DC5R throwing up engine light after having header + catback installed...

Hey all,

Just had a Buddyclub header and J's Racing catback fitted to my car. I noticed that after about half an hour of driving, an engine light appeared. Also, when the car is up to running temperature, when it is at idle the revs sometimes drop quite low, and the car feels like it wants to stall. Ive also noticed that occasionally the header knocks on the floor of the car under hard acceleration. The exhaust is also a de-cat system. Whether thats worth noting im not sure.

But can someone please help explain the engine light and how to remove it? The car seems to run fine, just the issue with the revs dropping at idle.

Any help would be great. Cheers.

1st of all the headers shouldnt be touching the floor under any circumstance.

2nd you shouldnt be running a de-cat system =P

3rd Maybe try reset the ecu? might fix the problem.

Well they dont always touch the floor, i can just hear them knock against it occasionally. And because of the Buddyclub header's design, the only way to fit a cat wouldve been to cut a chunk out of my header and catback, which i didnt want to do since they cost me a fortune. Its a race header, so having no cat is something i just have to deal with lol. But ill try the ecu reset. I just disconnect the battery for a few mins dont I?

Wild guess, but could it be O2 sensor related?

As for resetting your ECU, everything you need to know is in here:

http://www.ozhonda.com/forum/showthr...ight=Ecu+reset

:)

At guess mate, your engine light is due to the lack of cat in your exhaust system, have you still got the O2 sensor and the A/F sensor connected?? My brother had a similar problem when we fitted his toda headers, also race headers, but Adrian at Toda modified the headers to suit a cat, i would definantly recomend you to do this.
You can reset your ecu but it will most probably come back. Are you running an aftermarket ecu?? because K-Pro you can change settings in the ecu that will throw DTC's for certain emmision devises. Best bet is to check what DTC/DTC's have come on, here are a few codes that are related to O2 and A/F.

O2 Codes = 63-1 low voltage, 63-2 high voltage, 65-2 heater circuit malfunction. A/F codes = 48-3 circuit malfunction, 41-4 heater system malfunction, 41-1heater circuit malfunction, these will probably not be the codes you will have, my brother said his threw (catalictic converter not working efficiently/ not sure what code this is) you will need a HDS or a general scan tool to extract these codes, an advantage to the older hondas (2 pin bridge).

As for the knocking, not normal but not unheard of, might pay to check clearance of the exhuast to body and swaybar, most aftermarket headers will require you to swap from standard swaybar to EP3R swaybar, this will help with clearance issues and its a straight swap, you dont want to crack those nice new headers!!!. engine mounts are another important thing to check, if any of them are split you might want to replace them with stiffer ones, or inserts.

hope this helps you with your dilema.

I made a post on DTC codes listing all of them for dc5r. Check it out. Hope it helps.

Engine light - There is an o2 sensor before and after the cat in a DC5R. The secondary sensor probably isn't liking the amount of CO2 gases after the "cat", so thinks something is wrong. Also note there are hefty fines for not running a cat, and any cop that knows anything is going to be able to smell the lack of a cat... not to mention the DOT. In all seriousness, I would be running a cat if you intend to use the car on a regular basis (Would also reccomend a cat if you intend to use the car for street use).

Knocking - I beleive these headers are deisgned to be used with the stock sway bar. But the stock engine mounts in a DC5R are VERY soft. If you replace them with something stiffer you should avoid this knocking noise.

I tried the ECU reset, and the light is still there... It also hasnt fixed my weird idle issue... This is what is concerning me the most, as im worried it might be damaging my engine. As for the light itself, im pretty sure that its the lack of cat that is causing it. I do intend on putting one in, but since the exhaust system cost me a mint i need to save up a bit first. Can anyone explain the abnormal idle? The car will start fine, ill be driving along normally, then as i put the car into neutral to come to a stop, the revs drop low and the car almost stalls. However it hasnt actually stalled yet, just feels like it wants to. and it only does this for say 10-20 seconds, if i leave it idle for a while the revs will go back to around normal. But if i start off again and then come to another stop itll do it again. It only started doing this after the exhaust was fitted.

Any ideas?

It's fairly obvious.

You have no cat. The 2nd sensor is going "WTF is going on here, I shouldn't be reading this much CO2 gas", so it's putting less petrol into the engine, and making less CO2.

The stock ECU and sensors are designed to have a cat in the exhuast system. I wouldn't be surprised if you ruin the 2nd sensor with not having a cat there, as they are quite brittle.

GET A CAT! Even if you put the stock headers back on until you have enough money to get a cat fitted to the other headers.

Like 'Mattski_VtiR' and '45SET' said.... basically the 2 sensors are normally there with the cat, the 1st sensor (A/F) sits in front of the cat and the 2nd sensor (actual o2s) is in the middle of the cat. The 2nd sensor (o2s) compares readings of c02 gas in the exhaust continuously against the 1st sensor, and as the cats job is to reduce the c02 (which it isnt in your case without a cat) the ecu is making adjustments that are out of spec and therefore turning ON the engine light to notify you there is a problem (which is your missing cat).. The idle problem is related to the same issue of a missing cat too.. So if you GET A CAT FITTED or get an AFTERMARKET ECU as suggested you can resolve all issues and gain some performance too!!
Oh and if you run ur car with the engine light ON without the cat more than likely you will soon start to melt the rear bar around the exhaust pipe due to excessive heat from lean a/f ratio! and you will also damage your motor and probably sensors too if left long term.

just skimmed hrough his hread in 30 seconds.. knocking is because u have stock mounts, get billet mounts.

like i said in my PM, get a defouler.

resetting the ecu only eliminates the light until the ecu geos crazy n goes wtf at so much air passing though.

You will need this

1. Install an aftermarket cat
2. Install a cat defouler. This is a bung or small pipe that decreases the emissions to the secondary o2 sensor. It means less exhaust is read from the ecu , so it tricks it to think there is a standard cat installed and running fine.
After installing simply remove your ecu (unplug it ) for a minute or so and the check light should be gone - and the car should run slot better

As for the clunk under the car - this is the header touching the chassis or swaybar as the engine pivots
You either need a new rear engine mount or others , or perhaps you need the ep3 front swaybar ( required when installing some jdm headers on a dc5)