1989 740gl onboard codes

hapoo · Post by **hapoo** » 10 Apr 2006, 21:46

first off i am a new user but have been coming here for months and your archives have been very helpful.
My car is about to get junked it has been broken more then ran since i bought it in July (on advice from other volvo owners in my family, they always have better luck then i do though!)
I have had problems with the AMM and replaced it twice (first new second used) & ended up buying a used back up. It is still acting like it is the AMM but slightly different. It starts fine but if you let it warm it has a rough idle and trys to stall out if you hit the gas it is ok but still idles rough. If you put it into drive it stalls out but you can catch it from stalling by putting it in neutral and tapping gas but you will only make it a few feet! I have just recently been told by a old friend that their is a onboard diagnostic, he told me insert into 2 then press, etc etc. I did that and got 111 after looking online i saw that i should also insert into 6 when i did that it said 234. Well i think that is the throttle sensor but other people said that i my car does not have one. I live in a small town now and miss the city even more since there is no one that wants to work on volvos locally. Any advice would be great, I have personally changed alternator, battery, dist. cap & rotor, AMM (x2), air filter, plugs & wires and brakes (not relevent to this really though) & belts. I have a fuel filter but it is now just getting warm enough to do that (it is colddddd in new england!).So any advice would be appreciated!

thanks--Heather

wojeepster · Post by **wojeepster** » 12 Apr 2006, 16:11

heather when you replace the air mass sensor it is important to check the thermostat for the air box (not coolant thermostat) when this thermostat fails it feeds the air mass sensor with hot air and it will fail again! You can unplug the flexable hose that goes over to the exhaust it supplies warm air when first starting. . Your car does have a throttle position sensor and when it goes bad you can have the conditions you describe. It can be checked out with a volt ohm meter before you decide to replace it. Checking before replacing is cheaper! With key on the voltage to one of the wires should smoothly increase with a smoothly opening throttle. One wire is ground and one wire is 12v or 5v/ I hope I have not confused you. For a much better description on how to check a throttle position sensor I recommend Tracy martins book, "how to diagnose automoblile electrical systems" it is simply the best book I have read on automoble electrical systems. You can buy the parts you need from www.fpcgroton.com they have low prices. Try not to give up on it yet.

hapoo · Post by **hapoo** » 13 Apr 2006, 20:09

ok well i think that i am going to change my cousin had one (i called to make sure its right, it's new too!) he totalled his about 2 months ago. Is there anything i need to know about changing it? My cousin said i have to buy a special volt tool because it has to be adjusted? Then someone said that there is a period that it takes to relearn or some weird thing? any advice, it looks simple to remove & replace, if it just goes on and thats it. But is there more to it then that?
wojeepster, by the flexible hose are you talking about the one the only connects on one side and looks like aluminum accordian blows on the opposite side as the air box.
Also someone said to check idle air control valve, where is that? And also maybe fuel pressure? ahh i remember working on my uncles truck and thinking how easy it was! I enjoy the challenge but hey i'd like to drive her!
Thanks