Hesitation/stutter As Soon As I Touch The Throttle

[taynewguy]

Just for reference - the car is a 32 GTR, RB26 running PFC djetro

I'm pretty sure I know what the problem is (or do I?). I just wanna know if I can correct it easily.

So the story goes.......car runs perfectly, then after I changed to a "bling" clear timing belt cover > it stutters as soon as I hit the throttle - and then it revs as normal after that. So I assume I have done something to the CAS - despite being pretty careful putting it back on the way it came off

So am I right in assuming this is the problem and if so how can I correct it?

Is it something I can monitor on the hand controller and then adjust?

Yes I am a goose. Now that we are over that, can you help

Cheers.

[tmc_2]

Just for reference - the car is a 32 GTR, RB26 running PFC djetro

I'm pretty sure I know what the problem is (or do I?). I just wanna know if I can correct it easily.

So the story goes.......car runs perfectly, then after I changed to a "bling" clear timing belt cover > it stutters as soon as I hit the throttle - and then it revs as normal after that. So I assume I have done something to the CAS - despite being pretty careful putting it back on the way it came off

So am I right in assuming this is the problem and if so how can I correct it?

Is it something I can monitor on the hand controller and then adjust?

Yes I am a goose. Now that we are over that, can you help

Cheers.

Id be guessing CAS as thats really all u could have touched? is the base timing still corect?

You may need to test the CAS.

Unless somethig else went bung and it was just a coincidence.

[ookami]

I know a guy whos car did this before. His problems were resolved when he upgrade to forged pistons and got the whole engine balanced and rebuilt. I know thats not much help.

[tmc_2]

If ur CAS is not dying and ur timming is correct, id take a stap and say the airflow sensor is stil ok but not reading correct voltages - prob dying. ????

Take it to a reputable workshop who works on a lot of skylines.

[taynewguy]

tmc_2: I am running MAP sensors that are like 3 months old at best. Is it possible that they would start to die this quickly?

Any other suggestions?

[tmc_2]

tmc_2: I am running MAP sensors that are like 3 months old at best. Is it possible that they would start to die this quickly?

Any other suggestions?

Lol the first post i knew u had a Map sensor but then foget :S , yeah checking airflow sensor for u is usless.

Has ot be some sort of CAS issue. What are all the things u had to take or or play wiht to install ur clear cover besides ur CAS?

[taynewguy]

yep just the cas. would have to be a real coincidence if it is something else.

[mad082]

it is probably your TPS (throttle position sensor) is slightly out of place. try adjusting it either way and see what that does. you should only need to go a fraction of a turn.

[Al]

I run a Wolf3d, also MAP sensor.

This is common and is easily fixed by the tunner. With the wolf there is an area of the map that compinsates for the off idle throttle response. If you have touched the CAS then it is a good idea to get your mechanic/tunner to check the timming, if the stutter is still there after they adjusted the CAS, then the tunner should be able to easily tune it out.

Just to clarify the problem:

Have the car in nuetral, then stab the throttle (only 1/2 throttle required), as the engine comes off idle there is a slight stutter.

[taynewguy]

Yep that's exactly the problem - I say I have put the timing out due to moving the cas. Need a timing light to bring it back to the original position correct? most likely 20 deg at idle.

[RANDY]

Timing light, yes.

I think the R33 GTST's (like mine) are 15BTDC, and you could be right with 20 for your GTR. Check manual and then check timing. Rule that out first. =-]

[Al]

Manual is useless.

If the dejetro is anything like the wolf, the ecu dictates the position of the CAS. Not too sure how it works but i know my mechanic fiddles with the CAS , using a timing light, after the car is idling and b4 the tune.

[taynewguy]

Hmm - you may have a point Al. I have set it back to 20 deg using a timing light and it is better but hasn't solved the problem completely. It was sitting way off - something like ~35 deg. Doesn't take alot of cas movement to be out 10-15 deg obviously.

At least the massive numbers on the knock sensor are gone though. When it was running like sh!t, I saw numbers up to 100 and this is while driving like a grandma. Knock is back to normal (like 10-20max) after testing it out today, giving it a little bit of stick.

Still not not happy with it. Although the remaining doubt may just be me being overly cautious and looking too hard for a problem.

[Al]

Manual is useless.

If the dejetro is anything like the wolf, the ecu dictates the position of the CAS. Not too sure how it works but i know my mechanic fiddles with the CAS , using a timing light, after the car is idling and b4 the tune.

Forgot to mention, the adjustment of the CAS is for th "base" timing, the timing is then adjusted/controlled via the tunning of the ecu.

[Cubes]

taynewguy,

Did you resolve the problem? Was it worse when the car was cold?

[taynewguy]

Yeah I adjusted the timing back to 20deg and that all but eliminated the stutter.

Put it up on the dyno and checked everything to be sure. The tune is fine and still makes ~250rwkw consistently without any knock etc

But to answer your question - Yes does still happen when the car is cold. Once it's warm the stutter is gone - not ideal but I can live with it for now.

[Cubes]

Thanks....

Curious.. Are you still running the std throttle body/cross over rubber joiner and IC pipe joiners?

I've just discovered my comp cover to IC pipe joiner is leaking slightly and it displayed the same characteristics as your problem. Pain in the arse when cold but ok when warm.

[taynewguy]

All intercooler pipes changed to hard pipes. But I didn't change for that reason - still had all the symptoms with the stock piping.

[Adriano]

Thanks....

Curious.. Are you still running the std throttle body/cross over rubber joiner and IC pipe joiners?

I've just discovered my comp cover to IC pipe joiner is leaking slightly and it displayed the same characteristics as your problem. Pain in the arse when cold but ok when warm.

Yeah, but he's running a djetro, so a leak in the piping will not effect the running like with an AFM

[Aif]

hmmm, i had issues with my idle when i first got it, changed my oil and the problem seemed to go away but is now back again, im not sure if its the same problem or something similar. My car is as follows:

S1 R33 GTST

K&N panel filter

FMIC

Cat back exhaust

button clutch

i've got NGK irridium plugs, and have just done the filter and oil change (motul 8100 5w-40w), last week i changed my o2 sensor and now when the motor is cold it idles sweet, around 650rpm, but when its at op temp the idle drops to 500 then 350ish then goes between them in 4sec intervales. i touch the throttle when taking off at the lights and it stalls 2 out of 3 times, i pullup and BAM stall, , , WTF ? ! ?

im gonna clean my AAC and my AFM, i havent had it tuned since i got it (1 yr ago), so it could be that.

any ideas,

Aif