Got a 2000 GSR w/ OBD1 P72 a few months ago. Opened up my ECU today to find something was fried. Is this due to the infamous EVAP / IAT plug mistake? It looks like it is "Q3". Everything I read on here said that Q31 would be fried but I think that was for P28's.

 

bump

 

What was the car doing? How did you know that your ecu was the problem...ECU are very sensitive...There are numberous thing that could've happened...Maybe used the wrong jumper harness...Is it chipped? Static electricity is the big killer of ECU's...You need to post more information friend!

 

All I'm really looking for is what that resistor (I think that's what it is) is controlling and that will tell me everything I need to know. I opened the ECU to chip it; it's a stock ECU.

The car was lacking power below 4500 rpm but after I took out the ECU I noticed some of the wires that were pluged into the jumper harness connecter that plugs into the stock OBDII connecter on the car were pushed in all the way. I pushed those in and the car seems to be running alot smoother and has more power in the lower rpm range.

Also, the car doesn't ever fully warm up. Pointing to either the IAC or Thermostat.

 

Very interesting, sound like high resistance at those pins...I am glad you cought that, are you sure that its the right jumper harness! Also...I would be looking at a bad 02S, because the 02 sensor and Engine Temp Sensor also works with the thermostat, if that cat O2 sensor becomes to hot it will send a message to the PCM, telling it to cool it down, meaning bring in more air and fuel or just fuel would be the intruputation of the PCM. And if the ETS isn't working correctly if at all, than the thermostat either wont open, or stay open. If it is open all the time, this means that the engine is cold all the time which equals bad MPG. And if it closed all the time = overheating. A stuck open condtion can also be due to air bubbles in the coolent system, a stuck closed condtion can be a bad thermostat or one that was installed backwards.

 

Interesting... So the O2 sensor has a temp sensor on it too? I did forget to mention it gets bad gas mileage. I have to see if that was fixed by plugging in those pins. I'm guessing it's the ETS / IAC sensor but want to confim.

Bottom line really is what that resistor is for that was blown. If it was for the IAC, I would have my answer.

 

The O2S main job is help seperate and help burn the emissons, but also due to the presious metals inside of a cat it must only reach a certain temp for the cat to work properly thus it need a temp sensor within the O2S. The PCM then compares the O2 readings and temp from o2s and ETS. To adjust air fuel mixture in the PCM programed maps.

 

I hear what you are saying and this is why I was asking if you are running the correct jumper harness, because a wrong pin input can cause you fry an ECU...

 

It looked like everything lined up. Should I check the model number on the jumper or what?

 

yes...do!

 

No number on the harness. I will take pics tomorrow (my camera battery is dead)

 

Yeah that would help...See there is a difference between OBD1, OBD2A, and OBD2B...I think you might be running the right year convertion match but for a different type of honda...So this when it becomes an issue, as some pin might not be in the same spot from one jumper harness to another.

 

It is OBDI P72 Manual Trans. 37820-P72-A01

 

If your old p72 ecu was chipped, see if you can pick up an OBD1 P28 and insert your already programed chip in it. It seems from my expierance that the P28 SOHC VTEC ECU works really well. I never really had issues with the P28's its the P72, and P06's that I've had issues with in the past...Forgot you said it was stock...see if you can have someone make you a stock fuel map for a 2000 GSR, then install that chip in a P28, as finding another OBD1 p72 can be hard to do sometimes.

 

My mistake, last night in the dark I missed the number on the jumper. It is 20651 1

This is the most my car ever warms up.

 

The temp looks normal dude, on hot days or in stop and go traffic you should only be at half, anything more, and I would say that you are having issues, but that temp reading looks fine, I wouldn't worry about it, as for the harness...who is it made by, as different manufactures have different part numbers..

 

Temp should be about half way. As I said, that's the warmest it gets; most of the time in the summer it is 1/8th or less up. In the winter, it was always right on the line next to the C and no more.

There is no manufacturer on the harness. I'm fairly confident it isn't the harness. Again, knowing what part fried will tell me everything... even if it is the harness.

 

temp gauge looks fine to me also. Thats where mines sits. Don't know about your winter issues, mines stays the always, when warmed up.

 

Well you are from MN, so it's cold there...here in cali at about 70 degrees my car stay at the 1/8 mark pretty much year round, unless I am stuck in traffic, then I see it move to about 1/2 mark...and when I stayed in Vegas during the winter in 40 degree weather it would be really low...So like I said it seems pretty normal to me. Put yeah track down the part that fryed and what it controls to better find it's nature of fualt....I remeber seeing a ECU brake down of components...Under an urbdata link...Try researching hondata or chrome site...They should have picture of component brake down. GL bro! Login off...got to go see my son...

 

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