Just another sr issue..

[SR20DETsilvia]

Hey Guys,


Having a slight issue with a friends car..

1991 Silvia s13
Red top sr

Mod list:

Oem internally
Apexi head gasket
Arp main studs
Five-o 550cc injectors
Z32 maf
Isis 3871r turbo
Rs enthalpy tune
Isis fmic w/Hks bov
255 walbro pump

The issue is when coming into boost it hits fuel/boost cut or at least feels like that. If you are light on the throttle you can rev all the way up with no hesistation issues.

Things i've checked/swapped:

Coilpacks, tps, boost leak, vac leak, spark plugs, ignitor, fuel pressure, maf, intake tube..

I'm running out of options..

Just look for ideas! Thanks.

[di-devol]

There is no fuel cut on these engines. What's your plug gap?

[Kingtal0n]

whats the voltage of the maf signal wire when it happens?

And yes SR20 does indeed cut fuel under the right circumstances. But it would be like hitting a wall, a sudden decel, complete loss of power. Is that what you are experiencing?

more likely its the knock sensor giving trouble. when the knock sensor fails or becomes unplugged, the engine will typically pull timing, and you will lose almost all power. It feels different then fuel cut.

Yeah, it could be the plugs too. Do a tune up of course, before trying to diagnose any engine problems. Change the plugs, clean the air filter, check for oil in the hoses of the valvecover and turbocharger outlet, what do the plugs look like? Check the compression if you can just for the heck of it. Just to know.

And get a wideband on it if possible.

[SR20DETsilvia]

There is no fuel cut on these engines. What's your plug gap?

Plug gap is 0.030 have also tried 0.028 0.033. Also two different sets of plugs (6's and 7's)

[SR20DETsilvia]

whats the voltage of the maf signal wire when it happens?

And yes SR20 does indeed cut fuel under the right circumstances. But it would be like hitting a wall, a sudden decel, complete loss of power. Is that what you are experiencing?

more likely its the knock sensor giving trouble. when the knock sensor fails or becomes unplugged, the engine will typically pull timing, and you will lose almost all power. It feels different then fuel cut.

Yeah, it could be the plugs too. Do a tune up of course, before trying to diagnose any engine problems. Change the plugs, clean the air filter, check for oil in the hoses of the valvecover and turbocharger outlet, what do the plugs look like? Check the compression if you can just for the heck of it. Just to know.

And get a wideband on it if possible.

The voltage on the maf is good, I also swapped with his spare z32 maf and both check out OK

It isn't a sudden decel, more like a sudden pause in acceleration. It's like spark blow out. I've been reading more into knock sensors and was going to try that next. As well as I finally got his led to work on his ecu and it's throwing 13 which is coolant temp so I have a spare I'm swapping in ASAP.

As for the plugs they are brand new (less then 100kms), air filter is new, turbo is new hoses are new, everything I've already looked over. I was also thinking about doing a leak down and a compression test this week.

I have a wideband installed in this car, the a/f's look pretty good.

There's another issue with the car, the wiring from the JDM harness isn't matching up to the orginally ca18 dash harness so waiting on the proper harness and cluster. Either way the issue is if you go to start the car after its sat you have to hold the throttle wide open to get it to fire so my guess is partially due to the wiring/code being thrown.

[Kingtal0n]

check the plugs to make sure they are still nice white/tan after you fix the cts.

[SR20DETsilvia]

check the plugs to make sure they are still nice white/tan after you fix the cts.

Changed CTS and plugs are good.

I'm going to check the knock sensor next..

[idahotuner]

does it seem to get worse as the car warms up, and not as bad when it is cold? find some one with a cas and swap it out see if that makes a difference, pull the cover off yours and see if there is oil or corrosion on the disk inside, if so it very well may be the problem, i just had this issue my self

[steve shadows]

1. How much boost are you running?
2. What is your base ignition timing? Re-set/check per FSM just to be sure
3. This is why I like PFC you can see if you're maxing our your injectors.
4. Try a smoke tester or smoke machine style leak down tester.
5. Get a proper good condition harness.

:bow:

[idahotuner]

coolant temp sensor would do this also, so if its throwing that code very well maybe be the issue

[trxrx7]

people always forget to check the grounds from the motor i have had that before went over everything and it just turned out to be that the engine was not properly grounded(not saying that this is the case but could be)

[steve shadows]

people always forget to check the grounds from the motor i have had that before went over everything and it just turned out to be that the engine was not properly grounded(not saying that this is the case but could be)

YES! and specifically the coil pack harness main ground that should go to the back of the head and the firewall...

[ultimateirving]

1. How much boost are you running?2. What is your base ignition timing? Re-set/check per FSM just to be sure
3. This is why I like PFC you can see if you're maxing our your injectors.
4. Try a smoke tester or smoke machine style leak down tester.
5. Get a proper good condition harness.

:bow:

This is what i wanted to know steve!
I agree we need some more information to go off to try and make sure he has the optimum setup.


Do you have consult cable hooked up?