Honda D Series Forum banner

1 - 17 of 17 Posts

·
Registered
94 dx coupe
Joined
·
24 Posts
Discussion Starter #1
I have an eg coupe with a JDM D15B swap running on a P28 ECU. It has been running a little rich then all of a sudden it is running REALLY rich.

Symptoms: sign of running rich on plugs, black accumulating inside muffler and around the back end of the car (smells like unburned fuel also), small misfiring, idles super low at times, gas mileage is awful for this D15B.

What can I do to lean it out? I was told a VAFC could do the trick as I could adjust the A/F ratio, and also play around with setting VTEC. Was also told an actual tune would be a lot better but I don't know much about chips and all of that + the cost of it all.

It has been running like shit lately from it running so rich. I'm surprised it doesn't almost just die sometimes...
 

·
Registered
Joined
·
119 Posts
Don't even know if it is chipped, but at this point. I just want it to run correctly.
You are running an ECU with fuel maps/ignition timing maps all for the wrong setup no wonder it is running rich. Get either a chipped P28 with a tune for that motor setup, or get the proper ECU for the engine.

Everything is precisely programmed to work with the engine - things such as fuel injector size, type, spark, timing, everything down to the displacement and compression ratio. So often, throwing things into a car will usually run but not optimally; how many guys are driving around pig rich on a basemap due to this...
 

·
Registered
94 Integra
Joined
·
1,225 Posts
I wouldn't be surprised if the "all of a sudden" was caused by the o2 going bad. If the map was too much fuel for the motor & the O2 was doing serious fuel-reduction corrections, it going out would appear as a sudden fuel problem. Even if it was and you replace the o2, you still need to correct the main issue.

An AFC may work but not as well as the CORRECT FUEL MAP. It's also very likely it will be installed incorrectly (that's the *most* common issue with them), and it also costs a lot more than having someone chip your ecu and burn a p08/d15b map.

You will also want to replace the spark plugs at the same time since you've likely fouled them by running so rich. If you don't fix this ASAP, chances are you'll ruin your rings from the excessive fuel - if you haven't already. A compression check probably will be your 1st step.
 

·
Registered
94 dx coupe
Joined
·
24 Posts
Discussion Starter #11
I wouldn't be surprised if the "all of a sudden" was caused by the o2 going bad. If the map was too much fuel for the motor & the O2 was doing serious fuel-reduction corrections, it going out would appear as a sudden fuel problem. Even if it was and you replace the o2, you still need to correct the main issue.

An AFC may work but not as well as the CORRECT FUEL MAP. It's also very likely it will be installed incorrectly (that's the *most* common issue with them), and it also costs a lot more than having someone chip your ecu and burn a p08/d15b map.

You will also want to replace the spark plugs at the same time since you've likely fouled them by running so rich. If you don't fix this ASAP, chances are you'll ruin your rings from the excessive fuel - if you haven't already. A compression check probably will be your 1st step.
Checked the CEL codes and got these back.

Code 7, code 10, code 22, and code 41.

I've heard the JDM D15b's didn't have an IAT sensor? Which concludes that I am running a stock P28 ECU and need a P28 with a P08 basemap? If so, I'll order one right now!
 

·
Registered
Joined
·
119 Posts
Yeah order the chipped P28 with a P08 basemap; as long as your injectors and everything is relatively stock it should run well. Another thing to do is to make sure your ignition timing is set correctly, if it is too retarded it will run rich as the spark is firing too late in the stroke. Do you have a timing light, someone correct me if I am wrong but It hink 16 degrees BTDC is what you want - this has to match what the ECU has.
 

·
Registered
94 dx coupe
Joined
·
24 Posts
Discussion Starter #13
Yeah order the chipped P28 with a P08 basemap; as long as your injectors and everything is relatively stock it should run well. Another thing to do is to make sure your ignition timing is set correctly, if it is too retarded it will run rich as the spark is firing too late in the stroke. Do you have a timing light, someone correct me if I am wrong but It hink 16 degrees BTDC is what you want - this has to match what the ECU has.
It gave a faulty IAT code and there's one hooked up onto the skunk2 manifold that is on it. It's white so I assume that is it. I ordered a new IAT thinking that might fix that issue. When I let it idle and unhook the connector, nothing happens.
 

·
Registered
94 dx coupe
Joined
·
24 Posts
Discussion Starter #14
Yeah order the chipped P28 with a P08 basemap; as long as your injectors and everything is relatively stock it should run well. Another thing to do is to make sure your ignition timing is set correctly, if it is too retarded it will run rich as the spark is firing too late in the stroke. Do you have a timing light, someone correct me if I am wrong but It hink 16 degrees BTDC is what you want - this has to match what the ECU has.
And also, how do I check the timing? I've never had to do all of that. This has an AEM cam gear on it
 

·
Registered
94 dx coupe
Joined
·
24 Posts
Discussion Starter #15
Also, the radiator fan is hooked up to run 24/7. Keeping the engine a little on the cooler side. Wouldn't that also cause it to run rich? I don't want my rings to wear any more than the already have.
 

·
BATSLOMAN GIVES NO FUCKS.
Joined
·
4,098 Posts
instead of asking and waiting for a spoon to feed you, do a quick search to see how to check timing. same goes for how to fix your fan switch. also, not sure if I mentioned it yet, google a fsm for your generation, download and troubleshoot
 

·
Registered
Love the Civic
Joined
·
1,817 Posts
Also, the radiator fan is hooked up to run 24/7. Keeping the engine a little on the cooler side. Wouldn't that also cause it to run rich? I don't want my rings to wear any more than the already have.
My fan is on all the time too. Have it wired to a switch, havent fixed all the previous owners wiring jobs yet. Pretty easy to wire in a relay if your is gone/bad. I have never had it make my engine run rich though.

And also, how do I check the timing? I've never had to do all of that. This has an AEM cam gear on it
Im with slo, you are asking the basics, which is fine, but these are easily figured out by searching youtube, that is how I learned how to do both of these tasks you asked on.

You need a timing light, and the search on you tube, this will help more the words explaining the process.
 
1 - 17 of 17 Posts
Top