SR20DET Issue

[twofortysex]

Hey Guys,

New Here been searching for a while to find out what to do with my SR20DET that is acting funny. Any and all help is appreciated.

1992 240sx S13 with SR20DET w/ FMIC , HKS BOV, 255LPH Fuel Pump, Greddy Boost Controller and Turbo Timer. That's all I know of engine mods.

It's cold here, so I had to boost my car. Seems to have started all this, after that I took it for a drive, it was acting up but nothing I thought was bad, I was entering a highway and giving it about half throttle and boost was spooling and I let off the throttle, the engine backfired louder then it ever has. I kept driving and it wouldnt accelerate, If i put clutch in it was stall then fire back up rpm gauge was bouncing around all over the place. Got it home, has an idle that fluctuates and cant rev it with no load passed 3k sometimes only 2k.

Symptoms
-fluctuating idle
-spitting fuel and black smoke out the tail pipe
-no boost

What I have done so far;
-vacuum leak test with brake cleaner
-check all lines for crack etc
-unplugged MAF sensor to see if it made a difference it didnt
-Unplugged O2 Sensor to see if it made a difference it didnt
-MAF Looks clean
-Intake Piping all sealed and looks like no leaks
-Bypassed turbo with MAF and the car ran great!

It just isnt making sense to me,

Any help, where to start, what to replace what to look for would be greatly appreciated as maybe I can drive it once more before the snow falls

Cheers Everyone!

[2_Liter_Turbo]

Sounds like a bad MAF to me. Typically, you can't free rev much if the MAF is bad. Also, the engine is obviously having trouble with air/fuel ratios, and even with a bad o2, you can still free rev it up higher than what you're getting. Also check your ecu coolant temp sensor. When those go bad, it can cause the car to run really poor.

[twofortysex]

Sounds like a bad MAF to me. Typically, you can't free rev much if the MAF is bad. Also, the engine is obviously having trouble with air/fuel ratios, and even with a bad o2, you can still free rev it up higher than what you're getting. Also check your ecu coolant temp sensor. When those go bad, it can cause the car to run really poor.

I will replace the MAF, seems like more than half the problems that arise from an SR20 is because of that thing. What do you look for to check the ECU Coolant Temp Sensor?

thank you

[2_Liter_Turbo]

Sounds like a bad MAF to me. Typically, you can't free rev much if the MAF is bad. Also, the engine is obviously having trouble with air/fuel ratios, and even with a bad o2, you can still free rev it up higher than what you're getting. Also check your ecu coolant temp sensor. When those go bad, it can cause the car to run really poor.

I will replace the MAF, seems like more than half the problems that arise from an SR20 is because of that thing. What do you look for to check the ECU Coolant Temp Sensor?

thank you

To check the continuity when cold vs hot. If you look at practically any Nissan service manual, it will explain which pins. I honestly would have to look as well. If you don't have one, you can look for a 240SX or S14 SR20 FSM via the link in my signature.

[twofortysex]

I got the manual, I'll take a look tonight at what you have advised. Update tomorrow.

[buckwild240]

check the maf by using a dmm to see what kind of voltage you are getting out of the maf, also have you checked for a boost leak? Sounds pretty likely.

[buckwild240]

really you need to make a boost leak tester to see if its leaking.

[twofortysex]

turbo is blown. Thanks everyone for helping New and Bigger turbo time.