I need help from the Super Tech Gurus

[kclem69]

I'm on my 3rd ecu since I had the SR20DET installed in April of 2003. I seems that my car will run great for about 7 months, but then it will stumble at high boost for awhile, so I only can run stock boost. Then about a month after that it starts backfiring really bad during deceleration. And finally about a week after that, the fuel pump stops getting power and the car won't start. So basically my car is dead weight until I install a new ecu and start the whole process over again. The first couple of times I thought were just a fluke, but after the third time I realize that this is going to keep happening until I figure out and fix the problem. I'd planned on upgrading the turbo, injectors, MAF, and ECU, but I don't want to have to spend $500 every 8 months for a new JWT ecu. So I have to figure this out first. I have an S13 blacktop with E5 ecu in a 1990 hatchback. I would greatly appreciate any help you guys can offer, but I feel that this is going to be a problem that only the most advanced SR20DET gurus will be able to help with.

Thanks,

kclem69

[Pepperoni]

Do you check your timing when you first get the boost stumble symptoms? Or do you just wait until the car dies? I'm almost sure timing will cure the backfiring. However....I don't know why the fuel pump stops getting power. This has happened 3 times now? I don't think it'd be the ECU, even though that seems to "fix" it, but the ECU doesn't regenerate power to the fuel pump. What fuel pump are you using?

[SpeedRacer1]

My guess is bad wiring, or a really bad ground. There was a guy up here in WA that blew 2 ECU's. We opened them up and located the circuit that blew out. It was traced back to the Ignition On pin, which controls the fuel pump among other things. So whenever the ECU would blow, the fuel pump would no longer get a signal and the car couldnt start.

Its almost like deja vu, the guy drove his car fine for a few weeks. Then blew the ECU. Put in another one and blew it after 7 minutes. I do believe we traced it to a horrible gound for the negative battery terminal. Also his battery tray wiring was a little messed up.

Try opening up the ECU and look for fried circuitry. Then trace it back to the pin and figure out which wiring is causing the blown ECU's. Heres the pinout http://sr20det.nismo.org/srtech.htm

If you find that you had the same problem as this other guy, try talking to him on aim to see what he did to fix the problem (sn= jdm24zero).

[kclem69]

Speed Racer 1,

I think you might have nailed it. OK, I opened the ECU and did find blown circuitry. I've attached pics. It's the wire with the little white ball in the middle. This is the exact same spot that blew the last couple of times. The first time this happened the guy who did the SR install for me just resoldered the connections on the wire and it ran fine for a while until it blow again later on. That is putting a bandaid on a broken leg though. I want to find out what is causing this. I'm not good with electronics so I will need some help figuring out which pin this connects to. I've tried to trace it myself and I just can't figure it out. Thanks for your help guys. If I can't fix this, I'm facing the possibility of just getting rid of my car. I don't want to do that.

kclem69

[kclem69]

Well it won't let me post the pictures. I'll get them up as soon as I can.

[kclem69]

here are links to the pics:

ECU1

ECU2

[SpeedRacer1]

It appears you blew nearly the exact same part of the ECU as the other guy mentioned above. Here is a diagram based off of your picture. The guy blew his ECU's on the red stip of each ECU. You that white resistor runs to the green strip for the ignition power on one side, and runs to the gold capacitor on the other side. Hopefully the attachment works out. Try and contact him, it sounds like you have a wire that is not grounded, spliced or located properly. Try to get in contact with that guy to find out exactly what he did, if I see him first I'll ask him, but part of the problem was that he used the spare tire tie down in the trunk as his battery's negative ground (had a battery relocation kit).

[SpeedRacer1]

I just talked to him and he said he also changed the location of his wiring harness because his MAFS wiring became melted onto the turbo manifold. Thus all the wires became grounded. You may not be burning your ECU's in the same place as that guy, but they are being destroyed on the same circuit. I would imagine you have a wiring gremlin somewhere that isnt performing properly. Try to trace your wiring and see if its all routed and soldered properly and accurately.

[Phax]

You have a bad ground somewhere.

[kclem69]

Thanks SpeedRacer1,

The problem is, I'm terrible with the electrical stuff. I'll check the things I can, but I feel like this is something that I'm going to have to take to someone else.

Thanks again,

kclem69

[kclem69]

When you guys say "bad ground" are you only talking about the ECU, Wiring Harness, Engine, and Battery, or could my stereo or turbo timer grounds be causing this. I need the information to be as specific and easy as possible so I (the electronics idiot) can figure it out.

Thanks

[SpeedRacer1]

A bad ground would be some ground that has to do with the wiring going in or out of the ECU. So chances are its in the engine bay wiring somewhere. Dash wiring shouldnt cause any issues so the radio and tt aren't an issue. Try to find someone close to you who can take a look at your wiring.

About 99% of Nissan ground wires are black. Full black wires are usually grounds, so they should be easy to spot. Try and see if they are connected to a good (engine, clean chassis, transmission), clean point in the car.

[kclem69]

Thanks SpeedRacer1,

I'll check it out. If I don't find any suspicious ground connections then I'll have to take it to a local shop. I'd rather pay them to solve this problem now than have to buy another ECU in the near future.

kclem69