well this is my first post on this board so any helpful suggestions on my posting techniques would be appreciated.
i just bought an 89 240sx with only 91k on it:D and the car runs great. i just have a few questions for anyone that wants to repsond.
when i start the car up in the morning when it is cold it starts just fine and it idles at 2k rpm's like it should. (i think) and after i drive it and it is completely warmed up and i shut the car off. (like when getting gas or stopping at the store) well when i get in the car and start it up and the tach. will start at 1500 rpm and go up to 2000 and then drop back down to 1500 and go back up to 2000. the car repeates this idleing for about 5 to 7 times of going up and down then the idle will begin to rest at about 1050 rpm's. i dont know why it is doing this so i was wondering if anyone has the same problem. the car always does this after it is warmed up and i go to start it up. i have only added an obx racing cat back system and that is all i have done to the car since i have gotten it.
the other problem i am having is sometimes when i am driving down the road my speedometer will just stop working. then occasionally will kick back in and tell me the speed. idk why it is doing this so any info. would help.
newb question please respond
The speedo is electronic, so either the speed sensor circuit or the sensor itself is bad. Mine does it once in a long while, so I haven't felt like fixing it.
This first think you should do is pull the trouble codes out from the ECU and see what it yields. Start there and avoild throwing parts at it.
Here is a service manual: http://www.247motorsports.com/downloads/90FSM.zip
This first think you should do is pull the trouble codes out from the ECU and see what it yields. Start there and avoild throwing parts at it.
Here is a service manual: http://www.247motorsports.com/downloads/90FSM.zip
When my engine was stock, it used to idle around 1500 when cold, so I don't think anything is wrong there, but the high idle on a hot start is not the way it is supposed to be. Start with cleaning the MAFS, and check the engine temp sensor on the front of the head.
You can clean the MAFS with brake cleaner spray. Remove the AF housing, or whatever filter setup you've got, so that you can see down the throat of the MAFS. There will be a big hole and a little hole. Spray brake cleaner in the little hole but careful not to use the straw that comes with it. That straw will make the stream too strong for the little fragile wire in there to withstand.
Temp. sensor should be checked for resistance. The resistance to temp. ratio should be in that service manual. And make sure the connector on that sensor is in good condition too.
Our speedo, regardless of analog or digital, is wire-fed, so if the speedo problem is bad or gets worse you'll have to replace the speed sensor or check its wiring. It is on the transmission.
You can clean the MAFS with brake cleaner spray. Remove the AF housing, or whatever filter setup you've got, so that you can see down the throat of the MAFS. There will be a big hole and a little hole. Spray brake cleaner in the little hole but careful not to use the straw that comes with it. That straw will make the stream too strong for the little fragile wire in there to withstand.
Temp. sensor should be checked for resistance. The resistance to temp. ratio should be in that service manual. And make sure the connector on that sensor is in good condition too.
Our speedo, regardless of analog or digital, is wire-fed, so if the speedo problem is bad or gets worse you'll have to replace the speed sensor or check its wiring. It is on the transmission.
when u say MAFS u mean there are 2 of them to clean. i took the one that is just before the airfilter out of the square metal housing and sprayed it with electrical cleaner. is the other one at the intake manifold that looks like the other one by the air filter? (small black square) and should i completely take the MAFS out and clean them both. the engine is completely stock no mods done. (yet)
Mameluke, here you go: http://www.zeroyon.com/techfil...4.zip Try not to thread-jack.
Wild_maxx, the MAFS is the one at the AF, the other one that I think you are talking about is the throttle body. You can spray the throttle body down too, but I don't think that's your problem.
Wild_maxx, the MAFS is the one at the AF, the other one that I think you are talking about is the throttle body. You can spray the throttle body down too, but I don't think that's your problem.
somthing to check, not likely but this has happend to me many times when i forget to reconect it
the throttle position sensor, make sure that the harnes is attached solidly.
a full tune-up wouldnt hurt either. make sure that when the accelerator pedal is not pressed, that the throttle body closes all the way.also, try adjusting the idle ( unplug TPS) and turn the screw that adjusts the idle, its at the end of the intake manifold towards the firewall
the throttle position sensor, make sure that the harnes is attached solidly.
a full tune-up wouldnt hurt either. make sure that when the accelerator pedal is not pressed, that the throttle body closes all the way.also, try adjusting the idle ( unplug TPS) and turn the screw that adjusts the idle, its at the end of the intake manifold towards the firewall
i just cleaned out the maf housing and it didnt change a thing. i think i located the idle screw. it is on the rear side of the intake manifold and it is a little gold phillips/flat head screw? i adjusted it and it did lower the idle but didnt solve the previously posted problem with the idle jumping up and down after a hot start. so any additional information would be helpful.
oh come on people. 105 views and only 10 replies. and most of them are from me. i would really appreciate some help.
i have another question for anyone who is nice enouf to answer it for me. after my car is heated up should the temp gauge be right inbetween the third and fourth mark because mine is only sitting on the third. could that be a thermastat or something like that causing the engine to repeate the idle problem?
i have another question for anyone who is nice enouf to answer it for me. after my car is heated up should the temp gauge be right inbetween the third and fourth mark because mine is only sitting on the third. could that be a thermastat or something like that causing the engine to repeate the idle problem?
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masticatingcow
- Posts: 2338
- Joined: Fri Nov 07, 2003 8:39 am
- Car: 94 Mazda FD3S
Hey hey, calm down.
Fact is, you're asking questions that are difficult to answer online. When you ask where or what something is, it's hard to explain in text. Running diagnostics is the same way... it's just best to have someone who knows better stand over the car and see what's up.
That being said, here's my $.02. If you haven't had a whole lot of under the hood experience, it would be best for you to get your car to a mechanic. Explain what's going on, when it happens, and what you've done to change it. Besides having the FSM at their disposal, mechanics have YEARS of automotive experience that few can compensate for.
Good luck.
Fact is, you're asking questions that are difficult to answer online. When you ask where or what something is, it's hard to explain in text. Running diagnostics is the same way... it's just best to have someone who knows better stand over the car and see what's up.
That being said, here's my $.02. If you haven't had a whole lot of under the hood experience, it would be best for you to get your car to a mechanic. Explain what's going on, when it happens, and what you've done to change it. Besides having the FSM at their disposal, mechanics have YEARS of automotive experience that few can compensate for.
Good luck.