Ecu trouble ?

[markmullins]

Hey guys i would like to comfirm my issue.
im throwing a engine code for my tps , at first i replaced it, light went off but i still get same problem if i wot, or go past about 4k rpm i start backfiring and lurching. shortly after same code came back after maybe 1 short day of driving. i have a safc2 and safc has no problem seing the throttle postion. checked wiring from afc to ecu wiring is fine.

Could it be my ecu is jacked up ? note: i also get what people reffer to as clicking behind the stereo some times. i thought it was the iac adjusting. not sure.

p.s. compression is fine across the board timming is great , engine just rebuilt 500miles ago. fuel filter replaced , tested injectors , there good too.

 

[donmagicjuan]

When you checked the wiring from the AFC to the ECU, did you check continuity to the pin hole on the harness plug? Also, when you say the AFC reads throttle position correctly, did you confirm this when the problem actually occurs? I'm assuming you're getting a P012X code.

 

[markmullins]

Yeah i did check the connection to the pin hole and ecu harness connection. I put on a labtop with a odbii software the otherday it gives real time readings. Im showing the ecu sees a ( o ) zero throttle postition the even no matter what rpm. but the safc sees it fine.

Now im just looking for someone to help confirm its the ecu , or if anyother ideas . hard to get an ecu for a good price when your broke . haha

 

[steve]

Can you get a good picture of the top of the ECU board?

Steve

 

[markmullins]

Yeah Im sure can pull it and take a picture this weekend .

 

[Maglin]

Best thing to do is actually back probe the ECU harness with a DMM to check for the 5V TPS signal. Being you have a 98 I wouldn't just throw an ECU at the problem. Chances are it won't fix it. It's not the easiest thing to do and you can cause damage to the ECU if you do it incorrectly. Set your DMM to DC. Most now a days are auto ranging. If it's not you would probably set it to it's lowest scale as we are only working with a 0-5v signal. You are back probing so you are going to kept the ECU harness plugged into the ECU. You have to to get the 5V signal to the TPS to begin with. Look up the wiring scematic for your car to find out which pin it is. They are confusing at times. Best thing to do is know the location and wire color to best idenify it. You can put a very thing wire in the back of the harness on that pin and then hook the DMM to it and the chassis ground. Now just turn the key on and slowing start putting the throttle to the floor. You should see the voltage go up. You should also be albe to see this on the SAFC as well. If your SAFC is connected to the TPS wire at the Harness on the ECU then you can bypass the whole DMM as it's right their. You will want to check the place where you tapped the SAFC into for a break. The wire might just have broken. Grab the wire where it's connected to and pull it as if you where going to pull it apart haveing the center be where the SAFC is tapped into. You only need like 10 lbs of force. IF it breaks then the wire was corroded internally and you now know where to fix the problem. It's a very common problem when people tap into copper wire for it to corrod up into the shielding if it wasn't heat shrinked and hermatically sealed.

If the wiring is all good and you do get a good TPS signal at the harness to the ECU but you can't see a TPS signal with a scantool/datalogger then you will want to check your harness pins to see if the TPS pin has spread apart and isn't making good contact with the ECU. Pins are easy and cheap to replace and it's a fairly uncommon thing to occur but none the less I see it every now and then. If all this turns up nothing then you probably do need a new ECU.

IF the TPS did fail or was shorted to a 12v source or to ground the chances that you blew the TPS circuit in the ECU is pretty good. You could probably take it down to an electronics repair and have it fixed or at least see if they can repair the problem. Or just buy another ECU all together. If the later is your option I would look for a 95 ECU as it will have an EPROM with which you could run DSMlink with in the future. Or you could go to a MegaSquirt MSnS standalone for $300 if you have good soldering skills or around $600 all ready assembeled and ready for a DSM. From their the sky is the limit with aftermarket PnP standalones (AMS) and whatnot.

I'm a diagnotic tech and though I probably could go much further in detail on diagnosis I'm not as it's just to much for me to type. The few directions I've given you should help you out. If you are lost on a part you could PM me but I don't check the boards but maybe once a week so you would be best off googling it or asking again in the forum. Good luck and hope I helped you some.

 

[markmullins]

Thanks alot i didnt check with a ddm because the safc was getting a source, but i did already check the wiring its all good i did check the pin , but i guess to be sure i'll check it with the ddm and pin again never hurts might as well before i take the picture for steve . can i put a 95 gsx ecu with eprom and it will run like stock ?

 

[zalama1]

I got same problem with my 92 GSX. Logger shows all the sensor informatiom coming as 4.98 Volts. Pedal, coolant temp, IAT, barometric pressure. SAFC sees my pedal correctly from 0-100%. I'm thinking I have bad ECU. CPU allso says my battery voltage is 18.9 V, which is not true ! I think I can only say: "Rest in peace" for my 15 years old ECU.

PS. I have Megasquirt on the way...

 

[markmullins]

Yo Steve heres thoses pics let me know what you think . I took hi rez images , top and bottom . board number is MD346676.

TOP
http://mullinsmotorsports.net/images/p1010002.jpg

Bottom
http://mullinsmotorsports.net/images/p1010004.jpg


Mod Edit: HOLY MONSTER PIC SIZE, BATMAN! Leave them as links or resize them to post IMG's back up....

 

[markmullins]

bueller... bueller....bueller ,... could anyone else answer my question or help me on the pics given .

 

[steve]

I don't see anything that looks blown or overheated.

Have you followed Maglin's instructions?

Steve

 

[markmullins]

Yah i did every thing checks out . getting proper voltage. i just started throwing another code 2 days ago , vehicle speed sensor intermittent. out of now where . car just shuts off and has problem going . understand this is the tranny sensor but intermittent ? wtf ? could this be related in any way ?