Thread: jdm sr20de swap in b13 se-r.. warm start issue and HORRIBLE gas mileage

hey guys. I'm new to the forum and this is my inaugural post. Let me start by saying I've been a Honda guy for years and this was my first real nissan project. I picked up a 92 sentra se-r for $150 that had a broken valve spring and rocker arm (no damage to the piston or valve). I went ahead and bought a jdm sr20de to drop back in because I didn't trust myself to put the head back on that motor because it took me two days just to get it off. Anyway...

I finished up the swap and have no check engine light and it runs fairly good, but once its warm it doesnt like to idle if i turn it off and try to restart it. It cold starts absolutely fine. But on warm starts I can get it to start first try every time but it dies right back out if I dont hold the throttle for a few seconds. Also, I dont know if this is related but sometimes at lower rpm during normal acceleration I will get this SLIGHT bog or hesitation. Not sure if this is related to the warm start issue.

I really think my issue may have been when I removed all of the egr system. I figured if the car didn't like this it would throw a check engine light, but as I said I don't have one lighting up.

Could anyone tell me if they think my problems are related to me removing the egr system? And if so, what do I need to do to correct that? (without putting the usdm manifold back on and reinstalling the whole egr system).

I also thought that maybe my coolant temp sensor was reading wrong and causing the car to think its cold when it is actually warm and making it dump more fuel on startup than it needs.. but both temperature sensors were brand new on the jdm engine that I bought. (yes they were brand new usdm sensors and I read that the jdm ones will not read correctly)

I'm stumped as to where to begin troubleshooting because when I worked on hondas for years if they were getting sub 18mpg there would be a CEL for me to check and begin diagnosing. Unfortunately this is not the case with my sentra.

Oh also, Ever since I put the jdm swap in, my cooling fans run constantly. They didn't do so before the swap, and the only information I can get about that is possible bad fan relays. My issue with that is what are the chances of both fan relays failing at once during the course of a swap.

Any help would be greatly appreciated guys! Try to be easy on me as I am a completely and total noob to nissan's and can't get the honda "train of thought" out of my head lol



UPDATE: (I also posted this at the bottom of this thread but I figured I would add it to the original post as well so anyone can come in and immediately see this without having to go through the entire thread)

alright guys I just wanted to post an update to let you all know what I have already tried.

1. I have swapped the distributor and coil (also played with the timing adjustment on the distributor)

2. I have swapped the fuel injectors, rail, and fuel pressure regulator

3. I have swapped the two wire temperature sensor on the backside of the engine (passenger side)

4. unplugged the two wire temperature sensor while engine was running and the fans continued to run

5. Checked the spark plugs

6. played with the idle screw on the IACV

7. unplugged the constantly running coolant fans and then adjusted the idle per the instruction manual

8. bled the coolant system multiple times

9. double checked the plugs for the TPS and MAF



And again to recap, sometimes at lower rpm i get a VERY SLIGHT bog or hesitation until i give it a little more throttle while accelerating. I am getting HORRIBLE gas mileage- took me about a half a tank to go 100 miles. When cold starting, it starts right up but does have somewhat of an erratic idle (surges for a few seconds until it finds where it wants to idle. When starting it after it is warm (whether fully warm or partially warm) it will start but then dies again immediately if I don't give it throttle for a few seconds and let off of the throttle slowly. Also as I have said above, I am not throwing any check engine lights. I am completely stumped as to where to go from here.

ANY ideas or help would be greatly appreciated. I just need to get this thing running right so I can drive back and forth to school 70 miles per day.

The egr system wouldn't cause this type of problem. My engine runs just fine with the egr / aiv deleted.

Have you set the ignition timing?

Coolant temperature sensor?

I have not had a chance to set the timing with a gun yet but I have played around with adjusting it and trying to start it warm with no change. I even swapped dizzys just in case because I had an extra laying around. And as for the coolant temp sensors I was told they were brand new USDM sensors from nissan and they looked to be about as new as they come. I suppose if I cant come up with anything else I'll swap the sensors from the old engine to see if that changes anything.

I feel incredibly happy to know that this type of issue would not be caused by the EGR system not being present because obviously it wouldnt go back on with my JDM intake mani. I am wondering if I deleted it correctly (vacuum lines and whatnot).. I just found a line that was previously plugged that went to the charcoal canister that I plugged in which changed nothing. but there are also no vacuum lines running from the canister to anything else (the smaller lines).. could this have something to do with it?

i am also currently rebleeding the shit out of the coolant system as we speak to see if maybe there was air in the system causing a problem.

One thing I did not replace when I replaced all my seals and belts before putting the engine in was the spark plugs. I pulled them out and they looked fairly new and in good condition but I could be wrong. Could bad spark plugs cause a hard warm start and horrible gas mileage?

I think you're on the right track with the rebleed, fans on + poor warm start makes me think the ecu is getting a bad temp reading.

sounds like the head temp sensor is not a usdm unit. this will cause the fans to run and all the other issues as well. This is the sensor with the two wire plug not the one with the spade connector(gauge sender).

good deal. I will work on swapping that out and see if it changes anything. if the one spade connector sensor that works the dash gauge is also not a usdm how would I know that? would it read WAY wrong or stay pretty much within range?

If you have the wrong sender for the gauge it will read high all the time. From what I have seen they go from cold to over heating with no reading in between.

sounds like the sender is okay then. I have read normal the whole time. When I pulled the old two wire temp sensor from the old motor it looked as though it had some type of sealant on it (may have just been old coolant).. does this sensor need any type of sealant like rtv before I install it?