Vanos Rebuild Start Hesitation

[sapote]

With the pump attached?

Yes.

[jamesfoley]

measure directly at the pump two wires

With the pump attached?

[sapote]

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.

measure directly at the pump two wires.

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.

[jamesfoley]

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 EKP

[sapote]

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...

Check the voltage directly at the two wires connected to the pump during cranking and at 3000rpm

The pump relay is in the trunk. I think it has PWM modulated output signal to control pump voltage at different engine load.

[jamesfoley]

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...

[jamesfoley]

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.

[jamesfoley]

The normal cold starts were short lived, car back to hard starting when both stone cold and warm. 🤷

[jamesfoley]

Why do you need to work on the fuel regulator? What’s the measured pressure at idle?

Honestly it was just the next step after I did the pump. I have the regulator, just needed a shop with a lift that could fit it for me. Was also the next recommended step by the shop who sorted my VANOS timing so it’s booked in for Saturday.

Zero idea on pressures as I’ve not had them checked, though will hopefully get some readings on Saturday.

Do you have any idea if a DME update would help?

[sapote]

Why do you need to work on the fuel regulator? What’s the measured pressure at idle?

[jamesfoley]

I don't know much about the software version; on the cats, they should not affect engine running unless they are clogged up, but so far I don't see the evidence (post cat sensors with stuck lean signal at below 0.5v)

Googling the version number doesn't seem to yield many results which is odd.

At 120k miles it could probably benefit from two new pre cat O2 sensors so I'll get them both done once the fuel regulator is sorted. Just trying not to change everything at once mainly to lessen damage to my wallet...

[sapote]

MSS54 Software Version is 211322001301-J424 if that's what you're after?

I could understand if the cats aren't as efficient at 22 years old, but that's another bridge I'll cross once the car is running correctly. As far as I know post cat O2 are just to monitor cat efficiency right, so they're not going to change how the car runs

I don't know much about the software version; on the cats, they should not affect engine running unless they are clogged up, but so far I don't see the evidence (post cat sensors with stuck lean signal at below 0.5v)

[jamesfoley]

Read the DME software version to verify it's stock.
The SAP status was was 4 (no pump running) after engine running, and then switched to 1 (pump running). The DME should have detected the cold ambient with key turned on and before cranking. it's odd but I don't think it caused any problems.
One more thing: during driving, the post cat sensors follows the pre cat sensors -- acted like the cat efficiency were down and unable to clean the exhaust gas; Cats are not cheap so hopefully the mixture was so bad that the cats couldn't clean it all.

MSS54 Software Version is 211322001301-J424 if that's what you're after?

I could understand if the cats aren't as efficient at 22 years old, but that's another bridge I'll cross once the car is running correctly. As far as I know post cat O2 are just to monitor cat efficiency right, so they're not going to change how the car runs

[sapote]

Read the DME software version to verify it's stock.
The SAP status was was 4 (no pump running) after engine running, and then switched to 1 (pump running). The DME should have detected the cold ambient with key turned on and before cranking. it's odd but I don't think it caused any problems.
One more thing: during driving, the post cat sensors follows the pre cat sensors -- acted like the cat efficiency were down and unable to clean the exhaust gas; Cats are not cheap so hopefully the mixture was so bad that the cats couldn't clean it all.

[jamesfoley]

This shows pre cat bank1 sensor1 didn't drop below 0.1v during the SAP running, while bank2 sensor1 was well below 0.1v and it looks much better than bank1 sensor. So I think it's worth to replace B1 sensor1 and hope it will solve the fuel status 8 issue. Do you have stock DME software or aftermarket tuned version?

One odd thing: I never seen the secondary air status starts at 4 then drops to 1 to run the air pump. It normally starts at 1 in cold ambient and then switches to 4 after pump turned off.

As far as I know I have a stock DME. Is there any way to check this?

Its an EU car if that makes any difference? Also I started logging before I started the car, possible the PID didn't update quick enough when it started?