2001 C70 T5 Stalls and Rough idle

perkunas · Post by **perkunas** » 21 Oct 2016, 23:08

So my 2001 C70 T5 has started acting up recently. This somewhat correlates with a drop in temperatures and increase in rain.

At first, the car would not fire from cold in the morning - it would take a couple of key turns. Then, after a couple of days and after a couple of tries to start it, it had a somewhat lumpy/pulsating idle. On that same day, the coolant temperature needle started wandering around so I decided it's the ECT and replaced it with a Meyle analogue. This fixed the no-fire problem.

However, now the car starts normally but then immediately stalls. After a couple of starts it does fire up but the idle is still pulsating a little bit.

No CELs present.
MAF is somewhat fresh (~10k km)

I'm thinking, maybe a ECU reset would help? Since there was an issue with the fuel mixture (ECT) but now it's been fixed.

I'd be interested in hearing any other suggestions.

Post by **abscate** » 22 Oct 2016, 03:51

You can definitely try an ECZu reset by disconnecting the battery but evaluate the plugs, coils and all the vacuum system for leaks if that doesn't help.

Svieks!

Post by **cuhfs** » 23 Oct 2016, 06:48

May be worth testing if its the MAF in case yours failed? (Easy DIY fix)
Car is well known for ETM issue so can't rule that out as a "worse case" possibility.

You wrote "somewhat lumpy/pulsating idle"

Sounds like "hunting at idle"
Reference: https://www.matthewsvolvosite.com/forums ... hp?t=17252

My 2001 C70 had the "hunt at idle" and ran bad until i replaced ETM with http://xemodex.com/us/products-for-volvo/

Hopefully yours is fixed by following abscate post above.

perkunas · Post by **perkunas** » 23 Oct 2016, 09:39

I am aware of the ETM issue, but it's not the case this time. It's more of a poor firing condition in one of the cylinders.
Though now its seems that on some cases it starts OK, on some cases it will crank but won't start and also sometimes it will crank and start but immediatelly die.

I'm trying to rule out fuel pump relay and the immobilizer antenna ring, but I wouldn't be surprised if both were failing (neither was ever replaced, not that I'm aware of)

perkunas · Post by **perkunas** » 26 Oct 2016, 08:22

Issue still persists... Though now it seems it's primarily a crank but no-start problem.

Is anybody aware of how the fuel pump relay works? I've been trying to hear it running when I turn the key to ignition for the first time and it seems like it always runs. Yesterday it fired up both times normally, but today I was having issues both in the morning and in the evening.

I'm thinking maybe the fuel pump primes normally, but the pump is turned off by the relay when cranking (same as headlights) and when the car starts it's turned on again, though it might not turn on due to a faulty relay and then the car dies/no start.

Post by **abscate** » 26 Oct 2016, 14:07

Perkunas...you can jump the relay with wire or even a paper clip and see if that helps. Details in the VRD, and I think I posted up,pix for Nurse Amy when she was troubleshooting hers

perkunas · Post by **perkunas** » 26 Oct 2016, 23:03

I'll try doing some proper troubleshooting throughout the weekend...

Though right now it seems from the sound that the fuel pump starts just fine and that it's a no-spark issue. Also, after the 4th or maybe 5th cranking attempt the red light under the winshield next to the dolby speaker started flashing very rapidly as I was cranking. Could this possibly indicate an immobilizer issue?

firestarterpro · Post by **firestarterpro** » 26 Oct 2016, 23:38

I would check for a vacuum leak between the throttle body and the air filter housing. I had the same problem and ended up duct taping the accordion thing until my new one came in the mail. When it rained, it sucked in moisture and sputtered light crazy.

Also, you can check the fuel by the injectors. Theres a Schrader valve at the right end of the fuel rail. Push it in, if it squirts, u have pressure. Each time you turn the key to II the pump shoots fuel to the inejctors so it is ready to crank

perkunas · Post by **perkunas** » 27 Oct 2016, 02:47

Mine's a turbo so there's quite a bit of pipework under the hood, though I'll give it a shot. Though for now I'll start tearing the steering column apart and inspecting the antenna ring. I've had intermittent issues with it before.

firestarterpro · Post by **firestarterpro** » 28 Oct 2016, 03:27

Also, if it is a vacuum leak roughens the idle, you should be able to hear it during idle.