Missing at high RPM

[Pro3racer]

Simply put, when at high rpms at full boost(17psi), i am missing, roughly two misses per gear, in every gear. Any help?

 

[Gamble97]

did u do a tune up? try new plugs/wires or check the gap on your spark plugs

 

[Pro3racer]

New plugs, i'm running NGK 7's, gapped correctly at 28, and new Accel 7mm wires.

 

[Gamble97]

did you try to turn the boost down? maybe your hitting fuel cut

 

[Pro3racer]

I know i need to back the boost off, but i have hit fuel cut, and this was not nearly as severe, and the engine didn't "cut", it just struggled and missed.

 

[Cool Mr Steve]

I hope you have already done a boost leak test, as that is one of the main reasons for our cars to have issues like that. If your boost leak test checks out (and I see you've already covered your bases with the plugs and wires) you may want to check out your coil pack. I struggled with slight hesitation issues for awhile before stumbling onto my bad coil pack. It's easy to test, so you might as well. Good luck

did you try to turn the boost down?

And you call yourself a DSM'r. Just kidding.

 

[viper995]

Ignition Coil pack?? maybe bad

cool mr steve maybe right.

 

[Mr4G]

Your spark plug gap may be incorrect and your boost may be blowing your spark out. This has happenned to me.i solved the problem by buying NGK BPR7ES and setting my gap at .028. good luck.

 

[Pro3racer]

If you read, my plugs are perfect. I never thought of a boost leak causing a miss, only a very rich situation, but i can now see your thinking. I recently found out my VC cracked, so i have a leak there(pcv valve area).

 

[jongreene]

do u have a 255 fuel pump?

 

[Cool Mr Steve]

If you read, my plugs are perfect. I never thought of a boost leak causing a miss, only a very rich situation, but i can now see your thinking. I recently found out my VC cracked, so i have a leak there(pcv valve area).

A boost leak will definitely cause the car to miss as a result of an overly rich situation. However, a leak at the valve cover is not a boost leak. If your hearing air coming from the valve cover it's most likely valve seals, which is no bueno. I don't wan't to sound like I'm nagging you, but have you did a boost leak test yet?

 

[1gcrazy]

With forced induced engines, the higher you boost the smaller you'll want to gap your plugs. If you can gap them larger than normal without getting a miss the better because(as long as your coils strong enough) you'll get a stronger spark in turn a better chance at burning more fuel. I know this is true in Domestics(Chevy, ford, chrysler)
Someone back me up on this one.
Also, do msd boxes work well on our cars? Anyone had any luck? I had one on my truck and it was minimal but still worth it in my mind since it was n/a.

 

[leet]

Are you by chance utilizing an adjustable Fuel Pressure Regulator to control that Walbro 255? Where is your fuel pressure at?

If not, you are running quite rich, which will cause issues.

 

[Pro3racer]

I know, I know, i need an AFPR really bad, but money isn't flowing right now at the speed i need it to be. My valve cover is actually cracked right at the PCV valve, so much that i had to throw sealent over the crack until i can get another one. I'll do a check tomorrow on my plugs, turn my boost down, and do a leak test and report back.

 

[Cool Mr Steve]

I didn't even notice that you didn't have an AFPR... Did these problems by chance start after the install of the 255?

 

[Pro3racer]

No, i have always had a 255..for the last year or so. The car was perfect then, it has happened since i bumped the boost from 13-16-17, then it got cold out.