1JZ hesitation

[Buttocks]

I've got a MA61 powered 1JZ. when accelerating hard in 3rd gear i get some hesitation (mostly in third) I've changed the plugs and gapped to 8mm, i've changed fuel pumps (from standard to a Walbro 255lph) i've installed a S-afc (didn't expect this to do change anything as its a interceptor) changed the intercooler to a aftermarket job, also hit what i pressume is boost cut a couple of times in 3rd and its running no boost controller
Anyone had a similar problem with there 1JZ

PS: when i unhook the plug from the back of the S-afc the car runs like shit, stalls out and chuggs, thought unplugging it wouldn't do anything at all

[sideshow]

best thing to do is remove safc and run stock setup
then run std boost or atleast below 10psi

then see if it still does it again

i have fixed afew 1js with similar probs and most of time its the coils

[BigWorm]

It's a bit hard to run less boost if the boost hasn't been turned up.

Has the S-afc been tuned? It seems wierd that it's affecting things so much. I think you need to look into that.
What size exhaust do you have?

[Buttocks]

The car was doing all this before the Safc went on so its not the Safcs fault, its running stock boost (well the setup anyway) the exhuast has the stock dump but the rest is a 3inch all the way with no cat

[chrisellis]

You can hit boost cut in high rpms with an cat free exhuast. What is this hesitation u talk about though, does it feel like some kind of cut?
Car will run like crap when u disconnect the plug at the back of the afc because u just stoped the air flow sensor input to the ecu.

[chris davey]

I would check the coils for any cracks.

You could gap the plugs down to .7mm.

Check the plugs on the coils also.

Any check engine light to check error codes?

[Buttocks]

The hesitation is a small loss in power then it regains it then losses it again, boost seems steady. Its not a cut out.

[chris davey]

so like a miss?

Or like a lack of fuel?

[Buttocks]

But mostly only on 3rd gear, i'll put a pressure gauge on the fuel line see what happens

[BigWorm]

I've seen old/blocked fuel filters cause all sorts of problems, might be worth checking (although not the easiest to get to, & not easy to find a replacement, at least if you're in a hurry).
As Chris says check coils & plugs, maybe regap the plugs.
Mine did something similar recently, but I put it down to running not so sensible boost levels at the time.

[e30-323ti]

The hesitation is a small loss in power then it regains it then losses it again, boost seems steady. Its not a cut out.

Sorry to bring old threads back from the dead, but.

Just had the first circuit outting with the 1JZ, and seemed to have a similar issue.

At first I though it might have been fuel surging, so went and topped it up but no joy.

The miss/hessitation/cut-out seemed to occur only after 6laps or so.
So I though it may be the coils getting a bit hot??
The car will run fine after a cool down and will be sweet for another 6-8laps before it happens again, that doesn't sound like a coil issue as I imagine if it has got a crack etc... it would start to do it all the time when under load??

I did notice on the boost gauge some peaks at 1.11bar (running everything stock), is it possible the WG actuators are getting hot/sticky and then boost cutting??

Bit hard to replicate the problem on the street with out killing someone or getting arrested.

Oh, and the power steering wasn't very happy, would start making odd sounds (about the same time), took the lid off and it was smoking away, bit of a worry, cooler time I think.

[stradlater]

coils can tend to play funny buggers when they get hot, so don't rule that out.

[e30-323ti]

Well I whipped out the coils, 5 of them have cracks under the blue rubber isolation boots, only 1 extends beyond the rubber boot (possible cause of problem?), 2 are reasonable (down to the rubber seating groove) and 2 I'd call minor (5-7mm from the end).

The engine will run perfectly fine on the street, with a decent hard drive, no miss under load etc...
Only happened at the track after 6-8 laps of giving pure assholes

Peoples thoughts??

I have a spare set so I'll find them anyway and have a look at them.

It will be a major pain if I have to wait till track days to do the fault finding

[EldarO]

my coils werent that bad visibly, but were the sole cause for my car running like old dried up dog shit.

if they look sus, they are, either wrap them in sparkeys tape (temp!) or get a better conditioned/new set.

Eldar.O.

[Endless]

Try replacing the one with the crack beyond the rubber boot for starters, or if you don't want to screw around just replace all of the ones with visible cracks then you can rule coilpacks out all together really... although it's strange how only appears after a few laps?