally.

So... "Open loop" AKA no O2 sensor does NOT mean richer than usual. Richer than usual does NOT mean more power (leaner is more power).

[BigD]

I dunno man if your mechanic still can't figure this out, it's time to get a new one. With the debugging you've done, there isn't much left to check. You know you have the right amount of fuel at the injectors so from here it's either the injectors themselves or the timing (by this I mean everything the computer would be taking care of, including the pulse width, pulse timing etc). Get the injectors flow tested and cleaned if you haven't. If those are fine then it's something electronic. Maf (bad or backwards?), some sort of DME glitch (ask a buddy with an E36 to borrow one, don't forget to swap in your chip), dead TPS...

[windsor318is]

With a bad O2 it would be running in or equivalent of open loop mode - which is always rich. So if anything you'd have more power than normal, just shit fuel economy. So you confirmed that you have proper fuel pressure at the rail now?

yup i got proper pressure now, as much as i wont, handy when i get the blower on there. so i guess its not the o2 then. im very close to driving this thing to RMP im sure they would sort this out. im going to let my mechanic finish off the exhuast and figure out whats going on with my brakes, then decide what to do. i dont think the dealership would like to tackle this, but i might talk to them.

[BigD]

from the air/furel meter, and the butt dyno, its got about 160hp. would it run this poorly with a bad o2 sensor? might have to try another one. and it is in one bank in the headers if thats a reason as well?

With a bad O2 it would be running in or equivalent of open loop mode - which is always rich. So if anything you'd have more power than normal, just shit fuel economy. So you confirmed that you have proper fuel pressure at the rail now?

[windsor318is]

You don't need a different DME. How do you know it's running lean?

It sounds like you need a working oxygen sensor hooked up...

from the air/furel meter, and the butt dyno, its got about 160hp. would it run this poorly with a bad o2 sensor? might have to try another one. and it is in one bank in the headers if thats a reason as well?

[e30s52]

the dme's are basicly the same. just stick with your 413

[matt]

You don't need a different DME. How do you know it's running lean?

It sounds like you need a working oxygen sensor hooked up...

[windsor318is]

alright so i installed the 325ix unit, its alot bigger, and all i had to modify was the vent pipe that was blocked off.
after that i sealed off the factory FPR and installed the BMP FPR set it to about 60 psi at idle and its still running lean, but the car runs now, the fuel pump was shot.next i think i might look for a 506 dme, lemme no if you see one around. im almost ready to burn this car, and so is my fiancee!!
next up is the booster issue, and install the exhaust, cant wait for that

also, it seems like it picks up a bit more power after 4000rpm, but not much more, anyone have this before?