Motor won't rev over 5200-5300rpm... WTF???

[Alky V6]

Frame 1118. Why does the timing jump up 4 degrees? The knock starts in immediately after the jump up in timing.

 

[Alky V6]

What parameters are you using to check your afr?
O2 Volts only?
ECM afr looks off. Why?
No W/B afr reading. Why?
Exhaust temp looks low for gasoline?

 

[Alky V6]

If you lower the boost level a little (22 psi), does it still knock?

 

[yullose]

Frame 1118. Why does the timing jump up 4 degrees? The knock starts in immediately after the jump up in timing.

I think 256/sec airflow is where the TT chip picks up control... So the jump in timing (I think) represents that transition....

If the MAF keeps dropping back and forth from 254 to 256, that might explain the problem...

I think that may be a better question for Eric to answer... I'll try to get him to chime-in...

I 'gotta head out for a coupla hours in a bit... so I won't be a ble to follow the thread 'till later tonight... (Car show in Pottstown)

 

[yullose]

What parameters are you using to check your afr?
O2 Volts only?
ECM afr looks off. Why?
No W/B afr reading. Why?
Exhaust temp looks low for gasoline?

I have the WB off the car right now because it was acting goofy... I think I smoked the O2 sensor by running the leaded race fuel across it.

The alky and fuel pressure is turned a little higher than needed, just for a little insurance... hence the low EGT's. I know it's a little fat, but not so fat as to create this problem... It really does run crisp and clean, right up to the point it has the problem.

Jason at RJC mentioned a possible MAF sensor problem too when I talked to him on Thursday.

 

[Ed Valvo]

Bigger valves require more spring pressure to close under boost so your springs might work with iron heads but not your TA heads. Have you tried to rev the engine under low boost yet?

 

[jasjamz]

My MAF readings do the same thing. Never caused an issue for me. Valve springs may be your issue. I have more spring pressure than you and a smaller "bump stick".

 

[bison]

My MAF readings do the same thing. Never caused an issue for me. Valve springs may be your issue. I have more spring pressure than you and a smaller "bump stick".

I have the same beehives on my GN1's and they have been to 6700 at least 3x so far. No bent valves. I shift at 6300 and have not found them to be a problem

 

[TurboBuRick]

I'm a little skeptical of a plug or wire issue. The car runs fine up to 5000rpm. If it was a weak s-plug or wire, the condition would be more boost related. Not rpm.

RPM issue points more toward a sensor or mechanical problem.

At this point I'd check the valve spring pressures.


One more thing, on the logs you posted, I'm not seeing the wideband signal. You are running a lm-1? Are you able to view the wb data on your pl?

Well... the plugs didn't help.

Go figure......

 

[jasjamz]

I have the same beehives on my GN1's and they have been to 6700 at least 3x so far. No bent valves. I shift at 6300 and have not found them to be a problem

What is you seat pressure open and closed if you don't mind telling?

 

[yullose]

What is you seat pressure open and closed if you don't mind telling?

Yeah, I'm getting more curious about this info as well...

I certainly wouldn't have a problem throwing a set of springs on it if needed.

If that turns out to be the problem, I will be more than a little pi$$ed with TA Performance...

Having the build sheet here in front of me should make it pretty easy to confirm the springs that are on it... and should help to find a set of compatible beehives for it.

I spent about $4000 with TA in the last month or so... and got two bum parts from them in the process... One of the head studs they sent me had the wrong threads cut in it... luckily I had a few oddballs here to use in place of it. Another issue was one of the adjusters in the rocker arms didn't have a hex broached into it for an allen wrench. I asked them to send me a new one... and they did, but charged me $13 for it.

I may just pull a couple springs and verify the numbers before going any further.

 

[Eticket]

I seriously doubt that you have a valve spring issue. Everyone likes to point at that when rpms are an issue, but that's normally a problem on much bigger cams (longer duration and higher lift) and motors dropping boost.. not, not making rpms.. we're talking solid rollers spinning past 7000k and 30psi.

I'm still thinking it's electrical! ok.. I've run out of 2 cents.

 

[jasjamz]

I think with all he has been through it wouldn't hurt to pull a few and check them. 145/400 here.

 

[bison]

What is you seat pressure open and closed if you don't mind telling?

I never tested. Heads are as assembled from Champion.

 

[ttypewe4jim]

Hey art sorry I didnt make it up there tonight i just came in from working on the car.. I got stuck at a house fire till about 5pm and that totally messed up my plans I didnt get done messing with the car till about 10 mins ago

 

[yullose]

Hey art sorry I didnt make it up there tonight i just came in from working on the car.. I got stuck at a house fire till about 5pm and that totally messed up my plans I didnt get done messing with the car till about 10 mins ago

Sorry to hear that... you missed a good show... I think every hotrod in a 100 mile radius was parked on High St last night.
We got there at 4pm and barely made it in. They had cars in parking lots and up/down every side street. I've never seen so many cars in Pottstown before.

McDonalds was packed afterwards too... I left early because my 3yr old was getting grouchy, but I think a few guys went out on the bypass to race a little later on.

There's always a little something happening in Pottstown.

 

[yullose]

I seriously doubt that you have a valve spring issue. Everyone likes to point at that when rpms are an issue, but that's normally a problem on much bigger cams (longer duration and higher lift) and motors dropping boost.. not, not making rpms.. we're talking solid rollers spinning past 7000k and 30psi.

I'm still thinking it's electrical! ok.. I've run out of 2 cents.

Yeah... I hate to think it's the valve springs and I'm trying to look at everything else before I go into the motor. Honestly though, I'm really running out of ideas.

I thought the MAF sensor 254/256 fluctuation might be something, but reading the posts here, doesn't seem to concern anyone else.

I had a brainstorm yesterday... and thought about unplugging my Autometer tach. I've had tachs cause me problems in the past. It's not likely an issue, but at least something else to try.

 

[turbo6man]

H,i I was just watching a video about my innovate motorsport wideband, and it was showing how to use a wideband while datalogging to deterime if you have a misfire condition. This should work for any manufacture's wideband that has the datalogging ability. I thought this might be very handy in checking to see if you have an electrical issue.The info I am talking about starts at 8 minuets and 39 seconds of the video to the end of the video Here is the link: sniffer
Good luck

 

[Alky V6]

I would tackle the obvious first. Get that timing smoothed out at the transition and see if it helps the knock retard. That jump is no good.

 

[yullose]

I would tackle the obvious first. Get that timing smoothed out at the transition and see if it helps the knock retard. That jump is no good.

You know... looking at some of the older files, this occured at the same time too...

It looks like timing falls off gradually as boost increases, then all of a sudden it jumps up 3 degrees and there is a blip of KR and the motor falls off. It looks like the timing locks on steady at that point.

If the KR is pulling timing, why doesn't it show up in the PL files ?

Does the PL show programmed timing or actual timing ???