Volvo Penta GXi-E Low Power and 2 DTCs

swalker80020

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Assuming short run from idle to WOT and back to idle
Didn't see anything that stood out, so it may just be the low fuel pressure
I have use two different pressure gauges. I measured the pressure at idle and watched the pressure while under load at WOT and pressure never dropped too low (never went below 45 psi if I can recall)
 

wrench 3

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Thanks for the quick reply alldodge! I should have mentioned in my initial posting, but I have gone through those steps. However, I only used a multimeter because I did not have a test lamp and assumed a 12v reading on the multimeter would light up the test lamp. Is this true? Anyway, going through the steps lead me to Step 16: replace the ECM, which rather than replace, I sent in to be tested. Testing results came back: "All Sensors, Relays and IAC - Good", "Harness with Injectors - Good", and "IC and Bypass - Good". So, unless a multimeter is not sufficient and a test lamp is required, I could not find a short and ECM appears to be ok. If there was a short, can it be intermittent? Thanks again for any advice!
Usually when they tell you to use a test light it's because they want a lower resistance device in the circuit than a DMM. Sometimes to trigger another component.
 

BRICH1260

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I have use two different pressure gauges. I measured the pressure at idle and watched the pressure while under load at WOT and pressure never dropped too low (never went below 45 psi if I can recall)
Your high pressure reading should be near 60.
 

swalker80020

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Usually when they tell you to use a test light it's because they want a lower resistance device in the circuit than a DMM. Sometimes to trigger another component.
Good to know wrench, thank you! I have purchased a test lamp and will go through the service manual steps again using a test lamp when I de-winterize.
 

swalker80020

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Your high pressure reading should be near 60.
Thanks Brich. From what I remember, the pressure was 55-60 at idle and never dropped below 45 at WOT under load. What I can't remember is if stabilized higher. Another thing to test again when I can put the boat in the water.
 

alldodge

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Thanks Brich. From what I remember, the pressure was 55-60 at idle and never dropped below 45 at WOT under load. What I can't remember is if stabilized higher. Another thing to test again when I can put the boat in the water.
It should not drop below 55
 

Tail_Gunner

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I loaded my Diacom SW and ran the recording . . .

The two '41' codes are present as stated. This engine (MEFI-4) is a lot newer than my engine (MEFI-1), so I'm not familiar with some of values . . .

Here is a clip of the values while the engine was run up to WOT and then back down.


It looks like this engine has variable valve timing (???) . I'm not sure about the 45˚ +/- readings . . . I saw somewhere on the Internet that the MEFI does not give the best reading for this vs. automotive OBD2 data.

What is the history of this engine/boat? Did it ever run properly? Is there MEFI data from when it did run properly?

I would address the 41 codes (open circuit on EST module ??? maybe) Might that be a wiring issue? Then see where that leaves you.

34˚ timing advance at WOT does seem a bit high, but maybe it is OK. I wonder if it is trying to compensate for something that the ICM is not doing. :unsure:
It has been awhile since when did a 5.0 get vvt, 2oo4 penta using Mefi, just how does your timing jump that badly at low rpm...Gezz

Is this software Volvo or someone's custom tune?
 

Tail_Gunner

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It has been awhile since when did a 5.0 get vvt, 2oo4 penta using Mefi, just how does your timing jump that badly at low rpm...Gezz

Is this software Volvo or someone's custom tune?
And your knock sensors have been disabled?
 

Tail_Gunner

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Looking at Ted's readout the knock sensor is OFF, and no codes
While I cannot be sure it looks like a custom tune, easy enough to happen. Somebody sells a product on eBay stating Volvo ready. Looks like a big mess from here..I'm quite sure penta went to its own software in 02
 

Tail_Gunner

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Looking at Ted's readout the knock sensor is OFF, and no codes
LOl im getting so old it hurts, i was under the impression that vid file was the original file...Hmm maybe Ted has a connectivity issue..JK.
The 5.0 does not have VVT its a pushrod motor,
 

tpenfield

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I'm just the messenger here . . . the data is from the OP's Diacom recording. :unsure:
 

Tail_Gunner

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Then this software has been rewritten or Diacom is not reading correctly, the 5.0 is a push rod engine..no vvt in prush rod motors.. as to fuel pressure in a 5.0 mefi design...45psi is the target...i dont know where 50/60 came in..that too needs to be sorted out...who knows maybe i am wrong..dont think so.
 

alldodge

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Then this software has been rewritten or Diacom is not reading correctly, the 5.0 is a push rod engine..no vvt in prush rod motors.. as to fuel pressure in a 5.0 mefi design...45psi is the target...i dont know where 50/60 came in..that too needs to be sorted out...who knows maybe i am wrong..dont think so.
Its a VP with S/N 4012107862
GXI manual and the chart I have both list 50-60 psi fuel pressure
 

Tail_Gunner

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Its a VP with S/N 4012107862
GXI manual and the chart I have both list 50-60 psi fuel pressure
It would seem VP changed injectors in 05
The knock sensors and rev limiter are disabled, that is either a modified software or the Diacom cannot read properly Below is a link speaking to the subject... A simple email to VP for clarification would clean things up a bit, running someone's modified tune would be bad...aka knock sensor/ rev limter.
Ohh where is Don when you need him....more than probably looking down having a laugh and a grin..

Looks like 05 was the change period for ethanol in gas..that could well be the reason for change.
 
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alldodge

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I don't see them as being disabled (OFF-not active), they are just not reading a fault (ON-active). The MEFI is either OFF or ON and does it that way. The fault can be disabled by turning the flag OFF using SW like MEFIburn (I have the SW)
 

Tail_Gunner

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I don't see them as being disabled (OFF-not active), they are just not reading a fault (ON-active). The MEFI is either OFF or ON and does it that way. The fault can be disabled by turning the flag OFF using SW like MEFIburn (I have the SW)
That could well be, this is a mefi 4 system, and Diacom is interpreting the reading's. I would find it strange to report a circut off when it is actually operating. Then there is the rev limiter being reported in the same manner so perhaps your right.

Ive have no experience with Diacom perhaps i should not have made such a statement. I no longer have any of the mefi guides and that high pressure fuel rail was eye opening. So i did a little digging, Bup used to post at iboats, he is quite knowledgeable...below is a link.


this app just like mercruiser uses a HVS nor distributor - yes it looks like a distributor but is not. If it has been moved or rotated just a fraction or has been pulled out for any reasons - your cam angle is off - these HVS have to be properly phased. Timing is none adjustable as it all thru the ECM MEFI 4 and so is the spark events. The HVS just send sparks the ecm controls all of that. IMO Cap and rotor first and if the HVS has been pulled or moved then all of that needs to be phased properly to even get this engine running correctly. I believe these are problems looking in my crystal ball.

If this is your boat and or you are working on boats - I would have to say you better buy a real scan tool and learn how to use it. Good luck with it. I gave you the most solid advice to fix blindly and without a scan tool.

And by the way HVS = High voltage switch that what these distributor looking ignition set ups are called Not a distributor. PROPERLY phased is very important. This will set alarm and not show up on a scan as you have to look at cam angle from a real scan tool that reads and shows all perameters. Codemate LOL sorry but really is funny trying to work on boats with that.
 
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swalker80020

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That could well be, this is a mefi 4 system, and Diacom is interpreting the reading's. I would find it strange to report a circut off when it is actually operating. Then there is the rev limiter being reported in the same manner so perhaps your right.
Thank you tail gunner and alldodge. I am learning a lot reading your responses. Got any tips on how to properly phase HSV (which I will stop calling a distributor, lol)?
 

alldodge

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Clocking the HVS (not hsv) can be done in a couple ways.
1) make sure cylinder 1 is at TDC and drop it in as shown
2) Other is make the device in the PDF file and clock it that way (starts on page 14)
 

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