1989 civic DX d15z1/Hf tranny
 

Hi,
I recently swap my d15z1 motor with an Hf tranny that i rebuilt two weeks ago. Every since the weather has gotten cold my car has been throwing a code 48 and my mpgs has dropped considerably. Now its at roughly 35ish. I converted my car to obd1. My 02 sensor 5 wire wideband is brand new. Ive been scratching my head on what causes it to through a code 48 LAF? :(

Please help.

You posted this twice accidentally. I chose this one.

Need more info. Simply put, the code indicates a problem with the heated O2 sensor. Is it wired properly? Is there an open in any of the wiring? Did you test for continuity? Can you replace the current sensor with a known good one to see if the problem goes away?

I'm also just curious, how did you adapt the HF cable clutch for the hydro clutch d15z1 (VX) engine? Did you replace the gauge cluster too (the HF speedo is cable driven and the VX is the electrical signal kind of sensor). And I have been told on what seemed like pretty good professional authority that the HF and fourth gen Civics had a shorter countershaft than the 5th and 6th gen and therefore cannot be swapped... your case suggests maybe that's not true.

I just now noticed that i did oops.

I had my buddy try to figure it out yesterday and mentioned the heater sensor in the 02. The sesnor is brand new and i dont get it. Tested from the ECU to the sensor. Iam hoping its wired properly because the guy that help me put the engine in could do honda swaps in his sleep. Does the ECU need to be chipped or chromed whatever its called? He tested for continuity for sure with his meter. It did throw a code 41 but that was fix. He was puzzled but could it be where it was located? header be the issue?

Its still a cable clutch. I replaced the cluster with an 89 civic lx cluster. Its still driven from the cable that originally came in the car. All in all it fit like a glove D series to D series. I am not sure if a d16/17 would fit on hf tranny. I put the tranny in in like an hour. I could email you a picture of it if you want. Its a 93 d15z1 motor with a 91 crx hf tranny. 4 gen motor leans forward a little causing the motor mount on the driveside become pinched. It doesnt shake or rattle.

double check your grounds as well as the oxygen sensor wiring continuity.

+1 to slownugly's comment above: double check, even though you say it was already checked. Nice work with that transmission. Post up some picks, since you have them.

I'm a little confused too when you say you converted the car to OBD1 because weren't both the 93 engine and the 91 HF obd1 to start with? I guess I am wondering if you have the correct ECU for the d15z1 engine.

The 89 car would have been OBD0. To run the D15Z1 you need the proper ECU which is the P07. Is this what you have installed?

The O2 sensor circuit is very simple. If you get an O2 code it's the sensor, the wiring, or the ECU. If you have the correct VX P07 ECU, I would next check the wiring. If you used the stock 89 harness you needed to add extra wires for the O2 sensor. Verify they are connected to the proper locations on the ECU by looking at an ECU pinout. If the wiring is correct, the ECU is correct, it's your O2 sensor. Being new doesn't mean it's 100% guaranteed to work. Which brand is it? Did you get the proper O2 sensor?

I recheck and I couldnt find nothing. Its getting kinda of frustrating since with this swap I should be getting atleast 45 55 easily if ran right. My ECU is a p07-A00 and it is for a VX. I used a jumper harness that I bought from eBay that converts obd0-obd1. I did however used existing harness with the jumper. I dont have a picture for that. As for the sensor it reads on the box NGK NTK # 24300 L2H2 L1H1 5-wire Wideband Oxygen Sensor that i also bought from eBay. I wish I could borrow someones 02 sensor and see if thats the culprit, but you cant just buy and return stuff like that. Ill have to dive in again, but i might have to take it to a "Honda specialist" if i cant figure it out.

the 91 crx hf tranny is from an obd0 car. (rebuilt with bearing kit)
the engine d15z1 is a obd1.

On a side note : If you ever get an HF tranny replace the first 3 gears with a Dx gears because its gutless for sure. I should done that before i sold my DX. The HF now I can go 75mph in second gear redline at 6k. Super tall gears. At 77mph my car runs at 2300rpm top dead center for Honda gear ratio.

I posted one picture of my car. Ill resize the rest later.

Nice looking car! Love the HX 14" wheels (maybe they're 13" VX wheels), the chin spoiler, and general apparent clean look.

I think you're saying you rechecked for continuity and it all seems fine. The harness could be an issue. Did the HF have lean burn? I don't think it did. So I wonder if the wiring connections are correct in the jumper harness.

Yea I think the jumper harness itself would have to be modified as well. Not sure I never used one. But it's not throwing any other codes for the egr

You've got the right sensor, and the right ECU. It's the wiring. The stock harness for that car didn't have 5 wires for the O2 sensor. The OBD0>>OBD1 jumper harness you bought probably isn't designed for a 5 wire O2 sensor either. Find a service manual pinout for the P07 ECU, and find where the 5 wires from the O2 sensor connect. Check continuity from the O2 sensor connector (engine bay) to the ECU connector. Do this for all 5 O2 wires, and make sure all wires are going to the correct pins on the ECU.

Did you try unplugging the o2 sensor to see if it would run better without it, mileage should be better then 35mpg with the ecu running in open loop.
Only thing that I've seen that would kill an o2 sensor on a VX engine was over size exhaust.

Funny thing this set up worked over the summer. When the weather was hot the asphalt with hot and my o2 never came on. Now that the weather is getting colder the ground is getting colder my o2 has come on more often now pretty much all the time.I don't have a big exhaust but I do have headers on it because the card didn't come with a cat near the engine. I know that the Honda Civic vx comes with two catsconverters. I don't have the one that's in front of the engine and that one is pretty expensive along with the 02 sensor. Its pretty much stock after my header.

Mechanic did that on the testing and we couldnt figure it out. all I could think of is that it doesn't have a second Cat converter, but that cat near the engine is expensive.

Here are my pictures of my engine bay. My 02 sensor; hf to my d15z1 and header.

Now that you say the code wasn't present before, I would say the O2 sensor is bad. You said it was brand new, but how new? Why did you replace it to begin with?

I got a code 48. O2 sensor is only two months old. I didn't replace it it didn't come with the motor when I bought it. My guess is the heat sensor. I've read that these sensors need to be really hot.

The VX only came with one catalytic converter and the o2 sensor goes right on top of it, about 3" from the head, the header you have is most likely causing the exhaust pulses to just pound that o2 sensor to death, it's not tuned for a engine that size that is turning that slow, they are a sensitive o2 sensor that doesn't last long with over sized or leaky exhaust.

You are right on the pounding of the 02. I pulled it out I don't want to destroy it. Mine car is suppose to look like this guys. 1/3 way down I need that cat for sure. Crxmpg.com. I've got a lot of hestation in my probably explains the headers. I moved my 02 earlier to the back side of the engine near the original cat that came on the car. I drove around 15-20 miles and turned it off than turned my car on and my 02 didn't come on, but game me a code 48. SO from what you are telling me is that the header with high flow the 02 doesn't like it near or far unless near a cat where the air is slightly resisted by the cat but moving fast enough that the 02 throws a code 48. Hmmm.

It's not so much that the header you have has a "high flow" but that it has to much of a pulsed flow and when you let a gas enter to large of a pipe to suddenly it cools and it doesn't flow as well, so it could be that your o2 sensor is constantly using the heater to keep it warm or it could be that the exhaust pulses are to violent in the over sized pipe and is just rattling it to death.
Either way, I bet that if you replace the o2 sensor it will last a few months again before giving up until you fix your exhaust.

Yup, another difference is the aftermarket header is only in one cylinder tube in the header. The original vx sensor reads gas coming from all 4 cylinders. Not sure if that's a problem but worth noting. I may be able to get you a manifold and converter but you will most likely have to change the mid pipe goin from the new converter to the intermediate pipe.

I have like 4 extra vx manifolds but the converter is harder to find. But I know where one is.

Also I gutted the converter in my swap. (it was plugged with carbon) But I have the original lx converter downstream so it's still legal.

so it just needs to be collected in the exhaust manifold all 4 cylinders into one area so that the o2 sensor can read it. so you gutted the cat and it works great? I've got an HF exhaust manifold but I'm wondering if an EG manifold work with the downpipe? ice on ebay I could buy an HF cat converter for much cheaper than a vx cat converter. both the same size engine so I see why I wouldn't. here is a picture of the EG DX sedan exhaust manifold and downpipe with the o2 sensor.

I have 25k on the swap and I have no problems with it yet. Lean burn has been consistent.

I think the hf manifold is exactly the same as the vx and cx. That should work but you need the downpipe as well for the hf.

I just so happen to look at Craigslist and someone is selling a cracked hf exhaust manifold, cat and down pipe for $60. I already have a good Hf manifold. I really hope this fixes the code 48 issue.

Here is the cat, downpipe, iam going to buy tomorrow afternoon from an HF for $60obo

The picture of the 02 is where it was located over the summer and it work too, but thats when the weather was hot, ground etc. but moved it to the front after the engine light came on a lot and weather was cold and so was the ground. I was hoping it would fix it but it actually made it worse.

So when I take the header off and put the cat, downipe, and manifold on. IT SHOULD WORK lol. fingers cross.

I just bought one that style for my HX. Right now I have a 99-00 Civic EX exhaust manifold and downpipe, which looks much like an aftermarket 4-2-1 header. The primary O2 is located behind the engine way down by the cat. Research suggests that the longer "delay" from moving the O2 sensor can cause issues. My car runs fine except when it tries to enter lean burn, then it hesitates and kicks back out.

Yup that setup looks exactly like mine even the shield.

Keep in mind the 02 may need replacing from running it with the header. Here's one I found on eBay. Another member here got one from him and it worked perfectly.

http://item.mobileweb.ebay.com/viewi...d=261291158242

If that link doesn't work here is the item number

261291158242

My car did the same when it was in back of the engine and i could really feel it kicking in and out. Especially around 2600rpm or more and a lot of jerking in and out below that. Definitely lean burn works.

slownugly. Glad the set up is going to work. I hope i dont have to buy another sensor. I only had it in the front for a few days in the front of the engine. I had it in the back for month and a half away from the engine near the firewall or 3k miles. I put in that spot didnt think it mattered after I swap the engine in. Anyways, I took my 02 out and just plugged it until i get the set up in.

Let us know how it works. Hope you get away with ur sensor as well.

Ditto that. And also, when you get a chance, I'd love to see a new thread from you with pics on your trans swap. I would use it and link to it to update my list of Honda trans specs and swap possibilities: http://ecomodder.com/forum/showthrea...tml#post378478. Right now, that list follows the advice of a trans specialist who claimed the 4th gen trans could not be swapped onto 1992-2000 engines. But it sounds like you did it without trouble. That would be a useful thread too.

Anyway, good luck!

Well I finally got the exhaust today. its looking good too. ill put it in this weekend I hope.

I have a few pictures from my swap. Not a lot. A few pictures of my tranny open up too.

It still threw a code 48. But the used cat sounds clogged too. Not sure if that causes it to throw a code 48

There has got be something wrong with the sensor itself, the wiring, harness, or connections. That's specifically a heated sensor 0 2 Code. A clogged cat would be bad too, but if the code has appeared and you can't clear, I have to think the sensor itself or its connections is the top suspect. Have you investigated the pinout?

The mechanic guy check it out last week and could not find anything wrong with the wiring or pin out. I might have to fess up and buy another expensive 02 that I can't return if I open the package.

I'm going to hallow out the cat maybe. I put my header back on and put it on the original spot where it worked the first time. Just in case the 02 may work. The gasket for the cat has a small leak too.

You should be able to put a flashlight under the honeycomb and see through it. I vote use the hf exhaust and clean out the converter if you have to. I can send you an o2 that I have laying around that didn't throw a code. It had a bad stumble but it will give you the answer you need without guessing on a brand new sensor.

I've purchased a new 02 sensor today. This one has a red wire oppsed to blue wire. Not sure if there is a resistance difference. Ill eventually install the 02. I think I burned out my other 02 in less than 3000 miles. Thanks for the offer slownugly. My car had been averaging 28mpgs. With those numbers I should have thrown a gsr motor in it.

Well the new 02 sensor with the new exhaust, cat and downpipe still threw a code 48. I heard the oem one has 7 wires as opposed to five wires. So tomorrow I'm going to look at an OEM sensor.