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MCM73
Samba Member
Joined: February 20, 2021
Posts: 24
Location: Huntsville, AL
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 Posted: Wed May 19, 2021 5:25 pm Post subject: Open loop at idle Subaru |
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| Hey all! I have a 1984 Westy with a 1999 ej25. The engine has about 25k miles on a professional rebuild. The van runs great. My only issue is at idle. About 30 seconds after I stop it will go into open loop, rpm drop & run rough until the rpms pick back up. It will stay in open loop until I take off again. Sometimes it will kill the engine but most times just an annoying idle. All sensors have either been tested or replaced. Wiring is good. Scan guage reads all sensors & the info looks good. The only thing I can think is the ECU flash is somehow responsible. Anybody had or have this issue. It's driving me nuts. Any feedback would be greatly appreciated. Thanks! |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16853
Location: sticksville, ct.
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| Posted: Wed May 19, 2021 7:35 pm Post subject: Re: Open loop at idle |
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| MCM73 wrote: |
| All sensors have either been tested or replaced |
^^^
that's scary. replaced with OEM subaru or rock auto garbage?
what codes do you have?
need to know a few things...
fuel pressure?
fuel pressure regulator leaking?
injectors leaking?
vacuum leaks? (don't forget the brake booster!)
what is the ECT reading when all of this is going on?
what is the front o2 doing at idle? please tell me it's at least a denso or bosch (although bosch is kinda junk as of late)
lastly a photo of your engine, including air intake. i'd like to confirm a couple things.
i know, a long list i gave you. i'm willing to play if you're willing to put in the effort. what i'm not willing to do is stand by and watch you load the parts cannon and throw shit at this in hopes of fixing it.
also, do you know 100% what the donor car was? there were differences across the model line up that vary specifications...even ever so slightly that can make this a nightmare to work with.
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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Mac_Daddy_Westy
Samba Member
Joined: October 27, 2011
Posts: 154
Location: San Antonio, Tx
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| Posted: Wed May 19, 2021 8:45 pm Post subject: Re: Open loop at idle |
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I also have the same "Open Loop" problem, same EJ 2.5 subaru engine, 2000 imprezza. I have a ScanGauge II hooked up and get a 0325 code, which is a Knock Sensor failure.
brought a new sensor, installed, and still get the Check Engine Light (CEL) on, and knock sensor, and open loop.
Westy runs fine, NO power loss, no idle issues
here's a couple of pics, and yes it is annoying me to not being able to diagnose this issue so I can fix
_________________
'87 Westy with 2.5 Subi (auto trans) |
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Mac_Daddy_Westy
Samba Member
Joined: October 27, 2011
Posts: 154
Location: San Antonio, Tx
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| Posted: Wed May 19, 2021 8:51 pm Post subject: Re: Open loop at idle |
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_________________
'87 Westy with 2.5 Subi (auto trans) |
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Mac_Daddy_Westy
Samba Member
Joined: October 27, 2011
Posts: 154
Location: San Antonio, Tx
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| Posted: Wed May 19, 2021 8:54 pm Post subject: Re: Open loop at idle |
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could it be that on my my air intake dose NOT have a MAP sensor? causing this OPEN LOOP code?
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'87 Westy with 2.5 Subi (auto trans) |
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dgbeatty
Samba Member
Joined: October 26, 2006
Posts: 702
Location: Sacramento
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| Posted: Thu May 20, 2021 6:36 am Post subject: Re: Open loop at idle |
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Rather than playing parts darts do some detailed testing as outlined in the excellent Subaru workshop manual. Please post your test results and the section number of the relative workshop manual test (so that everyone is on the same page).
Don't have access to the manual section? PM me with the MY of your engine, also the VIN from the donor if you have it (and you really should).
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Schau in das Buch |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16853
Location: sticksville, ct.
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| Posted: Thu May 20, 2021 7:21 am Post subject: Re: Open loop at idle |
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^^^
thank you. i'm also willing to help as well but all the info you stated is needed for a successful diagnostic session.
imho the whole point of doing an engine conversion is to modernize the vehicle to the point where it makes it easier to diag and source DEALER (OEM) parts.
my skin crawls when i see people not grab a VIN from the donor or blindly drink the 'JDM' kool aid think that saving any and all info isn't important. i feel even worse for folks who buy a swapped rig not knowing this info is gold when it comes to solving problems.
subaru is evil in their own ways... wire colors change from the intake harness to the main harness....there are mid year and sometimes monthly changes in suppliers during production. more than once i have called subaru and they want the door date as well as the VIN
anyway, all of these codes/driveability issues are solvable but it's going to take some time with the proper diagrams and a meter to trace this stuff.
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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MCM73
Samba Member
Joined: February 20, 2021
Posts: 24
Location: Huntsville, AL
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| Posted: Thu May 20, 2021 7:52 am Post subject: Re: Open loop at idle |
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| Thanks for replying. I bought the van already converted. The only code for m getting & it's not often is the cylinder misfire p0301-4 I think. I'll get some more info and post it. I replaced the entire exhaust system recently because the old one was rusted & full of holes. It's a smallcar conversion. I did buy 2 new o2 sensors & they were name brand although Im not exactly sure which brand. I'll have to look at my receipt. Ill look deeper into scanguage & see exactly what's happening with the o2 signal at that time. Fuel pressure regulator is new. I know the previous owner threw parts at it but I'm it willing to. I'm going out of town this weekend camping & will post better info next week. Thanks again everyone. |
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MCM73
Samba Member
Joined: February 20, 2021
Posts: 24
Location: Huntsville, AL
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| Posted: Thu May 20, 2021 4:58 pm Post subject: Re: Open loop at idle |
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| I'm going to be the poor stooge that didn't know this very important info. I know or have been told it was out of a 1999 Forester. That's the extent of the info. I do have the receipt from the engine rebuild. I'll look & see if it's on there. If not I'll see if I can trace back 2 owners. I know the guy that did the swap did the harness modification himself instead of sending it to Smallcar. Again I'm going camping this weekend & will try to find the more useful info & post again. Thanks for helping. Love the van & love The Samba! By the way I bought my van through this site. |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16853
Location: sticksville, ct.
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| Posted: Thu May 20, 2021 5:59 pm Post subject: Re: Open loop at idle |
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99 forester *should* be close enough, but they had a few different emissions requirements (like CA for example) which may have a different ECU and throttle body.
get as much info as possible and even check your ECU (front and back) a lot of times i have seen folks sharpie the VIN on it
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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wesitarz
Samba Member
Joined: August 20, 2012
Posts: 1486
Location: Victoria,B.C.Canada
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| Posted: Thu May 20, 2021 6:10 pm Post subject: Re: Open loop at idle |
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My 02 2.5L O2 sensors were Bosch. You guys should invest $20 and get an OBD2 Wi-Fi dongle and something like the Torque-Pro app for Android ($5) so you get more information like fuel trims,A/F ratio, O2 sensor voltages etc.
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wesitarz
Samba Member
Joined: August 20, 2012
Posts: 1486
Location: Victoria,B.C.Canada
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| Posted: Thu May 20, 2021 8:25 pm Post subject: Re: Open loop at idle |
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| MCM73 wrote: |
| Thanks for replying. I bought the van already converted. The only code for m getting & it's not often is the cylinder misfire p0301-4 I think. I'll get some more info and post it. I replaced the entire exhaust system recently because the old one was rusted & full of holes. It's a smallcar conversion. I did buy 2 new o2 sensors & they were name brand although Im not exactly sure which brand. I'll have to look at my receipt. Ill look deeper into scanguage & see exactly what's happening with the o2 signal at that time. Fuel pressure regulator is new. I know the previous owner threw parts at it but I'm it willing to. I'm going out of town this weekend camping & will post better info next week. Thanks again everyone. |
Was it doing this before you replaced the exhaust system? Leak before the upstream O2? Vacuum leak? since vacuum is highest at idle. |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16853
Location: sticksville, ct.
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| Posted: Thu May 20, 2021 10:39 pm Post subject: Re: Open loop at idle |
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a leak before the o2 would show up as high fuel trim (running rich) but it would have to be a pretty massive leak in the exhaust.
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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Howesight
Samba Member
Joined: July 02, 2008
Posts: 3273
Location: Vancouver, B.C.
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| Posted: Fri May 21, 2021 10:20 am Post subject: Re: Open loop at idle |
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| MCM73 wrote: |
| I'm going to be the poor stooge that didn't know this very important info. I know or have been told it was out of a 1999 Forester. That's the extent of the info. I do have the receipt from the engine rebuild. I'll look & see if it's on there. If not I'll see if I can trace back 2 owners. I know the guy that did the swap did the harness modification himself instead of sending it to Smallcar. Again I'm going camping this weekend & will try to find the more useful info & post again. Thanks for helping. Love the van & love The Samba! By the way I bought my van through this site. |
Hi MCM73:
I recognize the labeling on your harness. That harness was built by Tom Shiels. He built my harness, which is why I know.
See his website here:
http://subaruvanagon.com/tom/ts_conversion.htm
I am willing to bet Tom will talk you through this problem. He will also have on file the build sheet for your harness.
_________________
'86 Syncro Westy SVX |
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11BC2
Samba Member
Joined: August 27, 2017
Posts: 495
Location: Cool, California
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| Posted: Fri May 21, 2021 11:14 am Post subject: Re: Open loop at idle |
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Oh, boy. Where to begin?
Knock sensor must be OEM: Hitachi or Bosch.
AFR and O2 sensors must be OEM: Denso or Bosch.
Any other brand will cause issues, sooner or later.
The knock sensor circuit in the engine harness is a shielded wire, so checking for short to ground on the signal wire is a good start.
The crimped on terminal end that makes contact with the knock sensor terminal end could be "loose".
De-pinning the terminal end from the plastic connector and tightening it up will help.
The same goes for the 9 pin engine harness connectors; loose female or bent male terminal ends will cause issues. |
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11BC2
Samba Member
Joined: August 27, 2017
Posts: 495
Location: Cool, California
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| Posted: Fri May 21, 2021 11:16 am Post subject: Re: Open loop at idle |
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| Boxer Rebellion wrote: |
| could it be that on my my air intake dose NOT have a MAP sensor? causing this OPEN LOOP code? |
MAP sensor is on the intake manifold, under the HT leads. |
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Mac_Daddy_Westy
Samba Member
Joined: October 27, 2011
Posts: 154
Location: San Antonio, Tx
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| Posted: Fri May 21, 2021 4:01 pm Post subject: Re: Open loop at idle |
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I have the VIN # of the donor Subaru EJ 2.5, have all records
_________________
'87 Westy with 2.5 Subi (auto trans) |
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MCM73
Samba Member
Joined: February 20, 2021
Posts: 24
Location: Huntsville, AL
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| Posted: Fri May 28, 2021 7:07 pm Post subject: Re: Open loop at idle Subaru |
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| Getting closer to a diagnosis. I hooked my buddies Bluetooth obd2 up & looked at some numbers. So far it all looked good. The one thing I noticed was the STFT at idle started climbing & topped out around 25% before it went into open loop. I ordered my own Obd2 & will get TorquePro. I want to look at all sensor info in real time & see what it's saying. I was only able to use my buddies for a few minutes. I'll post my findings. I know what the trim should be & want to make sure sensor info is good before narrowing down the culprit. Thanks for all the replys! |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16853
Location: sticksville, ct.
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| Posted: Fri May 28, 2021 11:17 pm Post subject: Re: Open loop at idle Subaru |
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| MCM73 wrote: |
| The one thing I noticed was the STFT at idle started climbing & topped out around 25% before it went into open loop |
positive or negative 25%? when it went into OL you have reached the ECU's maximum parameter or "adjustability" of the programming. basically the ECU said 'i quit, i can't compensate anymore'
when you say it 'started climbing and topped out at 25% i am going to assume it's positive 25%
if that is the case you most likely have a vacuum leak. positive fuel trim is the ECU ADDING fuel (too lean) and obviously negative would be SUBTRACTING fuel (too rich)
i would check for vacuum leaks and then the MAF if your swap uses one. subaru's don't like aftermarket electronics in my experience
DO NOT rule out the brake booster for a vacuum leak. you can cap off the vac port on the manifold to test
trickier to check would be a fuel injector but check fuel pressure and flow. i have the specs for what it want's in terms of flow if you need them
basically the ECU is adding fuel but you need to pin down why (providing your STFT is + not -)
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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MCM73
Samba Member
Joined: February 20, 2021
Posts: 24
Location: Huntsville, AL
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| Posted: Sat May 29, 2021 2:07 pm Post subject: Re: Open loop at idle Subaru |
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| Yes it was positive. One of the first things I did when I got it was spray ether looking for a vacuum leak & found none. I do know the previous owner replaced the MAF with a used one. I recently cleaned it with MAF cleaner & no change. When I get he OBD2 I want to verify all the voltages while running & at idle. If I'm correct some causes of a high STFT could be clogged injectors, clogged fuel filter or weak fuel pump. The filter is new. I'm not sure if torque pro will show dwell times. Also it's an external fuel pump & looks to be older. I don't think I'll be able to get any fuel pressure readings. I know the brake m/c was replaced with one from a BMW. |
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