Help me decipher my FAST data logs (and problem)

B

Blown86GT

Member
Joined
May 30, 2001
OK...a quick run down of what has been going on....two years ago I discovered I had a defective cam. Replaced the cam with the exact same grind and now I am down on power. I've used the same exact program as before.

Fortunately I recently discovered a data log at WOT the day before the Mustang layed 617 rwhp to the ground...So today I data logged a WOT run to compare the two. The baffling thing is the motor is ingesting the same amount of air and is running pretty close to the same air/fuel ratio.... The timing is the same as is the boost levels....it just takes several more seconds to run through third gear.....Any ideas????? I would be happy to send both logs to anyone interested at looking....

My combo is a 408 with an S Trim which makes about 8-10 lbs of boost depending on the air...

I don't think its the cam install since it is reading the same VE and psi...

I don't think its a fuel problem as the A/F ratio is 11 to 1....

And if it was an ignition, why would the A/F ratio be the same?

Maybe timing??????

The motor is in good health with 2-3 % leakdown in each cylinder...and I had FAST check out both the actual ECM, MAP and o2 sensor....

Paul
 
Sounds like you have researched this and reached decent conclusions. I would agree that it sounds as though the engine is healthy and things are in good working order.

That being said, how's the trans and/or converter? You'll never guess what I am thinking... :eek:
 
Craig...

Thanks for the reply, you have helped me in the past and I've appreciated it. And if you help me out with this, I will definately owe you a cold one as I've been scratching my head for a long time on this one....

I have a 5 speed manual behind this motor. The clutch isn't slipping as there is no sudden increase in rpms then acceleration.....the motor just doesn't make any power. Very baffling..

Paul
 
Originally posted by Blown86GT
Yes, the cam was installed the exact same...2 degrees advanced.

Paul
Click to expand...

Did you check it with an index wheel? Not all cams are manufactured the same, you should still check it with an index wheel. Just because you installed it the same way as the last cam doesn't mean you have the same timing.

+/- 2 degrees isn't all that uncommon, and I've heard of cams 10 degrees off. If your last cam was manufactured +2 and this one is -2 (or vice versa), you could have very different results. I picked up 9 MPH on my existing cam by changing cam timing only 4 degrees.

-Bob C.
 
Originally posted by bobc455
Did you check it with an index wheel? Not all cams are manufactured the same, you should still check it with an index wheel. Just because you installed it the same way as the last cam doesn't mean you have the same timing.

+/- 2 degrees isn't all that uncommon, and I've heard of cams 10 degrees off. If your last cam was manufactured +2 and this one is -2 (or vice versa), you could have very different results. I picked up 9 MPH on my existing cam by changing cam timing only 4 degrees.

-Bob C.
Click to expand...

No sir I did not. However, I didn't quite go into the detail in my above summary. This is actually the third cam I have tried with the exact same grind. When I initially swapped cams, I told comp cams my problem and they thought they might have misground the camshaft so I pulled it out and sent it off. The cam specs were spot on but they noticed a little wear on the distributor gear so they sent me another cam of the same spec. So this is in fact the third cam of the same specs I have tried....

I totally agree with your assesment. However, the car is down more than 40-90 hp. It feels as if its lost 400 hp...I don't think it would get out of the way of my stock 03 Mach 1 as it runs now...

I am at a loss...it seems as if it could be something simple but I am not seeing it...Thanks for your help and if you have any other ideas, I would appreciate it...

Paul
 
????????????

If you have finite dyno data as suggested by the number posted in your sig, why not do the dyno pulls again, and verify the real HP numbers??
It sounds to me as tho you are using the "butt dyno" as a comparo. Rite? wrong?

Also, as Bob has pointed out, the cam timing has to be verified. Is the timing chain set the same one, or is it new? Springs new?

My last cam fiasco resulted from a drive pin that was several degrees off when the cam was made... Not fun to find...:eek:

I'd like to see the logs...:cool:
 
Re: ????????????

Originally posted by Chuck Leeper
If you have finite dyno data as suggested by the number posted in your sig, why not do the dyno pulls again, and verify the real HP numbers??
It sounds to me as tho you are using the "butt dyno" as a comparo. Rite? wrong?

Also, as Bob has pointed out, the cam timing has to be verified. Is the timing chain set the same one, or is it new? Springs new?

My last cam fiasco resulted from a drive pin that was several degrees off when the cam was made... Not fun to find...:eek:

I'd like to see the logs...:cool:
Click to expand...

Yes I am using the butt dyno...There is such an extreme loss of power, there is no mistaken it. As I stated in a prior post, its not a matter of a few horsepower but a major loss of power. The Mustang would spin the tires at will in third gear. Now it won't spin them in first. The engine takes forever to run through the rpms...There is no mistaken the loss. Everyone who has helped me try to troubleshoot this agrees there is a large amount of power missing...

I can agree the cam timing would play a role in the loss of some power. However, this is such an extreme loss that I feel the problem is elsewhere. I know it is easy to dismiss the ole butt meter but trust me, there is no mistaken the large amount of power missing from the car....

I considered the springs...However, wouldn't faulty springs show up in the data logs in a round about way? As I said earlier, the motor is ingesting the same amount of air judging by the MAP readings and the VE. If the springs were faulty, wouldn't the MAP readings reflect this with a lower reading? Or am I way off base here?

Paul

I will send you the logs when I transfer them from my lap top to my desktop...Thanks
 
No power!

Paul said:
"I considered the springs...However, wouldn't faulty springs show up in the data logs in a round about way? As I said earlier, the motor is ingesting the same amount of air judging by the MAP readings and the VE. If the springs were faulty, wouldn't the MAP readings reflect this with a lower reading? Or am I way off base here?"

I had a spring issue w/ my GN. It would run OK, the data logs looked OK, but the HP was WAAAY down.
Max rpm was off by over 1000... Changed the springs and the car picked up 11 MPH.
Given your statement that 3 gear takes way to long to get thru, it could be low spring pressure not allowing the engine to rev like it once did.
Are the springs new?? What kind of cam is this?? Roller, flat, hyd roller,etc??

A leakdown won't tell you about the valvetrain.. only seat seal and ring seal. A cranking compression test will show poor combustion chamber pressure while the valvetrain is in action. I'd try it.

A dyno printout will show if the engine accelerates well at low speed, and will also tell us about upper end power by looking at the HP and TQ curves. Also, look at the RPM plot on the data logs. Are they similar in rise, etc??

U R rite about the "butt dyno".. It works as a rough guesstimate..
 
Re: No power!

Originally posted by Chuck Leeper
Paul said:
"I considered the springs...However, wouldn't faulty springs show up in the data logs in a round about way? As I said earlier, the motor is ingesting the same amount of air judging by the MAP readings and the VE. If the springs were faulty, wouldn't the MAP readings reflect this with a lower reading? Or am I way off base here?"

I had a spring issue w/ my GN. It would run OK, the data logs looked OK, but the HP was WAAAY down.
Max rpm was off by over 1000... Changed the springs and the car picked up 11 MPH.
Given your statement that 3 gear takes way to long to get thru, it could be low spring pressure not allowing the engine to rev like it once did.
Are the springs new?? What kind of cam is this?? Roller, flat, hyd roller,etc??

A leakdown won't tell you about the valvetrain.. only seat seal and ring seal. A cranking compression test will show poor combustion chamber pressure while the valvetrain is in action. I'd try it.

A dyno printout will show if the engine accelerates well at low speed, and will also tell us about upper end power by looking at the HP and TQ curves. Also, look at the RPM plot on the data logs. Are they similar in rise, etc??

U R rite about the "butt dyno".. It works as a rough guesstimate..
Click to expand...


Thanks chuck...I will try a compression check tommorrow. I will post the results....

It does seem like the car accelerates slow throughout the rpm range....down low, up top....

Paul

BTW--Its a hydrualic roller cam...
 
Spring check...

While you are doing the compression check, it might pay to check lifter preload by running the valves, and even pulling a couple springs and checking them.
On my deal, I had VERY little time on a set of springs that were installed new at 140# seat and 400# open at max lift. A check after approximately 50 passes and zero street miles, they were at 100 and 300..NOT good.
The mfgr concluded they were "killed" by hi rpm burnouts.

We now run the CC beehive springs made for BBC. They went on at 170# seat/390# open...Seem to work well, even tho some say a hyd roller won't operate w/ that much pressure. I run the preload at <.030". Just enuf to keep the plunger off the snap ring in the lifter.

One more idea... What's the battery voltage??
 
I agree with Chuck. Check the springs and go from there.

We have had that problem and the motor would simply fall off on the top end on a dyno.

What was happening was the turbo was blowing the valves back open because the springs could not hold correctly.

We have wiped out 3 cams trying to figure out what was going on.
 
I ran a compression check today as was suggested. It varied very little 178-183 in all 8 cylinders. I also hooked up the timing light to each plug wire to verify they are all firing and they were...I also reverified the firing order for the 100th time...its good.

I went ahead and reverified nothing has changed on the program either....all the parameters are set properly.

I know this is definately veering away from being a problem with the FAST system but I still would appreciate any help. Could it be possible the exhaust somehow is clogged?

I am definately going to get a couple of the springs checked Monday. I will post the results then.

Paul
 
Data log??

In looking at the data log,"Daybdy", the commanded A/F of 11.9 is never attained during the run thru the gear. However, I see that prior to the run, the commanded of 12.5 is being held.
I am seeing an actual A/F in the 10 to 1 range..
I am also seeing the VE very high at over 110 in some areas...

Is the run being logged in closed loop?? Do you have the setup for closed loop min and max rpms backwards??

Also, when you whack the throttle, the engine goes dead lean at 14+ to 1, and then reverses to full rich at 9+ to 1... Something going on there??
I also see the A/F as being in a wide range during the run from 9+ to 11.75.

A look at the .GCT file would help...

Also, log WOT 26Mar shows the same wild A/F swing from 14+ to 9+...
Boost is also jumping around. 6psi to 9 then??

Is the fuel pressure reg referenced to boost?
Does the Fp gain a psi for each psi of boost over base pressure?

A VE at over 110 at only 3000rpm and 3 psi boost is ???
 
Sorry I didn't have a chance to work on my car today....I was involved in an accident in where a truck ran a red light and plowed into my 03 Mach 1. Its totalled....When it rains it pours!

The 26 Mar log I let off on the gas and shifted, stayed in it for a second or two and got out of it...Thats why the boost dropped. As for the spike in the air/fuel ratio...I'm not sure why it does that. The regulator is boost sensitive, its a Paxton unit. As for the VE going over 110, I always thought a forced induced car had a higher volumetric efficiency than N/A cars....Am I wrong?

I will send the gct file tonight. I appreciate your help. Thanks

Paul
 
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