Sr20det Is this a stock ecu?

[Cerevo]

I got my s13 Sr20det in the car and its running horribly, long story short after chasing the problem all over the place I finally opened the ECU and found this:



Is that stock?
More specifically the board on the top. I can't find pictures online that look like this unless it's been tuned by someone. If I unplug that thing, should my ecu go back to stock (if it's not already)?

[Cerevo]

Oh also this is a code 62 ecu.

[blkvrtswp]

That is tuned with a daughterboard. No it will not run with the daughterboard unplugged, at least none I have ever used will.

[Cerevo]

I ended up finding out that you are correct. I unplugged it and flipped the ecu over and took off the cover, there was a switch that was on cj1 and cj2. I flipped the switch from cj2 to cj1 and plugged it in, the car was immediately easier to drive though still not perfect. I think it's down to my exhaust cam keeps jumping a tooth back because I need a new chain.
Thank you though! I wish I knew who made this daughterboard. it just says M377-2 MULT BOARD on the bottom under the 2 chips and there's no other indication of what kind of board it is.

[blkvrtswp]

I have like 6 unknown loaded daughter boards laying around.....

Switch usually means it has 2 fuel maps for regular vs race gas.

Verify your MAF and injectors are stock, you have no boost leaks, timing 100% right, MAF wiring right and if it still runs real rich or bucks/bogs it is probably tuned for a different MAF / injector combination. 550cc / Z32 MAF is by far the most common.

Good luck.

BTW since it starts and idles, you can probably sell it on ebay or NICO and use the money to get a working stock ECU if necessary.

[Cerevo]

hmm, well I unplugged the daughterboard and took it completely out, flipped that switch and plugged it in. Car runs better than it did but still sounds like it has a dead miss at idle. Driving around town it runs seemingly perfect.. I do need to check for leaks, need to make another tester since I can't find mine, I just bought a timing light, the cam timing is correct, I've checked it a hundred times and verified it with pictures from Jim Wolf etc etc, I know my injectors and MAF are the stock SR parts.

What's weird, it idles kind of crappy but it revs up nicely. When you get into it a little bit and start to build some boost it seems kind of choppy up to about 4k rpms and then it's like it switches to a different map maybe or something clears up and it wants to go! It builds boost after that without giving it anymore throttle but I didn't want to be hard on it so I let off. Any ideas? I assume a vacuum\boost leak would behave like this maybe.

[Cerevo]

Oh the other thing is I have a Wiring Specialties harness so I know for a fact 9since I haven't touched it) that it's wired properly for all the stock stuff

[blkvrtswp]

Interesting, could be tuned for stock injectors / MAF with a speed limit cut and revised more aggressive fuel map. You never know what you are going to find when you open up an SR ECU!

Try unplugging the MAF, see if the idle improves. If it does, perhaps the MAF is bad. Boost leaks can also affect idle. The real test would be to see the AFRs. I would be nervous about boosting high until you know for certain that your AFR is ok.

[Cerevo]

I'll try that too, I bought an afr gauge so I'll be putting that on when it gets here

[Cerevo]

Another thought, since the daughterboard isn't even int eh ecu at this point, I'm not sure that you can actually tune on the actual ecu can you? I thought that's what the point of the daughterboard was, so that you could switch the tune on there

[Seishuku]

That depends on the daughterboard, some of the ones out of Japan use a kind of hardware scrambling, so you "can't" change the tune (I say that, because it's a crappy way to do it, and is fairly easy to get around, if you know what you're doing)...
But, that board looks fairly straight forward, and you probably could just reprogram the ROM chips and use a custom tune.

The one that's in there is probably set up for larger injectors and possibly a larger MAFS, which if you're running all stock hardware (MAFS and injectors) would explain why it was running like crap.

[Cerevo]

Yeah I bought a whole swap and it had the stock injectors and a Z32 MAF, I think I'm going to try putting the Z32 MAF on and put the daughterboard back in and see how it does.

Thanks!


Oh P.s.
I checked for leaks and I had a huge one right on the intake manifold, got them all fixed, got my timing set to 15* at idle, and checked the tps its right around .45V closed but it still doesn't seem to be running any better... I think my timing chain might be stretched out because the tensioner looks like its all the way out and theres still quite a bit of slack between the cams so I bought a new one. would the chain being stretched cause the cams to be misaligned enough to run poorly?

[Seishuku]

Probably not, but replacing the tensioner with the newer ratcheting type (don't remember where to get off the top my head) would help a lot.
The problem with the old style one, is that it needs oil pressure to keep the chain tight, so with the engine off it would look like the chain is slack.

That's part of the reason why SR's rattle a little on cold start, chain runs slack for a few seconds while oil pressure builds.

[Cerevo]

I have the new type, and after looking at it closer, I think the reason it skipped a tooth a while back is because the chain got up on the side of the guide and when it finally settled back where it was supposed to the chain sort of whipped and skipped a tooth. It hasn't done it since but I'll be keeping an eye on that.

Almost got my z32 MAF on so we'll see if that brings it back to a normal running state