weird boost problem - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

slow240 · 09-03-2007, 08:52 AM

hello,
after running hard at an extended period in the rain, i suddenly experienced some sort of boost limiter. i usually boost to 15psi, but for some reason when im about to reach max boost the engine hits some sort of limiter. it sounds just like the bee-r rev-limiter only difference it just limits my boost. driving at partial throttle or anything except wot i can reach 7k without any sign of anything wrong. its just the boost gets limited at wot.

has anyone experienced this? any info is appreciated.

i have an s13 redtop, z32maf, 550cc injectors, emanage blue.

guitaraholic · 09-03-2007, 11:37 AM

damn, you have what sounds like the exact same problem I have. If you find anything out let me know, I'll do the same.

Gjohnson7 · 09-03-2007, 12:04 PM

Stock T25???????? Blov??????

slow240 · 09-04-2007, 05:11 AM

@gutaraholic, sucks to not boost to the usual levels huh. i hope someone can help us with this.

i have a gtir t28 and ssqv vta, but i was boosting 16psi fine for weeks with no problems at all. and from my experience if ever i was leaking from the vta ssqv it wouldnt sound or have symptoms as i have. or is it the bov??

slow240 · 09-04-2007, 07:03 AM

tried the car out again tonight. surprisingly the problem is gone. i guess driving on the highway at 150kph cruising speed in the pouring rain will cause some water droplets to slip through the filter and pass by the maf. my intake is placed right behind one of the airdams on my bumper.

i hope its just that...

guitaraholic, try your car out after a few days, maybe the water thats causing the misfire is all dried up by then.

skylindrftr · 09-05-2007, 03:05 AM

if you have a boost leak, i believe there is a sticky or faq on how to make your own home made boost leak tester...

guitaraholic · 09-05-2007, 10:16 AM

Thanks for the tip slow,, actually found my problem might be elsewhere though. I moved around my Boost Gauge to share the same vacuum line as the BOV instead of the WGA, and now I am getting a reading of 15psi and more (if I let it), so its stuttering because its boosting too high and either blowing out the spark or detonating, either way, I am keeping off the pedal for now. I have the WGA hooked straight off one of the vacuum line nipples on the manifold, still getting crazy boost. Anyone have any suggestions? I do plan on pressurizing the WGA to see if it functions like normal tonight.

Koopa Troopa · 09-05-2007, 10:49 AM

Water getting into your intake is just water injection.. It'll turn the drops into vapor and just super cool your fuel/air mixture.. Don't worry about water droplets getting into your shit..

slow240 · 09-06-2007, 12:35 AM

guitar, i think the best place to tap the boost gauge is as near as possible to the intake manifold. yeah sounds like you were overboosting, good thing your ecu cuts you off before you did damage.

koopa, yeah.. thats good after the maf. but i dont think water droplets on the hot wire of the maf is good. it could cause a spike in the maf voltage because of the sudden drop in temperature. maybe thats why the ecu suddenly limit the boost.

09-03-2007, 08:52 AM	#1
slow240 Join Date: May 2005 Location: philippines Posts: 17 Trader Rating: (0) Feedback Score: 0 reviews	weird boost problem hello, after running hard at an extended period in the rain, i suddenly experienced some sort of boost limiter. i usually boost to 15psi, but for some reason when im about to reach max boost the engine hits some sort of limiter. it sounds just like the bee-r rev-limiter only difference it just limits my boost. driving at partial throttle or anything except wot i can reach 7k without any sign of anything wrong. its just the boost gets limited at wot. has anyone experienced this? any info is appreciated. i have an s13 redtop, z32maf, 550cc injectors, emanage blue.

09-03-2007, 12:04 PM	#3
Gjohnson7 Zilvia Addict Join Date: Mar 2004 Location: Broken Arrow, OK Age: 44 Posts: 980 Trader Rating: (7) Feedback Score: 7 reviews	Stock T25???????? Blov?????? __________________ LSX Kouki Project, swap completed in Dec 09

09-05-2007, 10:49 AM	#8
Koopa Troopa Post Whore! Join Date: Sep 2006 Location: 北谷著, 沖縄県、日本 Posts: 2,565 Trader Rating: (3) Feedback Score: 3 reviews	Water getting into your intake is just water injection.. It'll turn the drops into vapor and just super cool your fuel/air mixture.. Don't worry about water droplets getting into your shit.. __________________ Buy my Stillway shifter!

09-03-2007, 11:37 AM	#2
guitaraholic Zilvia Junkie Join Date: Jun 2006 Location: Spanish Fort, AL Posts: 430 Trader Rating: (0) Feedback Score: 0 reviews	damn, you have what sounds like the exact same problem I have. If you find anything out let me know, I'll do the same.

09-04-2007, 05:11 AM	#4
slow240 Join Date: May 2005 Location: philippines Posts: 17 Trader Rating: (0) Feedback Score: 0 reviews	@gutaraholic, sucks to not boost to the usual levels huh. i hope someone can help us with this. i have a gtir t28 and ssqv vta, but i was boosting 16psi fine for weeks with no problems at all. and from my experience if ever i was leaking from the vta ssqv it wouldnt sound or have symptoms as i have. or is it the bov??

09-04-2007, 07:03 AM	#5
slow240 Join Date: May 2005 Location: philippines Posts: 17 Trader Rating: (0) Feedback Score: 0 reviews	tried the car out again tonight. surprisingly the problem is gone. i guess driving on the highway at 150kph cruising speed in the pouring rain will cause some water droplets to slip through the filter and pass by the maf. my intake is placed right behind one of the airdams on my bumper. i hope its just that... guitaraholic, try your car out after a few days, maybe the water thats causing the misfire is all dried up by then.

09-05-2007, 03:05 AM	#6
skylindrftr Zilvia FREAK! Join Date: Apr 2007 Location: Metro Detroit Age: 36 Posts: 1,099 Trader Rating: (26) Feedback Score: 26 reviews	if you have a boost leak, i believe there is a sticky or faq on how to make your own home made boost leak tester...

09-05-2007, 10:16 AM	#7
guitaraholic Zilvia Junkie Join Date: Jun 2006 Location: Spanish Fort, AL Posts: 430 Trader Rating: (0) Feedback Score: 0 reviews	Thanks for the tip slow,, actually found my problem might be elsewhere though. I moved around my Boost Gauge to share the same vacuum line as the BOV instead of the WGA, and now I am getting a reading of 15psi and more (if I let it), so its stuttering because its boosting too high and either blowing out the spark or detonating, either way, I am keeping off the pedal for now. I have the WGA hooked straight off one of the vacuum line nipples on the manifold, still getting crazy boost. Anyone have any suggestions? I do plan on pressurizing the WGA to see if it functions like normal tonight.

09-06-2007, 12:35 AM	#9
slow240 Join Date: May 2005 Location: philippines Posts: 17 Trader Rating: (0) Feedback Score: 0 reviews	guitar, i think the best place to tap the boost gauge is as near as possible to the intake manifold. yeah sounds like you were overboosting, good thing your ecu cuts you off before you did damage. koopa, yeah.. thats good after the maf. but i dont think water droplets on the hot wire of the maf is good. it could cause a spike in the maf voltage because of the sudden drop in temperature. maybe thats why the ecu suddenly limit the boost.