The normal cold starts were short lived, car back to hard starting when both stone cold and warm. 🤷
-
-
Just adding these two datalogs
Drive from cold: https://datazap.me/u/jamesfoley/e46-...ta=2-3-4-10-12
Drive from warm: https://datazap.me/u/jamesfoley/e46-...ta=2-3-4-10-12
Both times the car started without hesitation, but the logs still have a lot of fuel status 8's. Only pattern I can see is the post cat O2 sensors dip mostly where the status 8's appear.Comment
-
Okay so the fuel regulator is in and as expected it made no obvious change, logs still also report fuel system status' of 8.
While it was at the shop they hooked it up to a pressure regulator and when it struggled to start the fuel pressure drops pretty hard, so they're pretty confident its a fuel supply issue either with wiring, a kinked line, or a pump issue.
When it comes to pump wiring, is there anything else I should be checking here? In theory I know the pump is good unless I am horribly unlucky that my new genuine pump has the same issue as my old one, so that leaves me with some intermittent wiring issue to the pump, or an issue with the line from the pump to the regulator.
I'm going to guess that the fuel system status 8's are also related to whatever intermittent fuel supply issue I have is...Comment
-
Check the voltage directly at the two wires connected to the pump during cranking and at 3000rpmOriginally posted by jamesfoley View Post
The pump relay is in the trunk. I think it has PWM modulated output signal to control pump voltage at different engine load.Last edited by sapote; 04-01-2023, 02:05 PM.Comment
-
Today I learned there is another relay for the fuel pump in the trunk...
Just nipped out and removed the boot trim to find this:
You're saying this is also linked to the fuel pump?
I think what I realistically need is a way to monitor fuel pump voltage as I drive that plots a graph to see what its actually being fed.
Edit:
Ah, I think these are different between Euro cars and US cars, with Euro cars not having the EKPLast edited by jamesfoley; 04-01-2023, 10:11 AM.Comment
-
measure directly at the pump two wires.Originally posted by jamesfoley View Post
The logs files are similar to those before, except the SAP status went from 0 to 1 and to 4, not 0 to 4 to 1 and 4 which was odd as I said.
Comment
-
-
-
How would I go about this without tapping the wires? Not sure I trust myself removing the pump and probing wires that wayOriginally posted by sapote View Post
With negative fuel trims I'm a little confused how it could be a pressure problem. Negative trims suggest too much fuel / high pressure right? If the pressure was too low with either the pump failing or potential kinked line with low pressure, wouldn't I see high positive trims / lean engine issues?
I'm wondering if perhaps I have an issue with the fuel return line, but then I guess fuel pressure would read too high...Last edited by jamesfoley; 04-02-2023, 12:56 PM.Comment
-
I don't know the best way to measure the pump voltage w/o cut off the wire insulation; you could measure the the trunk relay pin that connect to the pump.Originally posted by jamesfoley View Post
Yes, negative fuel trim means mixture was too rich, but since your mechanic said the fuel pressure was low and so we suggested to check the pump voltage as it's a new pump. checking the pump voltage is easy so you should get this out of the question.Comment
-
sapote I have this log with a big chunk of idle, and the MAF rate is still as high as the old MAF I had fitted: https://datazap.me/u/jamesfoley/e46-...0&data=1-14-17
That being said I don't really know for sure what a normal value here should be.Comment
-
If you look at the air charge table in this post,
@ idle (0% throttle area, 870rpm) an air charge of 18.8% is listed.
Engine displacement = 3246cc = 541cc/cyl with a density of 1.204 kg/m3 it equals as 100% = 651.38 mg/stroke
18.8% would mean (@870rpm) -> 122.46 mg/stroke = 17.2 kg/h = 4.776 g/s
You measure 5 g/s which is 4.69% off. I wouldn't expect to much from this.​
From experience 15-20kg/h I have seen and should be OK for this engine.Comment
-
Ah sweet, okay. Looking at the log that seems to be where the numbers are sitting so at least I can cross that off the list.Originally posted by Tomba View PostIf you look at the air charge table in this post,
@ idle (0% throttle area, 870rpm) an air charge of 18.8% is listed.
Engine displacement = 3246cc = 541cc/cyl with a density of 1.204 kg/m3 it equals as 100% = 651.38 mg/stroke
18.8% would mean (@870rpm) -> 122.46 mg/stroke = 17.2 kg/h = 4.776 g/s
You measure 5 g/s which is 4.69% off. I wouldn't expect to much from this.​
From experience 15-20kg/h I have seen and should be OK for this engine.
I've picked up a fuel pump connector with wires attached that I'm going to put between the connector in the car and fuel pump so I can tap the power without butchering the harness in the car. I'm not entirely convinced its a wiring issue as I can hear the pump prime the same every time, and it sounds the same both for when it starts normally and when it hesitates.
The only other things left on the fuel delivery side are the physical lines or the injectorsComment
-
Are you going to change the pre cat O2 sensors?Comment
-
I will do eventually, though from what I understand the car doesn't use these initially and is open loop until they warm up, so it wouldn't be the cause of the start hesitation.Originally posted by sapote View Post
I'd really like to get to the bottom of the start issue first, and then I have brakes to sort 😑Comment
Comment