M52, OBD1, S50 Cams, SSSquid Stage 2, G260, 2.93 Diff, Vtec like spike at 4k

[tonerrrr]

I'll see if I can get a video done soon of what happening but just like the title states, I'm getting a pretty serious spike in power at 4k in first gear. In second it's less noticeable, and in 3rd it feels like normal vanos linear power even starting around 3.5-4k.

My problem is, in 1st gear, I have very very little power until 4k. I feel as if I have a turbo waiting for it to spool or something. Is this because of my diff? Tune? Before the cams, it was pretty ballsy no matter what RPM you were at and of course more so at 4k+.

The tune I have was supposed to work OK with/without the S50 cams since I told Jesse at SSSquid I was getting the cams soon. I'm still waiting to hear back from him about what he thinks.

I've searched and found others with a similar problem even calling it Vtec like jump in power but the threads just went dead. If anyone has some insight please let me know if this is completely normal or not!

My only theory right now is that everyone has this happen with the S50 cams but they do not notice it since their diff/transmission isn't geared like mine (maximum ETA mileage ha).

[ncbrock]

did you do vanos seals?

[justin_l_]

Timing off a tooth?

[tonerrrr]

Vanos appears to be fine, I triple checked and turned the engine over by hand to be sure timing was correct after replacing the cams.

Here's a quick video

[328ijunkie]

Normal without a tune for cams on a m52



Is that a graphic representation of what you're feeling? (The pretune)

Or is this one more like it?


or this?

[tonerrrr]

This one seems more like it for sure, I added some lines to better see what what happening on the graph. The thing my video doesn't show is how it puts you back in your seat once it's around the 4k mark. I'd say this graph is close so maybe it's just normal?

[328ijunkie]

You highlighted the two HP curves lol. The torque curve is the 'put you in your seat' feeling. You also may be feeling a strong pull at ~4500 or so because of a flatline/dip before that where the power flat lines similar to the blue graph here:



Which then suddenly wakes back up after flatlining giving you a feeling of pulling hard.

You also may just have a wonky AFR issue down low that gets sorted once the engine gets up to speed

[tonerrrr]

Thank you for the insight, I know I highlighted the HP but that's what it looks like it feels if that makes sense lolol

This one looks like it kicks in early... I guess the thing to do is put it on the dyno and see how it looks as well as wait to hear back from Jesse.

Here's where I highlighted the torque but mine comes on a little later. The spike is there though.

[tonerrrr]

Did my vanos, rattle + seals, 100% fixed and a world of difference. The new cams must have accentuated the vanos problem as the vanos seemed fine beforehand, points to ncbrock for being correct!

[squidmaster]

Did my vanos, rattle + seals, 100% fixed and a world of difference. The new cams must have accentuated the vanos problem as the vanos seemed fine beforehand, points to ncbrock for being correct!

I know this thread isa little old, but I wanted to come in an say I'm glad you got it worked out! Vanos can be a bastard to take care of. Did you ever take it for another dyno?

[tonerrrr]

I'm waiting on a dyno day with a friend who knows a friend to do a couple pulls, I'll report back once it gets done!