SR20DET cutting out at boost, possibly bad MAF? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

igreek · 11-07-2011, 04:40 PM

I've finished my S13 SR20 swap and I'm having problems. As I described in this thread, it breaks up when it gets into boost. Bought new plugs, gapped them at 0.28, adjusted TPS, did a boost leak test and didn't find anything. Plugged out coilpacks, one by one and engine bogs a bit with each one. Plugged out injectors one by one and does the same thing. So, those seem to be fine. Otherwise, double checked everything else.

What is making me think that it's the MAF is how it reacts when I mess with it. If I unplug it, it'll bog down for a second but then build up and have a better idle then when it's plugged in; plugged in it revs, but cuts out when it hits boost, and plugged out, it hits that normal no MAF wall. Also, when it's plugged in vacuum is at 18-19 and 22-23 when plugged out. Doesn't something seem strange there? Decided to pull ECU codes and I'm getting 12; which I'm reading is the MAF. Does all this point to a bad or going bad maf?

It works fine WOT, until it hits boost and then everything cuts out. Could it be that the MAF is going bad and it messes up during boost? I'm pretty much stuck at this point. Do you guys think it could be the MAF?

harrypotter · 11-07-2011, 05:02 PM

What spark plugs?

igreek · 11-07-2011, 05:07 PM

NGK bkr6e-11s. I thought it was spark blowout at first, but I'm really doubting it at this point.

jr_ss · 11-07-2011, 05:42 PM

Swap your MAF with someone that has a known good one. Trial and error. You could also pull voltage on your MAF to see if it's within range.

harrypotter · 11-07-2011, 10:04 PM

Maybe igniter chip thingy

cotbu · 11-12-2011, 03:05 AM

A lil late but...
Pulling the mafs plug while running will cause a code. You have to clear codes do a pull then check for codes.
This doesn't seem like the mafs based on that, but rather a fuel problem and or timing.
Check timing and fuel pressure, also do a power balance injector, and coil pack test.
These power balance tests are at idle, you should pass both.

I'm not saying it's not mafs related as it could very well be, a wiring problem.
If you're losing a connection during boost or mafs fails during boost, checking codes at that point will indicate a bad mafs and or wiring.

just another> s13 · 11-25-2011, 03:35 AM

Quote:

Originally Posted by igreek

NGK bkr6e-11s. I thought it was spark blowout at first, but I'm really doubting it at this point.

I'd put ngk bkr7e/4644 plugs in it. My car didn't like the 6's, guess its to hot of a plug. My car would break up coming into boost with them so I switched to the 7's and it cleared up, not sure if this will work in your case, you might be having other problems.

anarchyperf · 11-25-2011, 03:56 AM

Your running a S15 turbo? What are you tuning with and what fuel pump do you have?

Kingtal0n · 11-25-2011, 04:18 PM

Do a boost leak check

rcdad123 · 11-25-2011, 11:28 PM

if the plugs are fouled, you could be experiencing ignition misfire. i would definitely go with a colder set of plugs. i like the NGK BKR7E gapped at .015. yes .015. use a feeler gauge to measure the gap. also check your engine harness grounds. a loose ground can also cause the same problem, happened to me. good luck

11-07-2011, 04:40 PM	#1
igreek Leaky Injector Join Date: Sep 2009 Location: Georgia Age: 28 Posts: 84 Trader Rating: (5) Feedback Score: 5 reviews	SR20DET cutting out at boost, possibly bad MAF? I've finished my S13 SR20 swap and I'm having problems. As I described in this thread, it breaks up when it gets into boost. Bought new plugs, gapped them at 0.28, adjusted TPS, did a boost leak test and didn't find anything. Plugged out coilpacks, one by one and engine bogs a bit with each one. Plugged out injectors one by one and does the same thing. So, those seem to be fine. Otherwise, double checked everything else. What is making me think that it's the MAF is how it reacts when I mess with it. If I unplug it, it'll bog down for a second but then build up and have a better idle then when it's plugged in; plugged in it revs, but cuts out when it hits boost, and plugged out, it hits that normal no MAF wall. Also, when it's plugged in vacuum is at 18-19 and 22-23 when plugged out. Doesn't something seem strange there? Decided to pull ECU codes and I'm getting 12; which I'm reading is the MAF. Does all this point to a bad or going bad maf? It works fine WOT, until it hits boost and then everything cuts out. Could it be that the MAF is going bad and it messes up during boost? I'm pretty much stuck at this point. Do you guys think it could be the MAF?

11-07-2011, 05:02 PM	#2
harrypotter Zilvia Junkie Join Date: Jun 2010 Location: Crestview FL Posts: 574 Trader Rating: (19) Feedback Score: 19 reviews	What spark plugs? __________________

11-07-2011, 05:42 PM	#4
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,056 Trader Rating: (34) Feedback Score: 34 reviews	Swap your MAF with someone that has a known good one. Trial and error. You could also pull voltage on your MAF to see if it's within range. __________________ My SR20VET

11-07-2011, 10:04 PM	#5
harrypotter Zilvia Junkie Join Date: Jun 2010 Location: Crestview FL Posts: 574 Trader Rating: (19) Feedback Score: 19 reviews	Maybe igniter chip thingy __________________

11-12-2011, 03:05 AM	#6
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 47 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	A lil late but... Pulling the mafs plug while running will cause a code. You have to clear codes do a pull then check for codes. This doesn't seem like the mafs based on that, but rather a fuel problem and or timing. Check timing and fuel pressure, also do a power balance injector, and coil pack test. These power balance tests are at idle, you should pass both. I'm not saying it's not mafs related as it could very well be, a wiring problem. If you're losing a connection during boost or mafs fails during boost, checking codes at that point will indicate a bad mafs and or wiring. __________________ LoverTechnologies "Half Broken Things!"

11-07-2011, 05:07 PM	#3
igreek Leaky Injector Join Date: Sep 2009 Location: Georgia Age: 28 Posts: 84 Trader Rating: (5) Feedback Score: 5 reviews	NGK bkr6e-11s. I thought it was spark blowout at first, but I'm really doubting it at this point.

11-25-2011, 03:56 AM	#8
anarchyperf Zilvia Member Join Date: Dec 2010 Location: Nazareth, Pa Age: 36 Posts: 194 Trader Rating: (1) Feedback Score: 1 reviews	Your running a S15 turbo? What are you tuning with and what fuel pump do you have? __________________ www.anarchyperformance.com - Your source for 240sx Performance! https://www.facebook.com/anarchyperformance - Like us on facebook Email: [email protected]

11-25-2011, 04:18 PM	#9
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	Do a boost leak check

11-25-2011, 11:28 PM	#10
rcdad123 Zilvia Addict Join Date: Jul 2011 Location: san diego Posts: 639 Trader Rating: (0) Feedback Score: 0 reviews	if the plugs are fouled, you could be experiencing ignition misfire. i would definitely go with a colder set of plugs. i like the NGK BKR7E gapped at .015. yes .015. use a feeler gauge to measure the gap. also check your engine harness grounds. a loose ground can also cause the same problem, happened to me. good luck

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