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Upside

Engine still stalls at idle...update

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On 8/21/2019 at 6:28 PM, Upside said:

can't I just buy a new wiring harness and replace it?

Money isn't the issue its the time I am losing.

If I thought a mechanic could fix it I would have already paid one, but they don't seem to know this particular engine.

 

Jeff

The harness retails for well over $900 and would take me a couple days to replace. It would seen that either the wires from ECM to IAC are failing, or the ECM is getting bad data to one of it's input loops, and is telling the IAC to do something stupid. Curt is right, as sometimes you need to find a level three tech experienced in Diacom diagnosis protocol, as at some point throwing parts at the thing just becomes cost prohibitive. Not too many of those guys around, but most OEM factory reps know who they are and where to find them. That fact that she works for a short period with a new IAC tells a story. Either the issue is with the pins, or perhaps the first 12" of the IAC feed harness that gets disturbed with each change-out, or once the new IAC goes through as single heat cycle and the ECM relearns, the processor is using faulty data to set the IAC idle null-bias voltage. W

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On ‎7‎/‎4‎/‎2019 at 6:04 PM, Upside said:

7. Went to replace IAC and noticed the top screw was not tightening.  Tried different screw and it was also stripping, indicating the problem is actually inside the throttle body.  The IAC won't tighten now.  I am pretty careful so not sure how this happened or if it happened before I owned the boat.  Any suggestions?

Pictures of the chaos below

https://imgur.com/a/eryOepwu

Jeff, sorry you're losing all this boating time because if this IAC valve.  Did you fix the one screw that was stripped or not grabbing tight on the top of the IAC?  I never saw you mention if you had fixed that but I would start with that.  Get that IAC seated nice and properly first and then go from there.

 

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Are the harnesses hard to swap? Maybe I can try that. Will try and find level 3 tech through google.

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19 minutes ago, Upside said:

Are the harnesses hard to swap? Maybe I can try that. Will try and find level 3 tech through google.

It's not a job that I would like to do, and on a boat that age, disturbing a working "vintage" harness that has been cooked in the engine bay for so many years is asking for trouble. They get stiff and insulation gets brittle over time, and likely you will break off half the retaining clips trying to get the connectors apart. I would however concentrate some careful inspection on the first 12" of the wire pair leaving the IAC. W

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I have a volvo mechanic coming on tuesday.

sent them the list of what I have done so far as well as some of the feedback from here.  will let you know what it ends up being if they can fix it!

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OK So the volvo mechanic made it out today.


I had put together an email summary of all that has been done along with some of the feedback here and from Curt over the phone.

Engine was not idling without help.

They hooked up the laptop and noticed some codes.  LINK TO DIACOM https://imgur.com/a/4eHQS

 I asked them to check the ECT and they said looked normal.

They also unhooked the throttle cable and played a little with it to see if it was set correct since I told them it idled slower than the good engine.

They checked the "lower fuel pressure"   all was good

They reset the codes showing on the report with indicated TPS low voltage. I had replaced that part previously.

The engine ran and stayed idle and we did a sea trial.  TPS error code did not come back.  They concluded that perhaps the problem was the uncleared error code.

The "knock sensor" code is still there but says not active.  They said "we should check that part make sure its connected right" but when we got back we all forgot and they left.

 

So I did explain to them that it worked before for 1/2 day but then acted back up so I am leary. But they spend quite some time with the laptop connected going through the paces and he is 15yr volvo tech.  

I get back in town Sat and gonna take it out again and hope for the best.  Curt anything else I should do?  I can pull plugs sat and take picture.

Jeff

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On 8/27/2019 at 6:20 PM, Upside said:

OK So the volvo mechanic made it out today.


I had put together an email summary of all that has been done along with some of the feedback here and from Curt over the phone.

Engine was not idling without help.

They hooked up the laptop and noticed some codes.  LINK TO DIACOM https://imgur.com/a/4eHQS

 I asked them to check the ECT and they said looked normal.

They also unhooked the throttle cable and played a little with it to see if it was set correct since I told them it idled slower than the good engine.

They checked the "lower fuel pressure"   all was good

They reset the codes showing on the report with indicated TPS low voltage. I had replaced that part previously.

The engine ran and stayed idle and we did a sea trial.  TPS error code did not come back.  They concluded that perhaps the problem was the uncleared error code.

The "knock sensor" code is still there but says not active.  They said "we should check that part make sure its connected right" but when we got back we all forgot and they left.

 

So I did explain to them that it worked before for 1/2 day but then acted back up so I am leary. But they spend quite some time with the laptop connected going through the paces and he is 15yr volvo tech.  

I get back in town Sat and gonna take it out again and hope for the best.  Curt anything else I should do?  I can pull plugs sat and take picture.

Jeff

Deleted. Computer glitched B4 finished. Will post again.

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-

On 8/27/2019 at 6:20 PM, Upside said:

OK So the volvo mechanic made it out today.


I had put together an email summary of all that has been done along with some of the feedback here and from Curt over the phone.

Engine was not idling without help.

They hooked up the laptop and noticed some codes.  LINK TO DIACOM https://imgur.com/a/4eHQS

 I asked them to check the ECT and they said looked normal.

They also unhooked the throttle cable and played a little with it to see if it was set correct since I told them it idled slower than the good engine.

They checked the "lower fuel pressure"   all was good

They reset the codes showing on the report with indicated TPS low voltage. I had replaced that part previously.

The engine ran and stayed idle and we did a sea trial.  TPS error code did not come back.  They concluded that perhaps the problem was the uncleared error code.

The "knock sensor" code is still there but says not active.  They said "we should check that part make sure its connected right" but when we got back we all forgot and they left.

 

So I did explain to them that it worked before for 1/2 day but then acted back up so I am leary. But they spend quite some time with the laptop connected going through the paces and he is 15yr volvo tech.  

I get back in town Sat and gonna take it out again and hope for the best.  Curt anything else I should do?  I can pull plugs sat and take picture.

Jeff

Glad to see progress.

Great to see data.

Thoughts:

- Have confidence in whomever visited. Other than getting distracted and forgetting about the knock sensors, they did good. We've all forgotten a thing or two. I sure have. I sure will again. 

- The ECT is functioning normal. This is now ruled out.

- LV TPS Fault. The motor started 22 times since last fault, and would have cleared after 50 starts without fault. Can't explain why it didn't stop affecting things. It's supposed to unless the condition still existed. What they did to clear it is similar to a hard reset on a computer or iPhone. Setting all that aside, this fault will affect idle so that makes sense. Why it faulted and why it didn't clear are the questions. The 5V reference signal and ground come from the ECM, and power the ECT and MAP as well (albeit from different pins). The ECT and MAP are functioning so this rules the ECM and ground coming from the ECM out. The TPS signal wire is fine based on current data, so it's ruled out for the moment (but may come back into play). The ground coming from the TPS might have an intermittent issue. Or, considering the history, the TPS failed and replacement rectified the issue other than needing a hard reset. We need to get some hours on it. If the idle problem doesn't reappear, we move on. If it does, we grab the multimeter and start probing the TPS wiring.

- Knock Sensor Fault. There are two. One on each side just above where the oil pan and block meet, down from the gap between the two rear cylinders on each bank (5-7 and 6-8). Neither is being seen by the ECM, thus the two "inactive" faults. (Inactive doesn't mean they are inactive, i.e. normal.) The cause can be as simple as a loose ground, loose connection, corroded terminal, oil/crud contamination on/in the terminal or some combination. Odd that both are off-line. It's going to be a little tight, but we've got to get down there and get these back on-line. Being "inactive" doesn't contribute to the idle issue, so this is just a parallel problem to troubleshoot and rectify. Please keep in mind the knock sensor is important to protecting the engine so kindly consider not running a whole lot until fixed. 

- Desired idle compared to actual RPM doesn't make sense. Desired idle is the RPM target for that engine temperature (and throttle position); and was what it should be. Engine temperature correlates with ambient and short running time; and that’s also what it should be. Actual RPM is higher than it should have been though. Perhaps the throttle was goosed to warm her quicker. Perhaps she was already on the water. Probably nothing to worry about.

- Plugs. No need assuming you mean spark plugs. If you mean knock sensor, yes pull, clean and re-seat. 

- FWIW. The RPM histogram looks great with about 84% of runtime < 2,000 RPM. There's a lot of life left. Something to consider, after all of this is in the rearview mirror, get her out and run in the 2,500 to 3,000 range an hour or two per month to get her hot and the carbon out. Lot's of low speed runtime usually builds a lot of carbon, which can cause other issues as time goes forward. No biggie. Just a consideration to keep in mind.

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You've probably got it licked now, will be interesting to hear if it's solved for good.

Regarding IAC's on this motor, mine went right around 300 hours (classic).  I replaced it.  A few hours later it broke.  I mean BROKE, as in the boat starting acting all weird and when I pulled the arrester the pintle was literally disengaged from the body and was only still sitting in place because there wasn't enough room for it to fall out.  Plus, with the replacement IAC it idled okay but it was never really "right", it was a bit quirky.

I bought an OEM ACDelco part and it is like night and day.  Boat starts and idles exactly as it should.  The one that broke was some cheapie off Ebay.  So, if you've been replacing them with non-OEM IAC's, I would strongly suggest to buy the OEM ones.  ACDelco part #217-435

I believe you've ruled out the IAC but just some input from my experience...

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Why I do not buy from the web when I need dependable parts.  

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This is all good info and I will be on the water Sunday to see how it runs for awhile.

Agreed on the OEM parts only, lesson learned.

Thank you all this is a great community.

Jeff

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I have not read every post. But the engine in question, it is fuel injected. Yes? If yes, the idle is controlled by the ECM. Sound like its being starved for fuel. I still think fuel pump.

You have tred a lot of things, why not swap out fuel pumps and see with the starboard engine. I just changed mine and it took me 45 minutes the first time. Three water, three fuel lines and 2 connectors. And 4 bolts!!

Too easy not to do.......

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Thank you for the suggestion Iggy.

I will be out on the water today for a test to see if it is still running.  I will add the fuel pump swap to the list of potential items to check if problem persists.

Jeff

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Well today was a success on the water.  Engine ran and idled fine the entire trip.  Still have massive anxiety but this is the second run (first being with mechanic after reset) and so far so good.  Will probably take it out again tomorrow for a little more of a run.  Thank you all.

Curt I have some thoughts on the knock sensors will text you


Jeff

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Thank for the follow through. I know the anxiety of not knowing if you really fixed the issue...  

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