Starts, stumbles, and dies...

[r4esh]

Been working on my swap for a few months now and just finishing up.
The setup is: 1989 e30 325i - with m52 (96 328is motor), Zf transmission, OBD1 conversion, red label ecu, s50 intake, 540 hfm, tuning from TRM. All new sensors. Also.. currently no O2 sensor hooked up.

When I turn the key the car starts, feels a rough, then after about 20-30 seconds it stumbles and dies. If I throttle up I can keep the car alive easily, but if I hold my foot in one position on the pedal it will slowly decline in rpm and eventually die until I tap my foot to change throttle.

Here's the weird part. IF I unplug the MAF and start the car, it holds idle at about 500rpm and doesn't die - but it is rough.

My tests: I've tested fuel and spark. Ensured fuel lines were hooked up properly. Tested injectors. Checked spark. Double checked c101. Double checked vacuum. Cleaned ICV.

My thoughts: Bad MAF maybe? TRM chip possible programed for the wrong MAF (even though I paid the up-charge for the 540 hfm tuning)?

I don't know anyone in Tucson with a 540 hfm I can test and I don't want to order another and find that isn't the problem, so I figured I'd quiz you guys and see what your thoughts are.

Thanks,
Dillon

[r4esh]

BUMP: I got another 540i 3.5'' MAF sensor from the junkyard today... tried it, and nothing changed... Perhaps this one is failed too??? I'm out of ideas... the car idles with the MAF unplugged (limp home mode), so I can't figure out what else it could be. Looks like I'll be buying a new one ($350 bucks... ARG!). I just pray that's the problem and I'm not wasting $350...

EDIT: Here is a video of what's going on..

[Adrian_Visser]

Call TRM and make sure they programmed your chip right.

[gregslow318i]

stomp test for codes first, then get an o2 sensor. then try it again.

[e30s50dan]

or unplug your O2 sensor and see if it runs how about fuel pressure?if it starts,will it run with starting fluid

[Red88]

Thinking about it last night I remembered about the stomp test, as Greg said. I might have gotten the connector Bill needs for his OBDII reader, not positive though. I'll fill you in today.

[r4esh]

Alright guys. Stomp test yeilds:

1224 = Intake Air Temp. Sensor

Today "Red88" (Danny) came over and brought his 2.5'' e36 MAF to test in the car and it 'ran' - sounded a LOT better, but still had trouble holding an idle. (this could be because my chip is programed for the 3.5'' MAF?)
We did another stomp test after his 2.5'' MAF was plugged in and we got code:

1281 = Control Unit Memory Supply

So... perhaps I've got a combination of bad MAF aaannnddd bad DME??? IF anyone in Tucson has a Red Label DME I could test, that would be awesome... Otherwise it looks like I've got to buy a new 540i MAF... since I've been handed 2 dead used ones, I guess I'm off to the stealership for a new one.

[r4esh]

JUST called TRM and they verified that it is the right chip. Has anyone experienced code "1281?" what are the symptoms of that code?

[r4esh]

$305 on Pelican Parts for a replacement new one... Ebay has non-Bosch brand ones for $150.. anyone use one of these? Is there a way to just change the sensor inside the case for cheaper without having to buy an all new one? Anyone do this?

What do you think of this ebay one

[MattM]

1224: is the sensor unplugged? its located in the intake manifold near the vacum line for the booster.

i got this too, and in my rush to hook up the harness i had plugged the wrong wires into this sensor, swapped it around, and the engine ran better. check all your harness wiring, make sure everything is hooked up correctly.

dont just throw parts at the problem(especially expensive ones) the odds that 2 3.5 MAFs you tried were bad is very low, the odds of a single MAF failing is low(i have NEVER heard of this happening) they are not a failiure prone item. I would be more inclined to remove your TRM chip, and get a cheap, or borrow a 3" MAF, and try it then

the car should run alright without the 02 sensor.

also, have you checked for vacum leaks?

[r4esh]

There is a "temperature" sensor built into the MAF as well as the one that is plugged into the intake on an e36. I'll double check the one AT the intake... but I'm 95% sure everything is good there. I've checked for vacuum and can't find a problem/leak... and the fact that it idles without the MAF plugged in encourages me to believe that it isn't a matter of vacuum or other wiring issues. It only has the issue when I plug in the MAF. ALSO the other aid to my theories is that when we tested a working stock 3'' MAF (which it isn't tuned for) it ran 'OK' and didn't just die out on us.

One of my 3.5'' MAF was purchased here on the forums and the other was the dirtiest looking MAF I've ever seen... it came from a junkyard locally... so I'm suspicious that it isn't any good either.

[Red88]

Steve@blunttech.com can get it for $240.55. That includes overnight shipping. No returns on electrical stuff though I'm not sure if this classifies as electrical.

[r4esh]

Steve@blunttech.com can get it for $240.55. That includes overnight shipping. No returns on electrical stuff though I'm not sure if this classifies as electrical.

Thanks Danny again for helping out. I emailed him. We'll see what he says.

[r4esh]

Alrighty. New MAF arrived and it feels "better" but not much... didn't really move me much forward and I did a code test after installing the new one and got "1224" - Intake Air Temp. Sensor.

^ Is that for the one on the intake? If this this sensor was dead would it keep my car from idling and make it run rough? That's the only code I'm throwing.

EDIT: If there is no O2 sensor, would it cause the DME to run on 'Open Loop' ?? If that's the case, then would it be ignoring my 'software' and thus not function properly with the 3.5'' MAF AND larger intake manifold??? IF that's the case... then installing an O2 sensor would fix the "open loop" and it would operate off of the tune properly? I'm going to try this in a few days and post my conclusions.

[r4esh]

Okay... Still can't figure this out... I installed an o2 sensor in one of the bungs of the obd2 exhaust manifold to test this out... I got no change. I know that for OBD1 you have 1 sensor that reads BOTH banks (its connected at a 'Y' after the down-pipe) but I figured it would still be 'OKAY' just running it off of the 1 bank. I'm not positive about this though. Either way... New MAF installed and now we have an O2 sensor in there and it still runs rough, wont hold idle, and dies. Spark is good... fuel is good.... air is brand new MAF... I'm pretty sure its not vacuum, but will be pulling the intake today or tomorrow... Idle control valve was taken out and cleaned thoroughly and SHOULD be working because it WILL hold idle when the MAF is unplugged....

I'm still stumped on this, because if it holds idle with the MAF uplugged and it has a NEW MAF, then my only other guess would be 'software'??? I called TMR and verified they sent me the right chip... buuut.... maybe they didn't...

P.S. - Before I put in a new MAF, I got code 1224 = Intake Air Temp. Sensor, AFTER I replaced the MAF I still got the code. NOW that I installed an O2 sensor, I'm getting code 1226 = knock sensor 2.... My knock sensors are brand new...

I'm out of ideas! Help?!