RB25DET(s1) Problems

[redline racer510]

Finally got my car running but I have the strange problems that i cant seem to figure out.
1. Car hesitates and sputters and backfires. Car has new plugs, maf was cleaned with an entire can of maf cleaner, checked for vacuum leaks cant find any.
2. IACV screw doesn't affect idle at all.
3. When I give the car gas it sputters up to 3800rpm and it feels like its hitting some kind of limiter. UN-plugged the maf but it still doesn't rev past 3800rpm( I thought that when you disconnect the maf it goes into limp mode and you are not able to rev past 2500rpm, maybe my tach is off but it sounds like its revving a lot higher than 2500rpm
4. When i did the timing I set it 15btc but the CAS is turned almost all the way clockwise.

[Chrischeezer]

any codes on the ECU?

[Sileighty_85]

RB's sound like they are Reving high due to the 2 extra cylinders. Still throws me off sometimes.

What MAFS are you using?

[josephin510]

Hah I hope you have a bad Ecu. I i will let you use mine to check. Then raise the price to three hundred dollars.

Ps your best friend.

[trickey1991]

I had the sputtering backfiring problem , it was my aftermarket BOV I have to throw a washer under the spring to keep it from opening under idle. it was sensing a Vac leak, because I didn't use a recirc valve I use a dump to atmosphere Tial 50mm. Dunno your situation, are u using a aftermarket BOV?

also

Try making a boost leak detector

2" to 1.5" flexible drain rubber coupling ($4.47):

http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo2.jpg

2" Threaded PVC plug ($0.55):

http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo1.jpg

stop by a tire shop and ask for a bigger size valve stem
http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo10.jpg


You will need to make a hole in the plug and insert the valve stem in there (use epoxy/jb weld for best results):

http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo11.jpg


Then the plug will go into coupling like so (use epoxy/jb weld for best results):
http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo12.jpg


http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo13.jpg


Put a clamp on the coupling around the plug area (smaller clamp that comes with the coupling won't fit, it's too small, so you'll need to source a clamp from your garage or reuse one of the intake clamps. Or get one at home depot.) And here's the finished product:

http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/photo14.jpg


Take off the intake filter and pipe and put the tester on the turbo inlet:

http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/iPhone037.jpg


And get some air in there, using an air compressor or a compressed air can

http://i216.photobucket.com/albums/cc228/frenchconnector/Parts/Boost%20leak%20tester%20for%205%20bucks/iPhone036.jpg


(you can get it at home depot as well, and fill it up with air at gas stations). Pressurize it up to whatever PSI you can get, at least what you usually run, 21-25 or so. And listen for hissing. Use soapy water on hissing areas if you can't figure out where it's coming from.
But usual culprits are - IC piping couplers, turbo outlet pipe gasket, throttle body shaft gaskets (you can get replacement TB gaskets from WORKS and other sources) Make sure to keep your DV/BOV hooked up during the test (on UICP side) as it may be a leak source as well.
If you have an MBC - plug off the turbo line that goes in it (usually on the bottom of MBC) as MBC are supposed to let air vent, so it'll be doing just that during the test through a small hole unless you plug off that line (take off the line, put a screw in it).


P.S. You can also use your imagination at Home Depot and improve on this concept on your own! Also get some 5 minute epoxy if you don't have any in your garage and apply to where parts connect to avoid leaks.

[redline racer510]

Using a stock j60 MAF, haven't pulled codes yet, yes I alread made a boost leak tester and plan on using it. I am running a bosch recirculating valve which seems to be working really well, cant beat oem German parts. BTW I am running a vac line from the turbo intake to the wastegate, dont know if this is causing any issues or not just wanted to throw it out there.

[Kingtal0n]

Finally got my car running but I have the strange problems that i cant seem to figure out.
1. Car hesitates and sputters and backfires. Car has new plugs, maf was cleaned with an entire can of maf cleaner, checked for vacuum leaks cant find any.
2. IACV screw doesn't affect idle at all.
3. When I give the car gas it sputters up to 3800rpm and it feels like its hitting some kind of limiter. UN-plugged the maf but it still doesn't rev past 3800rpm( I thought that when you disconnect the maf it goes into limp mode and you are not able to rev past 2500rpm, maybe my tach is off but it sounds like its revving a lot higher than 2500rpm
4. When i did the timing I set it 15btc but the CAS is turned almost all the way clockwise.


1. Use that boost leak tester. If there are no leaks, then the problem is likely in the delivery of fuel, meaning the MAF could be wrong for the ECU, or the injectors or fuel pressure could be wrong, something along those lines. In other words, sputter and misfire is generally not caused by an air delivery or compression problem- which leaves only fuel delivery.
2. Something is fishy. Maybe it is blocked off, and you dont realize it? That screw, iirc, is just a port that is opened/closed based on clearance. So if the port goes nowhere, such that it is blocked, then it will affect nothing. But if air can flow through, and you tighten the space, then less air should flow through- resulting in a lower idle.
3. It could be that the MAF is simply not working, no hooked up correctly, or not reading at all. Try a voltage tester to verify the maf is working at least. Then test for the identical voltage on the MAF input wire at the ECU, to at least verify that the ECU is receiving the voltage from the MAF. Of course, it could still be that the ECU simply is receiving the wrong MAF voltage, such as if the maf were bad, or improper, or maybe the ECU is bad and refuses to read the MAF voltage.
4. Sounds like the engine may not truly be at 15btdc. Did you use a cheap timing light? Did you isolate the plug #1 wire, and reverse the timing clamp? Sometimes they are directional, and if you use the clamp in the wrong direction, it will read wrong.

[redline racer510]

You bring up some good points. Going to try to test a couple of things. Definitely going to take pics and give you guys updates.

[josephin510]

You bring up some good points. Going to try to test a couple of things. Definitely going to take pics and give you guys updates.

Try the ecu I let you "borrow" easiest to test. 300 bux/oil lines
you already tested for leaks.
Sounds like a bad maf to me if the maf had no effect when you plugged/unplugged it. Which I also have for sale (best friend Hookup 300)/oil lines)tonios not using that J60. He's using what ever one that came wiith the z32 ecu I gave him (can't remember).

Ps let me get that greddy bov.

[redline racer510]

Found the j60 MAF yet?

[Darius]

Verify the voltage and signal wiring to your MAF sensor. Did you shield the signal wire? If not, it will pick up noise and will deliver a faulty signal to the ECU.

And the CAS is almost always turned all the way one direction on RB's. I don't know why. After I did the LS2 coil swap, the CAS is set closer to the middle.