"Rev Limiter" feeling @ ~2500 RPM w/ Blower Installed

criticman · Mar 28, 2006

Running with the breather cap (I am assuming you mean an open filter element that screws into the fill tube top) did not cause you any problems? I guess that area just is confusing to me. I am not seeing why the hose from the oil fill tube runs to the TB on a stock setup...nor am I positive why it would work without that line hooked up and instead having a breather cap on the fill tube.

Anybody able to clear that up for me?

I am hoping to find time to regap the plugs this afternoon.

criticman · Mar 28, 2006

Well, Dave got back to me with word from PMAS/Pro-M. My MAF will not be here until next week at the earliest.

So, I am going to have to get this thing running with what I have if I have any chance of dynoing it on Saturday.

It sucks that I am not going to be able to work on it until Thursday morning.

Things I am going to try Thursday:

Un-Tee the fuel pressure regulator vacuum line and make sure it is solidly sealed.
Run the vacuum line from the top of the FMU to an empty port on the vacuum tree.
Make sure the tube is tightly connected from the oil fill neck to the conical filter box/shield from Paxton.
Install the 255lph fuel pump.
Get the bung welded on for the wideband and then get a buddy to ride with me to watch the wideband and PMS outputs...and hope I can get above 2500rpm @ WOT (I know both units data log, but to save time I will delay that setup/config and trust a buddy's memory and ability to read, lol).

If that doesn't fix it, I'll regap the plugs. If that doesn't fix it...I'll have a mental meltdown...or be posting here non-stop until I find an answer.

If anyone has any tips for my Thursday To-Do list in terms of making it better/quicker (i.e. a trick to a quick fuel pump swap, a quick check for vacuum leaks, the best place to run the wiring for the wideband, etc), PLEASE POST back with them and make my life a tad bit easier.

Mike92GT · Mar 28, 2006

criticman said:
Running with the breather cap (I am assuming you mean an open filter element that screws into the fill tube top) did not cause you any problems? I guess that area just is confusing to me. I am not seeing why the hose from the oil fill tube runs to the TB on a stock setup...nor am I positive why it would work without that line hooked up and instead having a breather cap on the fill tube.

Anybody able to clear that up for me?

The purpose of the hose from the TB to the filler neck on the stock set-up is to allow fresh air INTO the engine. Because it is right before the TB it creates an area of low pressure. Fresh air enters the engine here and is circulated in the engine to remove crankcase vapors. These vapors are in turn sucked out by the PCV system. You can't leave the tube hooked up for a SC application because it is after the blower, and everything after the blower gets pressurized. Leaving it hooked up would cause boost pressure to enter your crankcase. You will need to run a line from the V/C to the inlet side of the blower, but it sounds like you've already got that taken care of. If installing a power pipe you will need to install a 3/8 fitting in it to connect the hose to. Or you could run the breather, but doing so creates a small vacuum leak, as the PCV system will no longer be closed. Hope this helps some

criticman · Mar 28, 2006

That does help...a lot really.

jrichker · Mar 29, 2006

criticman said:
The ground idea makes sense - a friend of mine suggested that as well. He also said to remove any corrosion from the battery terminals. I did upgrade my alternator JUST before the blower install, but I also definately got on it without any issues after the alternator was installed (130amp PA-Perf.) plus I also upgraded the power wire.

What grounds need to be checked and how does one check them?

So that's one idea...anyone have more? Or any thoughts on whether or not aleborjas' idea will fix it?

Voltage drop testing of grounds.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection: more than .5 volts across a connection indicates a problem.
See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103 for help

Use a Digital Volt Meter (DVM) to measure the voltage drop across a connection or wire. Adding length to the test leads may be required, and does not affect the accuracy of the test. Use 18-20 gauge wire for the test leads if you have to lengthen them.
1.) Most grounds use the negative battery post as their starting point.
2.) The voltage will be small if the ground is good: less voltage drop = better connection.
3.) Be sure that the power to the circuit is on, and the circuit is being used in its normal manner. For instance, if it is a light circuit, the lights on that circuit should be powered on.
4.) To measure grounds, place one DVM lead on the battery negative post and the other on the wire or connector that goes to ground. Place the other DVM lead on the wire or connection you want to test.
5.) Read the voltage drop: Light duty circuits (1-5 amps) should show .1-.25 volts. Medium duty circuits (6-25 amps) should show .25-.5 volts. Heavy duty circuits (26 amps up) should show .5-.75 volt drop. A voltage drop lower that spec is always acceptable.

Tonys96Cobra · Mar 29, 2006

I had a good friend with the same problem a few years ago on his procharger car, minus the flickering lights. His problem was simply not enough fuel, seeing you still have the stock (old) fuel pump, and stock injectors, and you are trying to make 50% or more horsepower, I cant see it running right at all until you upgrade.

criticman · Mar 29, 2006

Yeah, I am hoping that is the case. I guess we shall see. Not enough time in the day right now though...

criticman · Mar 30, 2006

About to start trying everything that could be the problem. Wish me luck!

criticman · Mar 30, 2006

Alright, confirm which is the return line in my attached pic, A or B?

I am pretty sure I hooked up the FMU properly, but want to rule out any possible errors.

bluevenom867 · Mar 30, 2006

Pretty sure its A,fuel enters the fuel rails,the regulator gets it down to a certain pressure and send the rest of the fuel back to the tank.

Rick 91GT · Mar 30, 2006

A = RETURN

B = SUPPLY

Euphoric306 · Mar 30, 2006

Rick 91GT said:
A = RETURN

B = SUPPLY

makes more sense to me than the other way around, fuel enters injectors, any excess pressure is relieved by the FPR into the return line

bluevenom867 · Mar 30, 2006

Euphoric306 said:
makes more sense to me than the other way around, fuel enters injectors, any excess pressure is relieved by the FPR into the return line

Thats what Rick said.....

Fuel from the pump pressurizes the rails/injectors,the regulator regulates the pressure down to the desired setting by discharging excessive fuel back to the tank (from the FPR)

criticman · Mar 30, 2006

Alright, good, glad it was A. About to post a new MAJOR problem in a new thread so it gets attention.

criticman · Apr 1, 2006

Still working on the electrical issue. But an update on this thread...
-I ran a new vacuum line from the FMU to the vacuum tree where the A/C previously was.
-I reconnected the vacuum line for the FPR that I had previously (per Paxton's instructions) T'd into for the FMU.
-I made sure the crank case vent tube on the oil filler neck to the inline filter is solidly connected to the "box" that goes around the air filter.
-Cleaned the battery terminals with terminal cleaner to break down some corrosion and used a wire brush battery cleaner on the terminals and posts.

Car cranked right up, all was good until I slammed the hood and the chain of events set off the electrical issue.

I'll keep everyone posted on the "rev limiter" feeling issue once I get the electrical problem fixed and can crank the car again.

criticman · Jun 15, 2006

Electrical issue fixed. Now let's get this 'stang running strong!

criticman · Jun 15, 2006

So now all of my parts are here (namely, the Pro-M MAF). My best guess as to my next move is to install all of the upgraded fuel/air items and hope the issue gets fixed.

The other idea I had, since I can now drive the car to a shop, was to have the new wideband O2 bung welded in so I can make some runs with it logging, see if it can point to the problem.

Anyone have thoughts on this?

Tonys96Cobra · Jun 15, 2006

So what new parts did ya get? Obviosly a new maf, what else? Be specific, if you please.

criticman · Jun 16, 2006

Parts I have waiting to go on for this project:
-80mm Pro-M MAF, calibrated for use with 42# injectors, s/c, and boost pipe
-UPR boost pipe (I think they call it Boostmaster?)
-FRPP 42# injectors (brand spanking new)
-Kirban adjustable fuel pressure regulator w/ a nifty fuel pressure gauge (thanks Rick!)
-Walbro 255lph hi-pressure fuel pump
-Innovate LM-1 wideband O2 sensor w/ datalogging

I think that is everything, but it is late. So, now that you know the parts, what should be my first step? I am liking the wideband idea, just to see if it is a timing issue or a air/fuel issue.

Tonys96Cobra · Jun 16, 2006

Yeah, doing the wideband first is a great idea. That could prevent a lot of guesswork later on. Definitely keep us updated, as many guys here, me included, will be doing similar projects, hopefully soon!

"Rev Limiter" feeling @ ~2500 RPM w/ Blower Installed

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