Having JDM D15B swap problems

[mustninty]

I just got done blowing apart a JDM D15B/p07 head engine and having problems getting it to run well. I had the machine shop do a crank polishing and balance eveything, new gaskets and replaced some valves. It all went back together with no issuses and idles fine buuut. I'm getting a CEL code 3 (map sensor) and CEL code 14 (IACV). I have tried replacing both sensors with new ones and also the TPS. I had a buddy double check timing and few other things I did. Any help suggestions would be appriciated.

[add|ct]

So, are you saying you see get a CEL and the same codes are thrown?

IIRC, both the IACV(not the 'fast idle' valve) and the MAP are from the same part of the wiring harness. Check for wiring problems between the MAP wires/the ECU and the IACV/the ECU.

Read a Factory Service Manual, inspect the trouble codes section and also looking at the wiring diagram.

Usually, you can find one on ebay in a .pdf format for cheap. However, a JDM may have slight variation.

There usually is a test with a DVOM or ohmmeter. You can either back probe the wire itself(more risk of wire damage) OR test the pins inside the connect while it is disconnected from the MAP or the IACV. Again, referring to a FSM for 'expected' voltage(there may be a test with the Key On but the Engine Off and another test after the vehicle is in closed loop).

Any other symptoms? It could be a computer issue, wiring issue, or another area flagging these codes.

Do you have good negative grounds? You can perform a voltage drop test with a DVOM to see if there is resistance on the negative side of the system.

http://www.youtube.com/watch?v=FTGz0...endscreen&NR=1

[mustninty]

Originally Posted by add|ct

So, are you saying you see get a CEL and the same codes are thrown?

IIRC, both the IACV(not the 'fast idle' valve) and the MAP are from the same part of the wiring harness. Check for wiring problems between the MAP wires/the ECU and the IACV/the ECU.

Read a Factory Service Manual, inspect the trouble codes section and also looking at the wiring diagram.

Usually, you can find one on ebay in a .pdf format for cheap. However, a JDM may have slight variation.

There usually is a test with a DVOM or ohmmeter. You can either back probe the wire itself(more risk of wire damage) OR test the pins inside the connect while it is disconnected from the MAP or the IACV. Again, referring to a FSM for 'expected' voltage(there may be a test with the Key On but the Engine Off and another test after the vehicle is in closed loop).

Any other symptoms? It could be a computer issue, wiring issue, or another area flagging these codes.

Do you have good negative grounds? You can perform a voltage drop test with a DVOM to see if there is resistance on the negative side of the system.

http://www.youtube.com/watch?v=FTGz0...endscreen&NR=1

Yes I am getting CEL code 3 and 14. Yes IACV not the fast idle valve. I will trace wires out and check again for breaks in the line. The idle is rough but it holds the idle until it hits the middle of the temp gauge and it cuts off. I would venture a guess its when the car is completely warmed up and the IACV cuts closed and the map cant handle it and cuts the car off. That's my guess anyways. All three grounds have been cleaned up and reconnected. I would have to locate a meter to do the testing you mentioned above.

[add|ct]

So, it's cutting off once near/at full temp? I'd check the ECTS. The one that feeds the computer, not the dash gauge. This one will be near the thermostat housing. However if it WERE the IACV, you can start the vehicle AFTER it dies once at full temp BUT WITH THE IACV UNPLUGGED(the electrical connection only), and hold the RPMs at about 1,000 during the restart. Then, slowly ease off the throttle until it stays running. Will it stay running? If it does, I doubt it's the IACV itself.

As always, check for vacuum leaks but if the idle is rough I'd imagine it's not an issue there. It's possible something in the ignition system is failing...I vaguely remember when heat soaked some issues with the main relay on these cars cuts off as well as igniter.

[silversol]

The map sensor and the tps have the same 3 prong plugs and many people mix them up when putting things back together. it will throw the codes your describing.

[add|ct]

^HA! Great catch!

[mustninty]

I did mix them up at first and was throwing a CEL 3, 14 and whatever the TPS code is, I forget right now. I switched the TPS and MAP plugs around and the TPS CEL went out but the MAP and IACV are hanging in there. I have a backup MAP sensor I threw in after that in case I blew something up and it did not make a difference. I'm still looking around for a multimeter and possibly someone who has experience working it. I'm pretty sure I can figure out how to test the wiring myself but just never done it and want to make sure I'm doing it right. I should be able to get something going on in a few days and check back in with what happened. Thanks all for your info, I'm tired of beating my head agianst the wall on this.

Originally Posted by add|ct

^HA! Great catch!

[add|ct]

^I'm not sure if it's possible to damage to computer by plugging in the wrong thing or if the computer is just really thrown off from trying to read the signals from the wrong source.

You did try clearing the ECU by removing the 'back-up' fuse? Maybe it's stuck thinking the signals are haywire? Just a random guess.

[mustninty]

I did reset the ecu in between cleaning and troubleshooting. The battery cable got yanked each time.

Originally Posted by add|ct

^I'm not sure if it's possible to damage to computer by plugging in the wrong thing or if the computer is just really thrown off from trying to read the signals from the wrong source.

You did try clearing the ECU by removing the 'back-up' fuse? Maybe it's stuck thinking the signals are haywire? Just a random guess.

[thinkinglink]

i have a D15B with P07 ecu before. it ran like crap and gas milage was bad. Then I swaped the ecu to a P28 (USDM Si model), and then car runs smooth. I can't give you a good explaination, but i think it's worth a try with that motor if you can locate one to buy for cheap or borrow