Sr20det starts then dies immediently

[towlie]

So about 7 months ago I had this hatch with an sr that ran great. Daily drive the shit of out it. Fast forward the car was totaled, sr was pulled as sat for 6 months.

Today I try to start it in new car and it cranks, fires, rpms shoot up to about 2500.. Then it stalls.

Because it ran so well when I pulled it I can rule out tps, iacv and cas.

It was tuned on a power fc. It has brand new walbro 255. (No my lines aren't backwards :D)

Only things I changed during swap:
Sohc to z32 maf. Checked wiring about 30 times. I know it will need a retune but would that prevent it from starting?

Had several damaged connectors so I swapped those from a spare harness. (Coilpack female, few other random ones)
Also checked my work several hundred times

Any ideas? Bad maf/requires tune to start on z32 maf? Something else I'm missing ?

[fliprayzin240sx]

Are you trying to run the PFC on it? Did you change the maf setting in there for whatever maf you're running (stock or Z32 MAF)?

If it was set for stock and you slap a Z32 maf on it, it wont run until you change the setting in the PFC.

[ocn]

That z32 maf is more the likey the cause, you cant just swap those in and drive.

[towlie]

Yeah changed the setting. I know it won't necessarily be drive able but it should still be able to start/idle right?

I'm going to try finding another maf to swap and do from there

[ultimateirving]

unplug maf see if it idles in limp mode

[Mikester]

Yeah changed the setting. I know it won't necessarily be drive able but it should still be able to start/idle right?

I'm going to try finding another maf to swap and do from there

If you change the MAFS setting on the commander to Z32 (VG30DETT), it will run exactly as it did before as if nothing ever changed.

As far as the swap itself, it could have been running on whatever residual fuel happened to be in the rail; kinda like pulling the fuewl pump fuse with the car running to release fuel pressure. When I started my car for the first time (fresh rebuild), it took a few times of turning the key on/off to prime the fuel system enough (lines completely dry) to where it would start and stay running.

Check your fuel pump fuse, and verify you have fuel pressure... Sounds to me like it had fuel, then it didn't.

[cotbu]

The problem is lack of air, or lack of fuel based on what the op has stated. Yes the engine will start, but depending on how far off the tune is, it may not run with a bad, or disconnected mafs.

I think the tune is off, why mafs probably, but you are either getting too much air or too much fuel or vice versa. look at the wideband 10s-9s Hmmm? No wideband create a vacuum leak, by disconnecting a vacuum line, if the engine stays running you just confirmed your problem, it probably won't run forever like that but it should run. The other diagnosis requires raising fuel pressure by adj fpr or pinching shut the fpr vacuum line(don't disconnect this line for the first test for obvious reasons)
Because it ran so well when I pulled it I can rule out tps, iacv and cas.
If you did all of the correct testing and you're still having issues? Never rule anything out!
It could just as easily be timing related, but that list says no it ain't!

[towlie]

unplug maf see if it idles in limp mode

Ill try that after work tonite

If you change the MAFS setting on the commander to Z32 (VG30DETT), it will run exactly as it did before as if nothing ever changed.

As far as the swap itself, it could have been running on whatever residual fuel happened to be in the rail; kinda like pulling the fuewl pump fuse with the car running to release fuel pressure. When I started my car for the first time (fresh rebuild), it took a few times of turning the key on/off to prime the fuel system enough (lines completely dry) to where it would start and stay running.

Check your fuel pump fuse, and verify you have fuel pressure... Sounds to me like it had fuel, then it didn't.

It was a bare shell when I bought the new car so I see your no fuel in lines idea making sense. But before I'd start it I'd turn it to "acc" for a few
Moments and I could hear the pump priming. Wouldn't this happening several times get fuel back into the lines? I checked my fuses, ill pop off the main feed line and crank it to verify I'm getting fuel.

The problem is lack of air, or lack of fuel based on what the op has stated. Yes the engine will start, but depending on how far off the tune is, it may not run with a bad, or disconnected mafs.

I think the tune is off, why mafs probably, but you are either getting too much air or too much fuel or vice versa. look at the wideband 10s-9s Hmmm? No wideband create a vacuum leak, by disconnecting a vacuum line, if the engine stays running you just confirmed your problem, it probably won't run forever like that but it should run. The other diagnosis requires raising fuel pressure by adj fpr or pinching shut the fpr vacuum line(don't disconnect this line for the first test for obvious reasons)

If you did all of the correct testing and you're still having issues? Never rule anything out!
It could just as easily be timing related, but that list says no it ain't!

My wideband wasn't working before I pulled the motor but it would idle at a solid 14.7 all day (w/b on the dyno). I've replaced the sensor and it still isn't working.. Thanks stack lol. Ill start diagnosing more today after work.

Thanks for the ideas guys

[steve shadows]

Can you clarify a bit? You're running a Z32 maf now but you think you may have damaged the connector or the maf itself when or while the motor was out of the car?

The tune is a possibility but it would be fuel map related only. Also if you modified the motor then dropped it back in the car did you re-initalize the power-fc and get it tuned? I am guessing no?

Yeah sounds like it could be a few different things in the power fc as well.
If you want some more specifically tailored one on one help send me an email at [email protected] - Thanks!

[towlie]

Can you clarify a bit? You're running a Z32 maf now but you think you may have damaged the connector or the maf itself when or while the motor was out of the car?

The tune is a possibility but it would be fuel map related only. Also if you modified the motor then dropped it back in the car did you re-initalize the power-fc and get it tuned? I am guessing no?

Yeah sounds like it could be a few different things in the power fc as well.
If you want some more specifically tailored one on one help send me an email at [email protected] - Thanks!

I am running a z32 maf I purchased used. I have a new circuit sports z32 maf pigtail I wired in and checked the wiring a thousand times. Previously, I had a sohc maf. I doubt it's a connector/wiring issue, I'm leaning towards a bad maf.

I cleaned the maf with (light) compressed air and maf cleaner (Specifically). Sr started, idled nicely at dead on 1000rpm (how it used to) and revved nicely for a few brief moments.. Until it began stuttering, rpms dropping and rising (1.8k to 200~, then back up) and finally it stalled out. Then it did the same thing its been doing.. crank, turn over, stall out.

I'm gonna throw a different maf at it and see what happens. I know it needs a retune regardless of user selectable maf options.. I do not plan on driving it with out a tune on the new maf (save up and down my driveway to check brakes/drivetrain/etc) , I just want to make sure it runs before I tow it to the dyno lol.