SR20det running need serious tech help.

[TheVinylKingz]

Hello, I?ve been trying to diagnose my SR20DET (red top) but unfortunately I have not found the issue. What going on is that it cranks at cold starts, but when it hits operating temperature (my assumption) it starts to loose power. I feel it?s misfiring. The weird thing is that before hitting operating temperatures it boosts really good and it is very responsive. Prior to this problem I used to drive it with no problems. It all started when I was driving back home from work when all of the sudden I felt the car change its feel and drivability. Almost like it was on 3 cylinders. But till this day I haven?t had any luck changing parts and spending money to determine the problem. I seriously need help with this SR20det.

Mods:
Compression 180ish on all 4 cylinders
Rebuilt SR20det (red top)
Stock ECU 62 ( code 55 nothing is logged in the ECU when this issue happens)
86.5 pistons
T28 specR
Tomei PonCams
SR Stock MAF
87mm head gasket
Side Mount Intercooler
Stock 370 injectors
Walbro fuel pump

Sensors: coolant temp changed (same problem)
Spark plugs gone back and forth with heat range of 6 and 7 (same problem)
Coilpacks changed including igniter (nothings changed)
Swapped 370cc injectors for other ones to test out, same problem.
O2 sensor ( used fat one to see if anything changes, same shit)
Ka24e (single cam) MAF (still the same problem)
TPS reading at .48 and 4.19 at WOT

[jedi03]

have you tried checking the harness for internal breaks? also what boost are you running/hitting

[TheVinylKingz]

Originally Posted by jedi03

have you tried checking the harness for internal breaks? also what boost are you running/hitting

I?ve checked the harness, but visually it appears to be fine. I?m running on stock boost for the T28

[Trixzim]

Have you tried unplugging one coil pack at a time while the car is running to see if anything changes, but this leads back to a bad harness.

[EFITTZY]

Have you tried testing with another known good stock 62 ecu? Pop the cover off of yours and inspect for any melted or leaking capacitors $0.02

[TheVinylKingz]

Originally Posted by EFITTZY

Have you tried testing with another known good stock 62 ecu? Pop the cover off of yours and inspect for any melted or leaking capacitors $0.02

I?ve checked the ECU and there?s nothing leaking or shows signs of damage.

[TheVinylKingz]

Originally Posted by Trixzim

Have you tried unplugging one coil pack at a time while the car is running to see if anything changes, but this leads back to a bad harness.

I tried unplugging the coil harness, when I do I notice a change in the motors response. I then plug back each plug and goes back to normal

[TheVinylKingz]

So I took off the spark plugs and they appear to be lean, can anyone confirm they are lean?

[EFITTZY]

Originally Posted by TheVinylKingz

I?ve checked the ECU and there?s nothing leaking or shows signs of damage.

Great, but have you tested with another KNOWN GOOD ecu? Maybe an issue you can't see visually. Yes, plugs appear to show signs of lean mixture

[brndck]

just something to think about, but a "spec R t28" is going to move quite a bit more air than a t25, so if you're still on 370 injectors, and stock ecu, AND you're running cams, perhaps the ecu settings can't compensate.

measuring AFRs might help pinpoint the issue.

[nick_d_240sx]

That looks lean.

Okay, a couple of questions:

What if any modifications/upgrades did you make before running into this issue?

What going on is that it cranks at cold starts, but when it hits operating temperature (my assumption) it starts to loose power. I feel it?s misfiring.

Does the car start better or worse when it's hot vs. cold?

The weird thing is that before hitting operating temperatures it boosts really good and it is very responsive.

The stock ECU has engine coolant temp fuel correction that could be making it run better at lower ECTs.

Prior to this problem I used to drive it with no problems. It all started when I was driving back home from work when all of the sudden I felt the car change its feel and drivability. Almost like it was on 3 cylinders.

Again, was there any modifications made that may have affected the engine operation? Fuel, Airflow, Spark/Timing, Compression.

Have you checked the fuel filter? Have you checked fuel pressure? Have you checked the MAF(plugged in vs unplugged)? Have you checked wiring and vacuum lines?

I agree though, Stock ECU, Cams and T28 Spec R is not a great recipe. What psi are you running?
Those plugs look pretty lean to me.

[TheVinylKingz]

Originally Posted by brndck

just something to think about, but a "spec R t28" is going to move quite a bit more air than a t25, so if you're still on 370 injectors, and stock ecu, AND you're running cams, perhaps the ecu settings can't compensate.

measuring AFRs might help pinpoint the issue.

Good point I knew I would need to tune it at some point. I was just confused why all of the sudden the ECU is not compensating like it ran before this issue. I feel
It should have started to run like the way I’m experiencing as soon as day 1 on the first crank. It also shows code 55.

I got some SpecR 444/480 injectors. Would that create a rich mixture or would I need to tune it?

SpecR T28 running 444/480 cc injectors (up to this date it?s been debated which is correct on the Spec R injectors) unless I get them flow tested.

[Kingtal0n]

This how they should look when properly tuned
Not saying yours is properly tuned- only pointing out lean is favorable for idle/cruise situations.

The black ring around the outside, clean, unbroken, is important. Cant see yours up close enough.

If you don't have a wideband drop what you are doing and buy a wideband. You cannot diagnose or maintain any turbo engine without a wideband it is very difficult

I would
1. wideband
2. Pressure test
3. Verify maf placement and that the bypass is recirculated properly like an OEM system using a MAF

[TheVinylKingz]

Originally Posted by Kingtal0n

This how they should look when properly tuned
Not saying yours is properly tuned- only pointing out lean is favorable for idle/cruise situations.

The black ring around the outside, clean, unbroken, is important. Cant see yours up close enough.

If you don't have a wideband drop what you are doing and buy a wideband. You cannot diagnose or maintain any turbo engine without a wideband it is very difficult

I would
1. wideband
2. Pressure test
3. Verify maf placement and that the bypass is recirculated properly like an OEM system using a MAF

Thank you for the help, I?m going to invest in a wide band. I?ll keep y?all posted once I get this fixed!!

[TheVinylKingz]

Question: I bought a PowerFC a while back. My question is, can a PowerFC provide better monitoring than a wide band?

Also, this morning I connected the PowerFC. It would crank for 2 seconds and then it would shut down. Any opinions??!!

I bought it used.

[Kingtal0n]

power FC is a stand-alone it requires complete setup and tuning.
I used to tune L-jetro PFC here for $250 and D-jetro for $600 local
The engine will never run optimally on a base PFC tune without significant effort. It is rare anyways.

You have to adjust maps, fuel inj size, vacuum VE, delay period, etc... and globals for the L-jetro are useful

The wideband is an A/F gauge. the PFC is a controller for the engine. They are completely different things. You WATCH The wideband for many hours/days/years and learn how it reacts to tuning conditions. After 20 years I have developed an kind of... expectation for it's behavior and just by looking at a wideband I Can tell whether the engine is running properly or not. Its like the behavior of the gauge can tell us something that even the number on the gauge can not.

The PFC is just the computer component that the end-user is TUNING you are putting values, numbers, to make the engine run properly, some of that will show up on the wideband, some will not. The timing for example won't show much difference in the wideband, but its still a very important tuning cornerstone to configure.

You watch the wideband - and use this information to tune the engine using PFC.
The timing is intuitive to me, PFC and wideband cannot tell you timing. If you get it going I Can give you some timing values to shoot for though.

[burnsauto]

Just a question..

You mentioned you put in coils, did you put in new, oem coils? What about the ignitor? I know a lot guys use that ISR trash, but you get what you pay for, and companies like that factor in a certain percentage of crib death in their brand new parts.

Also, make sure all your grounds tied to the ignition/fuel system are as good as you can get them. The more stress you put on the engine once it's warmed up, the more it'll demand from those grounds, and they aren't up to snuff, things can get a little funky.

[TheVinylKingz]

Used, I have a set of used coil packs and got an igniter used as well. I imagine I could use a voltage meter to check proper voltage. Does anyone know proper voltage or a better way to check them?

[TheVinylKingz]

Thank you for the help everyone! This has been annoying dealing with and throwing in money. I feel the best thing to do is get it tuned. Anyone recommend RS- Empalthy?

[burnsauto]

RS is an easier route, but it may not solve your issue. I'd hate to see you sink 4-500 bucks into an ecu to find out that it's not going to solve your issue. There are cheap(ish) stand alone ecu's that can also help diagnose an issue through live data collection (like megasquirt), while also getting the car running the way it should after your mods.

The way you describe the problem in your original post doesn't lead me to think it's just the tune though. If it were a constant problem from the moment you start it to the moment you shut the engine off, sure...tune for sure. But it sounds like its a much more intermittent issue.

My advice, if you want any, is to get a friend with an SR. (if you don't have one, get one.) If said friends car runs well, spend an afternoon swapping parts related to the ignition system, and see how that changes things. I'd even change that temp sensor, just to be safe. It make take some time to slowly go through everything, but its better than throwing money at it without knowing the exact cause first. It doesn't sound like a boost leak, and unless the problem only happens when you start leaning on the fuel system (like when it's only hitting boost), it doesn't sound like a fuel pump voltage issue either. Running an engine with a bad MAF is pretty apparent right when you start it. And as you've described the problem is relevant to engine temperature. My thought process keeps going back either the ignition system, coolant temp sensor, a weak/bad ground, or a bad ECU that starts screwing up once the signal from the coolant temp sensor starts giving a certain reading (like when the engine warms up). Don't change things all at once, go little by little, changing out parts in phases, to pinpoint the actual problem.

Your plugs do indicate a leaner mixture, but not one that's super alarming. The ceramic around the electrode isn't browned, and the ground seems to have even coloring (that's a bit harder to see in your pics). The photos you got in response from Kingtal0n show an engine that's been tuned on the slightly rich side of the spectrum, which any reliable tune should be in. Sure, you'll make more power leaning it out, but power that's on borrowed time.

[TheVinylKingz]

Originally Posted by burnsauto

RS is an easier route, but it may not solve your issue. I'd hate to see you sink 4-500 bucks into an ecu to find out that it's not going to solve your issue. There are cheap(ish) stand alone ecu's that can also help diagnose an issue through live data collection (like megasquirt), while also getting the car running the way it should after your mods.

The way you describe the problem in your original post doesn't lead me to think it's just the tune though. If it were a constant problem from the moment you start it to the moment you shut the engine off, sure...tune for sure. But it sounds like its a much more intermittent issue.

My advice, if you want any, is to get a friend with an SR. (if you don't have one, get one.) If said friends car runs well, spend an afternoon swapping parts related to the ignition system, and see how that changes things. I'd even change that temp sensor, just to be safe. It make take some time to slowly go through everything, but its better than throwing money at it without knowing the exact cause first. It doesn't sound like a boost leak, and unless the problem only happens when you start leaning on the fuel system (like when it's only hitting boost), it doesn't sound like a fuel pump voltage issue either. Running an engine with a bad MAF is pretty apparent right when you start it. And as you've described the problem is relevant to engine temperature. My thought process keeps going back either the ignition system, coolant temp sensor, a weak/bad ground, or a bad ECU that starts screwing up once the signal from the coolant temp sensor starts giving a certain reading (like when the engine warms up). Don't change things all at once, go little by little, changing out parts in phases, to pinpoint the actual problem.

Your plugs do indicate a leaner mixture, but not one that's super alarming. The ceramic around the electrode isn't browned, and the ground seems to have even coloring (that's a bit harder to see in your pics). The photos you got in response from Kingtal0n show an engine that's been tuned on the slightly rich side of the spectrum, which any reliable tune should be in. Sure, you'll make more power leaning it out, but power that's on borrowed time.

Thank you for your response I really appreciate everyone?s time reading this thread and responding. Im going to take my time continuing to diagnose this issue. As a friend of mine described it, a gremlin or gremlins hidden within.

[TheVinylKingz]

Originally Posted by nick_d_240sx

That looks lean.

Okay, a couple of questions:

What if any modifications/upgrades did you make before running into this issue?



Does the car start better or worse when it's hot vs. cold?



The stock ECU has engine coolant temp fuel correction that could be making it run better at lower ECTs.



Again, was there any modifications made that may have affected the engine operation? Fuel, Airflow, Spark/Timing, Compression.

Have you checked the fuel filter? Have you checked fuel pressure? Have you checked the MAF(plugged in vs unplugged)? Have you checked wiring and vacuum lines?

I agree though, Stock ECU, Cams and T28 Spec R is not a great recipe. What psi are you running?
Those plugs look pretty lean to me.

Since the time that it was built it has
Never been modified. It used to run really well for a while, but all of the sudden while driving on the freeway, it just started running bad, as described on the original post.

I don?t have any FPR or boost controller to verify the boost it?s running. It has a T28 Spec R. From what I?ve read it?s maybe around 7lbs of boost stock.

[brndck]

Originally Posted by TheVinylKingz

I got some SpecR 444/480 injectors. Would that create a rich mixture or would I need to tune it?

you cant just throw different size injectors in and expect the ecu to be able to compensate.

you need an ecu that is tuned for the setup you're running, or, a ecu that can be tuned (like the power FC you bought) AND an experienced knowledgeable tuner, who will adjust the ecu setting and optimize the parameters while monitoring AFR and knock.

[LoSt180]

Which coolant temp sensor did you replace? There's two of them, a 2-pin and a 1-pin spade connector style. The 1-pin is for your gauge cluster only, the 2-pin is used by the ECU.

Running bad when the engine is warmed up really points to a bad temp sensor.

You should really have a consult cable at this point, and actually monitor what the ECU is seeing. So you can see the code 55 and check TPS voltage with a volt meter, but it's way more useful to see what values the ECU is actually seeing.

Running a T28 at wastegate spring pressure is a waste. The S14/15 used a wastegate solenoid to run that thing at about 11 psi stock, and the S14 came with the same 370cc injectors. You have room for improvement here.

[TheVinylKingz]

Originally Posted by LoSt180

Which coolant temp sensor did you replace? There's two of them, a 2-pin and a 1-pin spade connector style. The 1-pin is for your gauge cluster only, the 2-pin is used by the ECU.

Running bad when the engine is warmed up really points to a bad temp sensor.

You should really have a consult cable at this point, and actually monitor what the ECU is seeing. So you can see the code 55 and check TPS voltage with a volt meter, but it's way more useful to see what values the ECU is actually seeing.

Running a T28 at wastegate spring pressure is a waste. The S14/15 used a wastegate solenoid to run that thing at about 11 psi stock, and the S14 came with the same 370cc injectors. You have room for improvement here.

I swapped out the coolant temp sensor (2-pin). Today I took her out for a drive due to swapping out the o2 sensor, but the same symptoms presented. I’m beginning to think my injectors are no good due to the spark plug on cylinder 1 looking very rich and the others on cylinder 2,3,4 very lean. My TPS is in range (.48 & 4.19/WOT).

Maybe my Injectors are open causing the motor to display symptoms of misfiring??? I do have some 480/444 cc S15 injectors and i am tempted to see if I will get the same symptoms if I swap them out to diagnose. My reasoning is if I swap the injectors and don’t notice anything, then my 370cc injectors were bad, if I notice the same, then it’s something else.

My concern is flooding the cylinders with those 480/444 injectors, maybe lead to hydro lock?????

[LoSt180]

The problem with swapping out those injectors without adjusting the tune is that they will dump about 25% more fuel. Doubt it will be enough for hydro lock, but it will be stupidly rich.

Back to thermostat swap, what values is the ecu seeing? If values are good, then check other ideas, but if values are bad then check wiring. Hard to troubleshoot if you don't know what the ecu is working with.

[jdmgtom]

check your coolant temp sensor, under your intake manifold. I had similar problems where my coolant temp sensor harness was brittle and probably made a bad connection from vibration and heat.

https://www.wiringspecialties.com/s13srcoteses.html

[TheVinylKingz]

Originally Posted by jdmgtom

check your coolant temp sensor, under your intake manifold. I had similar problems where my coolant temp sensor harness was brittle and probably made a bad connection from vibration and heat.

https://www.wiringspecialties.com/s13srcoteses.html

I checked the Coolant temp sensor and the harness for voltage and continuity and it checked out good when testing with a voltage multimeter.

I swapped out my Injectors for another set of 370cc and same thing. My injectors and harness
Are reading correctly as tested with a voltage multimeter.


Im very suspicious that it may be my coil packs. Basically when I turn on the motor and I unplug each coilpack from the harness it changes it?s characteristic. However, when I check for voltage it shows a spike of ~ 3.0 + or - and then dips down to 0.00.

I?ve read that coil packs should be showing 5v when testing on a multimeter.

[Kingtal0n]

Its never going to run properly until you tune the computer using a wideband

[TheVinylKingz]

Update: forgot to mention the ECU is throwing code 11,12,13. From my research I’ve seen people say the timing on the SR should be 15, others say different.

Is this correct?
Also can I check timing by simply aiming the timing gun at the “crank case pin”?, or do I need to reposition at TDC before checking my timing?


Weird how CTS is throwing a code and I just installed a new one, including an Orilley SOHC Ka24e Maf

11 - Camshaft Position Sensor
12 - Air Flow Meter
13 - Coolant Temperature Sensor