Fudman

My daughters' 02 Civic auto has about 110K on it. In general, the car runs great. I recently replaced the spark plugs and forward O2 sensors. Immediately after I did that work, she gets an occasional hesitation when starting from a stop. The car does not stall but rather just doesn't get up and go. Letting up on the gas and then pushing the throttle usually clears it up and then the car drives fine. This usually happens with a cold engine but sometimes with a warm engine. However, the hesitation is sporadic (one out of maybe four times the car is started) and it only happens once during each driving cycle. It then does not occur until it is shut down and restarted (but only once every four times).

I only replaced the forward O2 sensors because that's all that's needed on my BMW (the rears serve no real purpose). I am a pretty good wrench and do all the work on my BMW so this came as a bit of a surprise to me. Should I replace the rear O2 sensors too? How about the EGR valve? Any suggestions or thoughts would be greatly appreciated. Thank you!

green01civic

Start by cleaning the EGR valve, Throttle body, IAC, and PCV valve. (Use CRC Throttle Body cleaner or something similar)

Fudman

Thanx, I'll give that a try.

Fudman

Should I remove these items from the engine to clean or just spray them down? My Haynes says I should also spray and clean out the bore of the TB. Can this be done without removing it? If not, I'll need a new gasket to reinstall.

green01civic

I think it's easier to clean if you remove it, especially to get the IAC off the side cause those screws are in there tight, so being able to work with it on a bench or on the floor is a lot easier than having to hunch over the engine compartment. I guess you can clean it on there, but I had to spray a lot of cleaner and scrub a lot to get mine clean the first time (cause I don't think the previous owner ever did), and I'd have been nervous to start the car with almost an entire can of TB cleaner sprayed down there :P.

Reuse the gasket for the Throttle Body (can replace if you want but mine looked okay, it's like silicone or rubber or something, it doesn't need replacement unless it's damaged).
No gasket for the IAC.
Replace the one for the EGR for sure (probably like $2 locally).
Reuse the washer on the PCV valve.

Fudman

Thanx for the feedback! I did a search and found a good DIY for cleaning the throttle body, IAC, EGR, etc. It complements the Haynes nicely and also recommends that I remove everything for cleaning. Looks like I need to put aside a few hours this weekend. Thanx again for the help!

pheaton

iTrader: (6)

Those are all good maintenece things to do. . So definately do those first..

You're sure that you didn't get any gunk or anything on the new sensor? They are pretty sensitive to stuff.

Did you do the relearn? I've heard of some cars acting a bit wonky for the next tank of gas or so after a new sensor.

Also, which brand did you get? Did you get exact fix, or universal?

Fudman

I was pretty careful not to get anything on it. I did put a tiny bit of anti-seize on the threads to facilitate future replacement. I used the straight up Bosch match, not the universal O2 sensor. It was plug and play.
I did not do the relearn (didn't know about it until I read the DIY thread yesterday) and plan to do that too.

Given this problem is more of an irritation than a major problem, I am sure these steps will resolve the issue. Thanx for the feedback!

dep

Fudman

Can you please let me know if the cleaning fixed the problem? Or was it something else? This sounds ver similar to my daughter's Civic's problem. It is a 2002 EX with just over 110K miles. It threw a code(check engine light came on) and our mechanic said the O2 sensor was bad and replaced it. That is when she started noticing the loss of power, usually once a day, and usually the first trip of the day. But it is intermittant, and the check engine light does not come on. He did replace the O2 sensor, but that didn't fix the problem. We also had the 110K maintenance done - drive belt, plugs, etc. Usually it is just a brief loss of power, but the other day the engine did die. It started right back up again. Unlike you, I do not do my own work. We are taking it in to Honda next Monday. Our mechanic was not able to reproduce the problem. Honda says unless they can reproduce it, they may not be able to do anything either. It would be nice to know if you found the answer.

Thanks.

gearbox

iTrader: (95)

have honda put a factory sensor and problem solved. these cars are very picky about the right type of sensors. either the first mechanic installed the completely wrong sensor or switched the primary and secondary. most shops use the cheapest part they can find to maximize profit, and many of those will not work at all. i would recommend sticking with the factory type sensors like NTK (some bosch sensors are repackaged as ntk) or denso. on a 2002 ex you have a narrowband sensor so the bosch will work very well. its only around $50 from the auto store. i changed mine 20k miles ago with bosch primary and secondary, and the car still runs great. before that i used the wrong sensor and had terrible hesitation and power loss.

dep

Well we haven't taken it to Honda yet. I asked the garage we took it to and they said they used a Bosch. Honda wants to check it out first before they "just throw parts at it". It only happens once a day, so it's not bad, but I would like to have it fixed since it's my daughter's car. They did just replace the front sensor. Should I try the re-learn process, and where do I find what to do? Thanks.

gearbox

iTrader: (95)

there was a recent thread in which someone found that bosch sensors for the primary spot, which normally work fine, have been swapped with the wrong sensor in the box at the factory. even tho the box and part number are correct, there is actually a secondary sensor in the primary box. i had the same problem installing the wrong sensor and that caused all sorts of hesitation and power loss. you really have to look at whats in the box before installing.

for example, primary sensor is on the right, secondary sensor is on the left with the plastic cap over it. the primary is supposed to have a longer tip with holes in it. when someone ordered a primary, they instead got the secondary sensor (thats supposed to go in the cat converter rather than the downpipe). you need to change that sensor out or it will only get worse until the check engine light comes on. the mechanic should have known better when he took out the old sensor and it did not match the new one. but in the end, bosch is at fault for putting the wrong part in the box.

ZFreak

Also, FWIW, the "OEM Honda" Sensors are just NTK sensors with a Honda parts sticker on it. So if you're looking to save some $$, just buy the NTK.

I've had problems with Bosch on my EM2 in regards to hesitation off of idle. Switched to the OEM Honda (i.e. NTK) and the problem immediately went away. I changed out the secondary sensor at the same time too.

gearbox

iTrader: (95)

bosch = ntk if you look at the sensor. at least for me it was.

ZFreak

Hmm.. I'll look at that next time I'm at the auto parts store. I was not aware of that. Thanks.

gearbox

iTrader: (95)

this was a couple yrs ago, may be different now. the main issue people seem to be having with bosch now is they are putting a 2ndary sensor in the primary box at the factory.

Fudman

Thank you all for your feedback. I pulled the new Bosch O2 sensor and replaced the original NTK O2 sensor into my car and the hesitation problem went away although a CEL has appeared. This appears to confirm what you have all said regarding Bosch O2 sensors on this engine. I am getting an NTK O2 sensor (#24291) and will report back when I install it.

motekeeper

Not for me. They look totally different.