1999 454 Mag MPI just quits - videos

ttmott said:
In this order -
Adjust the TPS with the primary butterfly stop screw - engine does not have to be running to do this.
Adjust the IAC with the secondary butterfly stop screw - engine does have to be running and at operating temperature to do this. I'd set the IAC as low in the duty cycle as possible.

Again, adjusting the secondary butterfly should not change the TPS zero.
Click to expand...

I agree with you but on several occasions now he has specifically said adjusting the secondary opens the primary. I don't remember this being the case but if his throttle body behaves this way it makes the adjustment problematic with the TPS.

I will also add why would they have two adjustment screws .....one for each throttle blade .....if you could not adjust them separately?
 
PlayDate said:
I agree with you but on several occasions now he has specifically said adjusting the secondary opens the primary. I don't remember this being the case but if his throttle body behaves this way it makes the adjustment problematic with the TPS.

I will also add why would they have two adjustment screws .....one for each throttle blade .....if you could not adjust them separately?
Click to expand...
I missed that and agree. But the secondary begins to open at a point after the primary is a percentage open. There is a slot in the actuating arm to accomodate that from what I can surmise. So, the secondary can be opened to a point without affecting the primary.
As a practical note why have a primary and secondary if not to stage the openings?
 
ttmott said:
In this order -
Adjust the TPS with the primary butterfly stop screw - engine does not have to be running to do this.
Adjust the IAC with the secondary butterfly stop screw - engine does have to be running and at operating temperature to do this. I'd set the IAC as low in the duty cycle as possible.

Again, adjusting the secondary butterfly should not change the TPS zero.
Click to expand...
Agree, except, if you grab the cam for the secondary and move it, you will also move the primary. If you move the primary cam, the secondary cam doesn't move until "half" throttle, as it should. I am seeing a bit of play in the linkage, so I believe there is some adjustment for the secondary, as you laid out above. I did the primary this morning, and the hunting is gone. YEAH! TPS voltage set to .55v and position % is 0. The idle was high (900+) even with throttle cable disconnected. Bumped the primary down to .45v and percentage still 0. Engine ran a bit worse, but the idle came down. thinking about moving back to .55, but not before I recheck timing. Secondary still out of the equation, and I know that is not factory, so once the timing is checked, I may use the secondary (which is moving the primary too, I swear!) to get back to .55v, or sounds right. Whichever comes first.
I will video my spare TB to demonstrate what I am saying.
 
370Dancer said:
Agree, except, if you grab the cam for the secondary and move it, you will also move the primary. If you move the primary cam, the secondary cam doesn't move until "half" throttle, as it should. I am seeing a bit of play in the linkage, so I believe there is some adjustment for the secondary, as you laid out above. I did the primary this morning, and the hunting is gone. YEAH! TPS voltage set to .55v and position % is 0. The idle was high (900+) even with throttle cable disconnected. Bumped the primary down to .45v and percentage still 0. Engine ran a bit worse, but the idle came down. thinking about moving back to .55, but not before I recheck timing. Secondary still out of the equation, and I know that is not factory, so once the timing is checked, I may use the secondary (which is moving the primary too, I swear!) to get back to .55v, or sounds right. Whichever comes first.
I will video my spare TB to demonstrate what I am saying.
Click to expand...
It won't take much of a turn on the screw to make a large difference in the IAC duty cycle. A small crack in the butterfly is a lot of air flow.
And that brings up a good point in that if the throttle shaft bushings are worn and there is play you'll play hell getting things to repeat. This is where you do the best possible.
 
for your viewing pleasure. I suggest that you download the 225 MB zip file into its own folder, unzip and then use folder tools to play all videos in the folder. They are numbered in order.
gotta go replace steering ram end seals on the cat. Maybe tomorrow am.
www.dropbox.com

4-6-24 startup.zip

Shared with Dropbox
www.dropbox.com www.dropbox.com
 
What huge progress......it warms my heart to see everything that you have gone through has almost got things sorted out.

I watched every video and your expressions captured everything.

Great work....and you certainly have earned a Phd in EFI on this one!
 
Heck yeah! Watched them all as well. Looks like you're almost dialed in! Great progress. Excited to see it move under its own power.
 
PlayDate said:
What huge progress......it warms my heart to see everything that you have gone through has almost got things sorted out.

I watched every video and your expressions captured everything.

Great work....and you certainly have earned a Phd in EFI on this one!
Click to expand...
douglee25 said:
Heck yeah! Watched them all as well. Looks like you're almost dialed in! Great progress. Excited to see it move under its own power.
Click to expand...
How the heck did you download the vids? I can't seem to pull anything from dropbox.
Never mind - I got them. They sound great - your face says it all!
 
370Dancer said:
for your viewing pleasure. I suggest that you download the 225 MB zip file into its own folder, unzip and then use folder tools to play all videos in the folder. They are numbered in order.
gotta go replace steering ram end seals on the cat. Maybe tomorrow am.
www.dropbox.com

4-6-24 startup.zip

Shared with Dropbox
www.dropbox.com www.dropbox.com
Click to expand...
So happy to see these videos. I watched all of them.

Onward and upward! Can’t wait to see the next videos
 
Close! The fuel pressure regulator would cause the popping upon acceleration. It sounds like the throttle blades still aren't synced if you're getting surging at idle. Once you get above idle and the butterflies open, it's likely more balanced and that's why it disappeared.
 
yup Trying again probably Friday. That's the port engine. Stbd still running out of throttle at 2000, so I've still got something going on there. I was surprised the advance was in the 30s at half throttle. Gonna grab a non Chinese timing light to see if this one's just crap.
 
The boat is moving under it's own power!!!
Two things can cause backfiring in an EFI engine - ignition crossfire and lean fuel condition.
Once you crack the throttle and the TPS is above 0 percent open the IAC is pretty much out of the equation. The ECM is injecting fuel mass based upon the manifold pressure. The TPS is now primarily for accelleration enrichment at this point (the ECM monitors rate of change in the TPS).
Fuel pressure should raise in direct porportion to the manifold pressure raising. That's the purpose of the little hose between the intake manifold and FPR. If the fuel pressure isn't raising with respect to engine load (manifold pressure raising) then the engine will go lean and can start backfiring.
On the off idle surging engine go through the TPS/IAC setup process. Check for loose linkages and fasteners or broken throttle return spring.
 
ttmott said:
The boat is moving under it's own power!!!
Two things can cause backfiring in an EFI engine - ignition crossfire and lean fuel condition.
Once you crack the throttle and the TPS is above 0 percent open the IAC is pretty much out of the equation. The ECM is injecting fuel mass based upon the manifold pressure. The TPS is now primarily for accelleration enrichment at this point (the ECM monitors rate of change in the TPS).
Fuel pressure should raise in direct porportion to the manifold pressure raising. That's the purpose of the little hose between the intake manifold and FPR. If the fuel pressure isn't raising with respect to engine load (manifold pressure raising) then the engine will go lean and can start backfiring.
On the off idle surging engine go through the TPS/IAC setup process. Check for loose linkages and fasteners or broken throttle return spring.
Click to expand...
Excellent explanation, thanks. The FPR was out of play as discovered yesterday after getting back to the dock. Could have been off when I was setting IAC value at idle, and or timing as well. The hose popped off the nipple on the FPR but didn't move, so I did not notice it until visual inspection. So, I'll just start over again on the setup.
I do see the IAC values changing, like the ECU is trying to utilize it even up to 1500 RPM. I'll look closer at the manifold pressure too.
 
Windy weekend until Sunday. Didn't get out to try to run them up. I have 2 small issues to deal with.
I think the Starboard battery bank is done, so disconnecting all and load testing them.
The port (newly built) engine is bleeding oil from somewhere when under pressure, even though the gauge pressure is nominal. Gotta find it. I'm down a quart just idling at the dock, and a couple of 5 minute runs. That's the most important right now. They are starting and idling fine, getting down to spec 650 RPM, and not losing it when I shift into and out of gear.
 
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