Car Cuts Out Abruptly at WOT - Help!

[540-S3]

Ongoing issue with car cutting out on WOT. Feels just like it's hitting the rev limiter.

I am thinking it is the fuel pump or CPS. Any ideas?

Same symptoms before and after the following maintenance was done.

• New fuel filter
• New plugs - old plugs looked normal
• New SC belt
• Oil change

Other issues, but I don't think this is related as this has been a problem for while.

• INPA smoothness - cylinder 4 is off the chart at 1040.
• Cylinders 1 and 2 are at 1/3 up the smoothness chart @350ish
• Random misfire
• Random misfire - cylinder 4
• Swapped coils 3 and 4 - no change
• Injectors are newly reconditioned, but not ruling it out.
• LTFT at -7% on 1-4 bank (5-8 bank is +3%)

[Mannyf540]

Was the fuel pressure regulator serviced ?
Just a thought..
Codes?

Second thought since it’s superchagred, may need a new fuel pump, since your INPAing, take it for a drive and monitor fuel pressure...

[540-S3]

Thanks Manny, FPR was changed not too long ago. On INPA where do I monitor fuel pressure?

Codes, but I had these long before this cropped up.
Random misfire
Random misfire - cylinder 4

[JimLev]

INPA doesn't monitor the fuel pressure.

[Mannyf540]

I’m not to sure, I’ve not played with INPA for quite some... it may or may not have that capability. Although I’m sure it must be able to.

If not do it the midevil way and tap in to the Schrader valve and monitor fuel pressure levels that way.

Clear all codes and take it for a drive. See if it continues to indicate cylinder 4, may be a bad or leaking fuel injector. I’m inclined to think it’s an injector issue perhaps, as you’ve swapped coils and the misfire stayed the same.

Maybe someone will chime in where in the INPA menu you can monitor fuel pressure.

[JimLev]

Nope, no fuel pressure sender so no way to read the pressure with INPA.
Will need to do it the old way at the schrader valve.

[Mannyf540]

[QUOTE=540-S3;30081363]Ongoing issue with car cutting out on WOT. Feels just like it's hitting the rev limiter.

Could you elaborate more on this? It’s a stick shift right? Or is it an auto? Maybe a slow dying crank sensor, any speedo issues? Any issues starting the vehicle?

[geargrinder]

Trims make sense if there's misfires on #4. Misbehaving #4 is probably sending raw fuel out the back, so then the closed loop logic is trimming fuel out to try to account for that.

I assume plugs are fine cuz duh you wouldn't have swapped coil without checking that too (right?)

I've heard of used injectors pooping soon after being cleaned before. Failing injectors can just lose it at high duty cycles so its possible the injector runs good up to a certain level of flow...

Might try injector swapping #4 too.

Is it a WOT cutout at all levels of RPM? Like if you WOT at 2.5-3k is it same as WOT at 5k?

[540-S3]

[QUOTE=Mannyf540;30081630]

Ongoing issue with car cutting out on WOT. Feels just like it's hitting the rev limiter.

Could you elaborate more on this? It’s a stick shift right? Or is it an auto? Maybe a slow dying crank sensor, any speedo issues? Any issues starting the vehicle?
Yes 6-speed. No speedo or starting issues. I was also thinking fuel pump

Trims make sense if there's misfires on #4. Misbehaving #4 is probably sending raw fuel out the back, so then the closed loop logic is trimming fuel out to try to account for that.

I assume plugs are fine cuz duh you wouldn't have swapped coil without checking that too (right?) Plugs are new, but was misfiring with old plugs too.

I've heard of used injectors pooping soon after being cleaned before. Failing injectors can just lose it at high duty cycles so its possible the injector runs good up to a certain level of flow...

Might try injector swapping #4 too. Okay let me look into this. Any software that can look a injector performance?

Is it a WOT cutout at all levels of RPM? Like if you WOT at 2.5-3k is it same as WOT at 5k? Does it under load at any RPM

[geargrinder]

Nothing can really tell you whats coming out of the injector without pulling it. The DME will sense if its short or open I believe, but often injector failures aren't that extreme, its more like partial failures in certain conditions. Last bad injector I had was only when it was super hot in the engine bay - I could run down the highway or park the car for a while to make it stop acting up but if I sat in traffic it'd get cranky...

[540-S3]

Nothing can really tell you whats coming out of the injector without pulling it. The DME will sense if its short or open I believe, but often injector failures aren't that extreme, its more like partial failures in certain conditions. Last bad injector I had was only when it was super hot in the engine bay - I could run down the highway or park the car for a while to make it stop acting up but if I sat in traffic it'd get cranky...

I happen to have a freshly cleaned set of injectors and the ones installed now were cleaned not to long ago. What's needed to replace just cylinder 4 injector?

[Mannyf540]

Yes sir, injector #4, since the misfire stays consistent on that cylinder. You’ve swapped coils and the misfire stayed on #4, so the next variable if the injector. I hope that resolves your isssue!

[geargrinder]

A trick a fellow forum member taught me last year or two... Pull the rail w/ the boxes attached so its much easier to get at the clips (and don't have to pull the box at all on the 'good' bank...)

You do have to disconnect the wire boxes from all the coils (ground wire plus all the coil plugs on each side), and disconnect the other wiring between the boxes and other stuff at the front of the car - knock sensors, cam sensors, that sorta thing.

Then you should be able to unbolt the fuel rail, pop the injectors out of the manifold, (they should stay captive in the rail due to the retainer clips) and lift it up with the wiring boxes attached, and prop it up (or hang it w/ a bungy from the hood or something).

Then you can remove the wiring-box injector clips on that side - easier to get at those clips now w/ the rail and boxes up in the air - get the wiring box free, then unclip the retainer for the one injector and remove it.

Gas will come pouring out naturally so you'll want to wear rubber gloves and have a tray or container of some sort underneath to catch that as it does, but not too much esp if you leave the car parked for a good long time before pulling it so theres no rail pressure. These cars don't seem to hold rail pressure hardly at all compared to others I've had. I guess I should say you sould use the schrader valve on the fuel rail to check and be sure and drain out with a rag and a screwdriver tip first. IME that doesn't do much (i.e. there's no rail pressure if car has been parked for a while, so hardly antying comes out) but its how you're supposed to do it...

You may not even have to remove all the injector clips, it may be you can get that one injector unclipped and pulled out without having to totally remove the box from the bank, but not having done it in a while I'm not sure...

[540-S3]

I wanted to add a bit more information on high smoothness readings on bank 1.

After starting the car this morning I noticed that cylinders 1, 2, 4 went off the chart, but 1 and 2 eventually came down. What could be causing that bank to read high at startup? O2?
LTFT are at 10% on that bank.

IMG_20180814_092345.jpg

[Mannyf540]

Perhaps you have leaking injectors, once the additional fuel burns up, it smooths itself out. How’d it go with #4 injector?

I don’t know how crucial the pintel caps are, perhaps it’s time to upgrade injectors...

[geargrinder]

Yeah... 1/2/4 on same bank - that or some kind of cold vac leak etc?

[540-S3]

• I will roll the O2's and report.
• I just pressure tested the intake - no leaks.
  (Not sure if this would see a leak at the valve covers)
• Cleaned the MAF - no change.
• Injector 4 has not been swapped out yet.

[JimLev]

Might be nice to do a compression test (TB wide open) just to get another data point and to rule out compression on those cylinders.

[540-S3]

• Changed out O2 on bank 1 with new replacement. I drove 50+ miles, but no change to LTFT - currently at -8.
• Hope to change out the #4 injector this weekend.
• Ran the car hard a few times this weekend and no cutout. Just drove it this morning and it just about stalled during normal driving. Still no codes.

[540-S3]

A trick a fellow forum member taught me last year or two... Pull the rail w/ the boxes attached so its much easier to get at the clips (and don't have to pull the box at all on the 'good' bank...)

You do have to disconnect the wire boxes from all the coils (ground wire plus all the coil plugs on each side), and disconnect the other wiring between the boxes and other stuff at the front of the car - knock sensors, cam sensors, that sorta thing.

Then you should be able to unbolt the fuel rail, pop the injectors out of the manifold, (they should stay captive in the rail due to the retainer clips) and lift it up with the wiring boxes attached, and prop it up (or hang it w/ a bungy from the hood or something).

Then you can remove the wiring-box injector clips on that side - easier to get at those clips now w/ the rail and boxes up in the air - get the wiring box free, then unclip the retainer for the one injector and remove it.

Gas will come pouring out naturally so you'll want to wear rubber gloves and have a tray or container of some sort underneath to catch that as it does, but not too much esp if you leave the car parked for a good long time before pulling it so theres no rail pressure. These cars don't seem to hold rail pressure hardly at all compared to others I've had. I guess I should say you sould use the schrader valve on the fuel rail to check and be sure and drain out with a rag and a screwdriver tip first. IME that doesn't do much (i.e. there's no rail pressure if car has been parked for a while, so hardly antying comes out) but its how you're supposed to do it...

You may not even have to remove all the injector clips, it may be you can get that one injector unclipped and pulled out without having to totally remove the box from the bank, but not having done it in a while I'm not sure...

Do I have to replace the o-rings on all 8 injectors? The o-rings are fairly new having been replaced 11k miles / 22 months ago.