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Car Forum / Ford / Ford Cars / December 2005How to tell when overdrive engages on 87 Aerostar
I've recently started driving my 87 Aerostar again and I suspect it's not quite getting the fuel economy it once did. Everything seems to be running fine but I do notice the transmission doesn't do the same pattern of shifting when I go up a certain long hill. How can I tell if the overdrive is kicking in? Count the number of times it shifts during a long acceleration on a flat grade? > I've recently started driving my 87 Aerostar again and I suspect it's > not quite getting the fuel economy it once did. Everything seems to be > running fine but I do notice the transmission doesn't do the same > pattern of shifting when I go up a certain long hill. How can I tell > if the overdrive is kicking in? Count the number of times it shifts > during a long acceleration on a flat grade? didnt you answer your own question? What happens when you move shift selector down a notch to D, rather than OD? Any OTHER errata? like idle problems? If so, check the TPS.  SignatureYeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price you pay..DEAL with it! >> I've recently started driving my 87 Aerostar again and I suspect it's >> not quite getting the fuel economy it once did. Everything seems to be [quoted text clipped - 9 lines] > >Any OTHER errata? like idle problems? If so, check the TPS. You could always through an OBD scanner on it and see what gear it is in at any time, as well as if it is locked. >>> I've recently started driving my 87 Aerostar again and I suspect it's >>> not quite getting the fuel economy it once did. Everything seems to be [quoted text clipped - 11 lines] > You could always through an OBD scanner on it and see what gear it is > in at any time, as well as if it is locked. Nope, that kind of data wasn't available on an 87 Ford of any kind. Bob I'm having trouble with the acronyms today. What's an 'OBD' scanner? > I'm having trouble with the acronyms today. What's an 'OBD' scanner? OBD = On Board Diagnostics. Your vehicle has a drivetrain scanning ability built-in. In the case of FoMoCo vehicles from '84 thru (most) '95, it's called EEC-IV, and a digital scanner is about $35. As far as knowing if you're in OD or not, just listen to the engine. In OD at 60 mph, it shouldn't sound like more than a warm-up (fast) idle. Sorry, I know this must be a newbie question. What's 'TPS'? > > I've recently started driving my 87 Aerostar again and I suspect it's > > not quite getting the fuel economy it once did. Everything seems to be [quoted text clipped - 13 lines] > Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price > you pay..DEAL with it! see info post on glossary terms: Throttle Position sensor, opposite the throttle butterfly crank And do you mind answering the other questions so we can help you out? > Sorry, I know this must be a newbie question. What's 'TPS'? > SignatureYeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price you pay..DEAL with it! Sure. Let me to take the opportunity to publicly thank Backyard Mechanic for all his help. You're one of the bricks, if not _the_ brick of this newsgroup and there are a _lot_ of ford owners who've benefited from your knowledge and willingness to help. Shifting from OD to D while moving at 60 mph doesn't seem to produce any noticeable difference in engine RPMs or speed. Once the car is wamed up, it idles O.K. Starting up on cold mornings, it displays some oscillation characteristics but nothing that hasn't been there in the past few winters. Once it gets warmed up it sounds pretty much like it always does. I still haven't had any tangiable confirmation that 4th is kicking in. I haven't had a chance to do the long straight level acceleration. My impressions are, so far, I feel the changes up to 3rd then, when I'm letting off the gas to maintain the 55 or 60 I choose to cruise at, normally I'd feel that slight engagement of the clutch converter (this is an A4LD transmission) and I don't think I'm getting that. I say "don't think" because sometimes that engagement could be pretty subtle. Now I don't know if it's happening at all. I don't suppose there are any ways to use the OBD to tell what's happening with the transmission? > see info post on glossary terms: > [quoted text clipped - 7 lines] > Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price > you pay..DEAL with it! > Sure. Let me to take the opportunity to publicly thank Backyard > Mechanic for all his help. You're one of the bricks, if not _the_ [quoted text clipped - 16 lines] > "don't think" because sometimes that engagement could be pretty subtle. > Now I don't know if it's happening at all. With this transmission, letting off the throttle or any quick TIP in or TIP out actually disengages the converter clutch. Tapping the brake pedal will too, even w/ steady pressure on the accelerator pedal. Reading through the posts it isn't clear - do you have a tach? You should actually be able to detect 4 "shifts" including TC lockup on normal, straight line level acceleration. When cold, the TC will not lock up until a specified engine temp is reached - I think around 90-110 degrees recalling from memory. To confirm your "gear" status, a tach would be the best tool. > I don't suppose there are any ways to use the OBD to tell what's > happening with the transmission? Not w/ EEC IV. Rob >Sure. Let me to take the opportunity to publicly thank Backyard >Mechanic for all his help. You're one of the bricks, if not _the_ [quoted text clipped - 19 lines] >I don't suppose there are any ways to use the OBD to tell what's >happening with the transmission? Is the engine reaching full operating temp? Won't shift to overdrive if it is, or thinks it is, cold. >> see info post on glossary terms: >> [quoted text clipped - 7 lines] >> Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price >> you pay..DEAL with it! > Is the engine reaching full operating temp? Won't shift to overdrive > if it is, or thinks it is, cold. Yes it will. The TC will not lock up until a certain temp, though. Rob >> Is the engine reaching full operating temp? Won't shift to overdrive >> if it is, or thinks it is, cold. > >Yes it will. The TC will not lock up until a certain temp, though. > >Rob None of my aerostars would shift into overdrive until the temp needle came off the pin. 90 and 92 3.0 liter. Don't know about 4.0 or 5 speed (1997) >>> Is the engine reaching full operating temp? Won't shift to overdrive >>> if it is, or thinks it is, cold. [quoted text clipped - 5 lines] > came off the pin. 90 and 92 3.0 liter. Don't know about 4.0 or 5 speed > (1997) Yes they did, it was the torque converter that didn't lock up until they were warm. When the converter locks up it does feel like another gear. The idea was to let the converter slippage help get the trans up to operating temperature. Bob Bob >>>> Is the engine reaching full operating temp? Won't shift to overdrive >>>> if it is, or thinks it is, cold. [quoted text clipped - 12 lines] > Bob > Bob The darn things run so slow that they'd stall under load in 4th when cold.Or in third locked. Whether by design or by chance, both of mine steadfastly refused to go into 4th for the first mile or so if I did not warm the vehicle up before leaving (which I seldom did). And I DO know the difference between lockup and overdrive(4th) |
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