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wilmatic
10-24-2010, 08:29 PM
we swap a jdm engine in an running american ecu and its running rich. What should we do to fix this issue? thanks

Facime
10-24-2010, 11:59 PM
You could start with a bunch more info on the car, what you have and ahvent checked and a bit more thorough explanation...otherwise I suspect you wont find much help around here.

wilmatic
10-25-2010, 12:28 AM
yeah, did that on the fly... but its the turbo pressure sensor. thanks

Facime
10-25-2010, 02:30 AM
seeing how the turbo pressure sensor doesnt have anything to do with fuel management...good luck with that.

ChrisD
10-25-2010, 05:16 PM
Yeah. Generally, these cars run rich. That's just the way it is. So what symptoms have you seen / found that lead you to think there is an issue, or that it is too rich?

Can always try the usuals, O2 sensor, AFM, plugs, cap, rotor, wires, clean injectors. But not the turbo pressure sensor, that does not affect the fuel management as Facime said.

wilmatic
10-25-2010, 06:29 PM
Yeah. Generally, these cars run rich. That's just the way it is. So what symptoms have you seen / found that lead you to think there is an issue, or that it is too rich?

Can always try the usuals, O2 sensor, AFM, plugs, cap, rotor, wires, clean injectors. But not the turbo pressure sensor, that does not affect the fuel management as Facime said.

They did a test run with it and said it was bogging (turbo is getting cut off) so they thought that it was running rich. But the turbo gauge is all the way to the left and not starting a zero like it was b4 the swap. And its throwing out code 34 and 52. what tube goes from the turbo to the pressure sensor? Just in case i can't find it.. thanks

Facime
10-25-2010, 07:59 PM
34 is "fuel cut" do to turbo overpressure. Either the wastegate is blocked or the pressure signal hose is leaking (compressor housing nipple to the wastegate actuator)
52 is knock. Its pretty unlikely, that if all other things are in order, that you would have knock if you were on the extreme rich side. Its more likely the boost spiked, the engine went lean and knocked.

This is the reason why we ask for more information when doing diagnostics over the internet. The more information you give, the more chance we have to give a decent diag on what is ACTUALLY going on, rather than relying on our psychic abilities.

T-spoon
10-26-2010, 01:37 AM
Yeah, the US ECU is going to fuel cut around.. I forget... like 11-12 PSI. The JDM wastegate SHOULD still stop you from boosting to ridiculously high numbers but as long as the TPS still has vacuum it's going to cause fuel cut at the USDM setting. You can just unplug the vacuum from the TPS, but strongly advise having a real boost gauge before doing so (the stock needle is fun to watch but useless for much else). I'm on a JDM 165 motor and ended up getting of rid of fuel cut that way with a boost gauge. It hasn't ever spiked higher than about 16 and is steady around 15psi 99% of the time.

I on the other hand think I'm actually rich, which is what led me to this thread. Failed emissions on CO. Time to check the O2 and engine coolant temp sensors!

wilmatic
10-26-2010, 07:42 PM
You could start with a bunch more info on the car, what you have and ahvent checked and a bit more thorough explanation...otherwise I suspect you wont find much help around here.

K. more info on the car. its a 91 US with a 93 jdm engine, the wire harness is 91 US. When you give it gas it goes but doesn't seem to have power till 3500rpm even then it seems sluggish. i was thinking the tps. can it be the engine wants more boost and the ecu wont give it? thanks

Facime
10-26-2010, 08:02 PM
the ECU doesnt control boost in any way. Boost control is purely mechanical (other than the TVSV which most people have bypassed by this point.) Do you have an aftermarket boost gauge to accurately monitor boost? if so what is the peak reading under load in the upper gears? I would double check that you have the wastegate pressure line routed correctly (off the compressor housing) and tightly, no leaks. Then reach under and try to move the wastegate actuator rod. If its not totally tight you might be getting some wastegate leakage. I start to develop boost at around 2200rpm.

So its a 91 harness using the stock 91 ECU? The fact that its a 93 JDM motor shouldnt be a problem, but someone with more second gen motor experience might need to chime in. Is the only difference with the JDM that it doesnt have an EGR? For our discussion here I dont think thats relevant anyway.

wilmatic
10-26-2010, 10:12 PM
it looks like i am missing a hose. do u have a diagram for this tube.

Facime
10-26-2010, 11:16 PM
for what?

wilmatic
10-26-2010, 11:28 PM
sorry the wastegate. forgot to quote

Facime
10-26-2010, 11:47 PM
Sorry couldnt find a graphic for one, but one hose is from the compressor housing to the actuator and there is another hose from the actuator to the TVSV, both are just short rubber hoses connecting 3/16" metal hoses.

wilmatic
11-05-2010, 11:07 PM
Alright i bought an adapter for my ecu to take the 93 ecu with the 91 harness and it seems to be better, but not its full potential. Whats the best way to find out whats going on.

tubasteve
11-07-2010, 04:38 AM
the code 52 if you still have it will pull timing like mad i belive until the sensor issue is corrected. i had a problem at the track i was boosting the wastegate was stuck shut, one good rattle from the harsh over boost and it killed the knock sensor(it was really old looking when i rebuilt my stuff.

wilmatic
11-20-2010, 02:42 AM
k, thanks guys for the input it was the knock sensor. new one installed and running strong.
http://www.burnoutbarn.com/images/DSC00284.jpg