Volvo Penta 5.7 GSI PEFS idle issue

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Rene.golik

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Hi all. I’m a little perplexed with an idle problem on my Volvo 5.7 GSi PEFS.
Can start the engine if I disable props and advance throttle slightly. Will hold and run perfectly at any revs above 1200. When I bring it under 1200 she dies.
 
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Rene.golik

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alldodge said:
Welcome
Classic problem of the Idle Air Control (IAC) valve
Click to expand...
Ah. I did suspect this. Bit of back ground. I started with clean fresh fuel from other source than tank. Changed fuel filter and low/high pressure pumps. Tested pressure of low pressure pump was 14psi. Had to install a shrader valve in line to TBI after high pressure pump all good at 30psi.
Removed TBI and cleaned, including IAC and fitted back together with new parts from rebuild kit. Injectors spraying in a cone shape and even. I turn key and get the two beeps. Start up and if quick enough I can throttle up and she purrs. If not she will start briefly and die.
 
alldodge

alldodge

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Rene.golik said:
Ah. I did suspect this. Bit of back ground. I started with clean fresh fuel from other source than tank. Changed fuel filter and low/high pressure pumps. Tested pressure of low pressure pump was 14psi. Had to install a shrader valve in line to TBI after high pressure pump all good at 30psi.
Removed TBI and cleaned, including IAC and fitted back together with new parts from rebuild kit. Injectors spraying in a cone shape and even. I turn key and get the two beeps. Start up and if quick enough I can throttle up and she purrs. If not she will start briefly and die.
Click to expand...
What you said does not change my mind
 
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Rene.golik

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The IAC looked pretty clean as did the rest of TBI. Also changed the internal fuel pressure reg. Did not have a multi meter to test IAC. Have ordered one.
Something else I forgot to mention. Let me regress. The smooth operation at any rpm over 1200 was only made possible after disconnecting the MAP sensor. With MAP connected I can start and throttle up but no matter what rpm I set throttle to she dies unless I continually pump throttle. When I disconnect MAP she will stay at whatever rpm I set it to on throttle.
 
alldodge

alldodge

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Always good to have all the info
With MAP disconnected the ECM is probably giving motor more fuel. Also disconnecting the MAP can throw a code

Motor needs to be scanned

Were the injectors replaced or just cleaned?
 
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Rene.golik

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alldodge said:
Always good to have all the info
With MAP disconnected the ECM is probably giving motor more fuel. Also disconnecting the MAP can throw a code

Motor needs to be scanned

Were the injectors replaced or just cleaned?
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No i just cleaned them. I have ordered a MAP as they only $80. And as i don't have a lot of time each time i go back home interstate i also ordered a new IAC and Throttle controller as they were cheap as well.
 
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Rene.golik

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Rene.golik said:
No i just cleaned them. I have ordered a MAP as they only $80. And as i don't have a lot of time each time i go back home interstate i also ordered a new IAC and Throttle controller as they were cheap as well.
Click to expand...
To be fair, i could not get the injectors out as they had a little rust around the rim and i did not want to break them or the housing. They look fine and equal and as mentioned the engine runs perfectly at any revs above 1200.
 
alldodge

alldodge

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Suggest don't buy from rock auto, bought "genuine Delco products" that didn't work. Bought same from local and GM dealer that did work
 
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Rene.golik

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Well, well, well! Problem solved.
After replacing a number of components such as MAP, IAC, servicing TBI with new kit and regulator, fuel filter, fuel and fuel pumps etc. I still had the same issue. It was only by mistake, while swapping over the MAP sensor, I realised that one wire on the plug from computer to MAP sensor had broken and was only making intermittent contact,
Replaced new plug to MAP and she worked like a dream.
Note to self - check all wiring harnesses and plugs first.
 
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gofast24

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Rene.golik said:
The IAC looked pretty clean as did the rest of TBI. Also changed the internal fuel pressure reg. Did not have a multi meter to test IAC. Have ordered one.
Something else I forgot to mention. Let me regress. The smooth operation at any rpm over 1200 was only made possible after disconnecting the MAP sensor. With MAP connected I can start and throttle up but no matter what rpm I set throttle to she dies unless I continually pump throttle. When I disconnect MAP she will stay at whatever rpm I set it to on throttle.
Click to expand...
Suggest your install new MAP and IAC. If you can find the GM OEM parts they will be a lot more reasonable $ . I have replaced the IAC on our 8.1 GSII-A with the GM part about 70% less $ than the VP
 
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