Mahalaleel

I have a 1999 Civic EX with 260000 miles. I get about 35 MPG around town during the warmer months, 30 MPG during the winter.

Now that it's getting warmer out again I noticed that my engine stumbles under load under 2000 RPM. When I start the car it idles very high ~1500 or higher RPM. After it is at operating temp it idles at around 400 RPM (accord to tach), but it is very smooth and consistent.

When I try to get moving if I let the clutch out completely and then give it more than 1/4 throttle (at ~1000 RPM) it stumbles horribly. If I only give it 1/4 throttle or less then it slowly gains speed without stumbling or misfiring.

Another example is that when I am in third gear, if the RPM are below 2000 and I give it more than 1/4 throttle it will not accelerate, but just stumbles.

Past 2000 RPM the car does great in all gears, other than the fact that my cousin said that he saw black smoke from my exhaust when I was going WOT.

What can I do to diagnose this problem? I'm worried that I'm damaging something, because other than being annoying, I still get great gas mileage and the car gets me where I need to go. I want to take care of this car and make it last to 300,000 miles if I can.

Arthas

Have you done a full tune up?

My accord has a similar problem although not as bad as you described it. I have my suspicion on the cap and rotor.

jbpnoman

Do a full tune up, and while you're at it, pick up a timing light and check your timing.

Voodoo7

change plugs and wires, and if you havent changed the cat im betting this is your issue. There is a good chance it is clogged and needs to be replaced.

h22steaksauce

No cel?

motegicivic

Def tune it up, cap rotor wires plugs. Might be a misfire, but not bad enough to trigger a code yet.

also, when is the last time you did your primary o2 sensor?

Mahalaleel

Have not changed the o2 sensors. The cat IS bad. For sure. CEL 0420. Would that affect the way it runs? This summer I'm planning to gut the cat, because replacing it is way expensive.

I will check the plugs, wires, etc. Could it also be the FITV? Or something to do with the idle air control?

Voodoo7

Yes the cat will cause the exact symptoms you are describing. Should clear up when you gut it, but still do a basic tune up.

motegicivic

A clogged cat can make the car run rough. There is no FITV.

Mahalaleel

OK. As soon as I get up to Idaho where my cousin has a garage I will gut the cat, do a tune-up, and try to fix all the oil leaks!

If I gut the cat do I need to get a post-cat o2 duper?

Today found one of the oil leaks from the VTEC cam adjuster! It's spraaaaying out of the crack between the two parts. When it stops raining I'm going to take it apart and replace some gaskets.

Mahalaleel

Well, on my drive to the shop the engine spun a bearing or threw a rod or something, because it's knocking really badly now.

Will a 1995 D16z6 work in a 1999 Ex? I read that I will have to change the wiring harness, get a new ecu, etc, etc. Is there something simpler/cheaper to do?


Basically, I need the most inexpensive way to get my car back on the road. I don't want it to be fast, I just want good gas mileage. I'm sure many components on my d16y8 are reusable or could be sold to finance a new engine.

Would I be better off finding a D16Y8 for more money? Or swapping and making all the mods? Or parting the car out? Or selling the car (running badly)?

I'm in a bad mood now

Any advice is appreciated.

jbpnoman

Get a Y8, or a Y7 from a 99-00 Civic. It'll be an absolute direct bolt in.

Mahalaleel

I found a local D16Z6 out of a 1995. Will that bolt up to my D16Y8 transmission, wiring harness, ECU, etc?

jbpnoman

Transmission, yes. Wiring harness and ECU, no. The Z6 is an OBD1 motor, and your 99 Civic is an OBD2B car. Also, legally speaking, Federal law states that replacement motors must be from the same year or newer. Obviously that's not exactly enforced in most locales, though. A D16Y7 or D16Y8 from a 99-00 civic will be your easiest replacement.

Mahalaleel

Dang. Honestly, I'm in Idaho, where they don't even do emissions, so I'm not concerned about uncle sam.

I can't find any d16y8's close enough to me . The d16z6 is tempting because it is 225$

jbpnoman

It's totally doable, it's just not a direct, everything plugs in perfectly swap. If I remember correctly, you'll need to reuse your distributor, and pick up the correct ECU for the motor, which would be a P28. You'll also need an OBD2B to OBD1 conversion harness ($10-$15, no big deal). Other than that, it's a pretty straight forward swap.

Mahalaleel

Looks like the ECU is ~120$. Found the harness cheap. Anything else I would need? Would the injectors from my d16y8 work in the z6?

jbpnoman

The Z6 and Y8 injectors are both saturated type, so yes, they should work.

HondaPartsHero

Search around $120 is too much. You'll need an obd2-1 distributor adapter as well.

jbpnoman

Not if he guts the Z6 and Y8 dizzies and puts the Y8 internals in the Z6, or he does a little bit of fabrication to mount the Y8 dizzy on the Z6. A dizzy adapter harness is pretty cheap though, so it would be the easier way to do it.

Also, you'll need to do this.

Mahalaleel

that cfk tricksays its for somebody is using the newer ecu, do I still need to do it if
I get the P28?

jbpnoman

Ah, right, nevermind. I wasn't thinking when I posted that. The P28 won't even look for the CKF.

Mahalaleel

thanks a ton for all the good info! I'll probably pick up that motor tomorrow

jbpnoman

If you're actually willing to spend that much on the ECU, I'd go through HA Motorsports and get a P28 with a Z6 tune straight from them for a little bit more. You can definitely find them cheaper though - just dig around in the market place. I paid $60 for mine about a year ago, with minimal forum browsing required.

I'd seriously recommend getting a virgin ECU, if you're buying one second-hand. You don't want to deal with someone's possible hack job.

Frankie Flores

you can also gain some of your money back by taking you cat to a recycle center.