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Car Forum / Volvo Cars / March 2007J Sweet: which component to check?
Re: 92 740 wagon B230 turbo LH Jetronic.... Ok...I finally ran my own tests today. Spark is strong to all 4 cylinders. Fuel pressure in the rail is 42 when cranking. I lifted the entire fuel rail/injectors up and watched them while cranking. They are not leaking fuel. When cranked they are spraying a LOT of fuel, I think it is way too much, from the first shot on. It remains the same large volume no matter how long you crank. So I figured out what is happening. On the first attempt to start car, it "fires" like it is going to start for about one second, then nothing--- because the cylinders are being flooded with gas. This is why it will not fire again at all unless the car sits for a day. Whatever it is, it was making the car run rich for a couple of months or so. Ocasionally during this time, the defect would get suddenly worse, and the injectors would go to max, flooding the engine...causing it to die while driving. I have a strong supspicion it is a bad or missing sensor input, probably not the ECM itself that is causing this. But....the ECM is not setting any codes to show what fuel control component is bad. THe crummy 82-88 740 Haynes manual I have says there are six inputs to the ECM that control fuel delivery/mixture: AMM, ECT, 02 sensor, plus an air control valve and transmission and charge overpressure switch. Problem is, I don't have specific info on how to test these components. Is there perhaps one component that, if bad, would make the injectors go full rich on cranking? I think that when a car *runs* rich, most likely thing is a bad O2 sensor...but doesn't the control system ignore the O2 sensor until the engine is up to operating temp? That would mean that it is not the culprit in this case. Thanks, Geronimo [ ... ] > THe crummy 82-88 740 Haynes manual I have says there are six inputs >to the ECM that control fuel delivery/mixture: AMM, ECT, 02 sensor, >plus an air control valve and transmission and charge overpressure >switch. > Problem is, I don't have specific info on how to test these >components. Is there perhaps one component that, if bad, would make >the injectors go full rich on cranking? [ ... ] Try disconnecting each sensor, one at a time, and see if one changes the behavior to limp-home mode. While you're at it, clean the contacts on each and make sure they're making a good connection. Gary  SignatureGary Heston gheston@hiwaay.net http://www.thebreastcancersite.com/ "The message should go out loud and clear that we are a tolerant country and we will not tolerate racism in this country." Tony Blair, UK PM Can't observe any change to limp-home mode when the car won't even start. Geronimo > [ ... ] >> THe crummy 82-88 740 Haynes manual I have says there are six inputs [quoted text clipped - 14 lines] > >Gary After what I went through with my '90 240, when people start a sentence with, "it was running OK, but then it..." I interrupt with "AMM." It drove me crazy when mine failed. I spent a week testing everything I could with an ohm meter and such according to Bentley. Since I live a good 25 miles from anywhere that could work on it or even just test it, I had to troubleshot it myself- it wasn't running well enough to drive anywhere safely. It would post a bad AMM code SOMETIMES but not all the time. If you can find a pick and pull yard, pick one up and switch it. Worst case is then you would have a spare, or one to sell on eBay. I bought 3 at the local yard- one to replace the bad one, then I picked up two more- one is in the car as a spare and one for the box of parts in the garage- you NEVER know... ;-) __ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate" > >Re: 92 740 wagon B230 turbo LH Jetronic.... [quoted text clipped - 31 lines] > >Thanks, Geronimo Well, I have another AMM which I kept when my 89 Volvo 740 non-turbo sedan died. It looks physically identical to the one in the wagon. There are two rows of numbers, the upper shorter number is different, but the very long number below is identical. So I am not sure if I can use this one inthe wagon--- 92 740 *turbo*. It might have different air flow from the sedan, since it is a turbo intake. Could kick myself for not removing the ECU from the sedan also! The other thing that will prevent it from starting is a bad crank pos. sensor, It is a new one, but still could have failed, so I guess I will check taht. Chilton says it is supposed to be between 200-500 ohms if good. Don't have a clue whether it could make the mixture way to rich , though. Also I need to know for sure which one of abt four emisson control/ECU systems the wagon has. I think it is LH Jetronic.... do I need to look on the ECU itself to verify? The other thing is that I got this CHilton manual today, and it shows the LH jetronic as having a SEPARATE fuel control module....although no parts dealers are listing a fuel control computer available for this car. Then elsewehere in the same manual it says that it is the ECU that sends the signals to the injectors. Thanks Geronimo >After what I went through with my '90 240, when people start a >sentence with, "it was running OK, but then it..." I interrupt with [quoted text clipped - 50 lines] >> >>Thanks, Geronimo > Well, I have another AMM which I kept when my 89 Volvo 740 non-turbo > sedan died. It looks physically identical to the one in the wagon. [quoted text clipped - 8 lines] > ohms if good. Don't have a clue whether it could make the mixture way > to rich , though. What are the numbers? I wouldn't trust ohm readings on sensors other than those for temperature, and I certainly wouldn't trust Chiltons. I doubt a crank sensor would make it go full rich. Have you tried connecting a 12V bulb to an injector plug and see if it glows with the key on but the engine not cranking? The injector rail is pulled up. I put a noid light on each injector, and it does not flash until cranked, and none of the injectors are leaking---they are all closed as they should be until cranked. I think they are spraying way to much fuel from the first pulse. SO that is why I am concentrating on some sensor component in control system. I got a Chilton as that was what was available from local store, I hear there is some Bentley manual, probably a lot better (don't know where to get) and I have the link to site with the actual electrical diagram----but pricey at $40. >> Well, I have another AMM which I kept when my 89 Volvo 740 non-turbo >> sedan died. It looks physically identical to the one in the wagon. [quoted text clipped - 17 lines] >Have you tried connecting a 12V bulb to an injector plug and see if it >glows with the key on but the engine not cranking? > The injector rail is pulled up. I put a noid light on each injector, > and it does not flash until cranked, and none of the injectors are [quoted text clipped - 6 lines] > where to get) and I have the link to site with the actual electrical > diagram----but pricey at $40. And you're sure it has a spark? Fuel flow with no spark will cause wet plugs as well. Well, I got one of those adjustable spark-gap testers that has ground clip, and checked each spark wire. Each one has a spark with it set to 20mm. I know it is a long shot, but would it be possible that the spark tests OK with the tester, but I am losing spark under compression, in actual operation? The only way I can think of to test whether they are still actually firing under compression would be to read current through the high-tension lead from the coil....but I have no gadget to do that. If there is voltage, but no current flow, then they have stopped firing. Plugs are new/clean. The distributor cap and rotor are new, but it has an old coil. It wouldn't be a bad idea to just replace it, since it is old....can I install a better quality high-output one than OEM? recommendation? >> The injector rail is pulled up. I put a noid light on each injector, >> and it does not flash until cranked, and none of the injectors are [quoted text clipped - 9 lines] >And you're sure it has a spark? Fuel flow with no spark will cause wet >plugs as well. > Well, I have another AMM which I kept when my 89 Volvo 740 non-turbo > sedan died. It looks physically identical to the one in the wagon. [quoted text clipped - 19 lines] > > Thanks Geronimo Since you don't say where you are, I'll assume you're in the US. Air mass meters are compatible for both turbos and non turbos with LH2.4. Non turbos started in 1989 model year (both 8 and 16 valve), turbos didn't get LH2.4 until 1990 model year. Exceptions are 8 valve non turbo 740s and 940s with Regina fuel systems (no air mass meter) and some later manual transmission 240s with LH3.1, which has a thin film type air mass meter, (looks completely different inside) as opposed to the hot wire type on LH2.4. So it sounds like your air mass meters are interchangeable. SignatureMike F. Thornhill (near Toronto), Ont. Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) Try searching the archives http://groups.google.com/group/alt.autos.volvo/topics for the following threads of a year and a half ago from my problem and solution: - save me from running around.... - still having problems with my 240 - Still trying to get it running right - AMM - more Q's - It's RUNNING! See if any of that rings a bell or three... __ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate" Before trying my spare AMM from my defunct 89 non-turbo 740, please confirm whether its compatible or not. there are three rows of numbers. The top numbers are different, but the lower two numbers are exactly the same. here is number on the 92 turbo wagon AMM: 489 30 1A 0280212016 3517020 here is number of the 89 volvo AMM: 281 10 1A 0280212016 3517020 Can I assume if the top numbers don't match it's not compatible and might fry the computer? No code such as 1-2-1 is being set for bad AMM. Thanks Geronimo >Try searching the archives >http://groups.google.com/group/alt.autos.volvo/topics [quoted text clipped - 11 lines] >'90 245 Estate - '93 965 Estate > "Shelby" & "Kate" The other thing I need to know urgently, while fuel rail is pulled up, is how much gas should an injector pump out when cranked for, say 30 seconds, for normal operation? If I knew, this I could verify whether the fuel controls are screwed up, putting out way too much gas like I am thinking. |
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