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240 High idle after highway run lh2.4

Neat Roy, but here is what the Green book 2.4 service manual says. Unless I am reading it wrong sure seems like it don't work if tps clicker ain't clicking right or ain't closing all the way. Yeah ECU don't care, but if throttle body not closed all the way then motor revvvvvs higher...
Enlighten me please ohh glorious moderator. Maybe your bible is a different version perhaps if you even got one....










Book says idle mainly controlled by engine temperature, maybe your temp sensor bad.
 
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I chased this same problem for a while, several years ago, code 3-1-1 and 1500-1700 rpm idle speed after operation over 2800 or something like that. Turns out the replacement cluster I thought was the same was actually only similar: most functions worked, but there was no VSS signal from the cluster to the LH. I would check the circuit board that the speedo is mounted to and make sure there are provisions to send the signal on to your LH unit. I was able to just do this visually and confirm that was where my problem was. A known correct cluster circuit board resolved the problem.

My experience with improperly adjusted TPS/throttle blade is an idle speed of about 1000 rpm, give or take, and no code.

Hope this helps, this type of stuff can be frustrating in its apparent simplicity but elusiveness. Much like the small block Chevy, also, they aren't quite "all the same", so be sure of what you've got and what you're using for diagnostic information.
 
^sounds frustrating to be sure.

You?re probably aware with the benefit of hindsight/more commonly available circuit diagrams now, that you didn?t need to change the cluster circuit board. The clusters have a double spade connector output for connection to a cruise control that is the same speed signal that the ecu needs for 2.4lh to function properly.

I posted above with the location of the connectors- that just needs to be connected to pin 34 on the ecu and that?s it.

Cheers
 
sbabbs said:
Neat Roy, but here is what the Green book 2.4 service manual says. Unless I am reading it wrong sure seems like it don't work if tps clicker ain't clicking right or ain't closing all the way. Yeah ECU don't care, but if throttle body not closed all the way then motor revvvvvs higher...
Enlighten me please ohh glorious moderator. Maybe your bible is a different version perhaps if you even got one....










Book says idle mainly controlled by engine temperature, maybe your temp sensor bad.
Click to expand...

I have 20+ years of experience servicing hundreds of Volvos running LH 2.2, 2.4 and 3.1. Volvo may have intended for the system to work the way they describe in your "Bible", however, in the real world, it doesn't. I just replaced a faulty TPS on a customer's 940 3-4 weeks ago. The idle had been set by opening the throttle plate via. the stop screw. The TPS was deader than a door knob. The idle was ~ 700 against the stop in neutral, ~ 600 RPM in gear. I replaced the TPS, set the throttle plate to 1/2 turn of the screw off of fully closed. The car started right up and settled to an 800-1,000 RPM idle no matter what the load. I've seen them exhibit this behavior too many times to count on my fingers alone. So far, I have never seen an LH car behave the way the manual says they will. IOW, your circled text.
 
Well 2021 ended with progress somewhat
Went to Groanman's and plugged his oscilloscope: we found out that there was no speed signal coming out of the cluster back to the ECU
Swapped the odometer unit with a good one (tested and a signal was coming out) the engine was still idling a bit high at around 1000rpm
So we adjusted it through the throttle body screw and it sat around 750-850 rpm
After several test runs at over 3000rpm it always came back to normal so I felt pretty confident and drove back home: 40 km of keeping the revs up over 3000rpm and checking it came back to normal... until I got about 3 blocks from home... it idled back at 1000rpm and did not reduce. When I turned it off and on again it was back to normal
At least its not 1500 like before...
 
Prime240 said:
Well 2021 ended with progress somewhat
Went to Groanman's and plugged his oscilloscope: we found out that there was no speed signal coming out of the cluster back to the ECU
Swapped the odometer unit with a good one (tested and a signal was coming out) the engine was still idling a bit high at around 1000rpm
So we adjusted it through the throttle body screw and it sat around 750-850 rpm
After several test runs at over 3000rpm it always came back to normal so I felt pretty confident and drove back home: 40 km of keeping the revs up over 3000rpm and checking it came back to normal... until I got about 3 blocks from home... it idled back at 1000rpm and did not reduce. When I turned it off and on again it was back to normal
At least its not 1500 like before...
Click to expand...

Story leaves the question: Was the behavior consistently paired with the 311 code set? Thought you had already swapped speedometers or clusters several times?
 
You don't adjust the idle on LH 2.4 via. the throttle plate stop screw. The IAC does all of the idle control. That's why it still isn't idling correctly. Back the stop screw out until the throttle plate is completely closed. Then, run the screw back up to the lever arm until it is solidly against the arm, yet, doesn't move the arm. The throttle plate should be completely closed. Now, turn the stop screw 1/2 turn in the direction that opens the throttle plate. Tighten the lock nut. Next, re-set the TPS. This will allow the ECU to properly control the IAC and keep your engine at the proper idle speed.

https://www.brickboard.com/FAQ/700-900/EngineSensors.htm#ThrottlePositionSwitch
 
cleanflametrap said:
Story leaves the question: Was the behavior consistently paired with the 311 code set? Thought you had already swapped speedometers or clusters several times?
Click to expand...

I did, several times, at least 3 different clusters where tried priot. Where they all bad? Cant tell cuz had not plugged an oscilloscope on all of them
Even 2 days ago we had to try two different units before we found one with a signal going back out to the ecu

You just made me realize we completely forgot to reset & check for codes
Thx for the feedback
 
2manyturbos said:
You don't adjust the idle on LH 2.4 via. the throttle plate stop screw. The IAC does all of the idle control. That's why it still isn't idling correctly. Back the stop screw out until the throttle plate is completely closed. Then, run the screw back up to the lever arm until it is solidly against the arm, yet, doesn't move the arm. The throttle plate should be completely closed. Now, turn the stop screw 1/2 turn in the direction that opens the throttle plate. Tighten the lock nut. Next, re-set the TPS. This will allow the ECU to properly control the IAC and keep your engine at the proper idle speed.

https://www.brickboard.com/FAQ/700-900/EngineSensors.htm#ThrottlePositionSwitch
Click to expand...

Alright! Thank you. Will do this
 
Okay so the TPS does matter then? Wow all I said was check it make sure it working... You saying you got 20 plus guess what I got 30 plus from 1990 auto docktor in Goshen volvo specialist is where I learned from the doc worked there for years, not any bible, a real persona. So your final decree is to make sure TPS is set correctly? Okay boss... Ha. All my first cars where fords. 65 fairlane sport coupe totaled into a bus first time ever drove it to school.. 64 mercury Marauder pikes peak champion ford FE motor. Few 351c torinos.
 
2manyturbos said:
You don't adjust the idle on LH 2.4 via. the throttle plate stop screw. The IAC does all of the idle control. That's why it still isn't idling correctly. Back the stop screw out until the throttle plate is completely closed. Then, run the screw back up to the lever arm until it is solidly against the arm, yet, doesn't move the arm. The throttle plate should be completely closed. Now, turn the stop screw 1/2 turn in the direction that opens the throttle plate. Tighten the lock nut. Next, re-set the TPS. This will allow the ECU to properly control the IAC and keep your engine at the proper idle speed.

https://www.brickboard.com/FAQ/700-900/EngineSensors.htm#ThrottlePositionSwitch
Click to expand...

Well? 1step forward to steps back? did this to reset the throttle and now the car idles steadily? at 1500rpm? FML
 
Have you ever tried running a different IAC? I had a car that behaves like that one time and swapped to a different IAC and it worked fine.
 
My 1994 940T was giving trouble, including occasional high idle. Codes were 1-1-3 and 2-3-1. The exhaust smelled of gasoline, indicating a rich mixture. I replaced the O2 sensor and the ECT sensor, but the problem remained. I replaced the AMM with a used unit, and the car runs well.
 
93618068_3705919662816648_5328266307781525504_n.png


It's finally solved
thanks to Groanman's painstaking and thorough work it now idles quietly at 7-800rpm

Car was giving code 2-3-1 Adaptive fuel trim too lean or too rich in part-load range
Started by taking the throttle body off and making sure it was perfectly reset and clean
Checked and cleaned idle control valve
Cleaned the MAF
reset codes

Check engine and code 2-3-1 kept coming back but right away... like as soon as you started the car not even idle for 1 min

Keep in mind we had made sure in the past that we had no vacuum leaks of any kind with a "smoke machine"

So we swapped the ECU

Problem solved

First time in 20 years of 240 ownership that I have to swap an ecu but hey... now it works!

Thx again Groanman!
 
I had a very similar problem. My '93 240 B230F M47 would report a 3-1-1 error at speeds higher than 3000 and idle at double that until the ignition was turned off. The problem was in the speedometer signal output from pin 31/6 to ECU pin 34, caused by a faulty chip in the speedometer. After replacing the chip everything is fine.

IMG-20220207-183313-5.jpg
 
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Petr Marek said:
I had a very similar problem. My '93 240 B230F M47 would report a 3-1-1 error at speeds higher than 3000 and idle at double that until the ignition was turned off. The problem was in the speedometer signal output from pin 31/6 to ECU pin 34, caused by a faulty chip in the speedometer. After replacing the chip everything is fine.

IMG-20220207-183313-5.jpg
Click to expand...
where did you get that chip? have the same problem. thanks in advance.
 
The chips seem to be readily available from multiple sellers on ebay:
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It's such an odd-ball chip, in an odd-ball package, that I wouldn't expect them to be counterfeited. They might be pulls from unused PCBs, but they're cheap enough and available in large quantities, so I'd expect they're NOS.

The 2nd line on the chips is usually "GERMANY", but I think I've seen Volvo 240 speedos with a 2nd line of "G ######" (my old pictures aren't good enough to make out the ###### numbers).
 
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