Hesitation, or misfire, WOT top of 3rd and 4th gear...?!

[FriedEGs]

Car: 1995 S14Engine: R33 RB25DET S1

Hi, guys.. I'm back again!! I just dropped in my motor and she runs well. Except:

At WOT near the top of 3rd and 4th gear the car misfire's and cuts out abruptly. If I let off the gas, and shift up the car drives fine. However, if I drive at 60% throttle up to the top of 3rd it will NOT cut out.. It's only happening under WOT. It feels like the fuel cutoff at redline, but this is happening around 5000 rpm. Plus, my car has NO problem getting up to redline (about 7k) in 2nd gear and with no hesitation at wot. (again, the problem is happening around 5000rpm during 3rd and 4th gear pulls under wot, only!

When I got on the freeway at wot in 3rd i noticed a puff of smoke after it cut out which I'm assuming is all the unburned fuel.. So, this leads me to believe it's a misfire and not a fuel problem. But the fact that this happens at higher rpm's under WOT leads me to believe that I might be running lean up top. The CAS is in it's stock location, lined up where the original tape from teh factory was placed....Motor is stock, with ngk's gapped at .030. I will test timing tomorrow but, for now, I just want some thoughts on what my problem is.

Any idea's?
Modified by FriedEGs at 12:55 AM 8/22/2007

[gawdzilla]

what kind of gas are you using?

its probably either blowing out spark or pulling timing cuz its seeing detonation.

have you tried putting in some higher octane gas?

[FriedEGs]

good question.. the car had some 87 in it from befroe the swap.. prolly around 1/4 tank... I added about 4 gallons of premium on top of that before I fired it up..

Maybe, it's time to fill it up completely!!

Shell 93 (my fav) or Sunoco 94?

[mello88]

I bet you have at least one bad coilpack(s). My friend's RB25 does the exact same thing, it will drive under light load just fine, but whenever you go WOT it sputters like you've hit a fuel cut regardless of the RPM. Another symptom would be hearing it miss occasionally at idle, and if you stand in front with the hood up, you should hear a loud CLICK (sounds similar to a relay clicking on) from one of the coilpacks when it misses. If this is happening, then one of your packs is on it's way out. Unplug each coilpack individually for 30 seconds or so, if the clicking/miss goes away then you've found the culprit... We did this on his the other day, he replaced one pack, which pretty much solved the WOT stutter. Last night he was complaining about a 5000+ stutter, we popped the hood and did the above diagnosis and found another bad pack! RB25 Series 2 fwiw.

Could be a variety of other things too, but your symptoms sound identical.. GL

BTW, you already know this, but you should only be running 91+ octane on your RB!

[Carl H]

lol, proly boost cut. check for leaks.

[FriedEGs]

I bet you have at least one bad coilpack(s). My friend's RB25 does the exact same thing, it will drive under light load just fine, but whenever you go WOT it sputters like you've hit a fuel cut regardless of the RPM. Another symptom would be hearing it miss occasionally at idle, and if you stand in front with the hood up, you should hear a loud CLICK (sounds similar to a relay clicking on) from one of the coilpacks when it misses. If this is happening, then one of your packs is on it's way out. Unplug each coilpack individually for 30 seconds or so, if the clicking/miss goes away then you've found the culprit... We did this on his the other day, he replaced one pack, which pretty much solved the WOT stutter. Last night he was complaining about a 5000+ stutter, we popped the hood and did the above diagnosis and found another bad pack! RB25 Series 2 fwiw.

Could be a variety of other things too, but your symptoms sound identical.. GL

BTW, you already know this, but you should only be running 91+ octane on your RB!

wow... everything you said matches my problems... I noticed the loud ticking, almost like a valve tick or a relay switching constantly, but i just figured that it was just the characteristics of the injectors... I also just found out tonight, that the car will stutter at any range, regardless of rpm.. Before, i just kept ripping through teh gears sequentially.... this time I pulled in 3rd gear at 3000 rpm and it sputtered much sooner... (around 4500)

Thanks for teh info!!! I will def test the coilpacks tomarrow.

[blurrbosi]

Def. coilpacks.

[TougeR32]

hi guys. new to this forum but on gtrcanada, NWN and a few others.

I have a 1990 Skyline GTST-T and i am having this same problem. First thought it was bad gas,:tried octane booster, then thought MAF: replaced, plugs:replaced.

I'm stil having hesitation under WOT but can accelerate slowly all the way up to 7000rpm.

Did the coilpack fix work for the above poster?

[mello88]

You probably have a bad pack somewhere too. Sometimes they are hard to diagnose, especially if you have a stable idle.

Here's another coilpack story...

Over the weekend I had an RB20-S13 friend come over complaining about a huge power loss and a deeper idle tone... Obviously missing on one of the cylinders. We pulled each coilpack connector plug at idle and listened for an RPM drop. #2 made no change in the idle... My RB25-S13 friend happened to have a late model RB20 coilpack he gave the dude, which solved the problem.

Sometimes you'll get a decent idle, but if you WOT it will stumble/miss. This is from a pack thats not 100% dead, it only gives out when it's hot and/or under a lot of load (like WOT). It seems that with these half-dead coilpacks you can apply <5% throttle and rev the engine to 3 or 4000 without missing. But the instant you go more than 5% or so throttle it will stumble and lose a ton of power....

[TougeR32]

that sounds exactly like whats happening to me. i can still accelerate quite quickly but WOT everything goes for sh*t.

Thanks, I will be pulling the packs this evening to check em out. will update.

[FriedEGs]

i haven't diagnosed teh coilpacks yet.. My plan is to test for boost leaks and get this boost gauge hooked up.. If I don't have any leaks, then it's back to the coilpacks...

btw, what's the correct way to test each of the coilpacks? The FSM says to test the resistance between terminals 1~2 but the pic shows the tester measuring from underneath, where the spring is located. The reading I get is completely different from the 0.6~0.9 reading i'm supposed to get. (somewhere around 1.4, 1.8, I think..)

Again, is there another way I should be testing these?

[matafied]

i dont think your gonna find the bad one by ohming it out, b\c it is still working correctly its just arching. i have had this happen to every rb i have worked on or came in contact with. i would take them off and wrap them in electric tape around the base of the coil, right where the plug boot and coil come together. reinstall and do your wot test this worked on mine for 6 mounths before i converted my ignition to Chevy

[FriedEGs]

Matified, thanks for the tips.. I'll give that a try..

I'm basically gonna save up to get a replacement coil system.. such as teh GM coils, or splitfire.. seems to be the best option for our motors...

[FriedEGs]

update: I just installed my boost gauge and learned a few things. My boost gauge is reading up towards 14-16 lbs. of boost, once i get near the top of 3rd or 4th gear. (Stock turbo and wastegate, no mbc, everything stock) Obviously, it seems like the wastegate is not doing it's job and NOT opening up at 7lbs.

Is it save to say that teh stock spring might be bad?

[Shocker]

sounds to me like you dont have the wastegate hooked up to a proper vac line. Thus overboosting, thus the cutting out/hesitation. Your stock ECU might be sensing detonation.....

Insure there are no rips or tears in your vac line to the wastegate. With no boost solinoid it should be making only about 6-7 psi with FMIC and exhaust. With the solinoid it will most likely creep to about 8 or 9 psi.

The actuator on the wastegate isnt bent or anything right?

[FriedEGs]

the actuator looks okay...

The solenoid has 2 hoses from it. The upper one leads down to the hard black pipe from the recirculating valve. The lower hose on the solenoid leads to a T-junction that splits between the cold pipe and the wastegate.

my engine is bone stock. Stock s14 exhaust, sidemount intercooler...etc.

[Shocker]

the actuator looks okay...

The solenoid has 2 hoses from it. The upper one leads down to the hard black pipe from the recirculating valve. The lower hose on the solenoid leads to a T-junction that splits between the cold pipe and the wastegate.

my engine is bone stock. Stock s14 exhaust, sidemount intercooler...etc.

Try plugging the top hose that goes to the BOV, and remove the T, so the wastegate just gets the signal from the cold pipe. Test drive and check boost. With the SMIC it should be about 5 psi.

[FriedEGs]

Try plugging the top hose that goes to the BOV, and remove the T, so the wastegate just gets the signal from the cold pipe. Test drive and check boost. With the SMIC it should be about 5 psi.

Basicallyl, this removes teh solenoid? I'll give that a try.

[Shocker]

Basicallyl, this removes teh solenoid? I'll give that a try.

correct try that and see what happens!

[FriedEGs]

No dice... i think it's plumbed wrong... shouldn't the cold pipe go straight to the solenoid and not a t-fitting? Then from the solenoid to the wastegate, that way teh ecu can override the boost a little?

I think I figured out what's wrong. By eliminating the solenoid through the test you suggested pretty much narrows the excessive boost down to the spring in the wastegate actuator. For some reason it isn't opening at the correct 7lbs. to open the gate. I guess the spring is bad.
Modified by FriedEGs at 12:58 AM 9/8/2007

[tiger]

hello I know this is in the RB20 forum but im having this same exact problem with my SR20, the engine has about 1,600miles on it. It loves to sputter and sound like a machine gun when i go WOT, I have noticed that this only occurs when the engine has fully warmed up. so it's probably one or more of my coil packs? What does using the electrical tape do, make the boot fit more snug?