Car idles great, then suddenly dies (logs + msq attached)

[jsdevel]

I've managed to get my car idling nicely. Starts after a few rotations. All is good, then it suddenly dies. It feels like fuel overrun cutting in.

In the logs (around 16 seconds in), I notice that when this happens my TPS goes negative. Beyond that, I'm not sure what else could be causing it. I've also noticed that MAT goes down very quickly and stays there.

A few notes about my car:

• '91 volvo 240 with a 4 cylinder b230 engine
• naturally aspirated
• intake manifold has isolators to reduce heat soak neither does it have coolant running through it

Any help would be greatly appreciated.

[jsdevel]

I was just looking at my tune, and saw

Code: Select all

<constant name="RevLimOption_fuelcut">"On"</constant>

. Could that have anything to do with it? Here's what rev limiting is currently set to:

rev-limit.png

In the logs you can see that my coolant level was dropping once the coolant fan kicked on. Here's where it was right before it died:

log.png

[jsdevel]

Sorry to be posting so much to my own thread

I just noticed that right when my car dies, CLT reaches a point in my ASE curve where fuel adder dramatically drops. Could it be that the fuel pump is cutting out because the ECU sees the sudden drop and considers the AFR to be too high?

ASE.png

[grom_e30]

it looks like the processor reset when the car died secL dropped to zero

[jsdevel]

Interesting. Why would that happen?

[jsdevel]

Also, if I hold TPS via the gas pedal at 10% (1100 rpm at present) the car runs fine.

[Matt Cramer]

Interesting. Why would that happen?

The battery voltage is on the noisy side. Where is the MS grounded?

[jsdevel]

Grounded at the engine. My LS coils share the same ground nut. Could that cause issues?

[jsdevel]

I adjusted my ASE curve to not engage once my car is warmed up and that seems to have worked. Had to adjust my fuel table accordingly. Am I correct in stating that ASE shouldn't be needed once your car is warmed up?

[jsdevel]

So it's definitely not dying as much with ASE disengaged. The fuel pump is still cutting out, but this appears to occur when AFR goes into the redline. Is this expected behavior?

[grom_e30]

a reset is like turning the power off and on again to the ecu so the pump relay will cycle off and on all sparks fuel injection will stop while the ecu is resetting

[jsdevel]

would battery voltage noise cause a reset?

[grom_e30]

i wood be taking a close look at he power and ground connections for the ecu

[jsdevel]

OK. Matt, grom_e30 thank you for the help and eyes. I'll be studying up on the battery noise and will fix that before posting here again.

[MustangMike]

I don't think any settings in MS will turn OFF the fuel pump with the engine is running. It might pull fuel or cut fuel which would cause the engine to die. If the FP is turning off it sounds like a physical issue. Loose connection, bad ground or relay etc.
If the FP is running but the engine is dying after ASE then probably your ve table is lean.
Edited: WUE and ASE both come into play, but ASE is only applied for hundreds of cycles which is usually less than a minute. WUE warm up enrichment should be looked at if it is dying after warmed up.

[jsdevel]

MustangMike, thanks for the reply. It turns out I'm getting resets in my data logs. Opened a few other topics around this issue.

[jsdevel]

I cleaned up my voltage. Car is still resetting like crazy.

2017-09-25_22.43.20.msl

My new theory: Invalid Closed Loop Idle Settings. Any help is appreciated.