🔴 SR20DET Rich Idle Diagnose - 240sx S13

[@markhutchinson3367]

I have been working on sr20s for 23 years now. I've seen many things over the years. There are many common issues with them which people have, this is one of them. One thing that people overlook are the O-ring injectors. When you install new injectors obviously you want to put new o-rings in it. If you don't put grease on them when you install them it can cut the O-ring and then it will leak fuel past the injector and straight into the cylinder. I personally experienced this myself on an sr20det I had. Take the spark plugs out, turn the key to the "on" position but don't start it. Look inside each cylinder and look for any fuel that's dumping in to the cylinders before you start the car. If you have fuel dumping in that means one of the O-rings (there are two) is no good on the injector. I would also recommend putting a stock ECU in it as well as stock injectors and mass air flow sensor if the O-rings are okay on the injectors. Putting it all to stock rules out any aftermarket parts. Also the O2 sensors could cause problems. I've seen people use an s13 O2 sensor on an S14 SR20 and it won't run right. I've also experienced that myself. I swapped to the correct O2 sensor for the year of the SR20 I had and it fixed all the problems with running too rich and bogging.

[@G_ROD11]

nice info

[@MichaelMontez]

Did you do an update on this issue? I have similar idle issues

[@danecarpenter8735]

I had this problem and eventually said screw it to the Nistune and just went Megasquirt. Good to know I'm not the only one that had this issue. Super Rich idle and would break up in revs. No leaky injectors. Had good spark. 22-23 vacuum. Car ran great minus terribly rich idle. It's like the ECU was ignoring the fuel table.

[@Spaceboy1799]

Were you sure it wasn't the tune? I have an Enthalpy tune, and was never retuned locally. Was actually thinking of going to Nistune..

[@danecarpenter8735]

​@@Spaceboy1799 It just started going into super rich like you and bogging real bad. I decided to start from scratch and go with an aftermarket ECU and am selling the Nistune SR20DET ECU. The price difference was minimal and I'll have more options with Megasquirt since it works off MAP instead of MAF. People have said they have gotten more control over timing with the Megasquirt. Megasquirt sells a plug and play setup for less than $1000. And also I'm going to go with an Innovative Wideband 4.9 and get rid of the AEM 4.2 I have. The megasquirt can use the wideband. I'm probably going to go with DW top mount injectors as well. Trying to build it up with something more robust. And possibly more appealing sell to later. I didn't know if the Cams and springs were causing problems, but seeing how you're having very similar problems it's good to know I'm not alone.

[@fuzz992]

My SR20det has a similar symptom. Its also RS Enthalpy tuned. As long as my engine is cold its all good. When it heats up, it richens and then dies. I can pull power off my injectors and crank it back up. Plug injectors back in and it floods. I really suspect my ECU after everything i've tried.

[@markhutchinson3367]

One more thing to add is that I noticed you have an adjustable fuel pressure regulator and then you also have a Nismo adjustable fuel pressure regulator on the fuel rail itself? Perhaps that is part of your problem. I would recommend getting rid of the Nismo adjustable unit on the fuel rail. You don't need two fuel regulators. If one goes bad it can affect the other. You could be bottlenecking or you could have blown out the Nismo one. Or it could be adjusted improperly.

[@Spaceboy1799]

Thanks for the comments man! 👍 Your suggestions are ones I addressed during my diagnosis stage. I'm probably will do a video soon and assemble all the video I have since this. Spoiler alert: The culprit turned out to be a faulty MAF. Also props to Martin at RSenthalpy as he personally be helped me diagnosis the issue over email and screenshots.

[@markhutchinson3367]

@@Spaceboy1799 ah yes, typical Nissan MAFS haha. Since you said you swapped it for another, I figured you'd ruled out that issue. Definitely possible to have two faulty ones though! It's common for the solder joints to go bad. You can open the top of them and resolder them. It's a typical fix on R32 R32 Skylines too.

[@tigardis]

@@markhutchinson3367 swear, between MAFs, CAM sensors (ca series), and the ignition module it's a wonder I'm still a Nissan fan

[@bernal4444]

Glad you uploaded again! You’re car is exactly what I want my s13 to eventually be. Just a 93 hatch with an sr and basic bolt ons (intercooler, exhaust, etc). How’s the t28 turbo been? I want pretty much same setup as yours with an ecu flash but sometimes tempted to go gt2871/gt28 but focusing on same maintenance for now. I also have a rich idle but not as bad as yours. Mine stays around 13.5. Do you have any input on what could be causing mine? Only thing I can think of is stuck open injector/leaking? That’s really odd for all the parts you’ve replaced and no changes.

[@Spaceboy1799]

I have ideas, but it's all a matter of process of elimination, and that basically just throwing money at it with the hopes that it's the problem. I made this video so others, smarter that I, can possibly spot something I don't know. Anyway, yeah the t28 is great imo. Its quick to spoil and pulls harder and harder toward redline. I love the setup, and it's been super reliable for 3 years. If you keep weight down it's plenty for a 2700lb car, and keeps it fun, but still challenging. I'm thinking worn timing components, possibly faulty CAS. Could be rings too as it's still on OEM rings and bearing.

[@Spaceboy1799]

Oh yeah I've tried 2 O2 sensors, both OEM grade. No change.

[@ericd928]

My sr20det is doing the same thing. What ended up fixing it. Was it the maf or the wiring to the maf. Mines driving me crazy an can’t figure it out. I Would really appreciate some help. I tried 3 different maf’s an mine was dyno tuned by RS Ethany also.

[@kennedywong9854]

Possible bad mechanical engine can cause running rich problem too.

[@Spaceboy1799]

turned out to be the classic...bad maf. i just happen to try 3 bad mafs during my diagnosing process.

[@josemiranda8465]

Any updates on fixing the rich idle problem..

[@Spaceboy1799]

I'm rebuilding the motor now. I can't be sure, but it seems like worn timing components and a tired oil pump.

[@dekacster]

temp sensor can cause something like this.

[@Spaceboy1799]

You're right. I have had them cause issues. I replaced mine twice during diagnosing. It turned out to be the MAF.

[@dekacster]

@@Spaceboy1799 im facing a spark related issue with my n14 sunny gti. Ive got harsh, but high idle (tanks to the big cams) limp mode (no readably check code, i have no diagnostic screw on my ecu) constantly running fan with good ect ohms (decreasing ohm to increasing temps within specs) good maf wiring but 23kohms on ignition coil earth :D right now im middle of the diagnostic.