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ST200 - where is my power?

S

Schem

CEG'er
Joined
May 5, 2009
Messages
75
Location
Krakow, Poland, Europe
Hi all,

According to THIS thread, I've replaced my non-ST200 airbox, with CSVT one, as ST200 airbox is obsolete, and hard to get.
CSVT airbox make my ride sound very nice, so it will stay.

But there's no difference in acceleration... so, intake replacing didn't change anything

So, I dynoed her...



Where are my horses?? :confused:

Please check THIS file - it is healthy (red) and mine (blue) ride torque and power curves...

The first one was dynoed at 57,2 F, mine at 86 F, so that's why I have less power up to 3500 rpm, I think.

But then, secondaries comes into the action, and "healthy" power, increases more, than mine... in the end ca. 20 HP is lost...

The torque curve is even worse...
After secondaries are opened, the other ST200 torque comes up, mine just do not comes down...

And secondaries are working for sure:
http://www.youtube.com/watch?v=YE5F3caDgtk

IMRC looks OK:


The piece of copper, which tells PCM that secondaries are opened, seems to be working...
Filters, spark plugs, cables and oil had been changed 1000 miles ago...
Ride runs smooth, starts flawless...
No problems at all, everything is OK with her, but she's too weak :D

So...what's wrong??
Too few gas after 3500 rpm??
Fuel pump??

I have ELM327 + ScanXL software + Ford Enhanced Add-on...
No CEL codes...

Which PID's should I check?
Air flow?
Throttle position??
 
what is your fuel pressure ? After i installed a Walbro i noticed a significant increase in acceleration. Lack of fuel pressure/flow could be the reason. Worth checking. ...G.
 
It can be the fuel fump... I'll check.
But for now, I've tried a little bit highway with ScanXL.

Here is my log (rpm, IAT [Celcius], MAF [g/min], IMRC response signal in Volts and IMRC on/off)

I marked Full Throttle as red.
http://w598.wrzuta.pl/plik/7jn8sIkNgaQ/schem1

It seems, that IMRC runs OK...
But the question is, if air flow is OK... after secondaries open, the air flow doesn't rapidly raises. It's less or more the same, as before...
Is it normal?
Can somebody check, how it should be?

As after secondaries open, there should be hard "kick" and better acceleration, I suspect air flow to be much higher, then before...

And in my case, there's no kick, and nothing happens...

If you tell me, that all is OK, I'll search the fuel problems...
And clean UIM and LIM :D
 
OK, I've checked almost everything.
Secondaries work for sure, I cleaned UIL and LIM and TB, changed oil and flushed engine before.

I also found stock airbox on e-bay, so the airflow is about 155,58 g/s max and the injector open time at 6000 rpm, WOT, is 25,7 ms.
Both are little bit bigger that on CSVT airbox, but my friend has 26-27 ms WOT at hight rpms... and he has stock V6 with ST200 software and non-svt TB optimized...

The fuel pressure is 3.2 Bar at iddling, 4 Bar at 4000 rpm... is it OK?

And where did you bought 225 Walbro?
Could you please, let me know the part no?

Compression is 12.5 bar on 1-2-3 and 12.0 bar on 4-5-6
How it should look like?

I'm waiting for 65mm Munstang GT TB, and my last chance is to tune it up after...
Or the pump? If it is not good...
 
Hi Schem; your fuel pressure seems OK at 3.4 and 4 bar (50-55 psi). The walbro i bought from a member on CEG. If you change your pump anyway, you need the fuel pump from an RS Focus (non return style).
Have you checked you exhaust system for blockages ? Are the catalytic convertors in good condition. I had one break up and it blocked the exhaust and slowed the car ...G.
 
Thanks!

If the pressure is OK, I'll let the pump live for now...

I also think about exhaust, but it seems to be in good condition... Oxygen sensors are working OK, emission is also within the norms.
I'll be sure after mounting the new exhaust, but I'd rather do it when the old one is broken.
So, it will be done, with MSDS headers and y-pipe, but not now.

The next thing is TB 65mm and tune.
And when the day will come, new exhaust... :)
 
...even if you are not going to change your exhaust, to eliminate it from the list of suspected faults.... you could check the condition of the catalytic convertors visually. By the way .. compression is quite even on each bank, nothing too obviously wrong. Normally if there is a problem, one or two cylinders are much lower than the rest. ... G.
 
gorman said:
you could check the condition of the catalytic convertors visually.
Click to expand...
Yep, but it's welded... :)
Uncut it to see inside? And then to weld again...
I'm pretty sure, that I'll break the screws while trying to unscrew it :)
If I break it... why not to mount the new exhaust... this is the thing I'm afraid of :)

gorman said:
By the way .. compression is quite even on each bank, nothing too obviously wrong. Normally if there is a problem, one or two cylinders are much lower than the rest. ... G.
Click to expand...
You're right. The engine is not new, but all cylinders looks similar...
That's good and bad info... :)
I'm happy that the engine is healthy, but I still have no idea WHERE'S MY POWER...
 
you can easily see the main cat. by undoing the y pipe. The rear bank cat. you can see from below.. the front cat. i'm not suggesting you cut it open.. would need a camera probe. The best you could do is see if there are bits of broken off cat. in front of the main cat. Are you sure the linkage between the front and rear secondaries hasn't popped out ? this causes a loss of power and has happened to me ...G.
 
Hmmm, camera probe... :rolleyes:
I'll take a look again, but Y-pipe and headers are rusty... I'm afraid I won't connect it back...
And, as I said... I'd rather not to spend money for new exhaust, now...
In the future for sure, but not now.

Secondaries work OK - on saturday, I took off UIM and LIM, so I'm sure all is in the right place...
 
.. have you ever changed the fuel filter ? quite cheap and will need doing if you get an RS or walbro pump ....G.
 
Yes... It was the first thing I did...
All filters, Motorcraft ST200 plugs, Motorcraft wires...
The engine runs smooth and without any problems... just not enough power :shrug:
 
seems like you have everything in the engine area covered.. which comes back to the exhaust system. BTW.. you'll love that 65mm TB
icon10.gif
. You know that garage stole your airbox .... they didn't swap your ecu too did they ? .G.
 
Your'e the devil and make me spend my money for the new decat. exhaust :laugh:
I won't sleep 'till I do it...
And it was so good, stock exhaust... "almost new".... :laugh: uhhhh...
Life is hard...

I've checked, and the UIM open is 66.5 mm... Flow meter is 70mm, the pipe (this black gum) is 80mm
So... the 65 TB will be perfect, instead of 60mm one :laugh:

According to the ECU - after TB swap, I'll remap her... so... we will see...
 
.. spray plenty of anti-sieze spray on the bolts. The exhaust should come apart if you take your time and be careful. I have headers and a main cat. I found it is the best compromise between performance and acceptable noise levels on long journeys. No cats. doesn't give enough noticable extra power to justify the noise. ..G.
 
I was also thinking of the main cat.
I like the smell better and I prefere engine grawl, then noise :laugh:

Maybe I stay with cheaper option... buy headers only, and leave the rest as it is...
 
you can always do the exhaust later if you are not entirely happy. From what you have been saying about rust .. i would get your headers coated ..G.
 
Is there any "how to" replace manifolds by myself?
I'm pretty sure that ordinary "exhaust-guy" here, won't do it right...

After I change it by myself, I can let him cut and weld the rest...
 
i've searched here and NECO .. anyone got the headers how to saved to their hard drive ? ...G.
 
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