DTAForum.com - a forum for the DTA ECU

A little update here:
I REALLY need to take a closer look at my alternator. Did some logging today and battery voltage varies between 12.1 and 14.3.
5v out to sensors are between 4.941v and 4.951v wich I assume is normal and OK.

Flickering is intermittent. Steady headlights when testing a modified map this evening, but when driving it earlier today it was flickering really bad. Might have something to do with high revs also.

Next thing to do is measuring voltage output directly from alternator, and on battery to check for voltage loss. I will keep you updated

Simple test to eliminate the alternator...is just disconnect it.

A little update for you guys.
I flushed the coolant today to refill it with actual coolant and not mucky brown gunk.

The alternator is making really bad bearing noises and it's binding up so the belt makes the tiniest squeeking noise. I'm guessing the binding in the bearings are "braking" the engine, and the ECU tries to compensate for rpm loss by opening the IAC more. This can probably also be my "misfire" I guess? Alternator rebuild time then!
I find it interresting that the alternator went downhill so fast. I've had the flickering lights for a while so I assume that is a ground issue. But when i swapped engines the alternator was swapped also. Both of the alternators has been working great in my other car, and puts out just shy of 14V.

Because of the times we are in now, I'm guessing it will be a while before I get new bearings. Still updating you guys when I do something more.

(Maybe I should start a thread in "Share your project")

That's a first - someone who will rebuild their alternator. I know we live in a throw away society but even back in the 80's no one rebuilt an alternator when an exchange unit and £25 was available LOL!

katana wrote:That's a first - someone who will rebuild their alternator. I know we live in a throw away society but even back in the 80's no one rebuilt an alternator when an exchange unit and £25 was available LOL!

Car parts are expensive in Norway. A new unit costs me around £250 at the cheapest place online, If I go to a store locally it costs $450 plus a core deposit of £40 for a new one
A set of bearings costs me around £20 locally I believe.

Last time I went to the toilet, there was no money coming out And I like to repair stuff that people often will throw away.

I've never had a brand new one at £25 !! lol even with exchange.

There must be 4-5 local places near me who rebuild, although usually it is just things like regulators/rectifiers and bearings, or brushes etc. All perfectly rebuildable.

Basically same as what any "recon" places are offering anyway

The problem has gotten way worse the last times I've used the car.
It seems like it misfires only on a light load and on idle. I would say everything below 60kPa it misfires so bad that tha car bucks and is everything but fun to drive.

I replaced the alternator to a different one. This one is not 100% because there is a bearing that whines. But it's putting out the correct voltage.
I logged VTS in DTASwin and saw that the voltage was fluctuating. When it misfires there was a significant drop in voltage, so I assumed that was causing the misfire. But after thinking I concluded that the voltage rop was caused by the misfire, and not the other way around.

Anyway, I did some measurements:
Battery voltage after sitting for a few days: 12,63V
Battery voltage between B+ and engine block: 12,63V
Battery voltage between anternator + and engine block: 12,63V
Charging voltage at battery: 13,83V
Charging voltage at alternator: 14,4V
Voltage drop between alternator + and battery + with no load: 0,11V
Voltage drop between alternator - and battery - with no load: 0,35V
Voltage drop between alternator + and battery + with high load: 0,14V
Voltage drop between alternator - and battery - with high load: 0,45V

Traced it down to a bad alternator ground to engine block. Replaced this and charging voltage went up to 14,3V on the battery.
This did unfortunately not solve mye misfire problem.
At load or boost there is no noticeable misfires, and the car runs great. But the misfire and bucking on steady cruise or low loads make the driving experience really really bad.
Any suggestions?

Here is a log: https://gofile.io/d/6Rlb7x

Go to diagnostic display. reset everything. Do a video capture of the screen and then start and drive the car, recording the screen whilst driving and whilst the problem is occurring.

And you aren't logging the likes of crank or cam errors

Also in the diagnostic screen there is a reset count, this will count up how many times the ecu has lost power, but honestly it sounds like nothing to do with the alternator, car should run fine without one.

I had my brother with me today, and we looked at rejected crank pulses, Sync errors, Teeth errors and re-syncronisations. None of them were counting when the car was misfiring.

Could it be a fuel pump/pressure issue? I read somewhere that their fuel pressure damper went bad and they had similar symptoms. My car does noe have a damper, but a pressure regulator that decreases pressure on idle to prevent running rich.
OEM feed pump in-tank, high pressure pump and under car and regulator. Injectors are Siemens Deka 850cc.