FRPP Intake Manifold stumble? (To keep or not)

I just installed my FRPP manifold, no stumbles here thusfar.

Love the internal pics. Anyone ever seen the inside of the stock one?

id put the ht1's back in just to see before i put the stock manifold back on. you say you changed the plugs and the manifold at the same time and that when the stumble started.....some have had bad plugs right out of the box before.

I stand corrected on the time I changed the plugs. My buddy and I were talking about the plugs being an issue when he remembered I didn't change my HT1's out until I put the nitrous kit on. Which was a good 5-6 months after the FRPP install. So I'd run the HT1's for 6 months after the FRPP, and then switched to a tighter gapped HT0 and still had the same issue.

Ask your tuner to check the partial throttle cam angle under 3.5k. Or, alternately, datalog and see how much cam advance you see. Different length runners between intake manifolds will want a different cam angle, and you are already limited by your phasers.

Simply put, it may be more a function of your combination of mods. A higher rpm cam, phaser limiters, and a high rpm intake manifold absolutely kill all mid range torque, especially if the partial throttle vct settings aren't optimized (which would require street tuning). Longtubes also change "drop in" settings for cams.

For some reason I've found some Ford tuners like to input known values and go with VCT settings.

Its something to check if you have exhausted other options, either way. Good luck.

I have a datalog of cam angle during the event. What number should I be looking for?

PM sent.

I <3 you Greg. Gonna call him tomorrow morning. I have my dyno session tomorrow evening.

Get this. I swapped out my GT500 TB for my stock TB so I can effectively run the HSW fogger plate. Car ran like I didn't do anything, EXCEPT, I did a quick WOT in 4th starting at 2.5k/rpm and the wideband absolutely pegged out 10.0:1 and stayed there the entire pull 'til I let off at 5k/rpm. When I let out I put it in neutral and let it roll down, the rpm's settled at 1k/rpm for the roll, and the wideband was going all over the place, swinging from 11.0 all the way to 18.0 and not like just touching it and coming back, but hanging at those fuel ratios for a few seconds and then swinging hard the other way.

*sigh* I really hope I get all this shit worked out. Stumble is still there at 3k/rpm after the TB change.

I installed my FRPP intake manifold a few days ago, zero problems thusfar. No noticeable power loss down low, feels like it pulls a little more on the 5000+rpm range. Also makes a bit of a whistle/whoosh when I nail it past about half throttle, when I am at low speed. Like that going to the GT500 tb does, but a little louder.

Im stoked with it so far, and cant wait to get my LTs on and my Hot Rod cams in so the manifold actually begins to matter. Until then, it is in there looking beastly.



(just adding another update since its been a few more days for any problems to have shown themselves)

You might call Chris at BBR and have a talk with him. I had a bad tune from a different company and BBRs tune fixed it. It felt like it was falling on its face around 3K. It was around $75. My 2 cents. Hope you get it figured out, once you do, the manifold is great

Memphis said:

You might call Chris at BBR and have a talk with him. I had a bad tune from a different company and BBRs tune fixed it. It felt like it was falling on its face around 3K. It was around $75. My 2 cents. Hope you get it figured out, once you do, the manifold is great

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If you're refering to it falling on its face at 3k as being at WOT that's not the issue. It does great at WOT. It's a driveability issue, and I'm not sure that I would even call it that. It drives perfect. It's more just a gremlin that only pops its face up under specific conditions, and I would just love the kill it or at least understand why it's there. WOT the FRPP is awesome. It pulled 363whp tonight at my dyno session. Tuner took another stab at the issue but to no solution. It seems to get better with less timing and more fuel, but the tunes we were playing with isn't something I'd be willing to drive on the street.

I can drive around the issue just fine. This is just one of those things I just have to understand why it's doing it, what's causing it, I really am beyond caring whether there's a legit fix for it or not, I just wanna know WTF it is.

My tuner knows Chris at BBR. I'm sure he's already discussed it with Chris. If I was to consult with another tuner I'd rather have my tuner talk to them himself, as I would only understand about 5% of that WTFOMG tuner language (short trim long term cam angle delta P Y-axis crazy MAF idle voltage). LOL. And if another tuner doesn't want to reveal "trade secrets" and help out on a minor issue, that's cool, I definately know he'll never see business from me for as long as I remember his name/shop.

01yellerCobra said:

Shouldn't that be the other way around? The fronts are the ones the ECU uses to adjust A/F. The rears are for emissions. At least that's how it is on the older computers.

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Yea sorry lol I got my sensors mixed up lol.

pm sent.

I'm very curious to hear what the problem is. I hope you'll let us know.

In the meantime, I'm another with the same manifold with no problems. Not that you really wanted to hear that, I'm sure.

UPDATE:

randys06v6 said:

I had a similar problem and replaced my o2 sensors and all was fixed. The passengers side basically clogged up on me meaning failed reading properly through certain rpms at certain throttle pressures. It all started when I put on my frpp manifold as well and the car just freaked out on me i guess and the o2 sensors went out lol. So I just replaced the rear 2 and all was fixed. The front 2 I have off becaue of my long tubes so I didnt worry about them

Could it also be in the tune for the o2 sensors? Meaning like maybe they didn't make the tune aware that the o2 sensors are moved further downstream, thus causing an issue with reading exhaust flow correctly especially at certain rpms?

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This is pretty much exactly what it was.


Kudos to Lito actually, in the very first set of datalogs I sent to him, though highly insufficient as they were, he noticed my cam angle wasn't changing. I brought it up to my tuner that the VCT looked like it was locked in the tune. He remembered in one of our many tuning sessions we had locked VCT out in an attempt to add/remove timing and fuel combinations. We turned VCT loose in the tune and did a couple pulls, it seemed to make things worse. The cams were advancing (at least, I assume the closer you get to "0" in the tune is advanced) towards 3k/rpm and the wideband was registering lean/rich spikes in very short intervals. Just for testing, my tuner decided to throw 20% more fuel into the entire tune. My idle was 12.5 and any throttle was pretty much pegged 10.0 but I'm sure richer. The popping went away, completely.

From there my tuner wiped out the tune files and started from scratch to exactly what the car should need, but this time gave the tune a more retarded cam profile at 3k/rpm. The car would still pop, but like 80% less than it did prior. We did a few datalog runs at 25%, 50%, and 75% throttle through the 2200-3400 rpm range and found the narrowband O2's were screwing us hard. For some reason the O2's were commanding more and more fuel at 3k than what the tune was calling for, but no timing was being pulled.

My tuner put the car in open loop and rewrote all the fuel tables and cam angle. Car ran flawless. No spikes, no backfires, absolutely perfect. I also used to have a startup issue on cold-starts after the car had sat overnight, the engine would rev up to 2800/rpm and sounded like dogshit as if it was backfiring the whole way 'til it warmed up a bit. Now it starts up at 1400/rpm and idles perfect. I also had an issue with idle surge/crash when coming down from gear, I'd be rolling the gears and say I was at 2500rpm and let it go to neutral, the rpms would fall all the way to 350 and then surge back up to 1100 and it would go back and forth like that until I came to a stop, then it would idle fairly normal. Now I can let out anywhere and the car drops to a perfect 850/rpm idle.

So it was a problem in the tune, but also a problem with my O2 narrowbands. I'm going to get a new set of O2's and see what happens when the car goes back into closed loop. But I gotta say, with the car running so good in open loop, I dunno if I wanna fvck with a good thing LOL.

Thanks Lito for getting the ball rolling! Will update again once I get some new O2's. Can't believe those things were screwing me up that bad this whole time.

Good deal, glad you got it all worked out.

702GT said:

My tuner put the car in open loop and rewrote all the fuel tables and cam angle. Car ran flawless. No spikes, no backfires, absolutely perfect. I also used to have a startup issue on cold-starts after the car had sat overnight, the engine would rev up to 2800/rpm and sounded like dogshit as if it was backfiring the whole way 'til it warmed up a bit. Now it starts up at 1400/rpm and idles perfect. I also had an issue with idle surge/crash when coming down from gear, I'd be rolling the gears and say I was at 2500rpm and let it go to neutral, the rpms would fall all the way to 350 and then surge back up to 1100 and it would go back and forth like that until I came to a stop, then it would idle fairly normal. Now I can let out anywhere and the car drops to a perfect 850/rpm idle.

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Sometimes my car does the same thing. I noticed when I would go to start it in the morning it would slowly rev up ~2500-3000 rpm and sound really bad like the car was stuttering. It hasn't done that for awhile now.

It does, however, idle like yours when coming to a stop. In the morning when I go to work, when I leave work for lunch, after any period of time the car sits, it idles so low it almost dies and then fluctuates upward while driving/coming to a stop, and up-and-down until the car finally warms up.

I wonder if it could be my tune (BBR) even though it just recently started the fluctuating idle issue once the weather cooled down, or if it's the O2 sensors. The start idle issue has only occurred ~7 or so times since April, which is the time I put the cams in.

I recently cleaned the throttle body and tried reinstalling the tune to no avail.

With L/T and no cats I don't think your O2's aren't getting hot enough, so the computer keeps adding more fuel. I had a similar problem with my TT setup and ended up moving the O2 sensors as close to the turbo out as we could and still had to set the tune to run open loop until the sensors reached a good temp.


Earl

longhornd00d said:

Sometimes my car does the same thing. I noticed when I would go to start it in the morning it would slowly rev up ~2500-3000 rpm and sound really bad like the car was stuttering. It hasn't done that for awhile now.

It does, however, idle like yours when coming to a stop. In the morning when I go to work, when I leave work for lunch, after any period of time the car sits, it idles so low it almost dies and then fluctuates upward while driving/coming to a stop, and up-and-down until the car finally warms up.

I wonder if it could be my tune (BBR) even though it just recently started the fluctuating idle issue once the weather cooled down, or if it's the O2 sensors. The start idle issue has only occurred ~7 or so times since April, which is the time I put the cams in.

I recently cleaned the throttle body and tried reinstalling the tune to no avail.

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The high-idle at startup would only do it when it was literally cold out. Summer startups when it's 90-100 out would start and idle normal. I'm kind of leaning on the O2's trying to put too much fuel in. As far as rolling idle surges, again I want to say O2's, as I'm in open loop and it's miraculously perfect now.

retfr8flyr said:

With L/T and no cats I don't think your O2's aren't getting hot enough, so the computer keeps adding more fuel. I had a similar problem with my TT setup and ended up moving the O2 sensors as close to the turbo out as we could and still had to set the tune to run open loop until the sensors reached a good temp.


Earl

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I have Pypes LT's and have the O2's in their proper bungs. Even with the lack of cats, a long tube header is designed to heat scavenge. I can see perhaps an O2 heating issue at startup, but once the car is pumping at normal temps the O2's should be good and hot. I can't move my O2's any closer or I'll be putting them in individual runners.

Ever find the solution?
I seem to be having a similar situation

theRedStorm said:

Ever find the solution?
I seem to be having a similar situation

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O2 sensors were bad.