civic vx: TPS/TAS test?

[dlb]

my wife's VX generally runs very well but it occasionally will hesitate for a second or so, usually on acceleration. also, i find it tough to maintain a constant cruising speed because once up to speed, i can feel the engine switch to lean burn and then the car slowly loses about 10 km/h of speed. when i try to give it light throttle to stay at cruising speed, i get no response until i've put the pedal way down. at this point i feel it kick out of lean burn and accelerate pretty hard, and if i hold the pedal constant it will accelerate way past the cruising speed i was originally at, and trying to attain again.

i'm a very careful driver and can manage to drive it fairly steadily but the occasional hesitation and slowing/surging is definitely noticeable. i've looked in the FSM and it pretty much says if there's no CEL, there's no problem, but i want to know if there's some test for the throttle position sensor, or throttle angle sensor as it's called in the FSM. anyone have any suggestions?

[Ryland]

Unplug the O2 sensor, you will most likely find that the problem goes away, at that point buy a new O2 sensor, make sure it's a 5 wire sensor with the right plug, Denso or NTK, it might be close to $200 and if it's not then there is a good chance that it's not the right one.

[cbaber]

It's more likely the O2 sensor causing problems, even though you don't get a CEL. I had a similar problem. My car would randomly cut out a highway speed. Sometimes it wouldn't idle. After going through a distributor and lots of other things, I finally decided to unplug the O2 sensor. When you do this the system stays open loop, and doesn't rely on the O2 sensor for data. When I did this the car ran perfectly, no hesitation or cutting out at highway speeds. After I replaced the O2 sensor the problem was fixed.

A word of caution, watch out for cheap aftermarket O2 sensors, especially on the VX and HX engines. These are wideband O2 sensors and my cheap aftermarket one won't allow me to engage lean burn. As my car tries the motor stumbles until it kicks out of lean burn. Out of lean burn, it runs great. It's simply a quality issue. I bought the cheap $170 one from RockAuto. I would buy the $360 OEM sensor if I could do it again!

[Ryland]

Amazon.com: NGK 24300 Oxygen Sensor - NGK/NTK Packaging: Automotive

http://www.amazon.com/Denso-234-5052-Fuel-Ratio-Sensor/dp/B001F7GKFG/ref=au_pf_ss_14?ie=UTF8&Make=Honda%7C59&Model=Civi c%7C752&Year=1993%7C1993&carId=002&n=15684181&s=au tomotive

I would go for the NTK one, I forget if it was a Bosch or Denso that I bought years ago that turned out to be an NTK branded part in the box.

[dlb]

it's funny because when we first got the car and my wife complained about the hesitation, i asked on here about it. someone suggested unplugging the o2 sensor so i did, but my wife only drove it like that for no more than 30 minutes and said she thought it was still hesitating. she's not the best for diagnosing stuff but i took her word for it.

fast forward to now, when i had forgotten about that incident. i decided i would try it again but drive it myself this time. i took it for a good run and the thing drove great, none of the above described problems. conclusion: the o2 sensor is bad, and don't rely on my wife for future help diagnosing these things.

also of note is that the previous owner had replaced the o2 sensor recently. i looked closely at it though and it is in fact one of the cheap ones so this is yet another case of the cheap sensors being garbage out of the box.

thanks, guys.

[Ryland]

The other thing that I have found will kill o2 sensors on VX's is bad exhaust or over sized exhaust systems.

[dlb]

installed the NTK 24300 o2 sensor today, went for a long test drive and all is well. i compared the old and and new sensors. the old one thinner, has red, orange, yellow, white, and black wires, and is stamped

L1H1
NTK JAPAN

while the new one is fatter, has white, yellow, grey, black, and blue wires, and is stamped

LZA09-E1
NTK JAPAN

i think it's really weird that NTK would make two o2 sensors that are quite different but are used in the same vehicle, and one of them doesn't even work properly. i wonder if it's confusion on the part of most parts stores or the way it's labelled or something.

anyway, glad to have it sorted out and looking forward to seeing if it helps improve the economy at all. my wife has been averaging 18.5 km/L (42-43 mpg) which we've been really happy with so if it gets a bit better, it's a bonus.

thanks for the help.

[slownugly]

I covered that a little in my sedan build thread. A09 is the right number. The cheaper ones have A08/A07/A06. Just in case anyone goes to buy a cheap one in the future check that number first.

[dlb]

yes, i remembered that from reading your build thread, slownugly. the only problem was that the parts place didn't have the correct A09-stamped sensor there so i needed a part # to get them to order it. turned out that NTK 24300 was the right A09 model, and i breathed a big sigh of relief. i will make sure to remember this for future reference.