Aftermarket Oxygen Sensor Causing Hesitation?

[good_jolly]

I have a 2000 Corolla in which I changed the oxygen sensor before the cat with an aftermarket Bosch 02. After changing I realize that there is a noticeable hesitation most of the time pressing on the gas from a stop.

It would have a delay for about 2 seconds than it would catch up quick and fast, like surging. I am trying to solve this problem as it can be very dangerous in city traffic.

While I changed the 02, I did sat most of myself on top of the engine in order to reach the 02. I wonder if I might have crush some hose that I didn't know of.

I also changed the 02 sensor behind the CAT with Bosch and I believe the CAT is dead as code P0420 is on. But the problem clearly exist after I changed the 02 before CAT with Bosch.

TIA

 

[AdRock]

Go get an OEM sensor and I'll bet the problem probably goes away.

 

[strongt]

I the Cat. is dead, your problem may be that your Cat. is shot and plugged up. Causeing a backflow problem.

 

[good_jolly]

Originally Posted By: AdRock
Go get an OEM sensor and I'll bet the problem probably goes away.


I still have the OEM that I will put back tomorrow. I am trying to figure if dealer sell a new gasket itself.

Originally Posted By: strongt
I the Cat. is dead, your problem may be that your Cat. is shot and plugged up. Causeing a backflow problem.


The CAT was replaced two years ago, I think I got a bad CAT. Recently, a shop told me to replace the CAT along with two new 02s.

At first I was trying to see that if indeed the 02 is bad and not the CAT thats why I replaced the two 02s. The car does burn quite much oil for quite some time until I switched to GC and M1 0W40 for cleaning and the consumption is much lower.

 

[MC5W20]

check the maf sensor also. most hesitation is caused when those get dirty.

 

[Autobahn88]

Exact thing happened to me last summer. I bought an aftermarket 02 sensor for my Saab and shortley after the car hesitated and bucked as the car warmed up. Bought an OEM sensor and the car runs great. OEM may cost more but it is definately worth it.

 

[mikered30]

For some reason, toyotas do not like Bosch products, I do not know why. NGK and Denso are OEM.

 

[shpankey]

A lot of people have the same problem with Bosch spark plugs. On the J-Body forum, tons of people have issues running them. Put in some AC Delco's and they run like a champ.

I'd buy some new OEM sensors, put them in and see if it fixes it. If it does, return the Bosch as defective.

I'm not a fan of Bosch at all.

 

[brianl703]

Try unplugging the oxygen sensor and see if that makes any improvement. A misfire could cause this problem too.

 

[lexus114]

Originally Posted By: AdRock
Go get an OEM sensor and I'll bet the problem probably goes away.


+1 get a Denso in their QUICK!

 

[Trav]

Don't be sold on a new cat too quickly.Toyota are notorious for PO420 even with new a cat.Bosch O2 sensors do not work well at all in these cars got Denso or NGK OEM fit not universal.

Look very carefully for any hoses or wires that may have got
disturbed,also check the TB to air filter plumbing carefully.
It sound like you may have a vacuum/air leak and is letting un metered air into the intake or throttle body.

 

[mechtech2]

The sudden onset means you may have broke an incidental part.
Vacuum or electrical.
Some people have had poor results with Bosch O2 sensors. It is unlikely, but possible.
But there had to be a reason you changed the O2 sensor, wasn't there?

 

[good_jolly]

Originally Posted By: MC5W20
check the maf sensor also. most hesitation is caused when those get dirty.
Originally Posted By: Autobahn88
Exact thing happened to me last summer. I bought an aftermarket 02 sensor for my Saab and shortley after the car hesitated and bucked as the car warmed up. Bought an OEM sensor and the car runs great. OEM may cost more but it is definately worth it.
Originally Posted By: mikered30
For some reason, toyotas do not like Bosch products, I do not know why. NGK and Denso are OEM.
Originally Posted By: shpankey
A lot of people have the same problem with Bosch spark plugs. On the J-Body forum, tons of people have issues running them. Put in some AC Delco's and they run like a champ.

I'd buy some new OEM sensors, put them in and see if it fixes it. If it does, return the Bosch as defective.

I'm not a fan of Bosch at all.
Originally Posted By: brianl703
Try unplugging the oxygen sensor and see if that makes any improvement. A misfire could cause this problem too.
Originally Posted By: lexus114
Originally Posted By: AdRock
Go get an OEM sensor and I'll bet the problem probably goes away.


+1 get a Denso in their QUICK!
Originally Posted By: Trav
Don't be sold on a new cat too quickly.Toyota are notorious for PO420 even with new a cat.Bosch O2 sensors do not work well at all in these cars got Denso or NGK OEM fit not universal.

Look very carefully for any hoses or wires that may have got
disturbed,also check the TB to air filter plumbing carefully.
It sound like you may have a vacuum/air leak and is letting un metered air into the intake or throttle body.

Originally Posted By: mechtech2
The sudden onset means you may have broke an incidental part.
Vacuum or electrical.
Some people have had poor results with Bosch O2 sensors. It is unlikely, but possible.
But there had to be a reason you changed the O2 sensor, wasn't there?


Thank you everyone for responding. The car idles fine and mid-high speed are fine.

Just only happen mostly from accelerating from a stop when *pressing* the gas a little hard. If one press the gas slightly, I recalled, it feels normal.

The reason I changed the 02 because the CAT has already been changed two years ago. The car does eat quite an amount of oil for the past 100K so I figured it's fouled or about time.

 

[good_jolly]

If I remember correctly, the shank or tube of the Bosch is shorter and has less air openings than the OEM. Just a thought.

 

[Mr Nice]

Yep, those Bosch oxygen sensors are really not that great on Honda or Toyotas

 

[citationxeleven]

Just did the O2 sensor on wife's 626. Ran bad and CEL on after the change. Removed the negative battery cable for 10 mins and reconnected. Runs great and no CEL now.

 

[brianl703]

Originally Posted By: good_jolly
The car idles fine and mid-high speed are fine.

Just only happen mostly from accelerating from a stop when *pressing* the gas a little hard. If one press the gas slightly, I recalled, it feels normal.


Those symptoms sound identical to a misfire issue I had on my '95 Ford Contour. It's a stickshift, and I could really make it hesitate bad by lugging the engine in 5th.

Replacing the plugs AND wires AND making sure that the sparkplug socket was clean (so it didn't leave a mess on the sparplug insulator) fixed it.

 

[mechtech2]

Even if you did not knock something loose or break it, there may be other problems compounding running problems.
A twitchy throttle position sensor, for xeample.
Try getting the codes read for free - there may be hidden codes that will pinpoint things.

 

[good_jolly]

I will be scanning the code with my basic scanner. Last time it didn't pick up a hidden code of the evap solenoid purge valve.

 

[good_jolly]

An update.

I scanned the car yesterday, it came up with slow response and running lean in reference to the Bosch 02 before the CAT that was replaced.

I had put back in the old OEM that I saved and the car is back to running normal.

As of now, I am positively sure that the CAT needs replacement since the two 02s are fine and that I could have gotten a bad CAT replacement two years ago.