Hi Guys,
I have a 98 HX (5 speed) with about 200k miles. I just got the car about a month ago. It ran well when I got it, but it threw an EGR low flow code after a week or so. I cleaned out the very blocked EGR ports, cleaned the idle control valve, throttle body.

The problem I am having started, I think, after the cleaning. I am not sure though, since I was so new to the car. After the car has warmed up a stumble develops right as you are just rolling on the throttle after coasting, or just driving along with your foot just barely on the gas. It acts just like there is a dead spot on the TPS. This happens much more noticeably when the car is warmed up and has been moving slowly (i.e. under hood temps starting to get higher) It is not a violent buck, but it acts like fuel is being cut for just a second. This results in an annoying jerking as you roll on an off the throttle while driving in traffic. If you hold the throttle just in the perfect position with the clutch in it will rev up to about 1500 then cut out and drop back to about 600, then rev back to 1500. It will do this for as long as you hold the throttle in that certain spot.

So far I have done the following:
-new plugs, wires cap and rotor
-new pcv valve
-new air and fuel filter
-new tps set exactly at .45 volts at idle
-tried to burp and bleed the coolant as much as possible
-cleaned idle valve again and again
-check to make sure the EGR valve appeared to be closed all the way
-done the idle setting and relearn according to the honda PDF on this site
-checked for vac leaks all around the intake using carb cleaner to see if the idle was effected

I am at a loss on this one, the idle valve seems to work fine, the idle stabilized right where it should be, and you can hear the idle valve operating through the intake like it should. I don't want to rule out a coolant bubble, but I have tried several times to burp it and am not getting any more air out of it. I am set up to test most anything, I have a multimeter, mighty vac and an OBD scanner that also can read live data. The car runs perfect otherwise, gets amazing mileage, and throws no codes at all. Am I missing something else??
Thanks in advance.

 

Did you also clean all of the carbon out of the EGR chamber passage ways?



Also, did you adjust the ignition timing to spec?

 

I did clean all the passageways, they were completely blocked. I have never touched the timing, I better do that. I have read to jumper a connector that is behind the passenger foot well to get the ecu into base timing. Is that correct? I wonder if my manual tells me what the base timing should be on this car.

 

You'll find a service manual diagram in the FAQs sticky.

 

ok thanks, i will do that and report back

 

I checked timing last night, it might have been off a degree or two, i adjusted it so it looked about perfect, i rechecked tps voltage, still at .45 volts at idle, burped the coolant again. The car ran perfect on my drive this morning (as it usually does) until I stopped at the parts store. When I came back out in 5 minutes, it was back to the same old. This is usually what happens, after the car is driven and then parked for a couple minutes (i.e. run to the store, get gas etc) Then the problem occurs. It acts like something is failing after it heat soaks. Not sure what else to check at this point.

 

The ECU does not use inputs from the primary O2 sensor until the engine is fully warmed up. Check whether unplugging the primary O2 sensor eliminates the problem (for testing purposes only).

 

good thought, i will try that. However, I don't experience the problem until I get into town, but I have already driven 15 miles at 60mph, so I think the engine is already warmed up fully as far as coolant temp, the problem never seems to occur until the car has sat in stop and go traffic, or been shutoff and then started back up after sitting a couple minutes.

 

When you get the chance, I recommend that you still try the O2 sensor unplug test. Could be a lazy O2 sensor.

You also might want to check for dirty/clogged fuel injectors and to test the FPR, coil, and ICM.

 

i will try the o2 sensor test today. would it be worth unplugging the egr valve to test in the same manor?
I had an odd thing happen, when I was adjusting the timing, I tapped on the dist. with my ratchet handle to bump it just a hare and the car started stumbling like crazy, the dist didnt actually move at all and after about 5 seconds it recovered. This prompted me to order a new coil since it looks old anyways. It was almost like there is a bad internal connection in the coil that got jarred. I think its a long shot, but I wanted to try that as well. So sick of this thing not running right.

 

Test the coil and its connections before replacing.

 

ok, the saga continues...I unplugged the o2 sensor and the problem went away, plugged it back in and it was bucking again. After I got it home, I pulled the o2 out to attempt to clean it up a bit (doubting that will do anything) and I noticed a hairline crack around the threads of the o2 bung. Pulled the heat shield and discovered a pretty substantial crack from the o2 bung back around the collector. I couldn't really hear any leaks, but there was black on the underside of the heat shield. I welded the crack back up, and the car seems to run better. I have not had the chance to drive it in town where it usually acts up, but we shall see if the exhaust leak was the problem. I think I am closing in on the issue. Just hoping I don't end up having to drop the coin on that expensive wide band sensor.

 

It might also be worth mentioning that the o2 sensor has quite a bit of whiteish buildup on it. I was able to carefully scrape most of it off and get it nice and clean.

 

I read someone who had success cleaning their O2 sensor by soaking it in gasoline. I'm not sure if it actually works, and I don't know if it's a good idea for a wideband O2, but it might be worth a shot if you want to clean it again.

 

well, the car has been running very well for a couple days now. I think it was the cracked manifold causing all of the issues.

 

Have you ever cleaned the oil breather box where the pcv plugs into?

 

i have not cleaned out the breather box, probably is pretty nasty if it is like everything else i have found. The pcv does seem to breath pretty well, but i should do that next time i have the oil filter off.

On a side note, I spoke to soon about the crack mani being the issue. It started acting up again, but this time I finally got a code, and it was the code for the wideband o2 sensor!! Finally I think i have the issue cornered. I ordered a new NTK sensor, and I think that is finally going to fix it!

 

man, this thing is driving me up a wall. I ordered a new sensor off ebay,

http://www.ebay.com/itm/150756745133...WNX:IT&vxp=mtr

its a real ntk, 5 wire, plugs right in, listed with the right part number...but When I install it I immediately get a code for heater circuit malfunction (a code I never got with the old sensor). I was quite sure this was the correct sensor for my car, but maybe I just got a bad one? It says it is a 24300, which I think is right? Don't know. Anyone have any ideas?

 

Edit:

I think you mean 7-wire O2 sensor.

Code P1166 or P1167?

 

not sure, my scan tool is a little funny with the readouts it gives for the codes that are not standard obd2. I said something about primary o2 heating circuit mafunction. I would go back out and scan it, but I put my old o2 back in so I can try to send this one back. The CEL stays off 95% of the time with my old one installed.The CEL comes back within 10 seconds of clearing with scan tool with the new sensor. I cant see what this sensor wont work, all the reasearch i have done on the inernet says they should, say the 24300 is the right part number....What are the chances that the sensor is just a dud? Never had that happen before.

 

How do you know if the code was for the primary O2 sensor if you don't know the code? Why do you think your OBD2 ECU would throw non-standard codes?

You could also jump the service connector, but the OBD2 code is best.

And what do you mean by this^?

 

Sorry for the confusion. I have an obd2 code reader, but for some reason anytime I have had a code for the primary o2 sensor it says "vehicle specific code found" Then I have to enter in the year, make, model...and it will give me a bunch of verbiage that I can usually make enough sense of to figure out the problem. I didn't write down exactly what it said because I was a bit annoyed. It was a problem with the heater circuit, sensor 1 bank 1. Now I cant go back and look at it without reinstalling the new sensor. Which I can do when it is light tomorrow.
I mentioned that the CEL doesnt come on with my old sensor in most of the time just to show that I don't think there is an issue with the rest of the harness. The code I get with that is only about 5% of the time, when the car is bucking badly I get a code that says primary o2 sensor Air Fuel out of range.

 

a little update, i replaced the primary o2 sensor with a new ntk sensor and immediately got a code for open circuit. Turned out that I got a bad sensor, I finally got another and installed yesterday. No code, but the car still ran similar to what it did before. A bit of surge under very light throttle. I don't think I should need to do a relearn with a new o2 sensor, but I did it anyways and it seems to run correctly. Does this make any sense? Or am I in for another annoying drive home from work with a car that still surges.

 

i am going to keep updating this thread in case someone else runs into the same issue, the new o2 sensor did not fix the problem. The car run a bit better, but still has the issue. I believe the issue is that someone had adjusted the throttle stop a bit because it was sticking (because there was a ton of crap around the butterfly). When I cleaned out that crap it started running badly because there was now a big airspace around the throttle butterfly. I adjusted the butterfly a bit more closed and re-adjusted the TPS. The issue is almost gone, I think it just needs a bit more adjustment. Almost there. I will post up again if my next adjustment cures it for good. What a pain in the ****.

 

If the throttle stop screw has been adjusted, then consider buying a replacement throttle body.

Are all CEL codes now cleared?