Input on hesitation at 4k rpm

[cjt671]

So I just had a thought and wanted some input on a "quirk" I've started to notice. I'm not too worried about it, but if it's fixable I'd like to. Car has a slight hesitation at 4k rpm that is pretty consistent. First thought was misfire/boost leak. Pressure tested and found no leaks, spark plugs are new ish, 2k miles bkr7e. Checked one and it looked fine gap was good. I'll check all later. 2.0 coil packs have 5k miles on them. So my question is if anyone knows of an issues with the vvt system on the car? Actuators sticking/failing? The rpm is so consistent and 4k makes sense to be when the vvt should kick in that I'm wondering if it could be an issue with that..

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[f4m0u5]

Some one this week posted almost the same problems at exactly 4k rpm and it turnt out to be a leaky injector.

What are ur fuel trims in block 32? And you say gap is good but didnt mention whats the gap at.

Lastly any codes? Did u scan with vagcom

[cjt671]

Some one this week posted almsot the same problems at exactly 4k rpm and it turnt out to be a leaky injector.

What are ur fuel teims in block 32? And you say gablp is good but didnt mention whats the gap at.

Lastly any codes? Did u scan with vagcom

Gap is 028, never considered a fuel issue.

Dont have vag com, I use a reader/blue tooth scanner. Wonder of my app can measure fuel trim, I'll check today.

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[f4m0u5]

You should invest the 20$ in a cheap vag cable. Some aftermarket readers dont show some codes and you can only see them with vagcom. I spent the other 99$ on the registered vag com so i could real all the measuring blocks such as 32

[cjt671]

I plan to, just haven't got around to it as other more costly issue arose, I can measure fuel trim on the app but I don't think the obd2 scanner sends that info..

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[cjt671]

So I can read fuel trims what kind percentage should I see at idle, part and full throttles?

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[f4m0u5]

The long term fuel trims what you want. . Theres technically 4 different readings. Bank 1 idle/bank 1 part throttle. And the bank 2 idle bank2 part throttle.

They should be around +/- 4-7%. But up to +/-10% is ok.

[616_S4]

It was my post about the leaky injector, and turned out to be leaking intake manifold!

[cjt671]

So I went about changing plugs and that helped with the 4k misfire at wot.. But now at around 10 psi under part throttle it's will miss occasionally..

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[cjt671]

The long term fuel trims what you want. . Theres technically 4 different readings. Bank 1 idle/bank 1 part throttle. And the bank 2 idle bank2 part throttle.

They should be around +/- 4-7%. But up to +/-10% is ok.

I'll double check but I believe that my long term reading for both banks is about 4%

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[cjt671]

So I went about changing plugs and that helped with the 4k misfire at wot.. But now at around 10 psi under part throttle it's will miss occasionally..

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You guys think plug gap? I also havent checked for vac leaks but im at -20 inches at idle...

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[cjt671]

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[cjt671]

Better pic,


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[cjt671]

Im gonna try plug gap.. It's at .028, think I should close it to .025 or go up to .032?

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[Bordom]

Im gonna try plug gap.. It's at .028, think I should close it to .025 or go up to .032?

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Gap lower for easier ignition. .025 will be ok and is still within spec

Everything graciously mispelled by Android

[cjt671]

Im gonna try plug gap.. It's at .028, think I should close it to .025 or go up to .032?

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.032 is factory spec and 2.0 conversion is supposed to allow running a larger gap, I might try both and see which runs better.

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[f4m0u5]

If you do have 2.0 coils that should be fine for gap. And did you store a misfire code for a certain cylinder? If it waas on one cyl only you can try swaping the coil to a different cyl to see if it follows

[cjt671]

If you do have 2.0 coils that should be fine for gap. And did you store a misfire code for a certain cylinder? If it waas on one cyl only you can try swaping the coil to a different cyl to see if it follows

No codes otherwise I would have done that.. Fuel trims look fine to you? Maybe vac leak?

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[f4m0u5]

Those fuel trims look fine (but we dont know if thats part throttle or idle fuel trims because with vag com there are 4 different ltft not just 2 like the torque app and what not.) if they are in fact part throttle then it doesnt seem like a boost leak but ur idle fuel trims could be out of wack wich would tell you its a vac leak.without vag com its very hard to diagnose theese cars. You could be storing a code just ur aftermarket reader wont read it it might only read full codes that illuminate the dash.

[dannyn424]

I gapped my plugs to .024

[616_S4]

any success with smaller gap? did you boost leak test? it can run fine, like mine but at times it overboosts and computer shuts it down.

[cjt671]

Those fuel trims look fine (but we dont know if thats part throttle or idle fuel trims because with vag com there are 4 different ltft not just 2 like the torque app and what not.) if they are in fact part throttle then it doesnt seem like a boost leak but ur idle fuel trims could be out of wack wich would tell you its a vac leak.without vag com its very hard to diagnose theese cars. You could be storing a code just ur aftermarket reader wont read it it might only read full codes that illuminate the dash.

My bad forgot to specify this is at idle.

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[cjt671]

any success with smaller gap? did you boost leak test? it can run fine, like mine but at times it overboosts and computer shuts it down.

It does generally run well, I won't have a chance to mess with the gap till tomorrow and I'll do some diagnostic pulls tomorrow, I'll post back if it helps,

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[christianb5s4]

I had the same issue back in the day, I had fresh coils and ICMs so that wasn't the issue. I gap mine at 0.024 and have no issues. Running copper NGK BKR7Es, going back to side fires since the NGKs don't last very long.

[cjt671]

I had the same issue back in the day, I had fresh coils and ICMs so that wasn't the issue. I gap mine at 0.024 and have no issues. Running copper NGK BKR7Es, going back to side fires since the NGKs don't last very long.

Roger, I'll go with a smaller gap first then, and Im sure that bad plugs was my first issue with the misfire at wot, I run the bkr7e's and they were about 3k miles. New plugs and wot misfire is gone, just now I've got one at part throttle

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[f4m0u5]

My bad forgot to specify this is at idle.

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Does the app ur using state long term fuel trim at idle or are you saying you just checked it while the car was at idle?

My torque app only shows one or the other. Im not positive if its odle or part throttle. But from the looks of it urs is one or the other also.

This isnt something you check while the cars idleing or while the cars driving under part throttle. You can actuslly check this with the car off its a stored number that doesnt move much except for when theres a problem or you just recently cleared your ecu faults

[cjt671]

Mine reads long term short term and current readings for each bank

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[cjt671]

So I swapped my boost gauge reference from fuel pressure reg to dv because I noticed it would leak slightly occasionally..and over 70 miles my ltft bank 2 went from -0.8 to -1.8, related to my misfires possibly? I read some where that ltft value helps determine fueling during wot is this relevant to our cars?

Gonna regap plugs this weekend

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[cjt671]

Gapped plugs.. Havent felt a misfire since, only been able to drive sort trips though

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[cjt671]

Drove home from work with the plugs at .025" which made the misfire worse and more consistent. Gapped plugs to .032 and the misfires are gone.

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[cjt671]

And they're back

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[cjt671]

Maf I'm thinking now.. Even though I just replaced it. Will not miss with maf unplugged

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[Timtheguru]

Replace your FPR. I had similar conditions, 15 year old thing just wasn't holding pressure at all driving conditions, new one does. It's a $30 bosch part from rockauto.com.

[cjt671]

Replace your FPR. I had similar conditions, 15 year old thing just wasn't holding pressure at all driving conditions, new one does. It's a $30 bosch part from rockauto.com.

Getting a replacement maf under warranty friday if it persists afterwards I'll look into replacing the fpr.

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[Bordom]

I like how we both have misfires at WOT, but part throttle acceleration is fine lol

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[cjt671]

I like how we both have misfires at WOT, but part throttle acceleration is fine lol

Everything graciously mispelled by Android

Lol my wot misfires are gone thankfully plugs were bad, so I can romp on her... But now just part throttle normal driving in anything over 10psi she'll misfire around 3500-4000k pretty badly, drives normal with maf unplugged

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[Timtheguru]

Getting a replacement maf under warranty friday if it persists afterwards I'll look into replacing the fpr.

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Seriously, do it anyway.. you'll thank me later, I promise. :) Mine ran fine with MAF unplugged as well.. fyi.

[christianb5s4]

I'm waiting on a new FPR as well, those can certainly go bad and cause those issues. Can't wait to throw the new one in, a failing FPR can also cause longer cranking when trying to start up the car.

[cjt671]

Seriously, do it anyway.. you'll thank me later, I promise. :) Mine ran fine with MAF unplugged as well.. fyi.

I'll definitely look in to it as preventative as my focus is keeping this car healthy for stage 3,

I'm waiting on a new FPR as well, those can certainly go bad and cause those issues. Can't wait to throw the new one in, a failing FPR can also cause longer cranking when trying to start up the car.

Car starts right up, I'm thinking mine's still in decent shape as I don't have idle, vac or wot issues

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[cjt671]

Still ducking at it.. new maf and the issue persists. 2nd gear part throttle will start bucking at 3k 3rd will do it at 4k

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