SR20DET Runs great when cold outside, but horrid when warm..

[romper_stomper]

Hey guys and gals..

First off, I have to say that it burns me to have to make a thread on this but after months and months of searching and diagnosing, I still have not seem to find anyone with a similar issue or reason towards a solution.

Like the title states,

If it's cold outside (50 degrees or cooler), the motor pulls very hard and has no issues what so ever. I could drive all day at operating temp and everything is solid.

But when it's warm (50 degrees or warmer), weird things start happening..

-pulls timing
-bucks hard 2,500-3,500 rpm
-stalls at every stop

The warmer it is outside, the worse the timing and stalling.

Stock sr20det (red top)
-Greddy front mount
-Odessey battery
-atmospheric bov <--may be the stalling problem

That's it.

replaced fuel filter and coolant temp

Need to check plug gap and maf voltage
I also have a new knock sensor that has yet to be replaced.

I just want to see if these symptoms are normal for 80 degree weather or if anyone else has had this issue..Once again, runs like a champ when cold out side, but shitty when warm out side.

Any advice would be greatly appreciated.

*Update*

Changed the fuel pressure regulator out with a new one and cleaned out the IACV. I blew out a TON of carbon buildup. I'm running a walbro 255lph pump with stock injectors at 7psi so I am thinking that my fuel pressure is bulldozing the stock regulator and causing it to run super rich. The car ran great after I made these adjustments so after much research, I have decided to purchase an adjustable fuel pressure regulator to hold the pressure down until further notice. I will keep an update once installed.

*Update*

Tonight I ran seafoam through the vacuum lines and blew enough smoke to kill a rain forest the size of a small country. The engine came alive No doubt. Smooth idle, no stalls, and extremely smooth power band. I think it's safe to say that I might have solved the problem.

*update*

Well here we go again. New fpr, seafoam treatment, and new plugs, car is right back to running like shit again. I just don't get it. It ran absolutely flawless the past 48 hours and it's like some asshole flips a switch and decides to run like shit..

Pulls time, stalls when clutch is pressed in (cant hold idle for shit).

Testing fuel pressure tomorrow. Seriously don't think that this is fuel pressure regulator related as there are thousands of people running walbro's with stock fpr's and injectors with zero issues.

Also testing IACV and Alternator.

Battery is an Odyssey pc680

*Update*

Replaced the tiny Odyssey battery with a new 400 cca AGM battery and tested the alternator. 13.8v (no load) and 13.5 (with load). The battery made marked improvement with throttle response, idling, and timing. I might be crazy but It seems that 13.5v is a little on the wimpy side. I thought that the sr alternator should be putting out more than that.

*Update*

Replaced fuel pump with a brand new Walbro 255lph.

Today was 70* weather and the car was barely driveable. Last week I made to separate 3 hour trips with absolutely zero issues and it was low 40*'s out side.

I just cant figure this out. MAF is functional. Dies once unplugged. IACV is functional. Dies when unplugged. Maybe alternator? ECU? Those are quite literally the last two items that might not have been changed out completely.

[steve shadows]

Have you tried swapping your coolant temp sensor? This is one thing I would definitely try. Thanks!

[romper_stomper]

Have you tried swapping your coolant temp sensor? This is one thing I would definitely try. Thanks!

Yes, I replaced it with a new one with dielectric grease.

[rcdad123]

check the intake air temp sensor.

[romper_stomper]

check the intake air temp sensor.

I didn't know SR's even had one. I'm searching for the location now.

[rcdad123]

check that, i don`t think sr20det have an IAT sensor. sorry. try a known good maf.

[1nasty240sx]

Your thermostat could be the problem have you checked that?

[romper_stomper]

As far as the thermostat, the only thing I have managed to look at is the temp from the gauge, but everything seemed to look ok as far as I could tell.

[ultimateirving]

What if you werent running a thermo.. that could be an issue, and what about ur coolant? what mix are you running?

[romper_stomper]

What if you werent running a thermo.. that could be an issue, and what about ur coolant? what mix are you running?

Currently running a Nismo thermostat with mixture of standard 50/50. I might need to test the anti-freeze to see if it might need to be replaced. I'm also already running a koyo with dual electric fans.

[silviaS14guy29]

your a/f ratio could be running really rich! the cold air is denser and helps burn the fuel better but when it warms up the fuel is having a hard timing burning completely which could cause bogging at low rpms and stalling at idle! something i have learned at school that might be causing your issue! let me know if that helped at all

[fliprayzin240sx]

Which water temp sensor did you replace? Just in case you didnt know, there's 2 of them and the fat/2-prong one is what you needed to replace.

[romper_stomper]

your a/f ratio could be running really rich! the cold air is denser and helps burn the fuel better but when it warms up the fuel is having a hard timing burning completely which could cause bogging at low rpms and stalling at idle! something i have learned at school that might be causing your issue! let me know if that helped at all

Wow..Its really funny you said that..Because today it ran like total dog shit. It had a horrible studder and seemed like it was a fuel issue..

So for giggles, today I parked it, and let it idle. I unplugged the vacuum line from the fuel pressure regulator while it was running and it was like someone flipped a switch. It idled like butter and smooth as glass. I didn't drive it but I rev'ed it up a few times and it sounded like it was ready to rock..

Could this be a sign of a bad fuel pressure regulator? or a bad fuel pump? There was no gas coming from the regulator when I removed the hose which I thought was strange.

[romper_stomper]

Which water temp sensor did you replace? Just in case you didnt know, there's 2 of them and the fat/2-prong one is what you needed to replace.

Replaced the temp sensor with this one shown (Part No. WT5000)

Buy BWD/Intermotor Coolant Temperature Sensor WT5000 at Advance Auto Parts (http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_coolant-temperature-sensor-bwd-intermotor_3488284-p?searchTerm=coolant+temp+sensor#)

[romper_stomper]

*Update*

Changed the fuel pressure regulator out with a new one and cleaned out the IACV. I blew out a TON of carbon buildup. I'm running a walbro 255lph pump with stock injectors at 7psi so I am thinking that my fuel pressure is bulldozing the stock regulator and causing it to run super rich. The car ran great after I made these adjustments so after much research, I have decided to purchase an adjustable fuel pressure regulator to hold the pressure down until further notice. I will keep an update once installed.

[fliprayzin240sx]

Make sure you get a gauge too...you lower it too much, itll give you the same headache.

[cotbu]

I unplugged the vacuum line from the fuel pressure regulator while it was running and it was like someone flipped a switch It idled like butter and smooth as glassI am thinking that my fuel pressure is bulldozing the stock regulator and causing it to run super rich
I'm not a rocket surgeon, but when shit don't make any sense, it's obvious. Someone is clueless and just shooting in the dark.

I just want to see if these symptoms are normal for 80 degree weather or if anyone else has had this issue..Once again, runs like a champ when cold out side, but shitty when warm out side.

Any advice would be greatly appreciated. NO. You need a tune up, and probably a tune.

[romper_stomper]

You need a tune up, and probably a tune.

*Update*

Tonight I ran seafoam through the vacuum lines and blew enough smoke to kill a rain forest the size of a small country. The engine came alive No doubt. Smooth idle, no stalls, and extremely smooth power band. I think it's safe to say that I might have solved the problem.

[cotbu]

I was talking about an actual tune up, but whatever works!
You should probably still change oil and plugs and maybe 02 sensor.

[romper_stomper]

I was talking about an actual tune up, but whatever works!
You should probably still change oil and plugs and maybe 02 sensor.

..which all has been recently done. It's pulling good vacuum and it's not pulling timing any more either. It's honestly running the way a sr should. No bucking, No stalling, no smell of gas, and pulls very hard. I have to have the only good running sr in miles..

[steve shadows]

Yeah I agree with a previous poster get a fuel pressure gauge and I would try swapping on another used or new nissan stock FPR. They CAN fail.

[romper_stomper]

*update*

Well here we go again. New fpr, seafoam treatment, and new plugs, car is right back to running like shit again. I just don't get it. It ran absolutely flawless the past 48 hours and it's like some asshole flips a switch and decides to run like shit..

Pulls time, stalls when clutch is pressed in (cant hold idle for shit).

Testing fuel pressure tomorrow. Seriously don't think that this is fuel pressure regulator related as there are thousands of people running walbro's with stock fpr's and injectors with zero issues.

Also testing IACV and Alternator.

Battery is an Odyssey pc680

[ultimateirving]

Did u do the boost leak test yet? what were the results.

[romper_stomper]

Did u do the boost leak test yet? what were the results.


I have no leaks what so ever. Neither boost leak or vacuum leak.

[romper_stomper]

*Update*

Replaced the tiny Odyssey battery with a new 400 cca AGM battery and tested the alternator. 13.8v (no load) and 13.5 (with load). The battery made marked improvement with throttle response, idling, and timing. I might be crazy but It seems that 13.5v is a little on the wimpy side. I thought that the sr alternator should be putting out more than that.

[romper_stomper]

*Update*

Replaced fuel pump with a brand new Walbro 255lph.

Today was 70* weather and the car was barely driveable. Last week I made to separate 3 hour trips with absolutely zero issues and it was low 40*'s out side.

I just cant figure this out. MAF is functional. Dies once unplugged. IACV is functional. Dies when unplugged. Maybe alternator? ECU? Those are quite literally the last two items that might not have been changed out completely.

[fliprayzin240sx]

Did you check your base timing? Maybe its too far advanced? o2 sensor?

[romper_stomper]

It has a z32 O2 sensor, but that's not to say that it might be bad. Also The timing 18* or 15* btdc. I have to check with the previous owner (close friend).

[romper_stomper]

The issue is fixed. Not sure if it was the ECU or bad connection to the ECU harness..

Checked ECU and noticed a solid RED light. I used a small screwdriver to diagnose the codes and the red light flickered for a second faintly, then turned off. Codes given were 55. I started the car and I could tell that the car was responding to the way I was handling the ecu when loose (bad connection i assume). Mounted everything back up and drove it for the past two weeks and have had ZERO issues. No stalls, no bucking, perfect gas milage, all during warmer weather.

[randmonds4]

But I am working on it.http://www.skincaretipss.com/24.jpg