Sr20 1/4 throttle response. Someone please help!!!!

[drftr68]

Ive been dealin with this problem for a while and ive tested pretty much everything i can. I really need help. The problem is that i can only give the car 1/4 throttle beforw it started spitting and sputtering no matter if im in boost or not. At idle i can hear it missing a lil too. Heres a list pf wat ive tested and replaced:
Maf sensor-voltage and signal going to ecu
Cam sensor-voltage and signal to ecu
All injector signal wires to ecu and resistance on injectors1,2,4 read 11.1-inj 3 reads 15.8
Checked coilpacks and signal to ecu*
Checked tps signal*
Checked fuel pressure-43 psi
Checked timing- 15* at tdc*
Checked vaccum lines and piping
Replaced:
Knock sensor
Headgasket
Turbo
Vaccum lines
Spark plugs
Tps
Maf
Ecu
Replaced coilpacks
Cylinder leakdown test
any sr gurus would be greatly appreciated ill take any advise and use it. Ive done everything short of replacing the wiring harness.

[Slidin240Wayz]

fuel filter

[drftr68]

Replaced it

[drftr68]

Oh and i replace. The fuel pump.

[s13drob]

Have you checked out the coolant temp sensor? Not the sensor for the cluster. The one for the ecu. It's probably making the car run rich.

I don't think the injector reading that high is normal. Iirc all mine wore in the 11s.

[drftr68]

Oh yea sorry i replaced The injector and where is the coolant sensor goin to the ecu?

[Om1kron]

take out your maf... like just the black electric part, check the little electrodes to make sure they're not covered in dirt, if they are grab an art brush and gently get the caked up dirt off of it, and replace or clean your air filter... if it still is driving like dick then replace the maf. Even if you replaced it, the replacement may be dirty too. Mine was.

[drftr68]

Ok ill try it. Also the car doesnt blow any smoke of any kind and if i get on the hwy like speeds of 70 too long my car will start over heating. And this prob doesnt just happen sometimes it happens all the time no matter wat.

[rc1honda]

How did the leakdown look? Overheating is not a good sign, but im not sure what would make you overheat, and run like shit at the same time. They maybe indepedent problems.

I would jack your front end up and take the rad cap off and let it run, and fill as neccesary. You could have air in your coolant system.

Are you sure the headgaket was put on correctly. Also you can try and retorque the head studs if you havent already.

[drftr68]

torqued and retorqued head studs, im almost sure that they are seperate problems. as for bleeding the cooling system i have done sr headgaskets before and not had any problems with overheating after i was done. leakdown looked good so i kno i dont have any bad valve seals or bent valves. i can drive the car all day long with 1/4 throttle and not have any overheating problems or bogging but as soon as i get on it, it willstart sputtering and missing as it climbs in rpms.

[Sterlz]

Thermostat?

[drftr68]

new and i installed a new oem water pump

[s13drob]

coolant temp sensor is right by the thermostat. theres 2 plugs. one 2wire sensor and a single wire one. its the 2wire plug.

it tells the ecu to adjust the fuel/air mix to faster warm up the engine. maybe its bad so the ecu thinks its still cold. whats the spark plugs look like?

check it out. The Nismo Shop : West Covina Nissan : Nissan OEM Coolant Temp Sensors - KA/SR (http://www.thenismoshop.com/ikorb.php?func=catalog&category_id=4802&product_id=13030)

[Rabboni]

I dont think its the coolant temp sensor. Ive driven my car without it connected several times, and it didnt cause any drivability problems like that. Plus if it was telling the computer that the ambient temp is cold, the car would run rich, and running rich keeps things cooler. Did you check fuel pressure under load, or just an idle pressure test?

[cotbu]

Have you checked the ecu for code?
When checking timing did you pickup the missing?
You could be running the knock map.
The voltages are important, ie. tps voltage closed and open. cts, mafs etc.
Why did you do a leakdown test? what were the results of the leakdown? Was the head and block decked? That list is just a few steps short of a rebuild.
If you could get some videos up, might be a little more help.

[koukimonster139]

do you have an aftermarket boost controller or afc sounds like fucked up settings on one of the two

[Z33dori]

its out of time......... not timed correctly.

[drftr68]

To answer cotbu ques yes everything was done that you said and i put a straight edge to the block and theres no mpvement of any kind wen i measured the clearance and i had the head resurfaced and it wasnt warped at all. I dont have any aftrmarket controllers of any kind.

[s13drob]

Hmm. If ribboni is right then idk. I would recommend to check it out though if it hasn't been checked/replaced.

[drftr68]

Ok i fixed the big problem after almost 6 months now i have a new one with a new wiring harness. The car ran fine for about 6 miles and i was able to get on it and then i floored it the last time and it started bucking and popping. I tryed changing the maf and it didnt change anything. Any ideas?

[drftr68]

Checked the tps, readings are good. Ecu has no codes, checked all wiring, vaccum lines and ic piping all is good. I pulled the plugs and their good but the car is running rich as hell at idle and it wont stay stable.

[Z33dori]

timing, timing, timing

[cotbu]

^^^I concur!

[drftr68]

Checked the timing its dead on. And the coolant sensor for the ecu has been replaced.

[steve shadows]

what condition is your ignition system?
\
How are the grounds for your ignitor?

Have you tried swapping another KA ECU in and out? just to see ?

I know you could probably get one for super cheap

How about your TPS voltage check? What are the readings closed and open?

Also Fuel Pump ?

What did you set your base timing to?

How about your vacuum system? Did you test it with a smoke machine tester? It's the only really legitimate way to test the sytem

[drftr68]

Yea thats the only way i would test the system is with a white smoke machine and i jave no leaks. Tps read .48 closed and 4.47 open so im good there. Swapped out ecus that gave me no change and the fuel pump is walbro only bout a month and a half old

[undesiredshoe]

What kind of spark plugs? Run some ngk coppers at like .038" or something.

[drftr68]

Hmmm worth a shot wat heat range?

[steve shadows]

And leak down or compression check didnt yeild anything?

[drftr68]

Nope all readings read great so no bent valves

[steve shadows]

Sounds to me like you have some sort of intermittent injector connection cutting out, or fuel pressure under load cutting out.


Also check your intake pipe to the inlet of the turbo. If you are still using the stock or rubber/plastic boot or pipe it must have a giant metal spring inside of it so it doesnt collapse under the sucking pressure of the turbo inlet sucking air in. This will commonly cause this issue when the inlet will suck air through the hose and the hose will actually collapse on itself.

I would also try swapping in a brand new maf sensor