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Old 05-18-2019, 10:07 PM   #26
NotSoFresh
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Quote:
Originally Posted by 2manyturbos View Post
What you describe are classic symptoms of a bad AMM. Borrow a known good AMM and throw it on there and I'll bet every one of those issues disappears instantly.
That is what I was told when I bought my car, turned out to be a vacuum leak in the line going to dash the vents.
OP: you cant just inspect the lines, you gotta pull them off and re-install them. More than once I have found hardened lines that are not sealing to the nipples anymore, but are not cracked or split. Or they split when removing them. If they come off easy with a pull, they are likely leaking. Over the years I have found quite a few bad lines this way that I didn't see when inspecting them visually.
Did you check the lines that go to the charcoal/vapour can?
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Old 05-18-2019, 11:46 PM   #27
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OP...there are new cheap AMMs for LH 2.4....google around, if you want to shoot parts at it.
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Old 05-18-2019, 11:58 PM   #28
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Quote:
Originally Posted by NotSoFresh View Post
That is what I was told when I bought my car, turned out to be a vacuum leak in the line going to dash the vents.
OP: you cant just inspect the lines, you gotta pull them off and re-install them. More than once I have found hardened lines that are not sealing to the nipples anymore, but are not cracked or split. Or they split when removing them. If they come off easy with a pull, they are likely leaking. Over the years I have found quite a few bad lines this way that I didn't see when inspecting them visually.
Did you check the lines that go to the charcoal/vapour can?
I guess you missed the part about the intermittent flat spot in the power band. Think. Does a vacuum leak come and go? There are too many indicators it is the AMM. A vacuum leak would still be leaking when the car is warmed up, yet, the surging idle goes away. Another classic failing AMM symptom.
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Old 05-19-2019, 12:18 AM   #29
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Quote:
Originally Posted by 2manyturbos View Post
I guess you missed the part about the intermittent flat spot in the power band. Think. Does a vacuum leak come and go? There are too many indicators it is the AMM. A vacuum leak would still be leaking when the car is warmed up, yet, the surging idle goes away. Another classic failing AMM symptom.
I guess I didnt express myself correct, I didnt intend to say that in this case it is not the amm.
I did want to express that old bad vacuum lines have a nasty way of hiding their issues, and causing symptoms seemingly unrelated. Visual inspection is not enough.

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One thing I have not seen is, Is the check engine light on? What codes does the ecu throw?
There should be codes if the engine is acting up like this. People are talking about ecu swaps, but not about if and what codes are being thrown by current one.
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Old 05-19-2019, 01:07 AM   #30
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That’s the one thing OBD 1 does not detect, a failing AMM. If the hot wire is broken, or, the AMM is unplugged a code is thrown. All kinds of running issues do not trigger any codes when caused by the AMM. Sometimes, the code for too lean/rich is triggered by a bad AMM.

Last edited by 2manyturbos; 05-19-2019 at 01:20 AM..
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Old 05-20-2019, 09:50 AM   #31
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Thanks for pitching in Roy! I understand unplugging it won't fix anything if its stuck open, but if its possibly a dying ECM, that could trigger it if it isn't. When i get back from the **** hole known as NTC, that CSI is going bye bye. Hopefully I can get around to double checking injectors sometime between now and Thursday night. I for whatever reason cannot find my Haynes book right now. What would the specs be on the ECT and the injectors?
Ok. To recap:
-No CEL, no codes pulled, 111.
-The ECM ECT was replaced in 2016
-Cap, rotor and plugs were replaced last IPD Garage Sale
-Vacuum lines were replaced last summer when the problem first started to rear it's ugly head
-Swapped AMM from my 91, no change in start up or driveability
-FPR, intake and exhaust mani gaskets were replaced when the ECT was(back in 2016)
-Inspected intake accordion and found no splits, cracks or holes. All good.
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#mclovethesenuts

-My car: White 1991 244, 330k miles. B230F LH2.4, AW70, R134a retro
-Wife's car: White 1990 244DL, T cam, 200k miles.B230F LH2.4, AW70 w/aux cooler, Virgos, tow hitch
-PSM 2002 Subaru WRX wagon: EJ205, 5MT, 120k miles, Perrin TBE
Rebuilding EJ207 shortblock to swap in this summer.
-1997 Subaru Legacy Brighton: EJ22, 5MT, 236k miles
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Old 05-20-2019, 11:05 AM   #32
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Bosch used at least two different ECTs; so a ECT for LH 2.4 is not the same as ECT for 1984 LH.

Engine Temperature Sensors

Scrolling down the page, "Diagnosing ECT Failures" is explained.
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Old 05-20-2019, 11:36 AM   #33
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Quote:
Originally Posted by 2manyturbos View Post
That’s the one thing OBD 1 does not detect, a failing AMM. If the hot wire is broken, or, the AMM is unplugged a code is thrown. All kinds of running issues do not trigger any codes when caused by the AMM. Sometimes, the code for too lean/rich is triggered by a bad AMM.
Prev Owner of my car sold it (amongst other reasons) because it was throwing the lean rich code occasionally, along with other running symptoms, and for all the world looked like a failing amm. If I am correct, according to him, He changed (more than once) it for the chinese re-pops and they failed fast, then he tried to get a reman bosch from ipd but they were out, refunded him and he couldn't find another good one.
I found/fixed vacuum problems and all symptoms went away. One was the dash vacuum hose that was uncracked but hard and leaking around the fitting. This vacuum leak varied depending on what the dash vents were set to, due to an additional leak under dash. The other was a cracked flame trap housing. Oh, there was also a check valve installed backwards.
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Old 05-20-2019, 11:37 AM   #34
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Yeah, I knew there were different sensors made by Bosch. For the life of me, I couldn't remember the webpage that had that info, thank you 84B23F.
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Old 05-20-2019, 12:23 PM   #35
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LH2.4 Pinouts and Diagrams

Note - LH's signal ground is on pin #5...this ground comes from wires hooked to intake manifold...so engine must be grounded to battery, so intake manifold is grounded.

As noted, "However, try checking your ECT wiring: Between pins 13 and 5 at the LH ECU (with sensor DISconnected) resistance should be infinite."
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Old 05-20-2019, 01:59 PM   #36
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Idle Air Control (IAC) valve? When mine was going out it would stall at idle since it wasn't doing what it was supposed to. A very easy fix to R&R.
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Old 05-20-2019, 03:08 PM   #37
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A 1990 240 came with the Pink label 561 and 556 ECUs. It is entirely possible you have a bad ECU.
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Old 05-20-2019, 03:16 PM   #38
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Maybe I can try guess and check with my 91 ECU? I didn't even pay attention to which ECU is in the car when I replaced the expansion valve when I got her AC working two years ago. LOL Non-the-less, I shall double check the ECT.
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Old 05-20-2019, 03:24 PM   #39
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Just swap ECUs and see what happens. It's really the EZK that controls EGR anyway. If that seems to make a difference, swap your 1990 ECU into the 91 and see if the symptoms follow it. 15A discovered over the weekend that the running issue he has been chasing on his 1993 940 Turbo was likely the ECU. He swapped in a later version, known good ECU and suddenly the intermittent miss went away. He has had the issue with that car for 3-4 years.
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Old 05-20-2019, 03:30 PM   #40
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Quote:
Originally Posted by 2manyturbos View Post
Just swap ECUs and see what happens. It's really the EZK that controls EGR anyway. If that seems to make a difference, swap your 1990 ECU into the 91 and see if the symptoms follow it. 15A discovered over the weekend that the running issue he has been chasing on his 1993 940 Turbo was likely the ECU. He swapped in a later version, known good ECU and suddenly the intermittent miss went away. He has had the issue with that car for 3-4 years.
Gross. Yeah. It started out as a rough cold start about four, five years ago, now it's a really rough start, and a PITA to start when the ambient temps are below 50 or so.
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Old 05-20-2019, 05:34 PM   #41
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Do CTS ohm meter and ground checks, before flipping...
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Old 05-20-2019, 10:49 PM   #42
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Grounds are good. Visually inspected the EZK and ECU, the ECU is a white label 561 and a pink label EZK, not sure the model though.
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Old 05-20-2019, 11:31 PM   #43
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The one ground wire from the valve cover to the fire wall had some build up, wouldn't call it corrosion, but it definitely needed a cleaning. Ran out of light and motivation for the evening. I tried to start it and it fired right up, still missing and blubbering though. Made some improvement. Couldn't get it voltage between pin 5 and 13. Resistance was around 9800 ohm? And the engine hadn't run, so ambient temp was 60°
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Old 05-21-2019, 12:14 AM   #44
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RE: 9800 ohm - If based upon measurement made at LH's harness disconnected from LH's box, then reading should be around 2300 ohms @ 68F(20C). At 32F (0C)-- about 6000 ohms. Your reading, if true, is informing LH to enrich extra fuel.

I highly suggest cleaning all grounds, at battery post, from battery to engine, and grounds on intake. One could do positive side also, with ground disconnected.

RE: voltage between pin 5 and 13 - This is done with ignition switch turned on, and LH harness plugged into box.

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Old 05-21-2019, 11:09 AM   #45
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Footnote - 9800 ohm reading at LH's harness should also be true when measured at CTS's terminals, if wiring and grounds are fit for duty. Either CTS is defective, wiring is defective, or ground not good if both of these readings are not similar.

If oxidation exist, either at terminal or internally in wire itself, your ohm reading will go higher, and cause a "flooded" starting condition.


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Old 05-21-2019, 11:34 AM   #46
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Assuming the block is well grounded to the frame, when I directly spec out the CTS, the reading shouldn't change, if at all, when I ground at on the block, chassis or negative battery terminal. The spade connector on the CTS was looking awfully oxidized. Not looking forward to replacing any grounds if they're bad
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Old 05-21-2019, 12:17 PM   #47
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Quote:
Originally Posted by KeizerBrickGuy View Post
Assuming the block is well grounded to the frame, when I directly spec out the CTS, the reading shouldn't change, if at all, when I ground at on the block, chassis or negative battery terminal. The spade connector on the CTS was looking awfully oxidized. Not looking forward to replacing any grounds if they're bad
If those readings are correct, that is a huge problem. I question whether they are correct. That would make the car run so rich you might not even be able to start it. Even if you could start it, the car would flood all the time. It would also make the ECU throw a code for a rich condition. You said in the post above, no codes.


Edit:


You are supposed to be measuring resistance between pin 13 and ground. Not between pin 5 and 13. That likely explains the reading you got.

Last edited by 2manyturbos; 05-21-2019 at 12:28 PM..
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Old 05-21-2019, 12:50 PM   #48
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Quote:
Originally Posted by 2manyturbos View Post
If those readings are correct, that is a huge problem. I question whether they are correct. That would make the car run so rich you might not even be able to start it. Even if you could start it, the car would flood all the time. It would also make the ECU throw a code for a rich condition. You said in the post above, no codes.


Edit:


You are supposed to be measuring resistance between pin 13 and ground. Not between pin 5 and 13. That likely explains the reading you got.
That would definitely explain it. So, I'll retest tonight, pin 13 and ground on the body. I'll check at the ECU harness as well as the sensor itself just to check and ensure the wiring between the two is viable. The car is running pig rich though when it starts up, so it's definitely getting fuel.
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Old 05-21-2019, 01:18 PM   #49
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I suggest you do a spray pattern test on the injectors. Snapple bottles, etc work great as flasks to have the injectors spray in. Pull the rail and have all four injectors in bottles set on the intake. Have your wife crank the starter and watch what happens at the end of each injector. Having the same type of bottle on each injector will give you equal volumes to compare how much fuel you are getting from each injector. What is of bigger concern is the spray pattern. I have dealt with a few 240s that had spray patterns so bad the engine ran terrible when cold and even when warmed up, had a rough idle. If the fuel isn't atomized properly, it blows spark out at low RPM. Higher RPM results in higher charge velocity which helps atomize the fuel. IOW, the car can run terrible at low RPM and smooth out and run decent at higher RPM.
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Old 05-21-2019, 01:35 PM   #50
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Quote:
Originally Posted by KeizerBrickGuy View Post
...spade connector on the CTS was looking awfully oxidized
Remove CTS's plug, then do an ohm test at LH harness....if infinity (Zero), leave CTS unplugged, reinsert LH harness, and start engine.

If the control unit receives a signal higher than 302F (150C) or lower than -40F (-40C), it will interpret the signal as a fault...the control unit will assume a substitute value corresponding to 32F (0C) on starting and 68F (20C) when the engine has started."
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