b727pic

iTrader: (1)

Running an 2bar SD tune...

I have tried everything from 10* all the way up to 23*(with meth) AFR as lean as 12.1:1 power output changes accordingly, the wall is still hit at the same RPM.

b727pic

iTrader: (1)

That was one of my intentions, but after 2 hours on the dyno......that was enough for one day.

Heads are new custom AFR 235's by Ed Curtis @ flowtech

Intake valve brand and size: Ferrea 2.080
Exhaust valve brand and size: Ferrea 1.600

Spring brand: PS4 Duals with titanium retainers
Spring loading: 155# on the seat at 1.820" installed height

b727pic

iTrader: (1)

OEM ignition coils, have tried OEM settings, as well as "tweaking" them a bit...no affect on my situation.

The original cam spec was for my 347, the cam seemed to be "marginal" for CA smog checks. So the Rhoads seemed to a logical approach to taming down the cam events at low RPM.

The Crank, Rods, Cam and lifters are about the only commonality between the 408 and 403 build. Given the issue is common to both motors, I guess its logical to assume either a crank reluctor issue??? or CAM/lifter??? given a choice between the two, I am hoping its the latter. If I have to pull the heads and change out the lifters, I will have to rethink my SMOG strategy...

SKULL

iTrader: (7)

i say reluctor wheel or sensor. know a guy with a 347 heads cam and will be sprayed does the exact same thing on the road. youll be going into it and at full throttle at 5500 the car completely falls on its face and almost stalls.

b727pic

iTrader: (1)

In his situation is he getting an SES light? any codes being thrown?

In my case Its very hard to tell on the street due to no traction. The back end feels like its on ice skates much above 4000 RPM. Engine is smooth and pulls to redline when unloaded, no misfires, no SES, nothing to point me in any specific direction. The only time I really can see and feel this issue, is on the dyno. At least up until I get some traction:

While I am having a hard time getting motivated, I am going to go ahead and pull the front end apart and "degree the cam". I rechecked all my install pics and am confident of the "dot to dot" install.



But as has been stated many times that doesn't mean there are not some variations in the gear set or crank key way. Just an awful lot of work which will probably net no answers. but I guess at that point if nothing is found I can toss in another cam and see what happens.

01ssreda4

iTrader: (96)

Needle in a haystack...Some good advice here, no need for me to repeat anything. Good luck OP.

C/Performance

I believe it is not the cam.
Have the car professionaly diagnosed before you start throwing money around.
Always go back to your basics !!!!

And again did you run the car N/a ?

Anyway good luck.

b727pic

iTrader: (1)

No NA run yet...

I have had two PRO tuners take a look at the tune....nothing obvious to them at the time??

Old Geezer

iTrader: (3)

Shut off the alky, put 5 gallons of race gas in it,,,Make some pulls to get back to back verifiable info.

That way, you can leave the boost and timing where you have it now, and will be safe.

b727pic

iTrader: (1)

from one old geezer to another....thanks for the input. However during the last dyno session I had made several changes one of them being disabling the meth, I did however take out about 5* of timing.

I had no KR during any of the tuning or pulls, so not sure how adding the race gas would help with further diagnosis? HP falls off at the same point regardless of timing or boost pressure.....

I did manage to get the front end of the car apart yesterday, should have some additional insight soon......the Odyssey continues

b727pic

iTrader: (1)

got a chance to do some measurements this afternoon, not really sure what it all means but here goes.


Cam card has the following spec's.

@.050 Intake Open 0* close 44*ABDC
@.050 Exhaust Open 52* BBDC 0*ATDC
Recommended Intake centerline 112*

After many measurements I came up with the following: The good news is that the crank and Cam gear Dot to Dot, are actually TDC.

Intake @.050 Open 2*ATDC Close 46ABDC
EXhaust @.050 Open 51*BBDC Close 0*ATDC

Intake centerline check,

peak lift -.050 close 75*
Peak lift + .050 open 153*

153+75=228/2=114*

So near as I can tell the intake side of things is 2* retarded? if anything shouldn't that help my upper rpm band??

ringram

try another set of coils..?

b727pic

iTrader: (1)

Hmmmmm, not sure on this idea since I am not getting any misfires?? always kind of thought of coils either working or not. My first tuner did play with the dwell a little bit, but it did nothing toward fixing the issue.

I will have to defer to guys with a lot more experience than I on this one. Coil packs aren't cheap enough to just throw a set on and see what happens.

Thanks for the idea though, will run this up the flag pole with a few guys and see what the consensus is.

SKULL

iTrader: (7)

the weird thing about the car i know of is that when you go full throttle at 5500 it has a 100% fuel cut and the car dies to 4000 rpms then will keep going but if you hold your foot at 98% throttle the car will pull all the way to the moon. as for codes i have no idea i never looked at my friends computer when he was tunning.

white01ss

iTrader: (37)

Bad TPS sensor or MAP sensor? Those are pretty cheap to try out.

GrannySShifting

iTrader: (10)

That is a TPS over voltage issue sounds like to me. Put a set screw or even something dumb like a vacuum cap over the TB stop so it just hits 99 or 100% tps, or look at your voltage and see if its much higher than 4.5v at WOT

Frost

iTrader: (45)

Or set the upper error threshold to 5.0V in the calibration...

b727pic

iTrader: (1)

forgive my ignorance, but is this valid in an OLSD tune? I know the TPS is showing 100%, but have not checked voltage? will have to do a little more and figure it out.

thanks for the reply's.

b727pic

iTrader: (1)

With the engine "off", logged a few minutes with the scanner for voltage on TPS. Here is what I have, and no clue what it means. I do find it interesting the 100% TPS is achieved prior to actual pedal stop (floored) yet voltage keeps climbing another .25V?

TPS 0%=.53V
TPS 50%= 2.31V
TPS 100%= 4.1V
TPS floored = 4.35V

Also code P0122 Throttle position sensor circuit low voltage (immature)

Car is apart for the cam degreeing, so can't start it up, not sure what codes are normal if any at this juncture???

white01ss

iTrader: (37)

I had to replace my TPS sensor because it showed 3% TPS at idle. My car had 33k miles at the time, but was 8 years old.

Things to double check in the 2004 GTO tune:

TPS Test Min Temp - Test with 150C to see if it helps
MAF Test Min Engine Speed - Set to 12800 RPM to disable
Abuse Mode RPM Enable - Set to 8192 RPM to disable