The Joy Of 240's, with issues... - Page 10

CosmicBike · Apr 30th, 2020, 19:36

Been focussed on fitting a new garage door the past few days, so with that and work not had much play time with Grace.
Issues go on. She is still driveable, but the first mile or so is very lumpy, and there is a hint of misfire even when warm.
Engine Management light came on yesterday, and I got a 1-4-4 code, 'Load Signal Missing From LH Unit'. A new code for me, some digging suggests maybe a fuel relay issue along with other bits. Relay removed, checked over, contacts cleaned, fault code cleared.
Rough, almost stalling idle persists, and engine will not rev intermittently. Almost all the faults seem to vanish above 2500 rpm.
Disconnecting the MAF and starting gives a very steady 600 rpm idle with no misfire and no issues with reving through to 4000rpm. 1-2-1 code correctly shows on the diagnostic box with the MAF disconnected.
I have a little more fiddling to do, there are some voltages to check in a few places so when the weather improves I'll sense check those bits. She does at least run and drive, so nothing that can't wait.

CosmicBike · Apr 30th, 2020, 20:01

Detail cut and pasted from the VolvoClub FAQ's

Testing AMMs and Calibration. This is a response from Python Injection (rebuilders of AMMs) to a question about testing AMMs.
From: Joe Evert, Director of Engineering, Python Injection
Subject: Re: Technical Question about AMM
The reason the OEM doesn't give a test procedure for calibrating the air mass meter is two fold. First of all BOSCH Hot Wire Air Mass sensors are not linear devices like a throttle position sensor. The output does not change the same amount for a given air change. To make it short, most linear sensors will give you say... 1 volt for 100cfm air flow, 2 volts for 200cfm air flow, 3 volts for 300cfm airflow etc. This is a linear device. Bosch hot wire sensors are not like this. They change a great deal at low air flows but once the air flow increases past a certain point, say 50% of what the engine can draw, they change very little. This makes the sensor very accurate at low to moderate air flows and good enough at high air flows. Just a small amount of inaccuracy at low RPM and the vehicle will run terrible. If the voltage for a given air flow is off by 100 milli volts at low RPM the car will barely run. At high RPM A 100 milli volt deviation will not even be noticed. Because of this it makes it next to impossible for the technician to accurately diagnose the air mass in the field. We use a calibrated flow bench that measures the exact CFM air flow to then compare the voltage to. This is not practical in the field because temperature, altitude, humidity and the mechanical condition of the engine will affect how much air the engine is drawing in. So just to say that the Air mass should have xx.xx volts at idle would be completely false since all these parameters must be accounted for. Also even if a range is given just a small amount of deviation in the output causes poor performance.
So what are you to do? For on-vehicle diagnoses the best way is just unplug it at idle; if the vehicle runs better it is most likely bad. This is because if the air flow sensor is off voltage at high RPM it will also be off at idle. Also if you are experiencing repeated failures you probably have a defective air box thermostat. This little thermostatic bulb is located in the air filter box and controls the hot air into the engine. When this fails it fails in hot air mode and routes hot air from around the manifold into the air intake. This will destroy the air mass meter in no time.

There is also some info on testing the MAF, Terminal 1 to ground should be 0 Ohms with the MAF disconnected, and Terminal 3 to ground should be 2.3volts with the engine running. Something to look at.

Othen · Apr 30th, 2020, 20:13

This is a really interesting thread.

This won't help you much: I don't know much about the later fuel injected engines - so I can't really help except to say the rough running sounds like a fuel/air problem (so not the ignition module/distributor etc). I am so glad I have an earlier 244 with a really simple carburettor; much of the allure of the 244 for me is its simplicity - no computers and very few sensors... big bits of wire, lumps of solder, simple mechanical things and lots of room. Many things can be fixed with a Leatherman and a piece of wood.

Apologies: that didn't help much; I think it is a fuel/air problem but I have no suggestion as to how you might diagnose or fix it.

Good fortune,

Alan

CosmicBike · Apr 30th, 2020, 21:45

Quote:

Originally Posted by Othen

This is a really interesting thread.

This won't help you much: I don't know much about the later fuel injected engines - so I can't really help except to say the rough running sounds like a fuel/air problem (so not the ignition module/distributor etc). I am so glad I have a later 244 with a really simple carburettor; much of the allure of the 244 for me is its simplicity - no computers and very few sensors... big bits of wire, lumps of solder, simple mechanical things and lots of room. Many things cam be fixed with a Leatherman and a piece of wood.

Apologies: that didn't help much; I think it is a fuel/air problem but I have no suggestion as to how you might diagnose or fix it.

Good fortune,

Alan

I'm a carb lover too, the 32/26 DGAV on my Capri is so much easier! If it were on the Pinto lump then I'd have said wrong idle jets, so yes it 'feels' like mixture related.

Othen · Apr 30th, 2020, 22:56

Quote:

Originally Posted by CosmicBike

I'm a carb lover too, the 32/26 DGAV on my Capri is so much easier! If it were on the Pinto lump then I'd have said wrong idle jets, so yes it 'feels' like mixture related.

I hope I didn't come across as being smug.

I'm sure you will get to the bottom of this problem, but I can't think of a strategy for diagnosing what is wrong apart from changing bits until it works properly.

Good fortune - stay safe.

Alan

Stephen Edwin · May 1st, 2020, 12:17

BUMP

Where are the usual advisers re diagnosing LH2.4 type issues please?

.

CosmicBike · May 2nd, 2020, 18:31

The fun continues.
Tested the MAF in line with the info found on VolvoClub and Haynes manual, all checks out perfectly. The brief 'burn off' is also working when you switch the engine off too.
Other things today. Tested the knock sensor, got 0.0v when back probing with ignition in Pos II, Haynes book says circa 5v. Sensor itself disconnected has a resistance on 0 Ohms. Running the engine with a timing light on the crank pulley should show a retardation of timing if you knock the block or intake manifold, I saw no change. Running with the knock sensor disconnected made no difference to running.

No real progress made, so instead I stripped the front end of the Capri in preparation for removing/repairing the wings.

Othen · May 2nd, 2020, 19:34

Quote:

Originally Posted by CosmicBike

The fun continues...

No real progress made, so instead I stripped the front end of the Capri in preparation for removing/repairing the wings.

... the Capri sounds like fun, I am quite envious of that one :-)

Stephen Edwin · May 12th, 2020, 16:15

Cosmic.

I can find on my desktopa a PDF of the Volvo Service Manual, the Green Book, section 2(23) . 1989-19..
It covers the LH 2.4 system for the 240 B230F. It is USA version but I'm told the essentials are the same as the UK version.

It specifically includes fault tracing.

You might like to message me to tell me your email address.

I hope this might help.

.

CosmicBike · May 12th, 2020, 21:08

Quote:

Originally Posted by Stephen Edwin

Cosmic.

I can find on my desktopa a PDF of the Volvo Service Manual, the Green Book, section 2(23) . 1989-19..
It covers the LH 2.4 system for the 240 B230F. It is USA version but I'm told the essentials are the same as the UK version.

It specifically includes fault tracing.

You might like to message me to tell me your email address.

I hope this might help.

.

I'd appreciate that very much. Grace hasn't been touched for a while, I've been isolated for 12 weeks so working from home....

Apr 30th, 2020, 20:13	#93
Othen Premier Member Last Online: Yesterday 22:45 Join Date: Jan 2020 Location: Corby del Sol	This is a really interesting thread. This won't help you much: I don't know much about the later fuel injected engines - so I can't really help except to say the rough running sounds like a fuel/air problem (so not the ignition module/distributor etc). I am so glad I have an earlier 244 with a really simple carburettor; much of the allure of the 244 for me is its simplicity - no computers and very few sensors... big bits of wire, lumps of solder, simple mechanical things and lots of room. Many things can be fixed with a Leatherman and a piece of wood. Apologies: that didn't help much; I think it is a fuel/air problem but I have no suggestion as to how you might diagnose or fix it. Good fortune, Alan Last edited by Othen; Apr 30th, 2020 at 22:31. Reason: Fat fingers.

Apr 30th, 2020, 19:36	#91
CosmicBike Senior Member Last Online: Yesterday 13:27 Join Date: Dec 2019 Location: Surrey	Been focussed on fitting a new garage door the past few days, so with that and work not had much play time with Grace. Issues go on. She is still driveable, but the first mile or so is very lumpy, and there is a hint of misfire even when warm. Engine Management light came on yesterday, and I got a 1-4-4 code, 'Load Signal Missing From LH Unit'. A new code for me, some digging suggests maybe a fuel relay issue along with other bits. Relay removed, checked over, contacts cleaned, fault code cleared. Rough, almost stalling idle persists, and engine will not rev intermittently. Almost all the faults seem to vanish above 2500 rpm. Disconnecting the MAF and starting gives a very steady 600 rpm idle with no misfire and no issues with reving through to 4000rpm. 1-2-1 code correctly shows on the diagnostic box with the MAF disconnected. I have a little more fiddling to do, there are some voltages to check in a few places so when the weather improves I'll sense check those bits. She does at least run and drive, so nothing that can't wait.

Apr 30th, 2020, 20:01	#92
CosmicBike Senior Member Last Online: Yesterday 13:27 Join Date: Dec 2019 Location: Surrey	Detail cut and pasted from the VolvoClub FAQ's Testing AMMs and Calibration. This is a response from Python Injection (rebuilders of AMMs) to a question about testing AMMs. From: Joe Evert, Director of Engineering, Python Injection Subject: Re: Technical Question about AMM The reason the OEM doesn't give a test procedure for calibrating the air mass meter is two fold. First of all BOSCH Hot Wire Air Mass sensors are not linear devices like a throttle position sensor. The output does not change the same amount for a given air change. To make it short, most linear sensors will give you say... 1 volt for 100cfm air flow, 2 volts for 200cfm air flow, 3 volts for 300cfm airflow etc. This is a linear device. Bosch hot wire sensors are not like this. They change a great deal at low air flows but once the air flow increases past a certain point, say 50% of what the engine can draw, they change very little. This makes the sensor very accurate at low to moderate air flows and good enough at high air flows. Just a small amount of inaccuracy at low RPM and the vehicle will run terrible. If the voltage for a given air flow is off by 100 milli volts at low RPM the car will barely run. At high RPM A 100 milli volt deviation will not even be noticed. Because of this it makes it next to impossible for the technician to accurately diagnose the air mass in the field. We use a calibrated flow bench that measures the exact CFM air flow to then compare the voltage to. This is not practical in the field because temperature, altitude, humidity and the mechanical condition of the engine will affect how much air the engine is drawing in. So just to say that the Air mass should have xx.xx volts at idle would be completely false since all these parameters must be accounted for. Also even if a range is given just a small amount of deviation in the output causes poor performance. So what are you to do? For on-vehicle diagnoses the best way is just unplug it at idle; if the vehicle runs better it is most likely bad. This is because if the air flow sensor is off voltage at high RPM it will also be off at idle. Also if you are experiencing repeated failures you probably have a defective air box thermostat. This little thermostatic bulb is located in the air filter box and controls the hot air into the engine. When this fails it fails in hot air mode and routes hot air from around the manifold into the air intake. This will destroy the air mass meter in no time. There is also some info on testing the MAF, Terminal 1 to ground should be 0 Ohms with the MAF disconnected, and Terminal 3 to ground should be 2.3volts with the engine running. Something to look at.

May 1st, 2020, 12:17	#96
Stephen Edwin Premier Member Last Online: Oct 26th, 2023 20:42 Join Date: Jun 2010 Location: Thurrock	BUMP Where are the usual advisers re diagnosing LH2.4 type issues please? .

May 2nd, 2020, 18:31	#97
CosmicBike Senior Member Last Online: Yesterday 13:27 Join Date: Dec 2019 Location: Surrey	The fun continues. Tested the MAF in line with the info found on VolvoClub and Haynes manual, all checks out perfectly. The brief 'burn off' is also working when you switch the engine off too. Other things today. Tested the knock sensor, got 0.0v when back probing with ignition in Pos II, Haynes book says circa 5v. Sensor itself disconnected has a resistance on 0 Ohms. Running the engine with a timing light on the crank pulley should show a retardation of timing if you knock the block or intake manifold, I saw no change. Running with the knock sensor disconnected made no difference to running. No real progress made, so instead I stripped the front end of the Capri in preparation for removing/repairing the wings.

May 12th, 2020, 16:15	#99
Stephen Edwin Premier Member Last Online: Oct 26th, 2023 20:42 Join Date: Jun 2010 Location: Thurrock	Cosmic. I can find on my desktopa a PDF of the Volvo Service Manual, the Green Book, section 2(23) . 1989-19.. It covers the LH 2.4 system for the 240 B230F. It is USA version but I'm told the essentials are the same as the UK version. It specifically includes fault tracing. You might like to message me to tell me your email address. I hope this might help. .

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