R33 s1.5 missing at 5,000rpm onwards.

[Killer33gtst]

Hi all, l didn’t want to put anything on the forum, however l am unable to work this out and am extremely frustrated, hopefully someone can give me some good direction.

the car blew a cooler hose, since then it has developed a miss at approx 5,000 rpm upwards.

the strange thing is that it now fowls only plug number 6.

all others are fine.

changed coil packs around and same issue.

new coil loom, same. Car runs, idles and drives fine, as long as you don’t go past 5.000 rpm.

running apexi fc. Has had tune. Developed this after the tune. However was running amazing until the hose blew off. 
Boost is a conservative 15.

if anyone can give me some direction it would be greatly appreciated.

regards.

 

 

 

[Ben C34]

Sounds like it had a boost leak ( the cooler hose about to pop off) and was tuned to suit that. Now boost leaknis gone tune is wrong.

 

Did you pressure test the cooler pipes before the tune?

 

[Killer33gtst]

Hi Ben,

hoses were all good at time of tune. 
All new and tight.

thanks for the thought.

 

[Chopstick Tuner]

I still wouldn't rule it out. It raises the question of why the cooler hose blew off all of a sudden, usually means it's been loose for a while. 

[Killer33gtst]

Hi,  the only thing l am confused with is at to why only number 6 is fowling???

thanks.

[joshuaho96]

On 5/27/2022 at 6:43 PM, Killer33gtst said:

Hi,  the only thing l am confused with is at to why only number 6 is fowling???

thanks.

Do a compression test then check the injector flow. If there's per-cylinder fuel trims make sure it's reasonable too.

[Killer33gtst]

Hi, have replaced no 6 injector.

compression was around 128 per cylinder.

thanks.

 

[Ben C34]

On 5/28/2022 at 2:12 PM, Killer33gtst said:

Hi, have replaced no 6 injector.

compression was around 128 per cylinder.

thanks.

 

When did you replace it?

[Killer33gtst]

After the hose blew off and the problem became apparent.

ii haven’t had it back for a retune.

 

 

[GTSBoy]

The information comes in dribs and drabs.

What about the spark plugs? Had them out? Changed them? Particularly #6.

[blind_elk]

There was a similar problem many years ago. Turned out to be a crack in the cooler piping was opening up at higher boosts.

[Killer33gtst]

Yes, plugs changed, several sets now.

has had new cooler piping both sides.

turbo  side to air filter done pre tune. Intake done only a week ago. Still same problem.

 

Car ran perfect after tube, 232rwkw. @ 15psi.

drove it 250kms after tune, no issue. Gave it a few short drives and it, again, was perfect.

blew the intake pipe to plenum off. 

once this happened it ran like shit.

changed plugs as they were all Fouled. 
since then it has had the issue.

Appreciate everyone’s input.

 

 

[tridentt150v]

When you say cooler hose....You do mean air intake hose don't you? ie not radiator hose? Just to be sure!

Check that you don't have a lazy pump?

[Killer33gtst]

After the hose blew off and the problem became apparent.

ii haven’t had it back for a retune.

 

 

[Killer33gtst]

Yes intake pipe to the plenum. From intercooler.

 

 

[Ben C34]

How sure are you that you dint have a boost leak?

You have to check by pressure testing. Just feeling clamps won't tell you.

[Killer33gtst]

We put a smoke test through the system.

[Ben C34]

Shit Man. I'm out.

 

 

 

Why didn't you actually write exactly what happened and what you did in the first post?

How  are people going to guess what the problem is?

[Killer33gtst]

 

Thought l gave a good summary of issue. 

Sometimes less is more!

[Kinkstaah]

I have seen a car foul plugs mysteriously more than others, and it turned out to be the diaphragm in the FPR that had failed, sending fuel into the plenum into two cylinders specifically.

Something mechanical has let go in the cylinder that is fouling. It would be very suprising to somehow make a tune that only fouls 1 cylinder unless you are playing with cylinder trims, which I don't think is very common on a powerFC.

You need more data available to you. Is the problem spark related? Fuel related? You may need a dyno to figure this out.