TBI Help

[Bill usn-1]

From the same site you posted.
Keep in mind that timing also affects vacuum. So you can adjust the distr at idle to see the affect it has.

Dyno Graphs
Xtreme Energy Camshaft™ Dyno Results

Xtreme Energy Cams™ bridge the gap between Magnum street cams and race only cams. Xtreme Energy Cams™ provide increased torque, vacuum, response, and power while still providing quiet operation of the valve train and the durability required in daily driven vehicles.

Dyno Results

Camshaft Part #12-234-2

Grind #XE256H-10

Duration @ 0.006":256° / 268°

Duration @ 0.050":212° / 218°

Max Lift w/ 1.5RR:.447" / .454"

Lobe Separation:110°

Lobe ID#'s:5441 / 5230

Intake Centerline:106°

Engine Type:Chevrolet 350 Small Block

Bore:4.040"

Stroke:3.480"

Displacement:356ci

Compression:9.25:1

Heads: Dart S/R

Intake:Edelbrock Performer

Carburetor:Holley #3310 Vac. Sec.

Exhaust:1 5/8" Headers

Max Torque:411 ft*lbs @ 3600 RPM

Max Power:330 HP @ 4700 RPM

Manifold Vacuum:18.5" Hg @ 800 RPM & 20" Hg @ 1000 RPM w/ no load.

[chug302]

Originally Posted by Bill usn-1

The fuel and log looks good.
So you need to look into your timing more.
Verify it is working properly.

I also noticed the map reading is almost 50 and warm idle.
You should hook up a vacuum gauge and compare the manifold vacuum.
Is the 6 cyl stock or does it have a cam?

I connected my vacuum gauge inline with the MAP sensor and it reads 18 at idle. I also put a fuel pressure gauge inline and my fuel pressure is 12 at idle and revved up.

I don't know the condition of the fuel injectors, I was just told the previous vehicle ran good. I took a couple short videos of each injectors spray while the motor was at idle. I was wondering if they look like they have a good spray pattern.

thanks,

Scott

http://dl.dropbox.com/u/27638873/MVI_2043.AVI
http://dl.dropbox.com/u/27638873/MVI_2044.AVI

[Bill usn-1]

How did the vacuum reading compare to the map reading?

Fuel spray looks ok.

Is the timing working properly?

[chug302]

Originally Posted by Bill usn-1

How did the vacuum reading compare to the map reading?

Fuel spray looks ok.

Is the timing working properly?

The Vacuum Gauge reading was in 18 in HG and the MAP reading was 40 KPA. An online conversion site indicated 18 inHG = approx. 60 KPA.

I tried swapping out the distributor coil and control module and it made no difference, so I guess the ignition is good. The mechanical advance of the rotor moves freely and doesn't seem to bind. I don't know what else to do to test the distributor/timing.

Scott

[Bill usn-1]

Things are a little different/confusing when using a pressure conversion vs the manifold vacuum. Even the calc I posted isn't correct.
From the parts FAQ.

This is the voltage to pressure table for a standard 1-bar MAP...
Volts, kPa
0.00, 00
0.30, 10
0.60, 20
1.10, 30 (approx 20 Inch mercury vacuum)
1.70, 40
2.70, 50
3.30, 60
3.80, 70 (approx 10 Inch mercury vacuum)
4.40, 80,
4.90, 100 (no vacuum; full atmosphere)

Your map looks pretty good.

Here's a complete conversion.



If your the one running the fuel only then the timing is all in the distr.

[chug302]

Thanks for the MAP info.
I'm not sure what to do from here.

I checked the fuel pressure 12psi (idle and load)
Vacuum appox. 18 (idle)
Voltage seems good.
You said the Injector spray pattern looks good.

I have two separate chips from Howell made for the 4.2 and it runs the same on both.

WinALDL data seems to look ok.

I swapped out the coil and the ignition module and it made no difference.

At this point I don't even have the EGR or any of the California emission hooked up (to rule out vacuum leaks in any of those components.) It runs the same either way.

I'm not sure what to try next.

Rebuild TBI?
Clean or get new Injectors?

Any ideas?

Thanks,

Scott

[Bill usn-1]

What's your main concern right now?
Have you logged data recently with BLM table?
If the fuel is fairly close then that's all the system does and your problem is with your engine/jeep.

What base timing are you running.
If fuel only then you should be set around 10*

[chug302]

My main problem is that it doesn't run right, especially after it warms up. I can drive along at 1800rpm ish, up hill or level surface and it will backfire. I know there's a lot more power to be had.
The engine was rebuilt approximately 1000 miles ago and ran good before the swap.

I don't have any error codes or check engine light.

I did the screwdriver to the injector and ear test. The injectors sound the same and good.

The base timing is set at 10.

The more I look at it I would say the idle is even a little rough. The I6 should be very smooth at idle due to the nature of the engine.

I believe there's something wrong that when fixed will bring this all together.

Scott

[Bill usn-1]

Was the only thing you changed the carb to TBI or did you change the distr also?

The one blm data file I saw looked pretty good. So that tells me you may have other problems.

Have you hooked up a timing light and watched the timing as you rev it up?

Are you running ported vacuum or manifold vacuum to the vacuum adv?
I would recommend the ported vacuum.
Check the parts required FAQ for the correct port to hook it to.
Also make sure the vacuum adv is working by applying vacuum to the hose and make sure the timing goes up.

Base timing is set with the hose disconnected and plugged.

[chug302]

Originally Posted by Bill usn-1

Was the only thing you changed the carb to TBI or did you change the distr also?

The one blm data file I saw looked pretty good. So that tells me you may have other problems.

Have you hooked up a timing light and watched the timing as you rev it up?

Are you running ported vacuum or manifold vacuum to the vacuum adv?
I would recommend the ported vacuum.
Check the parts required FAQ for the correct port to hook it to.
Also make sure the vacuum adv is working by applying vacuum to the hose and make sure the timing goes up.

Base timing is set with the hose disconnected and plugged.

My plan was to install the TBI with the existing ignition, but my over zealous brother swapped out the distributor while I was on a parts run, so both were swapped at the same time. Not my favorite idea. All of the work was done in Indiana, then I shipped it out to California where it and I are now.

I think I have had a timing light on it as it was revving, but I'm not sure. I'm going to go do that here in a few. I'm even going to put some tape on the Harmonic Balancer to extend the timing marks.
The distributor is hooked up to ported vacuum. I connected it to the non ported plug once just to see if it made a difference. It was quite funny, every time it a cylinder fired, the vacuum would cause it to advance really far, then the next cylinder would miss.

I will move my vacuum gauge to the ported port when I check out the timing advance.