car rev’s on its own.

[Lou]

OK so i own a 1992 Honda Accord LX and i am having all kinds of issues. First off when i start the car up it rev’s up to like 3,000 -3,500 rpms on its own then it drops down to like 1,100 or so. After i get moving then the idle will be around 900. But while i am driving other things happen. Not all the time but most times when i let go or give it gas the car will jerk. Some times at a low rpm say if i am going 30 in third gear, my car is stick shift, and i let go of the gas, the car will pretend like its on cruise control for a few seconds, then the car jerks and starts to slow down. sometimes longer and even might rise in speed sometimes like a few miles and hour. When this happens i put my foot on the clutch and the car revs and goes into neutral. When i put my foot back on the gas a minute or so later it will happen again. I can have my foot completely off the gas and it will rev when i press the clutch. I did a vacuum leak test with a cigar inside a FYI smoker i made and found no no leaks. I cleaned out the idle air control valve and the FIT valve as well. There was some carbon build up in them but i go it out with carb cleaner. The FIT valve is closed at idle and i could not screw the plastic round thing inside down anymore then it was, it was snug. Some one told me the TPS could be bad but i have not replaced it yet. I do not wanna spend money on something that is not broken. How ever when i try to unplug the TPS sensor when the car is running it will try to die and when i let go off the sensor it will rev up like it does when it starts. What could possibly be the problem. I know that i have to replace my lower tube seals for my spark plug chambers and i need to do a valve adjustment but would that cause theses problems? BTW i just got the seals in the mail yesterday and i am just waiting for this week end to put them in and do the adjustment. Please help. Thx Lou

Topic

[ekalb1027]

it does seem more than likely the TPS

[Lou]

OK ill try that then next i guess. My computer is not throwing any codes so

[Stephen Bowen]

TPS normally can be tested with a multi-meter.

This “Tech” gets it 1/2 right. He forgot to check the sweep of the TPS. That means you have someone in the car SLOWLY pushing the pedal in/out and watch the meter reading for jumps and drops. If the TPS is in good shape–you’ll have nice smooth readings up/down. If any area starts to jump? Then the TPS is considered defective and should be replaced. The jumping is when the wiper arm inside the controller hits a burnt spot/dead spot.

This test can also be done out of circuit using a resistance scale, but that uses a lot more ‘teccy’ terms that the average shade tree mechanic might not know or understand. Doing the voltage check with the signal return line and a good ground on a DC scale? That will tell you what you need to know.

S-

[Lou]

so is having one of those machines the only way to check? Because i do not own one. How much does 1 cost?

[Lorrin Barth]

I’ve seen them for five dollars. I never tried using one that cheap but I have one I got from Radio Shack years ago for 10 dollars. From there they go to the kind that graph and chart. Those are expensive. Often the cheaper meter types work best for automotive diagnosis.

[Lou]

OK thanks a lot. I am going to the Auto Parts store in the morning to get one.

[Stephen Bowen]

Cheap one goes for about $5 bucks or so from Harbor Freight Tools. Digital Volt-Ohm-Meter.

Better ones can be purchased from Radio Shack for a few bucks.

http://www.harborfreight.com/7-function-multimeter-98025.html

Dirt Cheap. Will get the job done, but not with style and is very low quality.

http://www.harborfreight.com/lcd-automotive-multimeter-with-tachometer-kit-95670.html

I’ve used this one. Fairly solid and also gets the job done.

http://www.craftsman.com/craftsman-multimeter-digital-with-8-functions-and-20/p-03482141000P?prdNo=2&blockNo=2&blockType=G2

Decent quality and it’s only $20 bucks.

S-

[Gary]

[quote=”LouTheHondaGuy” post=111205]so is having one of those machines the only way to check? Because i do not own one. How much does 1 cost?[/quote] I got a craftsman one for about 25 bucks. If I were a master electrician, I would fork over for a $300+ fluke 77 but as a mechanic I find that unnecessary.

[Stephen Bowen]

Heck, I’m a electronics tech for the company I work for. I get along just fine with a $39.00 multimeter. The one from Sears is also a great one!! I just recommend people stay away from the auto ranging ones for checking controllers. If they trip the auto range, it could mask issues–

S-

[Bill]

Make sure the cooling system is full and that the air has been bled from the system. A faulty thermostat can cause the problem also. If the engine is running too cool the PCM thinks the engine is still cold and will keep the idle speed high.

[Lou]

i ordered my multi meter a few days ago. It will be here tomorrow, then i will run what ever tests i need to run.

[Author]

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