Author Topic: Engine hesitation. (Read 21055 times)

St�ck · « **Reply #15 on:** August 20, 2007, 05:25:09 PM »

Appreciate that, I may take you up on it if it comes to that.

I just did a stomp test. The only code stored is:

1216 Throttle Potentiometer

Tell me what to look for to substantiate the code.

bmwman91 · « **Reply #16 on:** August 20, 2007, 05:32:04 PM »

I suspected mine for a short while. Unplug it and see if it stumbles. It should not stumble with the TPS disconnected, just run a bit rich. We'll see from there.

St�ck · « **Reply #17 on:** August 20, 2007, 05:39:44 PM »

If I disconnect the TPS at idle the engine shuts off.

bmwman91 · « **Reply #18 on:** August 20, 2007, 05:54:23 PM »

That's interesting. Even if you disconnect it when the car is off then restart it?

St�ck · « **Reply #19 on:** August 20, 2007, 06:00:24 PM »

I can restart the car with it disconnected and it idles fine, revs in the same stumbling manner. Basically nothing changes.

Starting it with the cam sensor disconnected does not change the stumble either.

Also idles fine with the AFM disconnected, although it runs/revs like poo poo (to be expected)

e9nine · « **Reply #20 on:** August 20, 2007, 06:32:36 PM »

Quote from: St�ck;32062

Appreciate that, I may take you up on it if it comes to that.

I just did a stomp test. The only code stored is:

1216 Throttle Potentiometer

Tell me what to look for to substantiate the code.

Plug it back in - while at idle - wiggle the connector and see if the idle fluctuates....that will provide an indication as to you having a frayed wire or not. IIRC - there are 3 wires for it in the sheath.

dude8383 · « **Reply #21 on:** August 20, 2007, 06:43:40 PM »

You know, this is beginning to sound very much like the issue I had.

I had the 1216 error code as well. I tried swapping AFM's, I bought a new TPS sensor, cleaned everything out, inspected the wires...

It turned out to be my ECU! See if you can get your hands on a stock ECU...

bmwman91 · « **Reply #22 on:** August 20, 2007, 07:01:31 PM »

Quote from: dude8383;32073

You know, this is beginning to sound very much like the issue I had.

I had the 1216 error code as well. I tried swapping AFM's, I bought a new TPS sensor, cleaned everything out, inspected the wires...

It turned out to be my ECU! See if you can get your hands on a stock ECU...

Wow, that really sucks. Hope you got a good deal!

I have a spare 175 DME somewhere in here. I did a lot of experimenting on it, but as far as I can tell it was not damaged. That is up for borrowing as well, though I have not tested it since digging around in it. Eventually it will be my testbed for a car simulator so I can REALLY get an idea for how it handles various inputs. Anyway.....

dude8383 · « **Reply #23 on:** August 20, 2007, 07:09:59 PM »

I got lucky, my friend had one.

I bought it for $30 =)

St�ck · « **Reply #24 on:** August 20, 2007, 07:17:36 PM »

Quote from: e9nine;32072

Plug it back in - while at idle - wiggle the connector and see if the idle fluctuates....that will provide an indication as to you having a frayed wire or not. IIRC - there are 3 wires for it in the sheath.

I forgot to mention I pulled back the boot and the wires all looked choice. No problem here.

While trying to slide the throttle body off the studs enough to remove the TPS to examine it the tiny hose that goes between the TV heaters poped on me and puked coolant everywhere :mad: Thats fine though.. just gives me a reason to tear that *feature* out and bypass.

e9nine · « **Reply #25 on:** August 20, 2007, 07:39:47 PM »

If you believe the wires can't be frayed elsewhere - it could be a false signal from the diagnostic or something else AFM may be causing it. If the AFM passes the visual and readout test - try see if you can get another ECU to swap out.

I don't remember but is this issue new or was it pre-existing at purchase?

bmwman91 · « **Reply #26 on:** August 20, 2007, 07:57:59 PM »

I think he said it was preexisting.

I think it is safe to say it has been narrowed down to either the AFM or the ECU. From your inspection of the AFM it sounds like that is probably OK. If only the ECU was easy to inspect visually.....

ak96ss · « **Reply #27 on:** August 20, 2007, 08:17:58 PM »

{mumbles in the background}

Didn't I mention that...

/mumble

I have an extra ECU if you want to borrow it, or one I can sell you if you like. Either/or - I actually have two spares, I believe both to work fine.

St�ck · « **Reply #28 on:** August 20, 2007, 08:27:21 PM »

It is a prexisting issue.

I put everything back together sans the TB heaters and with a new FPR hose as the old one was wasted. I drove out to some favored back roads and proceeded to get on it. Put the car through its paces until I had to cool off because the brake pedal was just about useless... going to have to correct that some time soon too.

Anyways this is the first time I've really taken it out of city streets and had the ability to play with it.

If I take off from a rolling start in 1st gear at 800rpm or so (basically idling forward) and just hold WOT it will stutter all the way to redline without letting up. If I ease up just a bit then pound it back down it will stop the BS and pull cleanly. I was able to get it to do this consistently.

It will still stutter to redline if I give it too much throttle (but not WOT) off the roll, and hold it there.

While I had the TB off I removed the TPS and opened it up. All the wire/solder connections look very good, as does the carbon track. I bent the needles down a bit to ensure good contact and put it back together... obviously no difference there.

I should get Teaguer on the horn and see if I can drive over there and swap out with his AFM and ECU as he is local.

bmwman91 · « **Reply #29 on:** August 20, 2007, 08:46:34 PM »

That really kinda sounds like an ECU issue. Such intermittent and tempermental behavior is really odd. I would think any sensor issues would be consistent regardless of what you do before flooring it. I could always be wrong though, just when everyone thinks all the M42 gremlins were busted, a new one usually surfaces.

My issue was the opposite...stumbled horribly at part-throttle/low load, and went away on WOT.

Although unlikely, it could be the TPS still. Maybe it is vibrating internally causing voltage jumps and tossing the ECU in and out of open/closed loop running. Re-flooring it might resettle the contactor inside. Doubtful though.

I am betting on ECU at this point. Hit the T man for a spare.