throwing in the towel perhaps

warcraftjunkie · Post by **warcraftjunkie** » 05 Nov 2012, 15:05

So, I think I might be at the point of throwing in the towel on this car. Thanks for all the advice and pointers given on another thread of mine.

https://www.matthewsvolvosite.com/forums ... =1&t=50713

I just picked up my car from a local shop after they have thrown in the towel and recommended I take it to a dealership for diagnostics. Prior to taking it to them I have replaced the MAF, MAP, Battery, Alternator, and ETM (with a Xemodex). I have performed voltage drop testing on the B+ cable.

The shop pulled the turbo downpipe to ensure it was not a turbo related problem, checked wiring harness to MAF, Grounds, wiring from Alternator to battery, and even pulled the spark plugs to ensure they weren’t all fowled up. They couldn’t find anything.

It’s still idling rough and getting 9-15 mpg. Sometimes it seems to run great and then I hit a bump and it’s as if someone has pulled the power from it. When it does this the brakes lose their power boost and the indicator indicating “winter mode” flashes as well as the oil warning light. The shop said it’s as if the computer is telling the injectors to flood and that’s what’s bogging it down, but they can find no reason for that.

I’ll be taking it to the dealership on Thursday for the 30-60 minute diagnostic. Hoping with their VIDA/DICE they will be able to get more information than the small shop was able to get. I was thinking of taking to a Volvo indie shop that has about 40 years of experience but I’m not sure if he has VIDA… I’m at the point I don’t want to take it to someone just to pay them to shrug or take guesses.

I fear there’s a fault in the ECU. At some point I’m going to have to draw a line and not put any more money trying to get this running right.

Post by **anjill182** » 05 Nov 2012, 15:46

If it's the ECU you can get one cheap from a pick and pull.

warcraftjunkie · Post by **warcraftjunkie** » 05 Nov 2012, 16:28

True, I'd have to get one from Ebay or another parts seller as the local pick and pulls around here only have 2 1998 V70's... not compatible with the 99 V70XC I have.

Post by **erikv11** » 05 Nov 2012, 17:13

What about the ECT sensor?

And I thought the 99+ ECUs were married to the car, can't be swapped without reprogramming. Or did that start later ...

warcraftjunkie · Post by **warcraftjunkie** » 05 Nov 2012, 20:51

No codes stored that I've seen related o ECT. I've only read the codes with scanners at Autozone/O'Reilly so it's possible that they don't see those.

As far as the ECU's goes, I'm not 100% certain if they can be swapped... I think that you are right in that they are married to the car.

Post by **JimBee** » 05 Nov 2012, 21:12

If you're sure it happens when the car is jostled I would strongly suspect a sensor connector problem. Two connectors that can make your computer flood the engine are the MAF and I believe the O2 sensor connector.
I've read a post on here somewhere about the MAF sensor plug on some models known to make/break connection when they wiggle. The fix recommended was zip tie the MAF cable so it can't move. A simple test for that should be wiggle it from under the hood when the engine is running. If you have a multimeter, you can do a back-probe test on your MAF quite easily to make sure it's putting out correct voltages. This post explains how:
http://easyautodiagnostics.com/Volvo-MA ... est-c.html (you can use a 1 inch nail probe to slide under the insulator)

My '96 850 acted that way and I believe what finally straightened it out were actually two things. First, the pins on the O2 sensor connector were dirty. I cleaned them with solvent and dabbed on a little dialectric grease. Then, it was still running crappy and I'd been playing with the accelerator to keep it going, trying to warm the engine. Then I let my foot off the accelerator and just let it do its thing and after nearly stalling (300), then surging and back to stall and surge, it suddenly just straightened out and runs perfectly. I'm still amazed the computer knows how to reset like that.
I concluded that If the computer is trying to recalibrate and you keep shooting a signal for more gas (by jiggling the TPS)) you can keep the ECU confused. And if something else in that circuit keeps breaking/making, then each time it does that the ECU is getting out of sync again.
So those are a couple of quick check things to try.

Post by **northernlights** » 05 Nov 2012, 21:30

I was looking at your old posts, especially the part about being able to cause a fault by shaking the right side of the vehicle. I dug through the wiring diagrams that are on this site, and looked over the one labeled as 1999_S70_V70_C70_Late_Version. I assumed the engine management was ME7, as that is what IPD refers to with the late model V70's et al.

I marked a ground terminal on the attachment. It appears to be under and/or in front of the passenger headlight. It also appears to be the ground point for both the ECU and the TCU. Given its close proximity to the right side of the bumper, is that where you were shaking the car?

Eric

Post by **jblackburn** » 06 Nov 2012, 09:21

^^^Best piece of advice I've seen on this. It's got to be something stupid and little like that causing this issue.

warcraftjunkie · Post by **warcraftjunkie** » 06 Nov 2012, 11:09

northernlights wrote:I was looking at your old posts, especially the part about being able to cause a fault by shaking the right side of the vehicle. I dug through the wiring diagrams that are on this site, and looked over the one labeled as 1999_S70_V70_C70_Late_Version. I assumed the engine management was ME7, as that is what IPD refers to with the late model V70's et al.

I marked a ground terminal on the attachment. It appears to be under and/or in front of the passenger headlight. It also appears to be the ground point for both the ECU and the TCU. Given its close proximity to the right side of the bumper, is that where you were shaking the car?

Eric

Yes, I was mashing up and down on the front passenger fender. I'll take a look at that point.

Another bit of info I found this morning when I went out there to tinker with it before work. If I start the car and it's running (rough idle) and the fan for the heater/ac is on, it kills the engine. Doesn't matter if I have the AC set to on or not... or if it's set to heat or cold.... just when the fan blower kicks in, the car dies. There's a delay from when you start the car and the blower kicks in, but as soon as it does it dies. If I set the blower to off and start the car it will run (roughly), but as soon as I move it one tick past off, it dies.

warcraftjunkie · Post by **warcraftjunkie** » 07 Nov 2012, 20:36

Well, I removed the headlight on the passenger side as well as losened up some of the front grill so I could get to the ground point. It seemed to be intact physically. I touched my voltmeter to the wire harness attached to the bolt on the frame and the other end to the + side of the battery, I registered almost 12volts on it.

I started up the car after hooking everything back up and found that if I messed with the wire channel that delivers the ground point and it seemed to cause fluctuations to the idle when I wiggled it. Makes me wonder about the positive power delivery. I guess I'll find out tomorrow at the dealer... I hope.