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Old 05-14-2019, 02:39 PM   #1
KeizerBrickGuy
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Exclamation Hard Start, loping idle

Hey TBrickers!
So my Wife's 1990 244(LH2.4, AW70) has been acting up the last year or so, so much to the point she doesn't drive it anymore(driving her Subaru). It started acting funny about the time the Garage Sale came around. Figured it had been two years since it's last tune up with plugs, wires, cap and rotor. I did the tune up in the parking lot before departing for home. It started up fine and drove great. Queue the cold nights/cool mornings, it will crank a couple seconds and then finally start, once it does, it acts like its going to die and the idle is rough and loping like a massive cam. If you don't give it gas fast it dies. Definitely not a fuel issue, can smell gas. I thought maybe the cold start injector is leaking or triggering, so I disconnected it. Not much of a change. It only does it on a cold start, but if it's been running and still fairly warm, it doesn't do it. Timing appears to still be set. Vacuum lines are good, accordion hose is split-free I can say it does hesitate super intermittently from as stop when accelerating. I have been so busy with our new house and life, I haven't had much time to look into it further. But I do drive it a few times a month to/from work to keep it happy. I am at a loss, Carl has been trying to help with my diag, thank you again, Carl! Local TBrickers, help in person would be a huge help.

UPDATES:
-Verified FPR is still good and functioning, was done 2016
-Vacuum lines are intact and good
-ECT sensor was done 2016
-Replaced FPR vacuum line back in December
-Intake accordion new back in 2016, still no cracks
-Intake manifold gasket done in 2016

-After testing ECT, resistance was incredibly high for temperature and no voltage coming from sensor when KOEO test was completed at the ECM pin. When unplugged and engine started, does not exhibit original problems with loping, rough idle or acting like it was missing.
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Quote:
Originally Posted by 87_240TURBO View Post
#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

Last edited by KeizerBrickGuy; 05-23-2019 at 11:40 AM.. Reason: Update
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Old 05-14-2019, 08:36 PM   #2
84B23F
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Originally Posted by KeizerBrickGuy View Post
...it will crank and crank and then finally start...only does it on a cold start...
Replace FPR (Fuel Pressure Regulator)...Does it "prime" when key is switched to on position?
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Old 05-14-2019, 09:51 PM   #3
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It does the initial prime when I key the ignition, yes. I'll try the FPR from my 244 to verify.
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Old 05-15-2019, 12:39 AM   #4
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I'll try the FPR....
Bingo....listening to fuel pump may detect it running higher RPMs, which is due to FPR bypassing. One could always apply power to fuel pump fuse, for say 5 seconds, then start vehicle with pump running.

99% sure, FPR is the issue.
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Old 05-15-2019, 09:02 AM   #5
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FPR is a negative. I pulled the FPR from my 91 and it did the same thing. I replaced it about four years ago with a new Bosch unit. I did notice an exhaust leak possibly from the manifold-downpipe flange. It starts going away once it starts building heat. Thinking about cleaning the IAC tonight just to check the box as I haven't done it in a few years.
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Old 05-15-2019, 10:18 AM   #6
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RE: "...does it on a cold start, but if it's been running and still fairly warm, it doesn't do it. "

Does it have spark, does it have enough fuel, and does vacuum fitness exist....those are the relevant questions.

A shot of engine starter fluid into intake before starting cold evaluates spark. Not easy to check fuel's rail pressure on 1990, but one could evaluate brake booster fitness via removing vacuum hose from it, and place a thumb over its fitting while starting. If engine is idling fine in cold/warm/hot conditions, then IAC is fine.

Unknown if LH 2.4 uses default "cold start fuel amounts," but if engine is near operation temperature, it may use previous "run fuel amounts," which is what is being suggested by your inquiry above. If true, then engine is sucking too much air at startup (like brake booster shot)

Last edited by 84B23F; 05-15-2019 at 10:39 AM..
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Old 05-15-2019, 10:28 AM   #7
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Could also be a (largish) vacuum leak. Inspect all of your hoses - especially the flame trap hoses.
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Old 05-15-2019, 01:31 PM   #8
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Original ECU? The pink label 561 and 556 ECUs are notorious for going bad. Apparently, some of the white label versions do the same.
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Old 05-15-2019, 01:46 PM   #9
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Quote:
Originally Posted by 84B23F View Post
RE: "...does it on a cold start, but if it's been running and still fairly warm, it doesn't do it. "

Does it have spark, does it have enough fuel, and does vacuum fitness exist....those are the relevant questions.

A shot of engine starter fluid into intake before starting cold evaluates spark. Not easy to check fuel's rail pressure on 1990, but one could evaluate brake booster fitness via removing vacuum hose from it, and place a thumb over its fitting while starting. If engine is idling fine in cold/warm/hot conditions, then IAC is fine.

Unknown if LH 2.4 uses default "cold start fuel amounts," but if engine is near operation temperature, it may use previous "run fuel amounts," which is what is being suggested by your inquiry above. If true, then engine is sucking too much air at startup (like brake booster shot)
It's got good spark, vacuum lines are good, it will flood itself if it's cold enough outside.

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Originally Posted by quillc View Post
Could also be a (largish) vacuum leak. Inspect all of your hoses - especially the flame trap hoses.
Yeah, I double checked vacuum lines, they're all intact.

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Originally Posted by John242Ti View Post
Original ECU? The pink label 561 and 556 ECUs are notorious for going bad. Apparently, some of the white label versions do the same.
It is the original ECU. Most likely has the 561? It's an 89 build 1990.
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Old 05-15-2019, 01:58 PM   #10
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Are you going to be at the swap meet this weekend? If yes, hunt for a 933, 946, or 951 ECU, then install it in the car when you get home. I bet that will make it run normally again, after the ECU calibrates itself while driving for a bit.

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Old 05-15-2019, 02:04 PM   #11
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Do diag!

Air leaks are the first thing to check. Spray around with brake cleaner and listen for a change in idle.
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Old 05-15-2019, 02:56 PM   #12
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Quote:
Originally Posted by John242Ti View Post
Are you going to be at the swap meet this weekend? If yes, hunt for a 933, 946, or 951 ECU, then install it in the car when you get home. I bet that will make it run normally again, after the ECU calibrates itself while driving for a bit.

-J
I am hoping to get up to ipd this weekend, but not sure at this point. Low on funds for sure

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Do diag!

Air leaks are the first thing to check. Spray around with brake cleaner and listen for a change in idle.
Diag is what we do! Hoping to get a solid diagnosis by this weekend.
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Old 05-15-2019, 04:30 PM   #13
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This sounds spot on for a coolant temp sensor issue, or wiring for it.

Test the CTS

Check the grounds on the manifold. The round grounding rings actually have a butt connector about 6" into the loom there, where all the grounds go into a connector and come out as one wire with a terminal ring. I flowed solder into that junction and my CTS issues (hard cold start, Sooty marks, rich under boost) all went away.
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Old 05-15-2019, 05:43 PM   #14
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I replaced the CTS when I replaced the FPR, but for due diligence I need to check it and the wiring.

On an unrelated note, who has the green book for the 91+ 240 AC wiring and design?

Last edited by KeizerBrickGuy; 05-15-2019 at 06:29 PM..
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Old 05-15-2019, 10:10 PM   #15
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Quote:
Originally Posted by KeizerBrickGuy View Post
CTS/FPR...."If you don't give it gas fast it dies."
...press pedal 3/4 way down, hold, then start.

Not a vacuum leak issue, but ECM pushing additional fuel...if ECM's CTS was replaced, and not the temp gauge sensor, then ECM's ground side to injectors must have a longer duration to bring about too rich of a mixture. I'll assume idle switch is functioning correctly.

A fuel rail test might detect if an injector is leaking down....cold start injectors have had problems....so in the morning, if intake hose was removed, then rotate throttle plate on throttle body, and smell for gas...

Myself, I removed intake manifold, and had all five injectors tested/cleaned...100k miles on 1990-240...main injectors needed a cleaning.
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Old 05-15-2019, 10:22 PM   #16
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Correct, I replaced the ECT for the ECU. I need to spec out the TPS tomorrow and possibly readjust it, if needed. I have been looking for my injector noid light set to check the injectors before I pull them. I've thought about pulling them and getting them cleaned/tested in the past. It should probably be done either way. Ran out of time to test the CTS and it's wiring.
I might want to replace the exhaust gasket that is leaking before I really do anything else. That could very well be it.
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Old 05-15-2019, 11:04 PM   #17
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...I've thought about pulling them
I think cold start injector MAY be removed and evaluated on vehicle. Electrical plug will have to be removed, but maybe those two bolts can be removed, and slide out cold start. If true, then prime fuel pump...

Yes, one may have to remove IAC/intake hose/etc....but if intake gasket has not been replaced in years, jerk it all off, and replace PVC box, hoses/etc.

When engine is warm, fuel will vaporize...in cold weather, a slow process...hence, a leaking injector...most likely, cold start. It don't get used much, and line debris goes downhill to it.
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Old 05-15-2019, 11:19 PM   #18
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I unplugged it when it didn't want to start back in January and haven't plugged it back in. The intake gasket was replaced when I did the ECT. I'll start it up tonight to check it tomorrow morning before I head to work. Thank goodness my head cold is clearing up so I can smell.
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Old 05-16-2019, 12:47 AM   #19
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Quote:
Originally Posted by KeizerBrickGuy View Post
I unplugged it....
...leaking is a mechanical issue, not electrical.

"Among the signs of a faulty cold start valve are difficult starts, no start at all, engine flooding and start/stop issues"
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Old 05-16-2019, 09:03 AM   #20
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Originally Posted by 84B23F View Post
...leaking is a mechanical issue, not electrical.

"Among the signs of a faulty cold start valve are difficult starts, no start at all, engine flooding and start/stop issues"
I understand that. But it may not be mechanical. This vehicle is old enough that a simple sensor or connection could be bad. In a perfect world I would have this fixed by the time I leave for NTC next weekend
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Old 05-16-2019, 10:52 AM   #21
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Originally Posted by KeizerBrickGuy View Post
simple sensor or connection could be bad.
EFI is about inputs/outputs...and checking them one by one on older EFI systems (pre OBD-1)

For instance, with a good coolant temperature sensor verified with ohm meter, warm it up to hand temperature, then on a cold morning...hook LH's electrical plug to it, ground CTS out to battery, then start engine on a cold day. A simple test....that informs LH that engine is warmer than engine's block, which decreases fuel amounts

LH's CTS increases in ohms with increasing coldness. One could measure ohms at LH's wiring harness by removing harness from its box, then measure ohms at pin.

Either LH is dumping more fuel than is needed, or an injector is pissing away, 24x7x365.
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Old 05-18-2019, 10:14 AM   #22
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So no one thinks part of it is from the blown out exhaust manifold to down pipe gasket? Anyone else care to chime in? Roy, calling, Roy. I'd love to hear some knowledge from you on this issue
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Old 05-18-2019, 06:02 PM   #23
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Do an ohm meter test at LH 2.4's harness plug for CTS...if within specs, this may suggest a leaking injector.
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Old 05-18-2019, 06:53 PM   #24
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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.
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Old 05-18-2019, 10:01 PM   #25
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Quote:
Originally Posted by KeizerBrickGuy View Post
I understand that. But it may not be mechanical. This vehicle is old enough that a simple sensor or connection could be bad. In a perfect world I would have this fixed by the time I leave for NTC next weekend
If the cold start injector is stuck open, unplugging it will not change anything.

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So no one thinks part of it is from the blown out exhaust manifold to down pipe gasket? Anyone else care to chime in? Roy, calling, Roy. I'd love to hear some knowledge from you on this issue
No, it has nothing to do with the exhaust gasket. If the exhaust leak was causing a bad o2 signal it would also act up when warm.

One thing I have not seen is, Is the check engine light on? What codes does the ecu throw?
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