ryyo

I just got my '90 crx hf back yesterday after having a dohc zc installed. During the install, all the usual stuff was replaced (timing belt, water pump, cam and crank seals, spark plugs). After the install was initially done (a few weeks ago), there was an issue with the car stuttering on acceleration. There was also an problem with fluctuating idle. My friend doing the install wasn't sure what was going on, so he replaced the o2 sensor and fuel pump with new ones (fuel pump is Walbro 255lph). The car seemed to be okay when I picked it up yesterday. It was idleing nicely and ran pretty good. After about 30 minutes of driving around, the CEL came on. I checked the pg7, and it was displaying error code 1 (o2 sensor). Even with the CEL, the car ran fine.

I dropped by a friend's house for a little while, and after about 3 minutes from leaving the house and driving no more than 20mph, the CEL comes on again (Code 1). This time, the car started stuttering on acceleration as it did before replacing the fuel pump and o2 sensor. So I stopped, shut the car down, and then restarted. The car ran fine for another 40 minutes back to my house without a CEL.

I went to start the car this morning, and it started fine. But the idle was fluctuating pretty badly to the point where it was almost shutting off. After warming up, the idle was fine. I drove off, and after about 5 minutes from my house, the CEL turns on again and the car is stuttering while on the highway. I shut it off, restarted, and it ran fine for my 40 min. drive to work (although the CEL did turn on again, it ran fine).

So the CEL has been coming on just randomly, and sometimes the car stutters and sometimes drives well. The fluctuating idle happens when the car has been sitting for a while (at least a few hours). It's the same error code everytime. Any help in figuring this out would be greatly appreciated.
Thanks

ryyo

bump

ryyo

bump

IndySporty

Maybe you should try to replace the main relay and the distributor with a known good one. I had a CRX that acted like that once and it turns out it was the CYP sensor in the dizzy. it looked like cotton candy from all the windings in it blowing out all over the inside of the dizzy. The good thing about ZC is that they take a standard DX dizzy if they have the ZC sensor in the front cam, I think I have like 3 of them in my dizzy box.

ryyo

The main relay was replaced, but I haven't replaced the dizzy. I think I may try that. I've got an extra known good dizzy that I had on my other crx with zc.
Thanks

ryyo

Update:
Ok, yesterday I replaced the o2 sensor and that seemed to take care of the CEL. It didn't come on yesterday or today. But I was still having the "cold" start idle problems. Now I have more issues though. I went to start the car this afternoon, and the car would not stay on. Then I noticed that when I turned the key to the on position, the tachometer needle would move erratically. It took a while, but I did get the car started. While revving the engine to keep it on, the car backfired badly several times. When I let the car back down to idle, it would just die. I haven't replaced the dizzy yet, and my friend suggested that could be the problem. I see how that might cause the backfiring (I guess), but could that also cause the tachometer needle to jump while the car isn't even started?


Modified by ryyo at 8:57 PM 7/13/2008

hondasaurusrex

as far as the o2 is concerned, if your using an aftermarket header/downpipe combo that places the o2 sensor farther away from the exhaust ports than the stock manifold, you'll have issues with the o2 sensor coming up to operating temperature, they dont read properly until around 600+ degrees
also, check all your ground connections in the engine bay, and for starters check to make sure the rotor is tight, they sometimes come loose and cause issues

ryyo

Okay, replaced the dizzy and that took care of the tachometer issue (I think it had to do with the ignitor). But now I'm getting CEL's again for the o2 sensor, the horrible idle issue on cold startup, and the stuttering the first time the CEL comes on. I changed the spark plug wires yesterday. Today, I took the EACV off and cleaned it with Seafoam, but that didn't help. I did notice that the EACV was missing the "screen" on the one hole it's supposed to be on. I doubt that's causing any issues, but could that be or cause another problem?


Modified by ryyo at 9:13 PM 7/16/2008


Modified by ryyo at 9:27 PM 7/16/2008

ryyo

I also meant to mention that the exhaust manifold is stock (as in stock hf) and still has the cat.

hondasaurusrex

hrm...perhaps you have a wiring gremlin between the o2 sensor and the ecu, i've had that issue before, and the strange cold start up idle issue went along with it, and the sputtering when the cel intially comes on...

if in fact its a wiring gremlin, the cause is an intermittent short, causing the ecu to "see" and then "not see" the o2 sensor at random times....
let me guess, after the initial bog when the cel light comes on, it probably drives almost normal? because the ecu is now ignoring any o2 signal it might recieve, and is running on base maps...check your wiring, and also clean all the rust off of the o2 bung in your exh. manifold, the sensor grounds thru the mani, and a bad ground could cause the same issues....also read up in your haynes/helms (you do have one right?) the process for testing the o2 readings with a digital multimeter or digital voltmeter...that would tell you whether you have a lazy or contaminated sensor thats plainly not reading properly as a result of being exposed to excessive amounts of raw fuel(even tho the o2 is brand new, it can become contaminated faster than you'd believe)....good luck!!

ryyo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondasaurusrex &raquo;</TD></TR><TR><TD CLASS="quote">hrm...perhaps you have a wiring gremlin between the o2 sensor and the ecu, i've had that issue before, and the strange cold start up idle issue went along with it, and the sputtering when the cel intially comes on...

if in fact its a wiring gremlin, the cause is an intermittent short, causing the ecu to "see" and then "not see" the o2 sensor at random times....
let me guess, after the initial bog when the cel light comes on, it probably drives almost normal? because the ecu is now ignoring any o2 signal it might recieve, and is running on base maps...check your wiring, and also clean all the rust off of the o2 bung in your exh. manifold, the sensor grounds thru the mani, and a bad ground could cause the same issues....also read up in your haynes/helms (you do have one right?) the process for testing the o2 readings with a digital multimeter or digital voltmeter...that would tell you whether you have a lazy or contaminated sensor thats plainly not reading properly as a result of being exposed to excessive amounts of raw fuel(even tho the o2 is brand new, it can become contaminated faster than you'd believe)....good luck!!</TD></TR></TABLE>

Good info. Actually, when the CEL initially comes on, the car will bog and continue to bog. I have to turn it off to get rid of the CEL, and then the car will drive fine for a while. Eventually the CEL will come on again, and sometimes it'll bog again and sometimes not. It seems to be getting worse now, as in the CEL is coming on a lot and it's bogging more than it was last week.

IndySporty

You have to ditch that HF manifold with the cat in it. That is killing your powerband and probably providing so much restriction that the computer is getting bad readings from the O2 sensor because your exhaust is backing up so bad. The bad idling and erratic cold starts could be from a plugged up cat.

ryyo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IndySporty &raquo;</TD></TR><TR><TD CLASS="quote">You have to ditch that HF manifold with the cat in it. That is killing your powerband and probably providing so much restriction that the computer is getting bad readings from the O2 sensor because your exhaust is backing up so bad. The bad idling and erratic cold starts could be from a plugged up cat.</TD></TR></TABLE>

Actually, that's one of the first things I thought about, but then I was like nah, that can't be it. I've got an aftermarket header and exhaust, but was waiting until after inspection next month to install. Oh well, I'm going to go ahead and put it in this weekend. I do have a regular non-hf cat, so I shouldn't have anything to worry about.

DOHCED8

ud b suprised on that bro.. i had an RS*R header on mine.. the hf mani's ports arent big enough and even with a header u still have 2 "notch" a little out to get the proper flow.. with the hf manifold ur probably having too much back pressure befor getting through the exhaust and its overlooading the O2 sensor causing it to throw a code. good luck

DOHCED8

and just 2 b on the safe side make sure the timing is right as well.. i had some idiot do mine and it was off by 2 teeth.. its run but u wont have torque 4 crap

ryyo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHCED8 &raquo;</TD></TR><TR><TD CLASS="quote">ud b suprised on that bro.. i had an RS*R header on mine.. the hf mani's ports arent big enough and even with a header u still have 2 "notch" a little out to get the proper flow.. with the hf manifold ur probably having too much back pressure befor getting through the exhaust and its overlooading the O2 sensor causing it to throw a code. good luck</TD></TR></TABLE>

Cool, I already ported the header for my last zc. I hope this takes care of it.

hondasaurusrex

idk why i didnt think about the mani....must have read right over that part.....hope that header works

ryyo

me too...I'll be putting it on tonight so hopefully all goes well

ryyo

arggghhh...changed out header and CEL for o2 is still coming on at random. It actually seems to come on a lot at lower speeds, or when holding the rpm's below 3k. Sometimes it'll come on when I get on it, but that happens a lot less frequently. I probably should check to see if I'm running rich or lean.

hondasaurusrex

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondasaurusrex &raquo;</TD></TR><TR><TD CLASS="quote">if your using an aftermarket header/downpipe combo that places the o2 sensor farther away from the exhaust ports than the stock manifold, you'll have issues with the o2 sensor coming up to operating temperature, they dont read properly until around 600+ degrees
</TD></TR></TABLE>

ryyo

With this header, the o2 bung is in the same location as stock. Actually, it might be just slightly closer than stock.

hondasaurusrex

then i would suggest checking for continuity between the o2 sensor and the pin on the ecu....you might have a broken wire

ryyo

I'll be checking the continuity next. Just off hand, does anyone know which wire into the ecu it is? But I pulled the plugs, and it looks like I'm running lean. The plugs are all a white/light gray color. If I am running lean, what should I look at next? Fuel filter? I believe it's never been replaced. Or the injectors? Could it be bad timing? On my last zc I had to replace the cps, but I believe the ecu was throwing a code for that. I'm definately not getting any other codes than 02 sensor.

jlicrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ryyo &raquo;</TD></TR><TR><TD CLASS="quote">does anyone know which wire into the ecu it is? </TD></TR></TABLE>O2 sensor is ECU pin C16 - white wire

jlicrx

have you checked the fuel pressure? - fuel pressure not to spec can cause the O2 sensor to get bad readings