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1994 Civic Si
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Discussion Starter #1
Here's a little back story. I have a '94 hatch Si with a D16z6 and a 5 speed. When I bought it. It already had some basic bolt on mods and a chipped P28 ecu. It has been my daily driver for a while, but it has a nagging problem that I am finally trying to fix. It pings a lot at low rpms, under 3k. I ran 91 octane for a while, and it was great initially, but after a while, the pinging returned. Maybe the ecu adjusted and the timing is still too advanced. I tried to rest the base timing, jumping the connector, etc. but found that the bulb for the CEL had been removed. Replaced bulb. Hard CEL, Code 1. Checked O2 sensor, found it disconnected. Replaced O2 sensor, hooked it up, still hard CEL. This appears to not allow me to put the ECU in reset mode so that I can reset the timing. I have done a lot of searching, and I am finding that this may not be a simple thing. The chip may only use only open loop (there was no change in how it ran when I hooked up the O2 sensor). Ultimately I would like to figure out everything that I have here and what kind of chip or program I am running, but right now I'd just like to retard the timing a little so it doesn't ping at low rpm and then work from there. I know this is a long writeup, but I figured the more info I include the better you all may be able to steer my in the right direction. Thanks for any help that you can offer.
 

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BATSLOMAN GIVES NO FUCKS.
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unless you know what tune and fuel curve youre using, it wouldn't be beneficial to retard timing. find a stock p28 and reset timing per fsm
 

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1994 Civic Si
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Discussion Starter #3
If I use a different ecm to set timing and then put the ecu that I have back in, will it recognize that the baseline timing has been reset. Doesn't the physical position of the distributor and the running ecu have to be in sync somehow for the timing rest to work? What would be the difference from having the ecu disconnected and physically rotating the distributor and then reinstalling the ecu?
 

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BATSLOMAN GIVES NO FUCKS.
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you didn't read what I wrote. you have zero idea of what the timing is set at and the fuel curve of your chipped ecu is. therefore, if you mess with ignition timing, it may dump more/less fuel, run lean/rich, be advanced/retarded by an unknown amount. unless youre going to reset the tables yourself, run it stock. hell, if its not modified anyway, it shouldn't need a chipped ecu
 

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1994 Civic Si
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Discussion Starter #5
I did read what you wrote, and it is not stock. It has a Skunk2 Pro series IM, an AEM fuel rail. At least a approx. 60 mm TB, a 4-2-1 header, and I am trying to figure out what size injectors. Any idea how to identify the injectors? I recognize that I am new to all this, and I am trying to educate myself by doing a lot of reading. Unfortunately, as you probably know there is a lot of info out there that is BS, and I am trying to find reliable sources of info.
 

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BATSLOMAN GIVES NO FUCKS.
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sounds stock with a lot of pretty parts on it. stock injectors are 240cc. there is no need to upgrade fueling for a stock motor.
 

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1994 Civic Si
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Discussion Starter #7
Also, from what I have read, I could clip the J1 jumper wire on the ECU and it would stop referring to the add-on chip and run stock. Is this a viable option?
 

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1994 Civic Si
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Discussion Starter #8
So you are saying that the add-ons are all mild enough to run fine on stock programming?
 

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BATSLOMAN GIVES NO FUCKS.
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yes. you haven't done anything to need more fuel/timing. all you did was allow it to breathe
 

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ej8
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sounds like a can of worms.

You seem to have someone else setup and you have no idea what that have on it.

I would say put in a stock ecu or return the ecu to stock (j1 jumper)
and go over everything on the car and find what what each part is.

The oem injectors are good for maxing out the stock block on NA power.
 

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1994 Civic Si
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Discussion Starter #11
Yeah, it is sort of a can of worms, but it has been a pretty dependable one. Clipped j1 and took it out. at least for right now, no low end pinging the chip must have been adding a lot of timing. Still have a hard code 1 CEL. So I'll have to figure out how to get rid of that.
 

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ej8
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A solid cel normally means a bad ecu.
and you adjust the timing with a timing light and moving the dizzy. (Normally its in the center of the top bolt)

Then the ecu adjust timing from there +/- X amount of degs.
The ecu is stupid tho if you dont set the base timing to what the ecu believes it to be it will not probably adjust the timing.

I.e. base timing should be 16degs if the ecu wants to add 4degs it will try and should ne at 20degs

If you have your base timing off i.e. 10degs and the ecu wants to add 4deg to get to 20degs but you will end up at 14degs not 20 as the ecu wants.

So very possible that your chip is adding alot of timing and your dizzy could be very off.

Either way i would start with a good known ecu and jump the service connector and set the base timing
 

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1994 Civic Si
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Discussion Starter #13
So, then I guess I'm looking for an inexpensive ecu to use as a baseline starter and backup. Any ideas? P28s are pretty expensive on ebay. Even f it doesn't have all the features (vtec, etc), can a more common ecu for a 1.5 l do the job?
 

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BATSLOMAN GIVES NO FUCKS.
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you cut the jumper, it should now be a stock p28
 

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1994 Civic Si
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Discussion Starter #15
That's true, but this ecu still doesn't like or recognize my O2 sensor. I may be wrong here, but with the hard code, I can't get the ecu into baseline mode to reset timing. The last time I tried, the light blinked to indicate the code, but no change in timing as seen with timing light. I have read that others have put in a different ecu and their hard O2 code went away, they put back the original ecu and the code stayed gone. Seems like these O2 codes can be a PIA for some. It takes more than just R&R, clear the code and hit the road. Tomorrow, I will meter the wires, and go from there.
 

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BATSLOMAN GIVES NO FUCKS.
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why not replace the o2 first since it seems to be the cheaper option at this point? ya'know, since it was never plugged in to begin with
 

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97 honda coupe
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solid CEL means the main processor crashed for whatever reason and is running off the secondary backup processor, dumping fuel and retarding timing as its loaded with a worst case scenario map for fueling and timing.

Cutting the jumper should put you back to stock settings, check to make sure its completely cut, and that you didnt damage the pcb board. Also a bad burn on a chip, or a bent pin will cause this if the j1 is still connected. Once j1 is cut (correctly) the computer doesnt use anything from the area on the board within the dotted line on the board as j1 jumper is for an aux memory circuit.
 

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if your ecu is chipped, why dont you pay xenocron to send you a $15 stock base chip?

dont fart around. your setup is fully stock as far as the ecu is concerned, and that P28 with a stock map can happily run upwards of 11:1 compression and all breather mods without doing anything wrong.

even with a solid CEL you can still set timing. the ecu does not prevent you from adjusting something that critical to proepr engine function
 
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