Need Better Gas Milage!! Holley Projection. - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

Reply
 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 02-07-2003, 05:46 PM Thread Starter
Veteran
 
Join Date: Dec 2000
Location: Gray, Maine. US
Posts: 827
Thanks: 0
Thanked 0 Times in 0 Posts
 
Need Better Gas Milage!! Holley Projection.

Ignition Problems- Every once in a great while my jeep used to just shut off while driving. When it is in this state you can tell because when you turn the key it just cranks and you notice the tach doesnt move. After waiting a little bit it starts up and runs again. This had not happened in a long time but happened the other day. I put the voltmeter on the coil and it read 6.27 volts. Is that a little low??

Vaccum Advance- well there is none!! I unplugged the hose from the distributor and there is such a small vaccum it is like there is no vaccum advance. Now this hose is plugged into the base port holley says to use. Is this what is killing the gas milage? I can't seem to find any good source of vaccum on the projection base. So what should I do?

Backfiring - When I down shift and deccelerate in gear I get a loud bang back fire. If I shift into neutral while slowing down this doesn't occur. Now I only tested it once but with the fuel mixture down the backfire didn't occur. The only thing is with the mixture down when I try to start the jeep in the morning it never starts. I am going to email holley to see if they have any advice also but that is not a good feature.

It seems like maybe if the ignition was fixed it would start with a lower mixture. But there seems to be numerous problems so I really need some help. Thanks Mike

pbytrailz is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 02-07-2003, 07:14 PM
 
Join Date: Nov 2000
Posts: 2,687
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

Is it a stock ignition system? Electronic or points? Sounds like an area to concentrate on from the get go if it's been causing you problems. Weak and intermittent spark could certainly cause the problems you describe. Wish I knew more about the 360's but I don't. Someone will pipe up I'm sure.

Regarding the vacuum source, if it's ported vacuum, and I'd suspect that's what you should be using, it will have no vacuum at all at idle, as the port from which vacuum is being drawn is above the throttle plates. It's only when you tip the throttle plates open a bit that they become subject to vacuum. Got a vacuum gauge? You can verify this. Should have no vacuum at idle and vacuum should blip upward as you give it throttle.

You need a good spark and properly timed to give you good power and economy. Is your timing set close to spec? That should be good enough until you sort out that problem. After that, you should find the maximum advance you can give it by road testing and backing off from the point at which you get ping.

If the projection is like other fuel injection systems, it too relies on the ignition system for a source of impulses to gauge rpm and meter the fuel. Is there an 02 sensor? A map sensor? If there is a map sensor, it should not go to the same port that you hooked the vacuum advance, as that sounds like ported vacuum. MAP goes to manifold source. IE high vacuum at idle.
TiminMb is offline  
post #3 of (permalink) Old 02-07-2003, 11:44 PM
Official Historian
 
WILL's Avatar
 
Join Date: Sep 1999
Location: Hot Springs, AR
Posts: 8,339
Thanks: 1
Thanked 5 Times in 5 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

The only sensors on the projection is a coolant temperature sensor and a throttle position sensor. There is an optional O2 sensor for closed loop operation after the coolant gets to 70*F. It gets it's signal from the coil on stock and on mine from the MSD.
WILL is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 02-07-2003, 11:56 PM
 
Join Date: Nov 2000
Posts: 2,687
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

How about a MAP sensor?
TiminMb is offline  
post #5 of (permalink) Old 02-08-2003, 01:14 AM
Official Historian
 
WILL's Avatar
 
Join Date: Sep 1999
Location: Hot Springs, AR
Posts: 8,339
Thanks: 1
Thanked 5 Times in 5 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

Nope, no MAP sensor.
WILL is offline  
post #6 of (permalink) Old 02-08-2003, 09:34 AM
 
Join Date: Nov 2000
Posts: 2,687
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

Hmmm. With no map sensor involved, it's basically running on throttle angle versus rpm to determine air and fuel flow. They call that n-alpha, and it's really only used now on race cars that produce erratic manifold vacuum due to wild cams, and intakes. That sure puts a lot of importance on having a good throttle position sensor. From my followings of this board, I've heard a number of Holley users report bad TPS's due to water damage. You could easily test the TPS. They typically have 3 leads. It's just a simple variable resister. Typically some voltage, 5 volts on GM's, is fed to one end of the resistor. The other end of hte resistor is grounded. The throttle position moves a wiper up and down the length to produce a varying voltage in proportion to the throttle position. So you can either use a VOM Multimeter, digital or analog to measure a smooth and consistant voltage rise, or disconnect the wiring and measure a smooth and consistent change in resistance over the range of the throttle position.

Does this version of Projection have any ability to tune?

And how do your spark plugs look for color?

You've got to chase those gremlins out of your ignition system first.
TiminMb is offline  
post #7 of (permalink) Old 02-08-2003, 12:48 PM
Official Historian
 
WILL's Avatar
 
Join Date: Sep 1999
Location: Hot Springs, AR
Posts: 8,339
Thanks: 1
Thanked 5 Times in 5 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

There are five adjustments to the fuel map.

Main - moves the whole fuel map up and down.

The other four are at the "edges" of the fuel map square.

High RPM, idle, acceleration, and choke.

Once the coolant temp reaches 70*F, the "choke" is off and the fast idle solenoid turns off.
WILL is offline  
post #8 of (permalink) Old 02-08-2003, 01:37 PM
 
Join Date: Nov 2000
Posts: 2,687
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

If you are planning to keep the system, an inexpensive 02 sensor like they sell from Summit might help in tuning it to the best it can be. Have you met or heard of any others that have made this system work well for them? Have you done an extensive web search for that model to find others installs described?
TiminMb is offline  
post #9 of (permalink) Old 02-08-2003, 02:09 PM Thread Starter
Veteran
 
Join Date: Dec 2000
Location: Gray, Maine. US
Posts: 827
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

Hi. Yes I believe there is a problem with the ignition system somewhere. It is a stock jeep system. I just dont know where to start. I have almost thought that it was the ignition module that was the problem but never replaced it.

I think that timing will have a big effect but I don't have a timing light here so wont be able to check it for a while. As far as the o2 sensor I already have one just haven't installed it yet.

I have one local friend that also just got the system so that isn't much help. The only other person I know is WILL that has it.

As far as the vacuum advance you are right at idle there is no vacuum. But even when I get the rpms up the vacuum isn't half as much as on my old 258. I will have to wait til i have the timing light but I don't think it is actually advancing it.

I know this isn't the best system but it does beat the carb. Although it eats a lot of gas it does idle smooth, start right up with exception of ignition problem every now and then, and it idles on steep angles. I got it brand new for $350.

Thanks Mike
pbytrailz is offline  
post #10 of (permalink) Old 02-08-2003, 03:17 PM
Official Historian
 
WILL's Avatar
 
Join Date: Sep 1999
Location: Hot Springs, AR
Posts: 8,339
Thanks: 1
Thanked 5 Times in 5 Posts
 
Re: Need Better Gas Milage!! Holley Projection.

IMO, for $350, it's worth the hassles. You can always save for and assemble the Mega Squirt controller later and you'll already have the throttle body, O2 sensor, fuel pump and temperature sensor installed. All you'll have to do is get a MAP sensor. That's what is on my long term to do list.

First I have a FSJ to finish stripping and getting suspension and body mounts installed so I can swap my CJ body and drivetrain onto it.....
WILL is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome