montana tom Posted February 21, 2015 Share Posted February 21, 2015 Hi all ; Trying to help my neighbor out with his 96-2.2 5mt legacy. Problem; Start's in the morn normal runs for a few minutes ... stall's..restarts easy runs less than a minute stall's . If you try to drive it then it cuts out, rpms up & down . If you work with it ,after awhile it starts to run normal . I checked all the wire plugs to everything , looked over and cleaned mass air .all to no avail. During one of the 40 second restarts as it was trying to stall I unpluged the tp sensor and it quit trying to stall and went up to 1100 rpm (800-900 normal) I took it for a short test drive and it ran good . Replugged tp and stalls. I adjusted tp and it idled ! Yes... except 200 yards down the road and its cutting out...xxx ...pop hood unplug tp ... runs fine so I try driving it to town unpluged...(this won't work... ) ran like a raped ape ! 80 mph 4 miles in . and 4 back... I was shocked . I had a used tp from a jap takeout manifold , wont fit the throttle body but pluggs in to the harness ok. Plug it in idle drops to 800. This car had codes for mass air & tp as well as misfire and o/2 . when I first looked at it . I cleared the codes and even with all the stalling and cutting out , They never came back UNTILL I unpluged the tp ??? I went ahead and gambled his $ 69.00 for a hitachi tp sensor.... hope it works ok. Anybody familiar with these symptoms ? Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 21, 2015 Share Posted February 21, 2015 Throttle position sensors rarely fail on these, and are easy to test with a voltmeter. Unplugging the sensor will put the ECU into a default mode where it will ignore most sensor inputs and run on a fixed fuel/spark curve. It's not optimal but it's usually better than running like poo because of one of the sensors being out of whack. TPS codes are usually set because the sensor is not adjusted properly or someone has messed with the throttle stop screw on the throttle body. ECU has to see 0.5v from the sensor at closed throttle or it will set codes and cause idle problems. The sensor is adjustable so this can be achieved by checking voltage on the center pin with a voltmeter and twisting TPS slightly until voltage is correct, then tighten the screws. Check voltage on the TPS center pin with the key On and sweep the throttle slowly all the way to wide open. Should start at about 0.5v and climb smoothly to just over 4v at wide open. If the voltage drops out or goes to 0 at a certain point and can be repeated each time then the TPS could be bad. You can also check the TPS with an ohmmeter with it unplugged. Check center pin to either end pin and watch for smooth increase or decrease (depending on which pin you use) in resistance as you slowly open and close the throttle. If resistance ever goes to 0 or O.L.(infinite) and is repeated in the same spot each time, TPS is bad. MAF sensors on the 96 are known to have problems and will cause random stalling and rough idle. A solder joint in the sensor breaks and causes intermittent low signal to the ECU, which will make it run lean and/or stall. Very common and can usually be fixed if you can solder. Used sensors are cheap, but may have the same issue later. Another common cause for rough idle is a dirty idle air control valve. This is the one with the ~1" dia. hose running from the intake tube. Easy cleaning of this is done with some throttle body cleaner. Pop the hose off of the intake tube, stick the straw for the can into the end of the hose about an inch then pop the hose back onto the intake tube. Now you can start the engine and spray quick shots of TB cleaner into the hose. Work the throttle lever to keep the engine from stalling. Do a couple shots with the RPM up then let it return to idle so the valve will work back and forth. Repeat for about 2 minutes. Should use about 1/4 can of cleaner. Link to comment Share on other sites More sharing options...
ccrinc Posted February 21, 2015 Share Posted February 21, 2015 I'm not saying that this is in any way related to the problems with this car, but there is a 3rd piece which can cause a run lean/rich situation: the coolant temperature sensor on the coolant crossover pipe. If it fails or becomes damaged, the car will usually run too rich because the ECU isn't getting input from it and thinks that the car is always cold. Just FYI. Link to comment Share on other sites More sharing options...
montana tom Posted February 21, 2015 Author Share Posted February 21, 2015 Thanks Fairtax; second time you've helped . TP sensor was not the problem .. just like you suggested. MAF apparently is the culprit , switched it out with a good one from my 94 and she purrs. Heading back to the shop now to see about taking this old one apart to fix it. Thanks to you also ccrinc for your tip . 1 Link to comment Share on other sites More sharing options...
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