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I have a 240 wagon that hesitates terribly from a dead stop if you accelerate quickly. I have changed the air mass meter, spark plugs, plug wires, distributor cap & rotor, all the small vacuum hoses and the air filter. This has made no difference. Actually when I originally changed the air filter it made a big difference but it is still clean and it still hesitates. I would love to get some feedback on what the problem might be.
Thanks
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You might want to check the individual contacts in the connector for the AMM. These some times push backwards in the connector to the point they do not make contact with the AMM contacts.
Dan
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"I have a 240 wagon that hesitates terribly from a dead stop if you accelerate quickly"
Possibly weak ignition? Try replacing the ignition amplifier.
I don't know why IA's were introduced. Previous 240s run well without them. (Machine man, care to comment?)
Also check the voltage output of the O2 sensor. If it is continuously below .45V you may be running lean.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.
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I have had no problems with 5 240's related to the power stage / ignition amplifier. I do however have several known good spares just in case.
Dan
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The power stage / ignition amplifier is merely one single-coil step up transformer or huge transistor on a heat sink, yeah?
I'd imagine it'd be working or no.
Spares are good.
Sorry to do teh theroizin'.
cheers,
Duff Kitty
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Yes I can make a comment that you have a very valid point about the Ignition Amplifier.
I agree that seems to be an extra middle man in the scheme of things made over the many years!
I have made similar comments, like you just did, in past posts and more or less wrote it off as a total system revamp or upgrade in the electronics world to be better.
My excuse was that those components of the I/A handle more current and may be problematic. Having it separate makes for easier replacement or as we know getting serviced with heat sinking paste.
Imagine if they built it all into the one box that's under the glove box. Could say a lesson learned from the under the hood unit mounted directly forward of the exhaust header. Behind a battery, closer to the ignition coil, if that makes a difference and away from sources of radiate heat!
I really have limited knowledge of the real workings going on inside.
Art says I give him trouble in that I "speculate & theorize" somewhat.
I agree with him but always try to do it from what I do know and believe to be facts within a world realm of manufacturing and production of products for a purpose.
I only entertain myself and I keep a lot of it in my head but in conversations it leaks out. Writing is rather new for me, an experimentation if you will.
I think, I am like most people, quiet until you get me on my subjects of interest.
Art, in my opinion only, is more zoned into cracking it open and doing an analysis. He is a man that can write you a dissertation on anything he has a desire to do!
Compared to him, I am lazy and it probably does drive him nuts!
I suggest that our beloved Art Benstein, our electronics guru, could offer you up a far better technical explanation to your question.
Ask as you did to me! You will be better informed and not as glossed over as I do!
Thanks
Phil
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Uncle Gargano,
In addition to the other useful comments the other posters direct you in your diagnosis and investigation, may I suggest you check the OBD-1 for fault codes. The OBD-1 code reader is on the North American market driver side strut tower, rear, adjacent to the the brake master cylinder vacuum boost servo.
https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm
The Bosch LH-Jetronic 2.4/3.1 (3.1 with manual trans and no EGR on that 1992 240) and Bosch EZK ignition system will display faults in the event fault conditions exist in the system. The OBD-1 is invaluable, yet not faultless as a diagnosis tool. The engine control systems can be rather fault tolerant and have some leeway in compensating for less than ideal sensors and running conditions. I'll bet you find fault codes.
You may want to search the active brickboard article and the ARCHIVE at
https://www.brickboard.com/ARCHIVES/. Search for threads and posts using the symptoms you are having.
You may also want to check the following pages relevant to the engine control systems your mighty, if awesome, 1992 Volvo 240, shares with the Volvo 700/900 series in the now freshly updated 700/900 FAQ hosted right here for your convenience on the brickboard.
https://www.brickboard.com/FAQ/700-900/
A few other 700/900 FAQ pages you may want to acquaint yourself with:
* https://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm
* https://www.brickboard.com/FAQ/700-900/EngineSensors.htm
* https://www.brickboard.com/FAQ/700-900/ElectricalIgnition.htm
* https://www.brickboard.com/FAQ/700-900/EngineFIComputer.htm
* https://www.brickboard.com/FAQ/700-900/EngineFuelinjection.htm
* https://www.brickboard.com/FAQ/700-900/Exhaust.htm (Exhaust leaks in front of the 02 sensor location)
If not already in your possession, you may want to acquire the:
* Blue Bentley Volvo 240 service manual bible
* The Volvo 240 OEM green factory manual (PDFs abound on the i-net, eBay, and so forth (search brickboard articles for hints, hint-hint)
* Or the Haynes 240 (ugh), or Chilton and Clymer (Ugh) 240 manuals. Just be careful with fluid specifications or ambiguities as to assembly or diagnosis.
(Like incorrectly calling out Dexron III for your 240 series power steering fluid or the front hub assembly information. Use Ford "Type F" for your power steering fluid.)
As for diagnosis suggestions.
- Disconnect the silver accordion hose that connects the exhaust port (manifold) mounted heat shroud to the bottom of the air filter box. The thermosat in the air filter box has failed by now forcing incredibly hot air, in Summertime no less, to run past that frail AMM (or MAF sensor). If you state or nation performs a visual inspection of emissions controls, you can block the preheated air at the flap in the air filter box, replace the thermostat in the air filter box (avoid made in crappy CHINA versions), or glue or seal the hot air inlet shut.
- See https://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm#SlightHesitationonAccelerationSeveralDiagnosticChecks
- Check the fuel injector ground wires. A Volvo technical service bulletin. ON air intake port (manifold) runner #2 & #3 are each a set of two brown color wires crimped to a ring terminal and retain to the aluminum alloy intake port material. You may want to merely loosen and retighten. Add a touch of No-OX or De-ox around the terminal and under the bolt head. The Volvo TSB recommend flowing solder into the ring terminal crimp to minimize any continuity resistance to ground. (All Volvo owners with LH-Jet, Motronic, the Rex/Regina [king / queen?] system ensure the perfect ground for their electromechanical fuel injectors.)
- Verify 02 sensor connection, operation, and that you have no exhaust leak in front of the 02 sensor location at the front of the catalytic converter. The exhaust system union in front of the catalytic converter is a weakness and require recurring inspection. Also, verify the bracket that supports the header pipe weight in front of the header pip / catalytic converter union is secure. That mechanical connection serves as a ground for the 02 sensor. It's also sort of unsafe with an exhaust system flapping in the breeze as you tool the freeway at freeway speeds. The three sets if exhaust manifold to header-pipe retaining hardware (13, 14, 15 mm deep well hex socket) can loosen over time, yet not cause damage to the exhaust port to header pipe gasket damage (we hope).
- Uncle Volvodad already suggested cleaning the throttle body assembly and replace with new gasket.
- Uncle machine man suggest verify the heath of the fuel rail fuel pressure regulator (FPR). A failed unit will leak fuel into the connected vacuum line that secure to the throttle body, I think.
- With your check of the OBD-1 code reader at sockets 2 (fuel) and 6 (ignition), faulty knock sensor, throttle position sensor, coolant temp sensor, and other sensors may reveal a cause. With a multimeter you can verify whether sensors are faulty.
- Engine control system wire harness faults and connectors, connections to ground, or corroded connectors.
There may be other causes and suggestions others reply with.
A Blue Bentley Volvo 240 service manual bible helps as do the Volvo OEM factory green manuals.
Questions? Comments? A glass of fresh ultra lemony iced sun tea with nice Ceylon or Darjeeling tea?
Kitties? Fuzzy kitties? Extra fuzzy kitties? No, ultra fuzzy kitties (wishing they did not have fur coats)!
Damned Heat Makes me a Grumpy.
--
When in Oregon, never forget the Oregon Volvo Tuners!!!!!
Oregon Volvo Tuners: We help to establish and preserve your Volvo engine tuning in Oregon and beyond!!!!
On to the LOLz:
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I have a few questions as I see you are new and have zero postings.
Is this car new to you as in used and bought recently or has been good until recently? I gather from the filthy air filter, this car is new to you.
Am I wrong in this assumption? We know where that leads us armchair mechanics! (:-)
When you changed the AMM did you get the same numbered one or did you check to make sure its the one for that year car? It may have been swapped earlier!
The AMM is a big leap to purchase. What were the symptoms to prompt the change out?
What condition is the FPR or Fuel rail Pressure Regulator? It enriches fuel flow under acceleration.
What condition is the rear of the exhaust system?
How old is the oxygen sensor in the catalytic converter and do you know how old it is as well?
Have you done the other service maintenance mentioned in the other posting, before on this car or any other like it? Some experience background is helpful.
Can you determine the mileage on the engine or the car as a whole for future reference in your posts?
Welcome aboard this humble and friendly site!
Phil
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Sometimes a big improvement after replacing a part is not due to the part, it's due to "moving things around". This can mean that a bad connection was unplugged/plugged and thus fixed, a leak was solved by reassembling hoses and tightening clamps, etc.
A possible cause is an air or vacuum leak which the ECU can compensate for under steady conditions such as cruise or idle, but not when the throttle and engine speed and load are changing.
A couple of things to try - and cheap! Remove and clean the throttle body (TB), and when you reinstall it with a new gasket, be sure the throttle switch makes the prominent CLICK when you barely open the throttle from its closed position. Second, check the flex ducting from the Air Mass Meter to the TB. When you remove it to clean the TB, inspect all the folds for cracking and splits. The splits like to hide down in the bottom of the folds - look closely.
Similarly check the hoses to and from the Idle Control Valve.
--
Bob: Son's XC70, my 83 240, 89 745 (V8) and XC60. Also '77 MGB and some old motorcycles
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