1990 Honda Accord LX Revs up and down constantly/Speed Sensor
 

When I have my Car in Park, it constantly revs up as if im mashing on the gas every 2 seconds. What I have found out so far is, there is a grey tube that if disconnected it stops, but the engine gets louder and it will cut off if I start to drive it. Since im just learning about cars and I don't have a Service Manual I don't know what it is. But it must be some kind of air intake, because it sucks air.

Also sense im here, my Speed Sensor is not working correctly. Sometimes it works but most of the time it stays at 0. I just know sooner or later im going to get a speeding ticket. I know in cars there is a Wheel Speed Sensor by the rotors, but im not sure which wheel its on. Is it on the two rear wheels? Also it could be the circuits but I don't know how to get to that either. I do have a 12volt test light so test the circuits, but I don't know where to begin.

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (T3kNi9e)
 

Okay I have a 91 accord in i had the samething go on with the idle it your FITV needs to be clean out look at https://honda-tech.com/zerothread?id=1003988 and https://honda-tech.com/zerothread/1844067 in screw the i think its yellow part all the way down in inside the FITV.
http://is.rely.net/1-92-29998-l-1gbM...AmVuBW3hGg.gif

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (HennessyLane)
 

hey bro its your speed sensor the sensor is located on the top of your transmisson right by your termostate if it is a standard if automatic it should be simular good luck https://honda-tech.com/forums/images/smilies/emthup.gif

No the speed sensor is by the rear motor mount bracket, it has a harness which you can follow to it, it's on the back of the transmission near the firewall, it's pretty hard to see, it can get clogged with shit so you could prolly spray it with some canned air and see if that helps *In the hose connection ports*

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (HennessyLane)
 

sorry it is not the speed sensor!! we have two hondas and one of ours did the same thing!! you might want to try your map sensor or throttle body sensor!! good luck!! http://is.rely.net/1-92-30008-l-au16...EFX98SjN8A.gif

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (tracy7293)
 

Im studying to be a Automotive Technician and just because your two cars was something else, doesn't mean the same is true for me :/

I have recently bought the Repair Manual for my honda. So I looked at the wiring diagram and saw that the VSS has a ground that leads to the left front engine compt. Well it just so happens that when I first got my car and was learning to drive I accidently scraped the left front of my car on my gate backing up.

Well that left front is where the ground to the VSS so im thinking that the accident may have caused a lose ground causing my speed sensor to sometimes start working when driving. Also the speed sensor problems did not come until after that accident.

Now my problem is trying to pin point exactly where that ground is and figuring out whether it truly is that ground or not. Getting to it will require removing a few things so i'll have to do that when I get time. Also a power probe would be helpful, but I don't have one.

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (T3kNi9e)
 

check your coolant level with the surging idle, 90% of the time thats all thats wrong

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (T3kNi9e)
 

Good Gosh, I can't remember ever seeing a thread with this much 100%dis-information and 0% diagnostic information.
First; if the speed sensor faults there will be a CEL code stored in the ECU and the cruise control will not work.
Jumper the Blue 2 pin connector that is located behind the top of the passenger side kick panel, turn on the key and watch the CEL for flash codes.

Idle surging, one person here was close, Be sure the coolant is full AND the block burped at the T-stat housing 12mm bleed screw.

Open the top of the FITV with the engine warm and there should be no air bypassing/ hissing. If there is turn down the screw till it shuts up and the idle evens out.

The quick check for the IACV is to unplug it and the idle should drop a couple hundred RPM.
Be sure there is a little slack in the throttle cable, if it has been tightened to raise the idle it can cause surging from the TPS telling the ECU to change the timing as the air flow changes.

Sheesh come on people if ya can't 100% for sure help someone, don't go leading them astray with bad information. The OP needs straight foward diagnostic checks, not stories about what happened to a second cousins car once upon a time when there was a blue moon on the third thursday of the month.

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (hondadude)
 

i guess i shouldn't of assumed that everyone knows that a full coolant system means no air in it, nice save https://honda-tech.com/forums/images/smilies/emthup.gif

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor (hondadude)
 

My cruise control still works. Then again, I have never tried to use it while the speed sensor wasn't working. I tried it one day, when my speed sensor just happened to be working.

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor
 

this sounds like my problem...but my problem is as im driving and i come to a stop my car revs up to 3000 rpms and stays there...my odometer works and my cruise control hasnt worked since my power steering went out. i just put a new motor in my car and it was a automatic, but i changed out the fly wheel and clutch to the new motor from my old motor(new clutch also)..any ideas on why its reving so high..my local mechanic said it was probably the speed sensor but if my odometer is working fine could it still be it? also, my oil light stays on...im thinking it doesnt have anything to do with the revving problem tho?

Re: 1990 Honda Accord LX Revs up and down constantly/Speed Sensor
 

First welcome to HT. Second reviving a 3 year old thread is not going to endear you to the HT locals, that form your description has nothing in common w/ your problem. Learn to use the search function here, there have been lots of threads on your issue if you find no answer or still have ?'s start your own thread. Good luck to you in your search.