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Discussion Starter #1 (Edited by Moderator)
I have a 91 civic si with a fresh Z6 swap, PO dint wire up vtec and the car felt like it was hitting re limiter at 5k, so I wired vtec up from the jumper harness and still feels like its hitting rev limiter at 5k. The ecu is unknown due to the fact that the stickers were removed it just has VTEC written on it. I'm at a loss I've been searching and reading all day and found no relief. Has fresh plugs, wires, and dizzy. The speedo doesnt work and it has a surging idle when cold are the only other issues that I've found so far. Someone please help me, im a competent mechanic, but not familiar with Hondas at all.


Also has no 02 sensor and is only throwing code 1
 

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BATSLOMAN GIVES NO FUCKS.
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what is the code being thrown?
unknown ecu would make it harder, its a 91 so its obd0, does it have a jumper harness? if it doesn't, then its probably not running the proper p28 with obd0-obd1 jumper.


google what ecu the d16a6 would use, or source a p28 locally with a jumper and see if it helps
 

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Discussion Starter #3
It has a jumper and it's an obd1 ecu, it says vtec so I'm going to assume it's either a p28, p30, or p72. I'm in Hawaii and the scap yards here aren't the easiest place to source parts from but I'll look around. In the meantime any other ideas?
 

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It has a jumper and it's an obd1 ecu, it says vtec so I'm going to assume it's either a p28, p30, or p72. I'm in Hawaii and the scap yards here aren't the easiest place to source parts from but I'll look around. In the meantime any other ideas?
Speed sensor will do this. You mentioned your speedo doesn't work. When I swapped to my Z6, I kept hitting what felt like a fuel cut at around 4800 rpm. I run Neptune rtp so I was able to review datalogs and found every time I had that problem, it was not registering vehicle speed. Checked my speed sensor and the pigtail was dirty as all. Cleaned it up and presto.
 

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Speed sensor will do this. You mentioned your speedo doesn't work. When I swapped to my Z6, I kept hitting what felt like a fuel cut at around 4800 rpm. I run Neptune rtp so I was able to review datalogs and found every time I had that problem, it was not registering vehicle speed. Checked my speed sensor and the pigtail was dirty as all. Cleaned it up and presto.
As stated here if there isn't any input from the speedo it goes into a fail safe mode. I have a friend that has drove his car for years without a working speedo. He has his ecu tuned to bypass the speedo's input so he can drive.
Either replace the sensor or the wiring and see if that helps.
 

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Discussion Starter #7
Thanks guys, I'll check that out after work today. Its not a pm6 board, its obd1 and has been pocketed and chipped with what I assume is a stock map.
Can most tuning shops burn me a chip to ignore the O2 code?
 

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Discussion Starter #9
I'm not sure about the speedo being cable or sensor driven. I haven't looked at it, worked late today so I didn't get a chance to check it out today
 

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doesn't the 88-91 use cable driven speedos?
Yes I had forgotten that would have been cable driven 92 was the year it went electronic.

Thank you for the correction
 

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If you have a obd1 ecu in your car and it has a stock vtec ecu in it, it will hit a limiter due to the vtec speed check(has to be over~20mph).

If it is a chipped obd1 ecu you can overcome this issue by disabling vtec speed check and making sure any launch control functions are set to whatever your redline is.

OBD0 cars have a cable driven speedometer. The ecu gets the speed signal from the cluster.
 

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I dunno if I'm reading something wrong or others are. The ORIGINAL engine may have been an A6, but the Op stated it was a fresh Z6 swap..
 

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A Z6 is an OBD1 engine, they had electronic vss's. Your car is OBD0, it has a mechanical vss. Your ecu is looking for a speed reading from your cluster.

You need to either fix your speedometer issue(if you have a stock ecu) or you need to go into your map and disable launch control functions(if you have a socketed ecu)

Engine doesnt matter. This sounds like a ecu not picking up that the vehicle is moving.

Take a picture of the inside of the ecu and post it up.
 

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A Z6 is an OBD1 engine, they had electronic vss's. Your car is OBD0, it has a mechanical vss. Your ecu is looking for a speed reading from your cluster.

You need to either fix your speedometer issue(if you have a stock ecu) or you need to go into your map and disable launch control functions(if you have a socketed ecu)

Engine doesnt matter. This sounds like a ecu not picking up that the vehicle is moving.

Take a picture of the inside of the ecu and post it up.
This is the point I was getting to with my first post. Lol.

To the OP.. Any chance you can get more info about that burned chip?
 

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Thanks guys, I'll check that out after work today. Its not a pm6 board, its obd1 and has been pocketed and chipped with what I assume is a stock map.
Can most tuning shops burn me a chip to ignore the O2 code?
YES, they can also make sure you dont have launch control enabled. At the end of the day-your problem is with the speedometer. Fix the speedometer and enjoy everything working properly.
 

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Discussion Starter #16
Zero info on the chip, this car has been a damn nightmare because I bought it off of a buddy who bought it from a guy on base that did the swap and I have no contact with the original guy who swapped it. I'll post up a pic of the ecu after I get back from this appointment
 

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Fix speedo issue. You dont need a tune.
 

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Discussion Starter #20
Fix speedo issue. You dont need a tune.
X2

<img src="http://d-series.org/forums/images/smilie/tank.gif" border="0" alt="" title="Tank" class="inlineimg" />
I was told that the sensors were mix matched do to 0bd0 ecu using cable to drive the speedo and obd1 ecu using a sensor if I'm not mistaken? So wouldn't a tune be needed to ignore that sensor that isn't present in the car regardless of whether the speedo is working or not?
 
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