1999 C70 quit running while driving down the road ( recloned ECU) Topic is solved

[Clemens]

Shouldn´t it go to default with the disconnected MAF and run in limp home mode or throw a code? I thought this way an easy way to check for a bad MAf that if you unplug it at least it should run somehow. But maybe this was just for the 98 and prior cars...

[volvooh]

It finally did throw a code running it with and without the MAF. After it stalls I can intermidantly get it to start again by either disconnecting or reconnecting it.

[abscate]

Ive got a brand new MAF I can send to you to try. Ill confirm part number. I can send with turn signal lever - a freebie courtesy of Evan.

Disconnecting the MAF on a 1999 does not send you to limp mode (fixed ETM position). The ECU uses a default lookup table of fuel injection vs rpm which drives really well. most won't even notice the difference, except fuel mileage drops 15% or so.

Checked battery voltage after it quit running and I was at 12.2 v

Evaluating battery by voltage is a bit tricky. Let battery sit for one hour, then turn on headlights for 5 minutes, then check battery voltage and report back.

[volvooh]

"Disconnecting the MAF on a 1999 does not send you to limp mode (fixed ETM position). The ECU uses a default lookup table of fuel injection vs rpm which drives really well. most won't even notice the difference, except fuel mileage drops 15% or so."

Interesting. My son has a '99 S70 and I disconnect the MAF and did just that- really no difference @ idle. On the C70, it killed the engine immediately when it was disconnected. Using a combo of connecting and disconnecting I am able to intermidtantly get the engine to run for a short amount of time.

[abscate]

Ive got a feeling that disconnecting while running isnt a good test for anything - I don't know how gracefully the ECU transitions from the closed loop to the lookup table. Im not an expert on the coding, but the consensus from the "five-rivers" (top shelf) mechanics is disconnecting stuff while running is ill-advised.

If you shut down and then disconnect the MAF, do you get the same behavior?

Interesting. My son has a '99 S70 and I disconnect the MAF and did just that- really no difference @ idle. On the C70, it killed the engine immediately when it was disconnected. Using a combo of connecting and disconnecting I am able to intermidtantly get the engine to run for a short amount of time.

I don't think V70 and C70 use different engine management, but jimmy or mike will know.

Let me know if you want to try that spare MAF - part number Bosch 0 0280 218 108

Fulldisclosure _ I gorilla'd a mounting ear of it when I put it on my 99, so that ear is JB welded back on

[volvooh]

Understood. When it feels like starting, its starts both with and without the MAF. With the MAF it is a smoother start-up. Without the MAF it starts but it stumbles before evening out. I had just noticed when it stalled, I was able to eventually start it with ALOT of cranking with the MAF off...could have been an anomoly though.

BTW- battery values- 12.7 v, after 5-8 minutes with lights on (key in position II) 12.3 v. I am not sure with all this cranking how strong the charge is on the battery.

[abscate]

Sorry about that goose chase. That battery is about half capacity, but it should be ok - I would rule it out as root cause.

[volvooh]

So I was reading another thread, 2005 C70 with a similar issue to mine. Ended up replacing Cam, Crank and Fuel pressure sensor (did the MAF too without success prior). Seem to solve the issue...does the '99 C70 have a fuel pressure sensor?

I am going to try the crank sensor next.

[sleddriver]

Before ordering new sensors, check the sensor wiring. Over time the wire insulation crumbles and the copper oxidizes, turning brown & green. If both sensor wires touch, they'll short, and the ECU won't know where the engine is in its cycle, so it won't know when to fire the plugs.

Also note that the wiring harness side insulation can also degrade, causing problems. Even replacing the sensor won't cure the problem therefore.

Another problem is the inner connector housing contacts. They'll rot with age & heat and the wire can back out of the back of the connector, even though the male/female housing is 'clicked'. In other words, it'll look like it's connected, but its not. Very tricky that. And frustrating until you figure it out.

BTDT....

[abscate]

I should know the 'bastard' fuel pressure system by now, but I don't.

It does not return fuel to the tank like an -1998, so there must be a sensor and feedback to a pump control module. It is not like the P2 though.

Your fuel pressures were spot on though, 52 psi??

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