Hi guys and gals. Low power at high rpm still. Can anybody tell me where to test the accelerator pedal voltages with a voltmeter? I don't have a scanner. thanks

 

You need to put a voltmeter across the GY/W and the GY/R wires on the connector to the TPS. With the key on, watch the voltage across the range of the throttle to see if there is any flat spots. You should see no less than .37 volts at idle position and no more than 4.5 volts at full throttle. The the third wire, (BRN/W), is the ref. voltage and should be 5 volts all the time.

 

If you can find a way to bump up the full throttle position voltage closer to 5V what will happen? More power?

I'm gonna do this test Friday to make sure it's working right B4 dyno day on Saturday.

 

You don't want a full 5 volts at Full throttle. it will set a CEL. anything above either 4.6 or 4.7 will set a CEL. but up to that point your good to go! I just removed pedal stopper that goes across the pedal and put a bolt with a notch ground into it for a longer pedal stroke. Still need to do that on my 97 though.

 

was it not registering 100% before you did that? a lot of throttle pedals reach 100% in the pcm before they reach the max voltage, so doing things like that dont make a difference.

 

the PCM could care less about %. it only sees voltage. The % is a calculation of the scan tool. In my case the voltage was lower. Its been a few years but I think it was close to 4 volts. Did some research in the diagnostic manuals and found the 4.6 or 4.7 number and decided if thats the max that should be seen then there is no harm in getting just under the max. it didn't make a huge difference but it made me feel good.

 

Thanks all! I'll check those voltages and report back. If that's not my problem, I'm thinking injector o-rings. I did one (#1 cyl.) last weekend to learn the techniques. I have a set on order-thanks TJ for the link to the best priced ones. -Related question- Is there a way to rig a gauge to an oil gallery plug and see if my high rpm uphill loaded oil pressure drops out pointing me to the o-rings? I've been through the IPR and CPS etc. THANKS AGAIN.

 

Here ya go...

Here is what is needed to put a gauge together thanks to Swamps site.

If you don't have access to a scantool, then go to your local hydraulic supply
house, and have them make you up a mechanical gauge. You might spend $60
or so on high pressure hose, fittings, and a quality 0-3500psi liquid filled
gauge....but having this hose available for future diagnostics might be more
valuable than you think.
The hose which you will need will need to be about 40" long, rated for
(minimum) 3000psi working pressure (12k psi burst rating!) with the gauge on
one end, and a #6 female JIC swivel fitting crimped onto the other.
You will also need an individual fitting to screw into the head to go from the
head to the hose.
This single fitting will be a 90degree fitting # 5 "male boss" (sometimes called #
5 o-ring) on one end of the 90, and a # 6 male JIC on the other end of the 90.
Our local hydraulic shop would label such a fitting as 5MB-6MJ90
"JIC" is nothing special...it's just 'hydraulic talk' for a 37degree flare
fitting...standard hydraulic stuff here...nothing rare by any stretch.
Looking at the top of (either) cylinder head, you'll see the factory stainless
braided oil lines (one to each head) then you'll see a few bronze colored
plugs... (Engine off, of course) Using a 5/8" wrench, remove any one of the
bronze plugs, and install the 90deg fitting into the hole. (save the plug for
reinstallation , after testing). and the O-rings are reusable, unless brittle,
cracked, etc...
The single 90deg fitting will have a "jamb nut" on the O-ring side...screw the
fitting into the head, "aiming" the 90 away from the turbo, intercooler pipes,
etc...and then tighten the jamb nut, to "squish" the O-ring also locking the 90
from "spinning" around as you attach the swivel end of the hose to the 90. No
sealants, loctite, or teflon tape are needed on "JIC" or O-ring fittings...and
don't overtighten them...usually about 180degrees with a wrench past finger tight.

 

COOL-THANKS Action- I could probably get a custom HPX crossover mod line made up at the same time! Plus that long line would come in handy going to my shop vac for draining out the oil in the heads for injector work