Another sr20 sputtering thread

[redfox]

I see countless sr20 sputtering threads, and none of the solutions seem to work for me...

About 2 months ago I was driving into the costco parking lot (no more then 20mph), grab a parking spot and go inside. When I come back out, and start up the 240, my engine (SR20DET black top) starts to sputter like one of the intake pipes has come loose again. So I check them all and they seem to be attached. With no other options, I drive home, the sputtering was consistent through all the rpm range and there was no bucking/ lurching/ bogging/ dieing.

Car sat for about 2 months while I bought a house and moved in.

Fast forward to today:

Car still sputters at any RPM any any temp (please note that it's very hot in Texas so the car is never actually getting "cold", just colder then normal running temp)
I removed all my FMIC piping, verified there are no holes in the piping or connectors, and reattached it all.
Tightened up my exhaust and verified there are no obvious leaks.
Put in new NGK BKR6E spark plugs gaped to 32
Verified every coil pack is producing spark
Verified my MAF is grounding properly with a multimeter
Installed a new 90 300zx TT fuel filer (auto zone brand not OEM)
Used the wooden stick in the ear touching injectors method to verify they are firing

I'm out of ideas, anyone else have one?

[Tae-Hyun]

I went through similar issues with my vehicle sitting for a while, however it was a year. Started up on first try.

While driving, its started to sputter really bad. Checked maf - could be culprit.

Next could be the fuel - ie. injectors/fuel pump.

Have you tried to rev engine while in neutral?

[redfox]

I went through similar issues with my vehicle sitting for a while, however it was a year. Started up on first try.

While driving, its started to sputter really bad. Checked maf - could be culprit.

Next could be the fuel - ie. injectors/fuel pump.

Have you tried to rev engine while in neutral?

The engine revs, but the sputtering/misfiring increases at the same rate as the RPM's.

How can I properly check the MAF and injectors? I don't have any spares to swap them with.

[KiLLeR2001]

What is your fuel pressure reading? What pump do you have installed?

[redfox]

What is your fuel pressure reading? What pump do you have installed?

It's a Walbro 255LPH pump about 3 years old. I don't have a fuel pressure gauge, but the pump sounds fine, and there seems to be plenty of fuel pressure in the fuel rail.

[KiLLeR2001]

Get a fuel pressure gauge.

Also, check the coilpacks pull them out and inspect the sides for cracks. Make sure the springs are making good contact with the spark plugs and that they aren't corroded and everything looks normal. Just because they are producing spark doesn't mean they are producing adequate spark. Test the resistance (OHM) of each one as well.

edit:

Test the resistance of the injectors too. Should be around 11.5 ohms IIRC.

[redfox]

Get a fuel pressure gauge.

Also, check the coilpacks pull them out and inspect the sides for cracks. Make sure the springs are making good contact with the spark plugs and that they aren't corroded and everything looks normal. Just because they are producing spark doesn't mean they are producing adequate spark. Test the resistance (OHM) of each one as well.

edit:

Test the resistance of the injectors too. Should be around 11.5 ohms IIRC.

I just checked the injectors, and found the following resistances:

cyl #1 11.5Ohms
cyl #2 11.6Ohms
cyl #3 11.6Ohms
cyl #4 no reading at all

Looks like I need to find a new fuel injector to replace #4 with. any thoughts on where to source a new one?

BTW, THANK YOU for your help:bowdown::bowdown::bowdown::bowdown:

[KiLLeR2001]

People sell the 370cc injectors for the SR20DET all day long on here. Or if you want to buy a new one go to Autozone and order one for a '96 300ZX Twin Turbo.

[brudacille]

People sell the 370cc injectors for the SR20DET all day long on here. Or if you want to buy a new one go to Autozone and order one for a '96 300ZX Twin Turbo.

hmm... never knew about the 300zx injectors, good info... I learned something today, haha

[240sx-pat]

I just checked the injectors, and found the following resistances:

cyl #1 11.5Ohms
cyl #2 11.6Ohms
cyl #3 11.6Ohms
cyl #4 no reading at all

Looks like I need to find a new fuel injector to replace #4 with. any thoughts on where to source a new one?

BTW, THANK YOU for your help:bowdown::bowdown::bowdown::bowdown:


How do you properly check the injectors?????

[redfox]

How do you properly check the injectors?????

Unplug the harness from the injector and you will see 2 electrical leeds. Set your multimeter to detect resistance from 0-20 Ohms, and touch the leeds from the multimeter to the leeds of the injector. You should get a reading of ~11.5 Ohms.

[redfox]

New injector arrived yesterday, and I just got it installed. Same thing is happening. I can unplug the injector when the car is running, and there is no change. So now I think it's time to look at the 50 miles of wiring...fml

Anyone have any other ideas?

[redfox]

Oh, just fyi, I did test the injector before I put it in and was getting 11.6 to 11.9 Ohms resistance.

[delado]

you can also use q45 injectors. I forget what specific year though.

[redfox]

Another update...

I verified the injector is receiving a constant 14ish volts on the power wire (red). Next I unplugged the ECU and was able to verify 0.02 ohms resistance between the signal wire at the ECU (blue w/ black stripe, pin #112) and the signal wire at the injector (shows the wire is good). Next I started the car and measured the signal wire at injector 4, and saw a pulsing 13.6-13.7 volts, and compared it to the other 3 injectors and saw the same voltage (shows the ECU is telling the injector to squirt fuel).

So, the injector has power, it's being told to squirt fuel, I get 11.6 ohms resistance across the terminals of the injector... If I unplug injector 4 while the car is running, there is no change in how the engine is running, but if you unplug any other injector, the car damn near dies.

Anyone have ideas?

[redfox]

Anyone have any ideas?

[cotbu]

You need to physically see the injector squirt fuel, remove the rail and cas, disconnect the coil packs and spin the cas, KOEO. Then test the coilpacks the same way. You should know if you have spark and fuel after that.

[redfox]

You need to physically see the injector squirt fuel, remove the rail and cas, disconnect the coil packs and spin the cas, KOEO. Then test the coilpacks the same way. You should know if you have spark and fuel after that.

I'll give this a shot Sunday :) Thanks for the ideas!

[inopsey]

Another update.... If I unplug injector 4 while the car is running, there is no change in how the engine is running, but if you unplug any other injector, the car damn near dies.

Anyone have ideas?

what is your compression ? sounds like you are running on 3 cyl.

[Highway Riding]

Hot Start? Did you run in and out quickly? I learned the hard way that my SR doesn't like hot starts! NVM i see you think it is Injector related...

[usmctankmech]

Have you checked your engine harness for spots that have potentially rubbed through and are grounding out? Mine did that and as a result would break up really bad under accel and then the harness caught fire and i had to replace it. I ended up buying a new nissan one which had to be modified to run propperly.

[redfox]

Finally an update!

I managed to get outside today and work on the car a bit. I pulled the CAS out and verified all four injectors are clicking when I rotate the gear I didn't remove the rail from the manifold, just because it's such a pain). I also verified that when I rotate the CAS gear I get a yellowish spark on all four plugs. Something to note: these plugs are brand new, they only have about a combined total of 30minutes of idling time on them. When I pulled them out, plug 1 though 3 had a bit of oil on them, and #4 was covered in gas.

I'm all out of ideas and now I need to figure out how to put the damn CAS back in properly, as my damn markings rubbed off when I was rotating the gear.

Anyone?

[cotbu]

set engine TDC line up the dots per fsm insert cas.

You seem to have a problem with following directions, you also should have verified leaky injectors. this time when you start the car try with the throttle wide open.

If your car fire's up, shut it off, prepare work area for timing adjust. If it doesn't start try removing the fuel pump fuse. then start, if still no start get starting fluid then, start the car. This is only to get your timing correct, after you do that, check those injector for leaks. also charging or jumping the battery may help with that weak spark. problem could be anything ie. CP grounds. start up!!