So as the thread title says my car is running rich. Its a 95 hatchback with a D16Z6. I have replaced the FPR, fuel filter, spark plugs, O2 and Cleaned the K&N filter already. The car was throwing a CEL before, code 43, but since changing all that stuff and resetting the ECU the code has not returned but the car is still running rich.

 

Measure the fuel pressure and check for a stuck open fuel injector.

 

is there an easy way to check to see if an injector is stuck open?

 

Remove fuel rail with injectors. While securing the injectors in place, turn key to ON(II) [engine off). No injector should spray fuel.

 

 

There may be a hairline crack in the exhaust manifold behind the O2 sensor bung hole. This will read as a lean condition and cause the ECU to send more fuel. If so a cheap ebay header seems to be the way to go.

 

Did the injector test and no fuel came out so im guessing somthing is causing me to have high fuel pressure? I dont have a kit to test the exact number available but if I need to i can go out and get one

 

You can rent the fuel pressure testing kit at your local parts store. You can also buy something simple like this if you want a more permanent solution.

Is your car stock? Any modifications? Unmodified P28 ECU? Original engine?

 

Also definitely look into this^

 

Not the original engine, the ECU is an unmodified P28 though. Only mod is an exhaust everything else is stock.

Would I be able to feel any exhaust coming out around the bung if there is a hairline crack there? Also I dont know if this stuff matters, but I have also checked the ignition timing with a timing light and its spot on and the problem kind of showed up out of no where, It wasnt a gradual thing. Ill go get a fuel pressure test kit tomorrow when I have some daylight and come back with the numbers I get.

 

Do you see a crack in the header? If so, post a picture.

Also, if you see the CEL turn on while driving, pull over and leave the engine running while you jump the service connector.

 

no cracks in the header didnt feel exhaust coming out anywhere near the gasket either

 

some header cracks you won't see unless you take it off and inspect it.

 

I agree and this type of manifold crack is common to the 93-95 D16Z6.

It's on the side of the manifold close to the block and pinhole thin.

 

Ill take it off after my classes tomorrow and further inspect it. I managed to do the fuel pressure test today though and heres what I got:

This is with the vacuum line to the FPR disconnected and pinched


and this is when the vacuum line is hooked up to the FPR

 

took off the header and looked at it and the only thing I saw wrong,other than the header being old as dirt, is the broken bolt on the downpipe portion. Its been like this since I got the car could it just now be causing a problem even though its after the O2 sensor?



and heres a couple other pictures maybe you can spot something I missed.

 

Could a faulty MAP sensor be causing this problem without throwing a CEL?

 

The common crack area is in the exhaust manifold runner just behind the O2 sensor bung hole almost even with it.

If you're suspecting the MAP sensor I would advise you to replace the O ring under the MAP sensor. You can get one at ACE hardware that works (see pic) or get one at the Honda dealer part # 16075-P07-000, O ring (9.8x1.9)

 

Good ****, now if I could find a ACE hardware store around my area...

 

Theres plenty of ACE Hardwares in my area so ill stop by there and grab one of those and try that.

 

So I think I found out what has been causing my problems. I went to my friends house and put his P28 ECU in my car and the strong gas smell from the exhaust seemed to disappear. So today I opened up my ECU and in this area it looked problematic. Does anyone know if this could be causing my problem if its fixable?

 

Ohh crap, I don't know about ecu's internals, But being that some kind of damage has occurred to the "brains" of your car, I would call someone immediately and see if a new ecu is needed. That doesn't look good to me, and it seems to be causing issues already that will probably keep getting worse.
GL bro

 

Just looks like normal surface corrosion to me If your friend's ECU fixed the problem, then investing in a replacement ECU wouldn't be a bad idea. I believe you can get it from Xenocron for a reasonable price.

 

I didn't have time to actually drive around with his ECU in, just put it in and wiffed the exhaust a little bit. I want to try and find a P28 to borrow for a day or 2 to test out before I drop $100-$190 on one. Unless someone has one they're trying to get rid off.

 

P28's are a seller's market - you aren't going to find someone "just trying to offload" one. If your friend can, see if he'll let you borrow his ECU for a week. Alternatively, hit up a pick a part yard, go scrounging around the yard for an ECU from a 92-95 EX, SI, or Del Sol SI. You should be able to get a P28 for cheap. Just bring a screw driver and open the case to make sure it hasn't been chipped. If it's cheap enough, don't even worry about 5MT vs 4AT - you can spend $30 on a diagnostic ECU.