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Old 03-01-2021, 04:46 PM   #1
yugo4life
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Default LH2.0/2.2 help

***Current status***
- Running LH2.2 with 2.0 harness. No longer switching back and forth between 2.0 and 2.2 for simplicities sake.
- Pin#2 at ECU matches resistance directly at ECT sensor for various temperatures. Idle increases when ECT connector is unplugged.
- Idle increases when TPS is unplugged.
- No change in idle or performance when IAC valve is unplugged.
- Voltage at O2 sensor when warm is right around 0.104 volts. It starts at 0.125ish when the car is first started, but then settles quickly. When I blip the throttle, it increases to 0.116ish, but doesn't seem to change when I unplug the FPR vacuum line or spray ether into the intake. Nothing seems to change in idle or performance when O2 sensor is unplugged.
- Verified that brake booster, line, and check valve are good. No change in performance when these are bypassed.
- My cam sprocket pin has not been visually inspected, but the cam gear and crank line up perfectly when at TDC. Static timing has been checked and is spot on.
- Fuel filter, external fuel pump and O2 sensor have all been replaced.
- Valve cover and intake grounds cleaned.
- Has plenty of power when I was using LH2.0, but it had its own issues. I have ruled out fuel pressure because of this.
******************************

Last year, I switched from LH2.0 to LH2.2 in my 84 244 using the original 84 harness and repinning the AMM connector. All has worked generally well until last week. I went to back out of my driveway and as I pulled onto the street, the car died. It restarted like normal, but would die as soon as I shifted into drive or reverse (or even blipped the throttle). The idle was also a bit higher than normal, but would still die with any load.

I unplugged the AMM and nothing seemed to happen so I assumed the AMM was bad. To test the theory, I switched back over to LH2.0. It idled a bit rougher than 2.2 did when good, but otherwise seemed just fine. Over the course of this last week, it has continuously run worse every day until now it barely moves. It is running extremely rich as evidenced by plugs and general smell. There is a noticeable change in idle when plugging/unplugging the AMM. Two very odd observations - When it is first started after disconnecting the battery, it will run GREAT for about two minutes, smooth idle, good power (for a stock B23), etc. Then instantly will start running like crap, poor idle, rich smell, etc. It barely gets out of its own way. The other odd thing is that when it starts running like this, the brake pedal gets very hard, like the booster is no longer working. It will feel fine and normal during that initial two minutes though.

Recap:
LH2.2 - Idles just fine but will die when any load is applied. No change in idle when AMM is unplugged.

LH2.0 - Idles rough, smells rich and plugs were fouled. Idle changes when AMM is unplugged. Can't really get over 30ish mph. Runs great for a few minutes after battery is disconnected, but instantly reverts back to crap. Brake pedal is very hard when it is running like crap.

I am really stuck on what I should check next. I thought for sure it was the LH2.2 AMM, but now it makes me think that it is something else (or something additional) that is causing me woes since LH2.0 is having fits too. Could it be a vacuum leak, hence the brake booster not working as normal? I fixed one hose that was cracked, but it made no difference. It connects to the manifold right above the throttle body and goes down under the drivers side frame rail. I couldn't find any other leak points, but I will spray everything down tonight to see if I missed anything.

Am I just missing something obvious here? I did recently replace the ECM temp sensor a few months ago, maybe I disturbed the harness there and now its not reading correctly? I will check resistance at the ECM. Any other possibilities? Maybe two bad AMM's?

Thanks, Tim
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Last edited by yugo4life; 03-15-2021 at 10:08 AM.. Reason: Updating current status
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Old 03-01-2021, 05:14 PM   #2
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Check out the information on checking your AMM on cleanflametrap. Also I would check the engine coolant temp sensor and make sure the resistance changes according to the chart. A high resistance in that circuit will cause a very rich mixture and can even flood the engine. If you are using a heated sensor that should go into closed loop after only a few minutes. Long enough for the heater to warm the sensor. So, you definitely want to check that as well.
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Old 03-01-2021, 11:23 PM   #3
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RE: idle was also a bit higher than normal

Unplug brake booster at its inlet on intake manifold, and cap inlet on intake manifold.
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Old 03-02-2021, 02:36 AM   #4
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I've had received bad coolant temp sensors, new in bag. If you still have the old one, might be worth chucking it in for chuckles and seeing if the car strangely runs decent again.
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Old 03-02-2021, 04:58 PM   #5
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I second Johns experience on new bad sensors. I bought one last year that was only 5 ohms for my LH2.4 system. Brand new in the bag with the correct part number on the bag.
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Old 03-02-2021, 11:24 PM   #6
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Quote:
Originally Posted by dl242gt View Post
Check out the information on checking your AMM on cleanflametrap. Also I would check the engine coolant temp sensor and make sure the resistance changes according to the chart. A high resistance in that circuit will cause a very rich mixture and can even flood the engine. If you are using a heated sensor that should go into closed loop after only a few minutes. Long enough for the heater to warm the sensor. So, you definitely want to check that as well.
I will check out cleanflametrap tonight to see what I am missing. I am definitely getting some odd readings in the ECT circuit! With my multimeter set to 20K ohms, I only ever get 0 ohms from pin 13. Doesn't matter if the sensor is plugged in or not, still 0 ohms. At the sensor though, I saw anywhere from 2.43 (cold), to 0.94 (5 minutes of running), to 0.72 (8-10 minutes of running). This was measured with a lead on each of the two sensor terminals. I tried reading from each terminal to the battery ground and it still came up as 0 ohms. It makes me think the connector or harness is bad, but there is a noticeable difference in idle when I unplug/plug the connector while it is running, making me think the ECU is receiving some sort of signal from it. Am I just measuring the circuit resistance wrong at the ECU connector? Isn't pin 13 from the sensor and pin 5 ground?

Quote:
Originally Posted by 84B23F View Post
RE: idle was also a bit higher than normal

Unplug brake booster at its inlet on intake manifold, and cap inlet on intake manifold.
I did that and it raised the idle even higher while there was a leak. Plenty of vacuum and the idle would go up and down as I uncovered/covered the hole. Oddly enough, it only idles high on LH2.2. On 2.0 it seems to idle at normal speed, it just sounds like it is only with 2-3 cylinders.

Quote:
Originally Posted by John242Ti View Post
I've had received bad coolant temp sensors, new in bag. If you still have the old one, might be worth chucking it in for chuckles and seeing if the car strangely runs decent again.
Quote:
Originally Posted by dl242gt View Post
I second Johns experience on new bad sensors. I bought one last year that was only 5 ohms for my LH2.4 system. Brand new in the bag with the correct part number on the bag.
When I got this one I tested out of the car (room temperature, freezer, boiling water) and the resistances at those temps matched the chart. The connector on my old one disintegrated upon disassembly, so, unfortunately, I don't have that one to go back to.

This one is definitely throwing me for a loop at the moment, maybe it is multiple things and that is why nothing makes sense? Or I just don't yet fully understand the mind of an 80's Swedish engineer...
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Old 03-03-2021, 12:14 PM   #7
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Originally Posted by yugo4life View Post
84 244
If cylinder head is B17. B19. B21. B23. This part inserted into cam sprocket slot may be defective...this pin holds cam sprocket in place.
.
.
See 28a in this diagram

Volvo Part Number: 951963
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Old 03-07-2021, 02:37 AM   #8
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Quote:
Originally Posted by 84B23F View Post
If cylinder head is B17. B19. B21. B23. This part inserted into cam sprocket slot may be defective...this pin holds cam sprocket in place.
.
.
See 28a in this diagram

Volvo Part Number: 951963
I didn’t take the cam sprocket off but the timing marks for the crank and camshaft are spot on so I don’t believe this to be the issue. The intermediate shaft HOWEVER looked odd to me as it was right at the 3 o’clock position and I thought it was supposed to be closer to the 4 o’clock position. I moved it it one tooth closer to 4 o’clock and it idles smoother than it ever has! My issues aren’t altogether resolved, but we are directionally correct!

I stopped switching between LH2.0 and 2.2 as it only seemed to confuse me since it has different symptoms. I have LH 2.2 in and will continue to diagnose using only that. Currently it idles great but will die when you apply any throttle. I have not tried to put it in gear at all. I tested the O2 sensor and was only ever getting 0.03-0.07V so I suspect it has failed or heavily fouled from it running so rich. I was also never able to get any reading outside of 0 ohms when checking the ECT sensor at the ECU so I also believe that to be an issue.

I tried unplugging the AMM and absolutely nothing changed. If it was bad, wouldn’t it idle better?
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Old 03-07-2021, 04:31 AM   #9
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Ive been following along because I have a fairly similar problem on my 84 running LH2.0. It runs too rich, and I can't quite figure out why.

From my understanding, at least on LH2.0, testing the ECT at the ecu connector should be from pin #2 of the harness to ground. Im assuming you just swapped in the LH2.2 ecu and didnt mess with the ecu wiring, so maybe check pin#2 for ect signal.

As for O2, are you really measuring 0.07V? Because that should be very lean, and you mention it runs rich. Mine runs rich, and I measure 0.8-0.9V.

Im pretty sure you should be able to unplug the O2 signal wire and get 0.5V reference from the ECU. And you can also measure voltage from the disconnected sensor too, see if that gives any reading. But if youre measuring that lean, the ecu might be trying to dump in more fuel.
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Old 03-07-2021, 07:50 AM   #10
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Quote:
Originally Posted by John242Ti View Post
I've had received bad coolant temp sensors, new in bag. If you still have the old one, might be worth chucking it in for chuckles and seeing if the car strangely runs decent again.
* nothng wrng w/ coverng the obvious
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Old 03-07-2021, 12:33 PM   #11
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Originally Posted by yugo4life View Post
cam sprocket
My B23F had some 250,000 miles plus (odometer busted, of course), but that pin didn't hold, and cam sprocket slipped its position. Hence, yours will fail with time.

Distributor - IIRC, on 1984 B23F and on 1993 B230F distributors, where the cap touches the distributor's metal facing, there is a scribed mark for Number One cylinder on metal face. When intermediate shaft is correctly in its position, the rotor's metal tip is pointing mostly parallel to engine block, but a pinch towards front side of engine block, like this. Timing can be checked with vacuum line removed/plugged from Chrysler box.
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Old 03-07-2021, 12:53 PM   #12
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Quote:
Originally Posted by Wheetie View Post
O2 0.8-0.9V....rich.
As O2 sensors get worn out, up goes the voltage reading.

ECU's temp sensor should be ohm checked...when they fail, rich mixture.

I can't recall on which LH, but if temp sensor is unplugged, a default temp value is used...could evaluate O2 readings, on a slightly warmed engine by unplugging temp sensor wire.

RE: LH2.0, testing the ECT at the ecu connector should be from pin #2

Correct on LH 2.1/2.2

Pin 20 maybe O2 pin
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Old 03-07-2021, 01:04 PM   #13
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Originally Posted by yugo4life View Post
LH 2.2...but will die when you apply any throttle....O2 sensor...0.03-0.07V.....0 ohms when checking the ECT sensor...
Unplug O2 sensor, and see what happens...could check voltage at pin #20 when plugged in with high impedance volt meter.

Unplug ECT, and see what happens...I don't know if Bosch had a default temp then...Rex-Regina default is around 70°F...so if engine is started when colder, it runs lean until engine warms up...when temps drop down to say 40°F, very hard to start.
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Old 03-07-2021, 06:42 PM   #14
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Here are my observations after messing with it today. Still LH2.2 with 2.0 harness.

-Starts and idles just fine with smooth idle at 950rpm.
- Blips of the throttle will cause it to stumble and die. Too much throttle anywhere in the rpm range will cause it to stumble and die. It will rev all the way to 5000rpm nice and smoothly if throttle is applied very slowly.
-No noticeable change in idle or rev ability when O2 sensor, IAC or AMM are unplugged.
- Goes to 1200rpm when ECT is unplugged. No change in rev ability.
- Pin #2 of ECU @ cold = 1.94 kohm, warm = .79, hot = .35. This would only read this way if the ignition was off. If running, it read as an open circuit. I had my son watch the multimeter and it would read open anytime I unplugged the sensor and would go right back to the previous reading once I plugged it back in.
- The above resistance readings were also the same at the sensor itself although I had to read from pin to pin. Any pin to ground read 0 ohm.
- Pin #13 shows 0 ohms at all times.
- Pin #20 started at 1.12 volts when the engine was hot, but kept dropping slowly over a few minutes to .95 volts. It looked like it was still dropping, but I just stopped reading it. I have no idea what this would suggest.
- Voltage at the O2 sensor read anywhere from 0.15 to .04 V, all while hot. It wasn't jumping around while I was watching it, but I could check it at 0.15, remove the leads for 10 seconds, put them back on and it would read 0.4 or some other value in between. This was checked while the sensor was plugged in and the car running. I still suspect that this is bad, but I don't think it would cause the issues I am seeing. Open for debate though...

I am really stumped with this one. It happened so suddenly that it has to be electrical or some sensor. I have never had it stall out like this before. Shouldn't it run differently when the AMM is unplugged if the AMM is bad. It idles great though so I am not sure. Are there ever issues with dirty throttle bodies? It was running rich for a while so maybe that is contributing to it?

Last edited by yugo4life; 03-14-2021 at 12:38 PM..
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Old 03-07-2021, 09:21 PM   #15
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RE: Blips of the throttle will cause it to stumble and die.

Yes, its running LEAN...So...FPR is not holding pressure, fuel filter real dirty, or fuel pump is fizzling.

RE: AMM is unplugged

On LH 2.0, engine RPM will go up and down...rich mixture IIRC...too many years ago.

Just quick thoughts...I'll reread your comments later...
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Old 03-08-2021, 12:56 AM   #16
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RE: Pin #2 of ECU

Should say, on Pin #2 at ECU's wiring-harness connector, I read such and such ohms with the other probe on one of the engine's ground pins (pins 25, 11, or 5; which come from ground straps on valve cover).

RE: Pin #20 started at 1.12 volts...kept dropping slowly

Just means a lean mixture
======================

"I know all about the limp mode in a 88 240 dl where one can only barely hit the gas to go."

Someone suggests: "With the MAF sensor disconnected, the LH-Jet defaults to a "limp home" mode that runs the fuel mix really rich."
================

Maybe running in Limp Mode, or maybe not correct fuel pressure on the fuel rail. If vacuum is pulled off FPR (while someone is watching pin 20's voltage), there should be a change in O2 reading at idle RPM. Watch closely...ECU may adapt quickly.
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Old 03-08-2021, 10:38 AM   #17
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Originally Posted by 84B23F View Post
RE: Blips of the throttle will cause it to stumble and die.

Yes, its running LEAN...So...FPR is not holding pressure, fuel filter real dirty, or fuel pump is fizzling.

RE: AMM is unplugged

On LH 2.0, engine RPM will go up and down...rich mixture IIRC...too many years ago.

Just quick thoughts...I'll reread your comments later...
I just changed the fuel filter this week with no apparent improvement, but I will check the FPR and fuel pump.

When I have LH2.0 installed, it does exactly as you describe when I unplug the AMM. I have been running just LH2.2 to simplify the troubleshooting and it makes absolutely no change in idle or rev ability when the AMM is unplugged.

Quote:
Originally Posted by 84B23F View Post
RE: Pin #2 of ECU

Should say, on Pin #2 at ECU's wiring-harness connector, I read such and such ohms with the other probe on one of the engine's ground pins (pins 25, 11, or 5; which come from ground straps on valve cover).

RE: Pin #20 started at 1.12 volts...kept dropping slowly

Just means a lean mixture
======================

"I know all about the limp mode in a 88 240 dl where one can only barely hit the gas to go."

Someone suggests: "With the MAF sensor disconnected, the LH-Jet defaults to a "limp home" mode that runs the fuel mix really rich."
================

Maybe running in Limp Mode, or maybe not correct fuel pressure on the fuel rail. If vacuum is pulled off FPR (while someone is watching pin 20's voltage), there should be a change in O2 reading at idle RPM. Watch closely...ECU may adapt quickly.
I should have mentioned that all readings at pin #2 were with it grounded to a screw on the A pillar.

I will check the O2 reading at idle with the vacuum pulled off the FPR as you described.

Thank you for your input, it is greatly appreciated!!! Just going through what is best next to check is extremely helpful and keeps me from trying to check it all at once.
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Old 03-08-2021, 11:28 AM   #18
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If a person had a mechanic's multi-meter, one could watch for min/max voltage on pin 20...an older O2 sensor changes slowly, whereas a newer one changes faster...as I understand...but I don't know the time interval.

I always clean up engine grounds...on valve cover and intake, and also battery's hot/ground on both side. Vehicle is starting, so big cables are good. On my 1984, I ran an additional ground from battery to intake, but maybe overkill.
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Old 03-08-2021, 01:31 PM   #19
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I think your ECT readings you posted are in kohms. They seem correct if in kohms. So you might want to fix that in your post for anyone else reading through or following along.

At this point, if your O2 readings are to be believed, you are running very lean. I would try to do something to verify your O2 sensor is working. Leave your meter hooked up to the O2 sensor and watch how it responds to pulling the vac line off the FPR, rev’ing the engine, squirting some fuel in the intake. Anything to get it to budge, because Im not sure what to believe at this point. You’ve mentioned its running rich, it seems to have an AFR problem, and the O2 is reading lean. If you cant get the O2 readings to budge, might be time to consider replacing it.

If it is lean. You need to check for vac leaks carefully, and then do it again. Cap the intake fitting going to the brake booster line because you mentioned the booster gets firm when its acting up. So remove the booster, check valve and line from the equation. Does capping the intake fitting change the O2 reading?

As 84B23F has pointed out, the other problem could be not enough fuel. So check fuel pressure, Volvo spec is 35.5psi. Also, check that the prepump is working too, and possibly do a volume check. You can pop the feed line to the main pump and look at the flow. I can't find the actual spec, but a less scientific method is “like a horse pissing”. So if you're not getting a decent flow, the hose in the tank could be split and not delivering enough fuel to the main pump. This problem can be exacerbated when tank levels get below ~ half full / below split hose.

You should get your hands on the volvo greenbook for the fuel system, and at least read through it. You can probably use the lh2.0 since most of your stuff is still 2.0. But the AMM stuff wont be correct. But everything else should be relevant and you can get the specs for all the hardware and compare with yours.

Im not sure how TB is with direct links or if we shouldnt post them incase they get a C&D from Volvo. The LH2.0 book is TP30427/1. I ordered a hard copy off ebay because I like to have a copy in hands while I troubleshoot. PM me if you're having trouble finding it.

Im no expert. If I was, Id have my 2.0 system figured out and running fine. But Im going through a lot of the same stuff. So more like blind leading the blind.

Last edited by Wheetie; 03-09-2021 at 01:25 AM..
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Old 03-08-2021, 01:49 PM   #20
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Footnote - When a vacuum booster fails, additional air is added, which is not seen via AMM metered air...so, if brake booster's vacuum like is plugged at intake, this rules out another issue. After engine is shut off, brake pedal should still be easy to push for awhile...if hard...Bingo.
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Old 03-08-2021, 02:10 PM   #21
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Footnote - When a vacuum booster fails, additional air is added, which is not seen via AMM metered air...so, if brake booster's vacuum like is plugged at intake, this rules out another issue. After engine is shut off, brake pedal should still be easy to push for awhile...if hard...Bingo.
Exactly. Ive seen the diaphragms fail (sometimes you can hear the leak inside the car), or the check valve cracked and leaking, or the hose cracked. If we believe the O2, we might be looking for vac leaks and he had noticed a problem with the booster and pedal, so better to just eliminate the entire thing as the culprit.

Last edited by Wheetie; 03-08-2021 at 02:13 PM.. Reason: diagrams -> diaphragms
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Old 03-14-2021, 02:15 PM   #22
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I am leaning strongly towards the AMM, but maybe there are some differences in 2.0 vs 2.2 that would point to something that I have mistakenly ruled out. Things that have been changed with no apparent improvement in idle the way it runs- Fuel pump, fuel filter, 02 sensor.

I have ruled out a lean mixture simply based on the difference in behavior when I swap in the 2.0 AMM/ECU vs the 2.2 AMM/ECU. With no other changes besides the AMM/AMM connector wiring/ECU, 2.0 idles/runs rich (smell, black smoke), but doesn't stall when applying throttle. In fact, it runs great all the way up to 4000rpm*. When the 2.2 hardware is installed it idles great, but anything but the lightest application of throttle stalls it. If it put it in drive or reverse it will idle itself out of the driveway, but stalls the second I apply even the slightest load. Another difference in behavior is that the idle changes (surges up and down) when I unplug the 2.0 AMM, but does nothing when I unplug the 2.2 AMM.

*Confusing fact #1: 2.0 runs as strong as ever up until 4000 rpm where it absolutely falls on its face, will not accelerate any more, and blue smoke (oil) comes heavily from the tailpipe. But it is very repeatable right at 4000rpm in 2nd gear.
Confusing fact #2: I had 2.2 running great last night after hours of looking for exhaust leaks, replacing a couple of suspect hoses, cleaning the throttle body, and cleaning the AMM. I ran it for 10ish minutes and all seemed good, although I wasn't sure exactly what fixed it. This morning, it was right back to stalling with any load.

Random theory that contradicts what I have previously ruled out: There IS a vacuum leak somewhere, but the rich running of 2.0 masks it enough to drive.

With the new 02 sensor, I am going to check the voltage again, recheck the booster line again and reread the thread to make sure I haven't missed anything. I have used an entire can of brake cleaner to search for vacuum leaks, but so far, nothing definitive.
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Old 03-14-2021, 04:35 PM   #23
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Voltage with the new O2 sensor stay around 0.104 volts. It will get up to 0.125 on startup, but then settle back down in a few seconds. It will jump up to 0.116ish when I increase the throttle and let it go. When the FPR is unplugged, it pretty much stays the same, maybe +.001 or .002.

I rechecked the booster line again. With it unplugged at the manifold, the idle will jump to 3000rpm, but it still wants to stall if given too much throttle. If I plug the manifold, it idles nicely, but still stalls when given throttle.

***VERY ODD OBSERVANCE*** I don't know why I haven't noticed this before, but check the video below. When I blip the throttle to make it stall, there is an odd sound coming from the airbox where the hot air intake (I believe) used to be. When you put your hand over the hole and blip the throttle, you can actually feel pressure coming out. It doesn't do it every time, only when you really tap the throttle a lot.
https://drive.google.com/file/d/1XQG...ew?usp=sharing

I unplugged the vacuum line coming from the ignition controller and tried to vary the vacuum just by sucking into it to see if it was ignition related and found that, while somewhat difficult, I could still suck through it constantly. It didn't hold the vacuum like I expected a diaphragm to do. Is that normal? In the past, I have seen a graph that had the timing map, but I can't seem to find it now. My timing light seems to have crapped out on me as well so I will get a new one to check it. I have had it for 15+ years, so I guess I got my moneys worth...
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Old 03-14-2021, 06:07 PM   #24
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Find an automotive multimeter

The air mass meter depends on the measurement of current flowing through heated wires to measure air flow. It is also known as the hot-wire sensor because of its heated wire design, hence the "H" in LH. In the unlikely event that a wire should break, the warm engine runs, though without fuel compensation, in a "Limp-Home" mode. For "Limp-Home" operation, injector pulse time is fixed. For any rpm above idle, the ECU is programmed to deliver fixed pulses, typically 7.5 milliseconds.

I don't know if this could be measured with Infrared Thermometer

The LH hot wire is found within the air passage tube of the air mass meter and is made of a platinum filament. The hot wire is heated to a specific temperature differential above the incoming air when the ignition is turned on (the differential is measured in degrees Celsius).

LH 2.2, aluminum: 212F (100C)
LH 2.2 and LH 2.4, plastic: 248F (120C)
LH 2.4.1 and 2.4.2, plastic: 311F (155C)
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Old 03-14-2021, 08:36 PM   #25
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RE: AMMs

002 - LH 2.0
007 - LH 2.2

"AMM....but the volvo sensor at idle reads approximately 2.3-2.5 volts and rails out to a maximum of 5.05-5.10v. "

In other words, voltage variation.
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