sr20det hesitation in boost after new coil packs

[89240sr20]

Hello,
So my sr20det had a misfire issue for a while until I changed the coil packs today which resolved that, but now there's a hesitation under boost. The first time I drove it, there was a couple of small hesitations at the beginning of boost (around 4800rpm), but it pulled hard after that to redline. The car felt much faster with the new coil packs (like 20whp) after the hesitations (5200+). Later I took the car out with more weight in it and the hesitations got much worse, like it was cutting in and out of boost, even at rpms close to 7k. It also doesn't happen in first gear, but second and third. What I'm getting at is it gets worse under a load and only happens at wot. Another thing to note even before the new coil packs is my car has been more and more difficult to start when cold. It also studders when I initially hit the gas from a stop and its still cold (doesn't happen when warm).

Is it possible that the increased detonation from the coil packs is causing fuel starvation? Ive had a Walbro 255lph fuel pump in for 5 years. When I turn the key, I can hear it whine. Could it still be bad? If there was fuel starvation, would it show up as high injector duty on the powerfc? The injector duty hasnt been any different than normal. I'm going to pick up some new spark plugs to see if that's the issue. I replaced them 15k miles ago though. Im using ngk heat 7.

Any other ideas? Vacuum pressure appears to be good and boost pressure is good. Again, it did not hesitate in boost before the new coil packs, but it felt much slower due to the miss.

2871r @13psi
Stock engine

Fuel system:
Walbro 255lph (5 years on this setup)
hks 740cc injectors
Nismo afpr @4 bar fuel pressure (or it should be)
300zx fuel filter replaced 1 year ago

Thanks.

[centralcoaster33]

Just an idea... maybe check your MAF and your TPS and your timing?

[89240sr20]

Thanks for the reply. I'm going to pick up new plugs and gap them at .30. When I put them in, I'll clean the mafs and check the timing. If this doesn't work, I have a spare fuel pump somewhere and I could mess around with the tps some more. I messed with the tps a few months ago but couldn't get it to perfectly read the correct values (it never has since I've owned the car).

Maybe the ignitor chip?

[centralcoaster33]

Based on that, I'd go with just the TPS. Does yours have several wires from it? I mean, more than three? If so, it has a WOT / closed sensor in addition to the potentiometer. There is a TSB out there for revising the instruction to set the TPS. I don't recall exactly, but you ignore the variable voltage part of it and you look at the other wires and you have to twist it just enough to get zero or 5V on or off for closed or Wot. I don't remember. Search for that. I think you need to dial that in to get consistent throttle response. Cleaning the MAF is good. You don't have codes to help I guess? TPS adjustment probably won't throw a code and you've been messing with it recently and it would cause your symptoms... if that is what is wrong.

[centralcoaster33]

http://lyberty.com/car/Maxima_A32_docs/ ... 9-053b.pdf

heres that tsb

[89240sr20]

Thanks for the replies. Ill have to look into the tps, but the issue seems to be resolved now. I checked the timing and it was at 15 degrees. I cleaned the mafs which was surprisingly dirty and replaced the plugs (3 of the old ones looked fouled). I just did a second gear pull up a steep hill with no hesitation at all. On top of that, the knock was much lower than it used to be. It got up to 13 whereas before it would be around 60 after a full second gear pull.