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iTrader: (1)

I think I found the MAF test and Abuse mode screens????

Can't seem to find the TPS Min Temp Test, where is that at??

b727pic

iTrader: (1)

I have decided to go ahead and change out the lifters. While the heads are off I will route them to T&D for Geometry validation, and will be testing / adjusting valve spring pressures.

since I am not throwing any codes, not sure If replacing any of the sensors is warranted??

Once back together and on the dyno we shall see what progress has been made (if any). If this work proves nothing, then I will look at a possible cam change. EDC already has one picked out for me.....just in case.

Unless someone can identify something in the tune, at this point I am assuming its mechanical?

Monte4ever

iTrader: (2)

Excuse the newbie question but is the blower to small for the motors you had and have it on (P1SC)?

IDRIVEAG8GT

After reading part of this I come up with the theories:

1. Incorrect injector data for High Flow situation.

2. Fuel filter clogged.

3. Valve float.

4. MAP sensor skews MAF readings.

5. TB closes due to Trans Torque exceeded.

6. Cam over advanced.

7. Clutch/Torque Converter/Internal trans clutch pack slippage (whether you have either an automatic or stick.)

b727pic

iTrader: (1)

Some say yes.....

However I have the same issue whether I am pushing 15PSI or 3 PSI, so I don't think its the blower itself.

b727pic

iTrader: (1)

1 & 2: I would think any fueling issues would show up in the fuel pressure log and skew the AFR readings?

3: valve float is unlikely given the quality of springs and current seat pressure. Also unlikely to have valve float at the exact same RPM regardless of boost at 3 pounds or 15. However I am pulling the heads to change the lifters, and will be checking the entire valvetrain.....again.

4: Not something I know anything about, but am asking questions, any and all guidance would be appreciated.

5: TB is cable driven, the log shows 100% TPS throughout the pull.

6: Cam was degreed this past weekend, found the intake 2* retarded exhaust right on the money as compared to the cam card.

7: As for the clutch, I wont rule anything out, however it is a new ACT twin, and again the issue remains at 5500 RPM with 200HP difference between the 15psi pulley and 5 PSI pulley??

b727pic

iTrader: (1)

Heads were dropped off at T&D for rocker geometry and installation checks. after a couple days I received a call with interesting news.

It seems that my rockers while marked 1.7:1 ratio, were actually lifting at a 1.85:1 ratio. My cam card states .6001 / .6001 lift, I was actually getting over .650 lift. I suppose that it is possible I was seeing valve float?

In any case T&D is taking care of me, and the new question is, since I was really happy with my tq down low, am I going to be happy losing .050 lift on my current cam??? EDC has sent me an option I am considering. Cam swaps aren't terrible on these motors, but getting it all done at the same time does have some appeal......decisions, decisions.......

YellowToy/A

iTrader: (1)

What push rods length do you have? Maybe if they are to long and the lifters are bottoming out holding the valve open? This with the 1.85 might be tied together.

b727pic

iTrader: (1)

7.2" zero lash + .020 preload

YellowToy/A

iTrader: (1)

I think the stock length is 7.4. That sounds short to me.

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iTrader: (1)

you are correct about OEM length. However since I am running T&D Shaft rockers which is a whole new ball game.

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iTrader: (1)

Been a long haul, but I think we may have found the issue. Subsequent to finding the rocker ratio's being 1.85 instead of 1.7. I decided to have the springs checked just to be sure........well the results were not good. Took measurements at 1.85, 1.80, and 1.20. Seat pressures were barely 100#'s Open pressures in the mid 300's. Starting to look like valve float was the source of my issues, I guess the 1.85 rocker ratio pushing the valves past 650 lift took its toll in short order??

Not wanting to spend a ton of $$ with a whole new spring setup, it looks like K motions's K-800 will work with my Ti retainers and locks. Will be measuring the installed height, then testing the K-800's prior to final installation.

Also ordered a new cam more suitable to the 403, hopefully I can get all this going back together soon......

GrannySShifting

iTrader: (10)

I said it was valvetrain a couple months back, I know its a pain to tear stuff back apart but thats the first place to go. It probably wasnt that the springs were that soft to begin with just marginal, and floating them beats them up more and more and in turn floats more and more.

You are going to end up in the same predicament picking a spring without considering the cam, you should get a real lifter in there, and with the weight of the valvetrain in mind and lobes get an idea of what closing pressures you will need. Should have 160-170 on the seat minimum, worst case. Springs do settle, cheaper stuff more so than others, stuff that gets abused with shitty lobes more than others keep that in mind. Youd probably be better off with something even like a PRC 675 EHT kit, more room before bind, at least as much rate, you can set them up with more on the seat and they will be much lighter. $300 can make or break your $15000 engine/blower combo and burn up months of your time like youve seen. Not trying to give you a hard time at all, just dont want to see you post the same thing up now in a few months when springs still marginal, or later when they settle or something like that. Valvetrain control is #1 first priority

b727pic

iTrader: (1)

yes you did predict this scenario, and I thank you for your input. Had Valve float not been brought up I doubt I would have gone through all the hassle of pulling all the springs and checking them.

As for the current spring selection, I discussed these springs with my cam designer who thinks they should be fine. The K-800 should be right around 170# seat pressure and approx 460 at max lift. I have ordered a valve height micrometer, once I measure the install heights, I will then measure the actual spring values with my cam specs in mind and shim if necessary.

Thanks again for your input, its been alot of work, but I am sure it will pay off in the end.