replaced my 170k mile stock valvesprings

[litdog83z]

... and my car is slower now... ?????

I don't know what to think about this thing anymore...

A week ago I took it to the track:
Hot and somewhat humid outside, running 15psi of boost. Car feels flat on the top end, and only picked up 16mph from 1/8 to 1/4
Ran 14.4 @ 90 mph with a 1.99 60'

Well, I replace the stock valvesprings with a set of comp 980s installed without the stock cups, and the car feels pretty decent, but can't really tell mmuch difference..

Go to the track, and it runs a 15.0 @ 89mph with a 2.1 60', but it feels even flatter at the top of every gear and starts breaking up in the middle of third and rpm's and boost dropped until I let out of it. Boost feels harder to build on the line, etc..

Both weeks I'm trapping at about 750 mv o2, absolutely 0 knock.

I only ran it twice tonight, because something was obviously not right... no other changes to the car since then, except a new set of R44TS plugs gapped at .033 or so...

On the way home tonight, the car jerks faintly while i'm cruising, and feels like it weighs an extra 1000 lbs or so... It just doesnt feel right.

Any ideas? did I wipe a cam lobe with the new springs and very high mileage cam? It didn't run what it should to begin with, but it's just getting worse..

Mods:
Stock Engine with:
Stock Turbo, Transmission, Rear end
stock cracked header...
Walbro 340 pump, AFPR set at 41psi (where it runs best)
TT chip burnt for 91 & my 50lb injectors
Dutt Neck IC
RJC power plate
K&N cone filter/solid MAF pipe
15psi on adjustabe actuator (no more wastegate solenoid)

 

[SPOOLN]

Fix your cracked header, bring your mv up to .80-.81 your car should run faster. Also change your fuel filter....

 

[litdog83z]

yes, i know that'll help, but why does the car feel heavier and run slower now vs before the valvesprings...

 

[BlackBandit]

...no other changes to the car since then, except a new set of R44TS plugs gapped at .033 or so...

What plugs and gap were you running before? Do you still have the old ones and was there anything wrong with them? If you do have them you might try sticking them back in to see if anything changes. Plenty of people have had problems with new plugs. HTH

 

[litdog83z]

What plugs and gap were you running before? Do you still have the old ones and was there anything wrong with them? If you do have them you might try sticking them back in to see if anything changes. Plenty of people have had problems with new plugs. HTH

Before I was running the R44TS with .035 or so gap... I managed to break the passenger rear when pulling them, so I just bought a new set...

 

[V6 Beast]

Never tried 44's I always run CR43TS on street and CR42TS at Track. (The CR has bigger electrode) Through the hole in the valve cover you can put your finger on top of the rockers on 3 & 5 and compare the movement. When I wore lob out, the rocker on #3 moved considerably less. You can run it for brief periods with no valve cover and visually look while not getting too much oil everywhere.

If you have a header leak then it could be running rich when cruising because air getting into exhaust will make o2 sensor read leaner.


Sully

 

[litdog83z]

Yes, I know that the exhaust leak will cause it to run rich, but why does the car run worse now with the new valvesprings? The car has had a cracked header since I got it (it's been repaired twice, including a "professionally repaired, supposed to never crack again" header I bought from a TR parts vendor)

 

[The Machine]

I feel'ya

I'm battling this problem in another thread. Pull your plugs & read them. Right now mine is missing \ skipping, and the #3 plug is fouling. It's all black & sooty.

I just took my injectors in & had them flowed & stressed, and checked for bleed down, they were fine. I've also done the sp wires, different coil & module, diff ECU, plugs, a new walbro pump & hotwire.

My next step is to do as V6 Beast suggested & compare the lift of the rockers, most likely with valve the cover off.

Apparently these motors are known for problems with the #3 lobe due to an alignment issue with the lifter gallery, mainly the exhaust on that cyl. There are threads which cover that topic also, and how many aftermarket cams fail prematurely due to lack of reverse tapering on that lobe to compensate for the issue.

Once I've verified a wiped lobe, I'll begin shopping for either a strong flat tappet, with the proper provisions on #3, or a roller hyd setup, which supposedly does away with the issue "sometimes".

Good luck!
Jimmy

 

[neat]

If all you changed was the springs, there shouldn't have been a performance loss. My bet is that something you touched/messed with during the spring swap is not right. I really doubt the springs themselves are to blame for the performance loss.

Have you checked for vacuum leaks? A hose left unhooked somewhere? That would explain the increased lag and possibly the lay down up top.

Maybe there is a sensor or something unhooked somewhere.

I don't really have much advice other than to go back over the basic stuff like hoses and connections.

Good luck!

 

[litdog83z]

Yeah, it doesnt make a lot of sense to me either, only thing the springs could have messed up was a wiped lobe, so it's gotta have something to do with the spark plugs or something I inadvertantly messed up...

Now that I think about it, this is what it was doing the first couple runs when I first took it to the track. I lowered the fuel pressure after that and it made it run much better, so maybe it needs to be adjusted again because it's trying to work correctly now... My only explanation for running funny on the street under normal driving is that when I messed with the boost control, maybe I didn't get it set back up like it was before...

I have an adjustable wastegate actuator, and a TT chip. I have heard these have a quick spool thing built in where I guess it holds the wastegate solenoid open for it to spool faster... When I first put in the chip, the thing would just spool to over 20psi... Well I hooked it up again the other day after driving without it, and turned down the adjustable wastegate rod and got the boost right, but it spikes and surges and all sorts of lovely stuff. Does that mean my adjustable rod isn't tight enough? Maybe I can fine tune it to work right?