New sr20det in s13. Running rich! (Long read)

[KingTurd]

Greetings all! This is my first post to this forum as I am now the proud owner of a 1991 240sx (with Hicas) with a sr20det—like most of you who go to this forum.

After a month I finally got her running. I did all the work myself including custom intake, intercooler piping and exhaust. Everything from removing the old engine, inserting the new engine + rewiring was all done by me. Maybe 2% of the entire time spent was being helped by someone else. It wasn’t fun at times, but it was quite rewarding in the end. The engine bay looks rather messy since I haven’t done any cleanup, but that’s for another day. After owning a DSM for about 3 years I understand the word “customization” or my favorite phrase “I’m going to Home Depot to fix my car.” The first “official” day of taking the car home from my friend’s house, I noticed that it runs rich—very rich, and it seemed to be hesitant. Pulled the codes from the computer and got the knock sensor—turns out it was loose. I tightened it and it seemed to run much better, yet it still ran rich. However, it seems to be sluggish below the 3k rpm range. Above the 3k rpm range and when the boost is kicking in (around 10.5 – 11 psi), it pulls hard. The aggravating stench of gasoline cologne is quite irritating, and it leads me to believe that there is something wrong.

So the next day I take it back out to start diagnosing. Armed with the printouts from the FSM, I went to work. I checked the MAFS, TPS, Coolant Temp Sensor and o2 sensor. According to the manual, they were all within check. The mafs is from a SOHC 240sx, yet it still read the correct voltages at idle and at 3000 rpms. I cleaned it before installing it into the car. The TPS did not even have to be adjusted—it was fine. The coolant temp sensor resistance (when the water was almost near operating temps—the fsm has different temperatures and associated readouts) read about 0.40 to 0.45 kohms. The 02 sensor read about 10 ohms resistance. Coil packs had exactly 1 ohm of resistance with a 12v primary voltage. Spark plugs were changed the day prior to the investigation and still ran rich.

Fuel pressure was exactly where it should be, with and without the vacuum hose attached. I am using the stock 240sx fuel pump and I did not change the fuel filter. It has been at least a year since I have changed the filter, but the fuel pressure is right on cue. Could this be an issue?

I pressure checked the entire system with my pressure tester I made. No leaks even at 15 psi. One vacuum port (lower) on the tb is plugged up, the larger vacuum port goes to the BOV and the the remaining port goes to the FPR. The wastegate signal comes from the charge pipe as close to the wastegate as possible.

As for modifications (besides the entire project itself), here is a small list:

MBC (homemade, but works), TurboXS RFL bov that IS revented back into the intake, 2.5” custom made exhaust with no cat, FMIC

With all of this in check, I don’t know where else to turn to. I have a few ideas of what it might be; maybe someone can think of a solution:

1. EGR: When I finally had the car idling and running fine, I went to take a test drive when I realized I couldn’t turn my wheel. Boy would that have been a mess. Anyways, turns out the steering column was turning against the dump tube for the EGR. So I cut it and welded the end so that there wouldn’t be an exhaust leak. However, the other end of the metal pipe is open, the larger hose nipple and the small vacuum hose on the EGR valve itself are open and uncontrolled. Perhaps this is an issue?

2. BOV: I’ve read quite a few threads on here about how their car would not run right because of the BOV, as well as threads that say not to listen to that advice. However, mine does act rather funny. At very slight to moderate acceleration, once you let off the throttle the BOV activates and releases pressurized air. Instead of a normal “PSH” sound, it sounds more like “psh psh psh psh”—almost like its bouncing. At heavy acceleration at full boost, its one big “PSH” sneeze. The bouncing noise is rather alarming. There was a few instances where the car would accelerate oddly if you put the gas pedal in the right place—almost like the BOV couldn’t make up its mind if it wanted to be opened or closed. The car would very, very slightly hesitate as the BOV was “indecisive”. Two ideas about this one. The BOV vacuum line is coming from the TB from the larger port, which is also tee’d into the boost gauge. Would this have any ill effect? Second—the bov is adjustable by screwing the top to add more resistance by the spring. Also, there is the option of adding washers to increase it even further (which I have.) However, I am unaware of the procedure of adjusting the BOV correctly. As of right now, its basically sitting at as loose as possible. It seems that if I add more resistance to the spring, it will be harder for the vacuum to lift up on the valve to release air. If I am completely wrong about this please let me know.

3. Stock: I am thinking that perhaps the stock sr20det (and stock ecu with no modifications) runs rich via the factory? There is no catalyst to mask the fumes. I know my DSM ran super rich with no modifications to fuel/timing/etc, and after my exhaust was installed.

4. ECU: Maybe I should be checking the voltages at the ecu to make sure that the right voltages are getting to it?

If I think of anything else I will be sure to post here. I am sure I am leaving something out. I am sorry for the long length of this post but I wanted to make sure I covered everything. Yes I have searched the forums and I could not come up with anything.

Any information that anyone can give me is greatly appreciated! Hopefully I can learn a lot from all of you and hopefully share some of my input as well.

Thanks in advance!

[playastarkz123]

**** ...this is a long read

[FSUDrifter]

check your timing

[KingTurd]

I have checked the timing quite a few times, with the TPS sensor unplugged. I did everything as per the FSM--its set exactly where it should be.

I think I might have figured out the BOV problem however--I think that the spring is too stiff. I bought it from ebay from a guy that originally wanted to use it for his DSM. It almost sounds like compressor surge I can hear the fast "psh psh psh psh psh" very loud through the air filter. I checked its operation by watching the valve while revving the engine. The turbo (or whatever) makes the sputtering noise THEN finally opens. It seems to me that it needs to open earlier to prevent the turbo from working too hard. I have it adjusted to as soft as possible without risking the top popping off. I also moved the vacuum source from the TB to the brake booster line. It seems to be working, but wasnt I suprised when I shut off my car that my brakes werent as strong right after a shut off. Turns out it holds vacuum for a while after shutting it off.

As far as running rich, I still have no idea. I am thinking that the turbo needs rebuilt since I did notice some oil sprayed into the hot pipe near the turbo. I havent checked shaft play yet but Ill do that soon. I opened up the ecu to see if it was modified or chipped--there was no evidence of anything out of the ordinary. All the original epoxy (or whatever they use) is still smeared all over the top of it and it seems that nothing has ever been taken out. If it comes down to me needing an SAFC then so be it, but I still think that there is something wrong for it to be burning so fat.

[jaboyak]

I'm having this problem, too. HELP!!!!!!!!!