90 CRX B16 Swap Question

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snapz

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I swapped a JDM B16a into my 90 Crx HF. Everything works fine except vtec (imagine that). I've searched and searched and double checked my wiring from the ecu to the solenoid and pressure switch. I'm using a p30 ecu and it's throwing 2 codes. Code 10 (iat temp sensor) and a code 17 (vss). I'm still using the stock crx cluster with cable tranny. My speedo works so I'm confused as to why i'm getting the 17 code. I know the ecu is supposed to detect certain speed to enable vtec so I'm wondering if thats why it's not working. Any ideas as to why I'd be getting the vss code with the speedo working? Any help is appreciated.
 
you ecu thinks you are sitting still and that's why you don't have vtec. trace the wire that your ecu gets its speed signal from and there is probably a break some wheres.
 
you're not getting vtec because the ecu you're using is designed to run an engine with an electronic speed signal. your speed sensor is mechanical, and thus has no electronic output. get a pr3 or pw0, both of which are designed to run an obd0 b16. or if your swap is already converted to obd1, you'll need to change to a electronic speed sensor and add the appropriate wires. they however wont make that speedometer of yours work, you'd need to change to a jdm cluster, or swap in a later (eg, dc, ek, etc.) cluster.
 
I'm running OBD1. I was under the impression the jumper harness should have routed the VSS wire coming from the cluster (no2 wire from the 8pin plug) to the appropriate connection on the ECU (B10). I haven't checked the connection yet as I just found the pin locations. Someone please correct me if any of this is incorrect.
 
nah, if you're running obd1 then you're correct, however there is no speed output from that sensor of yours. it's a simple cable running from your cluster down to the sensor which just spins it within it's sheath. you need a electronic sensor to get rid of the light. which you'd then need a different cluster to be able to see your speed, as your cluster does not have the ability to read that signal.
 
I understand the "sensor" on the tranny is just mechanical and no electrical output from it but if the stock cluster creates a VSS signal which according the the manual is the A2 pin from the back of the gauges, then that signal should route to the VSS input on the ecu. The stock ecu had a VSS input so that's the wire I need to make sure is working and in the right pin. Is this not correct?
 
actually yes, you're right. the pin went from your gauges to pin b16 on the obd0 ecu, it needs to go to b10 for obd1. b10 (crank angle sensor) and b16 (vss) just need to be swapped if you havn't done so
 
you may have swapped them when you did your obd converion, so as bluej already stated, check that wire for breaks or loose connections. removing pins can sometimes loosen them up.
 
Ok checked vss wire and no continuity to ecu. Ran a new wire and vss light goes away. Still no vtec. My next ? Is does the stock tach have any wires that control vtec? Is there a rpm wire that goes to the ecu? I'm using an aftermarket tach and not sure I have any wires running back to the ecu (I didn't hook the tach up so I didn't think about it till now). Seems there is only a ground and the wire from the tranny but I'll check in a bit.
 
so you have no check engine light, and still are not getting vtec? check to be sure the vtec solenoid has a ground, you need to ground it somewhere other than the bolts that hold it together. run the ground down to the the thermostat ground if it's somewhere else. see if that helps.
 
vtec solenoid doesn't have a seperate ground it only has 1 wire that runs back to the ECU. The pressure switch has a separate ground and it was grounded to the thermostat housing. I'll be exploring the possible missing RPM signal to the ecu tonight to see if there's a break in that wire. If that doesn't fix it I'll be out of ideas.
 
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