Sr20 hesitation after warming up

[air]

My new sr will boost 8 psi when first cranked up (warm or cold).. but after driving for 5 minutes it starts to shudder when going into boost.

dave drove it and guessed the fpr couldnt handle the walboro 255s pressure and it was fouling the plugs

plugs are perfect.. they look dry and white/tan (didnt check gap but they are brand new bk6e)

wastegate actuator arm doestn move when it does this shudder..

if you keep driving (20 minutes or so) it will get so bad that under 20% throttle and at 5psi vacuum it starts to shudder..

it feels kinda like its getting WAY to much fuel and cutting out. if you stick your hand by the exhaust you can feel big bursts of air coming out in conjunction with the shudders.

BUT!!!!!! LOOK!!! if you turn the car off for 20 seconds and turn it right back on (even after a 20 minute drive) you can go drive again and it will boost perfectly for the first pull. Then the hesitation comes back.

any ideas?

[mistyblue240sx]

hey I've been having the exact same problem with my sr.....the car drives perfectly fine for the first 5 to 10 minutes then all of a sudden it starts to bog down when i step on the gas....and when i park it for a couple of minutes and drive it again the car runs fine for a few minutes again but then it start to hestitate again.....i hope someone has an answer to our problem.. also what i find strange is that sometimes it runs fine for the whole day....but once it starts to hesitate it doesnt go away unless i park it overnight ...

well these are a list of parts i have swapped out so far...

all 4 coilpacksall 4 sparkplugsnew fuel pumpgonna try to change out the maf when i get a chance..

oh yeah and my sr20 is stock no mods with stock ic and recirculated blowoff valve

let me know if you come up with anything

[mistyblue240sx]

oh yeah one more thing i forgot to add....when the hesitation happens i notice that the spooling sounding from my turbo gets really loud .....it kinda sounds like that im boosting like 30psi ....lol....but my car isnt moving and my blow off valve makes a really loud psssssshh sound....but it is recirculated.....

does your sr have the same symptoms AIR let me know

laterz

[air]

BUMP

yeah my car will sometimes drive good for 10 minutes and sometimes only for 1..

when it happens i can turn the car off for 10-20 seconds and start it up again and the problem is GONE.

this happens to the car even when its warm.

i dont notice the turbo spooling more or less when it happens though

my car is completely stock. like factory fresh stock.

i dont know about any other SRs, but my car will hit full boost in neutral.. at about 5500 rpm it hits 8psi or so

the hesitation will happen in neutral when i do this, but only after its been on awhile. if i start it up and rev it it always acts normal.

when i reved it in neutral i watched the wastegate actuator arm, thinking the wastegate could be fluttering causing it to act like it was dying. the arm stayed put so i know the wastegate isnt causing the problem. If it is a possibility though ido have a 12psi wastegate i can swap over to see if it fixes.. but like i said it doestn move even when the car hesistates so i doubt thats the problem.

i checked the spark plugs and they are tanish brown on the tips (which i hear is good) and gapped to .028

the previous owner said he swapped the MAF.. and it kept happening. I have the old maf to swap back on. What are the odds 2 mafs are bad?

I also have a walboro 255 pump.. If anything this should be making the car run rich right? could my FPR be going bad and after a few minutes it lets too much fuel get in under full load and therefore bogs the motor? can you flood a motor under full throttle when its already running?

wtf? SR people i need some input I'm a KA person and out of my league

[air]

bump

im really thinking its the MAF or some bad wiring leading to the MAF.

anyone heard of a MAF issue only occuring once the car is warm/after its been running for awhile?

what about a wiring issue that has occured recently. could my wiring be heating up and not conducting properly?

i replaced the coolant temp sensor yesterday with a spare one out of a KA intake manifold. it didnt help or hurt the issue from what i can tell.

[supreamS14]

Sorry I dont have an answer for you guys but I found that about 80% of sr problems are vac/boost related! Ive had some BAD problems that I thought were no way boost/vac. related but they were just that!

[air]

im starting to think its a bad wastegate..

i changed my fuel filter today to a OEM nissan ka24 one..

also played with the TPS.. its around .45 v at closed position

it still sucks

anyone ever experienced a bad wastegate to know what kind of symptoms it portrays?

[blinker_fluid]

sounds like you guys are describing timing issues, anyone check it with a timing light?

[air]

i dont understand how timing could affect it.. It works great when it is first started, then after a minute it starts ****ing up. this is the part that really makes it hard to troubleshoot..

either way, i will check it with a timing light when i get home. How do i go about doing this since there are no spark plug wires for me to clamp the timing lights sensor to?

[blinker_fluid]

I don't think its anything mechanical b/c it does it on and off, when something is broke it stays that way. If you turn the car off and the problem goes away its one of the electrical componets(90% of the time). When the timing is off it trips the knock sensor and the ecu retards the timing and that makes it hesitate. When I first did my swap I could hear the turbo spool all the way up but the car wouldn't really go anywere. Did the timing and haven't had a problem since.

Use a old KA spark plug wire and put it between the 1st coil pack and the spark plug. heres a link on setting the timing.zerothread?id=59684

[air]

ok i checked my timing its perfect. 15 degrees BTDC at idle.

my cas still has tape or something over the bolts like it hasnt been moved since factory.

[whiplash willy]

Check the gasket between the exhaust mani and your turbo, I had similar problems and that was the issue. The stock gasket sucks and commonly blows.

[supreamS14]

Just 2 make sure because Ive done it, Make sure the car is fully warmed up! I thought it was @ tdc and advanced it but when it warmed up I seen that it advances as it gets fully warmed up

[xpicer]

i also have the same issue with my car and from what i know my car has the timing perfect, I was also thinking that it could be due to a bad bov , has anyone ever experienced how that feels , because my bov before was not that loud but now , forget it it feels as if i had a hks bov, well any way mine is also recirculated and i though that maybe that the bov is leaaking all the time and there fore under preasure its loosing air and making the car run rich

[air]

Timing is good.

I dont know what else to check.. It gets better if you turn off the car and turn it back on, so it has to be something electronic right?

it almost feels like a cracked manifold or a bad mani to turbo gasket or something else boost leak related.. but i pressuretested for boost leaks and got nothing.

could bad mafs wiring be causing this? how do i check if the wiring is good between the maf and the ecu?

[WONit]

Go through and double tripple check all you IC pipes. I had the exact same problem with my Supra. Found that my lower IC pipe was split causing my turbo to overboost which threw a code to the ecu and went into a kinda safe mode i guess you could say. Cut the car off then back on. ran good for a few min,then back to running crappy...hope this helps!

[air]

bump.

i dont have any boost leaks. i pressure tested the piping from the turbo outlet to the intake up to 20 psi and it holds solid.

[fast_s13]

if you have a walbro fuel pump you need an adjustable fuel pressure regulator.and a twin turbo 300zx fuel filter

[mistyblue240sx]

hey sorry for bringing up an old post but I thought this might help some ppl out there with this problem.....

well long story short i had similiar symptons as described by AIR....I just kept on swapping parts here and there thinking there was something wrong..(read first part of thread for full details of what i have done so far to try and solve this problem)

so today i think i've finally solved my problem of the hesitation after warming up...

I did not have my stock boost solenoid or a boost controller hooked up to my wastegate....

i was told that these things werent necessary since i was just running stock boost...but i guess i was wrong.....because b4 i just had a line running directy from the nipple from my cold pipe to the wastegate....thinking that was good enough to control my turbo.....boy i was so wrong......Its like night and day now....i can really feel the boost come on and hold..

i guess after driving for 5 minutes or so the cpu was sensing that the turbo was overboosting or something so it goes into safe mode....thus retarting the timing....and making my car run like crap...

(so make sure you have your boost solenoid hooked up or just run a manual boost controller between your boost signal and your wastegate)

well sorry for the extremely long post....but i've been trying to fix this problem for like half a year...hope this helps others out there with the same problem..

good luck

[seanman]

NO WAY, i had/still kinda have this problem. but i think what it was/is for me is my clutch. my babys in the shop gettin her new spec stage 2 clutch put in so im gunna see if that helps. i also have a nismo adjustable fuel pressure regulator because i have a walbro 255 in my tank. And i've read on a few threads including this one that if you have a walbro then you need an adjustable fpr

[Zilvia33]

i really doubt it was your clutch making it break up.

But yea im having this trouble too.

For me it started about a month ago on a long road trip.

for the 1st 5-10 mins the car runs great perfecto., but after that as soon as it starts to go past 0psi on my boost gauge and starts to stutter and buckle. And if i continue to drive my car like this it gets worse, to the point where if i stop and let the car idle, it starts to drop down to like 400-500rpms and starts backfiring @ IDLE.

[dgracing29]

Yeah im having the exact same problem.

Someone help me figure it out. i have tried everything everyone is saying in here and it isnt working.

The difference is from some of you guys is my SR isnt stock.

Greddy Profec B Boost ControllerGreddy Turbo TimerMR Turbo ManifoldNGK PlugsGreddy VSPL FMICZ32 MAFSGreddy 3" Downpipe.ECU ROM TUNE

I think thats all i have to list to diagnose the problem. but who knows.

the cars maybe be different in horsepower but i have the exact same problems. someone help us out, i know someone has had this problem before.

p.s. my boost controller is not going into warning mode during the problem.

Just the same hesitation and harsh buckleing

[dgracing29]

bump

[dgracing29]

sorry for triple post but it would be awesome if someone here has had the problem and has a solution.

thanks

[240dk]

I just replaced my sr and I have the same problem. It will run fine until it gets hot, then it starts hestitating and sputtering. Iv been reading up on this issue all week, I came across something interesting today. I found a post on another forum that said thier coil pack harness was to close to the head and heater hose, where there is extreme heat, and they simply moved it and no problems. I just went and looked at my harness and it is in the same place his was Im gona try to move it tomorrow and maybe put some heat wrap around the wires. Ill let you know how it goes..If any one else figures it out plz let me know. thanks.

[240dk]

Well that didnt work, so im clueless on this problem.

[dgracing29]

I might give that one a try later today, but if it didnt work for you then i doubt it will for me.

[dgracing29]

Bump. really need some help with this. im surprised no one on here has experienced the problem and actually been able to diagnose it. i am stuck as are some other people with this problem.

[xpicer]

ok so well im still having this problem, well today im going to re check my maf harness with a multitester and check the continuity between the maf plug and the ecm plug , 2 wires should only have continuity with one pin on the ecu plug , but the other 1 is the feed for many sensors.

[240dk]

Ok guys as I stated before I had this same problem, and I have fixed mine. I dont know exactly what it is was, I did lots of stuff to my car and one of them or a combination of them fixed it. So here is what I did:

-New spark plugs, a hotter plug. NGK BKR7E-Completly rewired my maf from the harness to the plug with new wire-Checked and replaced hose clamps on the hose going from the cold pipe to the intake.-Put hose clamps on the vac line between my wastegate and hot pipe, I didnt have any before-Reset my timing

I hope this helps solve your problems. Iv been driving around for two days and has not cut up not once, and one of those times was for over an hour straight. Taking it to drift practice this weekend!!