VikingCX

I just bought my second hatch, a 99 Civic CX, and have been reading up for the past few days about issues and part swaps but wanted to know if there are some common items that typically go wrong on these cars?

My idle already sucks (2500 RPM and/or surging) so I'm working on getting a Z6 / Y8 manifold to fix that (since it comes with a spare IACV).

The car has a no-name EBay header on it along with a 2.5" exhaust that sounds raspy and shitty and has no cat. I'm going to weld in a high flow cat and replace the muffler with a nice Magnaflow or something more reasonable.

The 3.25:1 final drive is trippy. It has basically the same long *** gearing as my GT3RS, only with ALOT less power / torque to make the car move, haha.

I got some Stoptech pads I ordered along with ES motor mount inserts and a complete set of mounts. Gonna bleed the brakes and replace with a DOT 4 fluid, and do all the other fluids. Do people pretty much still only recommend the Honda brand fluid for the transmissions?

Is there an affordable LSD that works with an EX final drive?

kyden

if you replace the IM you'll have to convert to a 2 wire iacv, then use a chipped ecu.

mfactory makes a nice lsd, that's probably the best you're going to get from any cost perspective. I would just swap out the whole transmission to an EX unit though.

Axatax

You don't have to run the 2-wire IACV with these manifolds - you can block the port off and continue to use the 3-wire IACV on the throttle body. You just need to use the throttle rotor from a Y8.

Former User

Replacing the IM seems extreme at this juncture. Why not first try cleaning the IACV and checking for a vacuum or intake air leak? What CEL codes are thrown?

tony_2018

Forget the manifold swap and save money towards swap. Fix the leak and if there are any cel codes pull them and continue.

VikingCX

I already cleaned it and checked for leaks. I even re-sealed and checked the surface. Still a no-go.

The IM is a kill two birds with one stone fix. A better manifold and a working IACV.

VikingCX

I don't want to swap this car. I'm going to turbo the D-series in it.

In fact, some of my STI's stock parts are probably going to find there way on the car.

If the motor grenades itself I will likely swap in a B18C.

Former User

I haven't heard you mention any direct evidence that a bad IACV is the root of the problem. There are tests that can be done to pinpoint the issue. CEL codes?

VikingCX

OBD1 conversion and the 2 wire IACV would be good to go yea?

EX trans seem to go for $300 around here with questionable quality. I guess I could buy one and pull the gear stack out of it. Gonna need to do that to install the LSD anyways.

The MFactory is a Torsen unit? Any clutch types out there?

VikingCX

It's throwing a IACV code. It does not like cold starts at all, it will immediately idle around 2500 RPM and not come down until I restart the car. When I restart the car with a warm temp it will idle around 1500 RPM steadily, or sometimes surge between 1000 RPM and 1500 RPM, or sometimes even sit at 850 RPM and idle nicely but will go back to the high idle.

The IACV is pulling the air, so the pathway is hanging open. It's not leaking past the seal.

The signal to the IACV is working properly. It has the decel opening near the idle point, etc. Just the valve is allowing way too much airflow past.

Former User

What specific OBD2 IACV code? There's more than one. And while they are often referred to as IACV codes, there can be other causes.

Again, there are possible causes for this^ other than the IACV. What's the CEL code?