454 xli RPM falling and coming back up - Timing?

I am getting a intermittent issue of different types on both engines, I will try to explain as short as possible. Fuel pump change made no difference (or might have for worse on star), Changed the RACOR 320's, Replaced injectors. (1997 XLI 454 TBI MEFI1) 75 gallons of new fuel (this years)


Starboard - Runs great all the way up to cruise speed which is 3200-3300 on my boat. After about 1 min of plane it falls down, (about 2700-2800), After a second it jumps back up to 3300....Then it runs a min correctly then falls down again. If I keep playing with throttle it will not do it as bad, If I am at 2000 RPM plowing it will not do it. Could this be timing? Ignition/spark related? TPS? When I bought the boat I replaced plugs, wire and distributor cap and rotor and now the fuel pump and injectors. I have not had time to put fuel pressure gauge on it to see if it is dropping when this happens, I suppose this will narrow it down to fuel or spark or even 12v FP connection. Just curious if anyone has had similar issue before with remedy?

Port - Engine runs OK but has some irregular sounds in exhaust which has large mufflers so it is hard to tell but it has a small miss and chug sound unlike its sister. I think it is out of time. Question I have is I think this is my fault, When I replaced Dist Cap and rotor when I first bought the boat this time last year, The rotor I purchased did not seat on shaft all the way and when I went to start engines, it never fired..... after cranking 2-3 separate times. Pulled cap off and shaft was spinning in rotor. So when I did this, did I take it out of time when I put the rotor back on? More than likely shaft is now in different position falling on a different spark plug wire in distributor? Also this distributor is clocked in a different position than the starboard, Both are Standard rotation engines. The engines are MEFI 1 TBI so from what I read is they are base set from factory and should not need adjusting really? Yes/no?

Port #2 - When on plane, engine comes up strong, I get to 3200-3300, runs there 5 min and then the sound changes on that engine and RPM's start to climb higher without any throttle adjustment and sounds cleaner/stronger when this happens. Then I have to back it down a touch and it sounds different again but then it goes out of sync and I have to keep on throttles to keep it sync'd up? Could this be part of a timing issue too? Over my head.


Anti siphon valves are going to be next stop but after that I am just not sure where to go except to the check book to hire in a tech. I just like to know what they are talking about so I can keep them grounded. Any help is appreciated.

pressure gauge is where i would low rpm and under a load it just ends that step

Wow.... lots of potentials here.

I may not the best one to be making suggestions for this system.
Hopefully one of the other more experienced TBI guys will chime in here.
However..........

You most likely have EST ignition systems and EST ignition modules.
These systems delay the spark event, and then decrease the delay as per engine demands.
Engine demands = increase in RPM (above BASE advance), knock sensor influence (if equipped), temp sensor influence (if equipped), etc.

Two things that will affect engine RPM while under load:

• change to the fuel delivery F/A ratio
• change to ignition spark lead

If a sensor is causing a change in RPM....., that may perhaps explain what's going on.


BTW..... the clocking of the one distributor housing does not mean much.
As long as the triggering device and rotor are indexed correctly, and are positioned for #1 cylinder (TDC C/S plus BASE advance), and as long as the firing order is correct........ the distributor's housing orientation should not matter.



.

Ok so had a tech come. Starboard had antisiphon valve sticking
and had piece of rubber in it. That cured the falling down on that engine.

Hooked up laptop to port and timing was off like 12deg high. Also did it with light. He backed it down to 10 from 22. However my total advance is way high on both engines. Like 42. Seems like it should be 30-32?

Engine idles les much smoother however Ive lost wot on this engine now. I have to use other engine to help it get up to throttle. Really worries me. It would at least be strong and hold cruise rpm before these adjustments. Now it has nothing from 75-100% throttle. Like it doesn't even try to keep going.

Fuel pumps are new, injectors are new, racors just changed. Now I'm scared to run it hard with this timing all out of wack. Cap and rotor also changed. Plugs last year. May pull them since it was out of time.

I'd call the tech back and ask WTFO?

You need to have adequate pump pressure and it needs to be verified...

And the timing needs to be set correctly; once set, it shouldn't need regular adjustments.

Me in blue text again.

Mccoy38 said:

Hooked up laptop to port and timing was off like 12deg high. Also did it with light. He backed it down to 10 from 22. However my total advance is way high on both engines. Like 42. Seems like it should be 30-32?
Total advance numbers are rather meaningless without an associated RPM.
This guy should be including the rpm at which he's seeing this much ignition advance.
Examples:
42 degrees of full-in advance @ 5,200 rpm may not be an issue.... although this engine should not be operated at 5,200 rpm.
But that same 42 degrees of full-in advance @ only 3,000 rpm would most definitely be an issue.
That much ignition advance at that low RPM would cause very destructive Marine Load Detonation.

Now I'm scared to run it hard with this timing all out of wack.
I would be also.

Click to expand...

42 was at like 3000 rpm's. So if it is this high how is this corrected? It is way over my head.

It was weird bc both engines are set that high.

Pump pressure is at 13 psi through all throttle ranges with old pump and new pump.

Mccoy38 said:

42 was at like 3000 rpm's. So if it is this high how is this corrected? It is way over my head.

Click to expand...

Again, some of the guys are better equipped to answer your questions.

It may be posible that your EST system is throwing out 42* at this RPM while there's no load on the engines.
Yet while under load, and when further engine data is acquired via the ignition module......., the system may cut this back.

Be willing to pay for proper diagnostics that will indeed identify the problem.
Then and only then, proceed via a written work scope "Quote" that states the work will correct the problem.
Otherwise..... you're letting them haphazardly spend your hard earned money.

.

RicardoMarine said:

Again, some of the guys are better equipped to answer your questions.

It may be posible that your EST system is throwing out 42* at this RPM while there's no load on the engines.
Yet while under load, and when further engine data is acquired via the ignition module......., the system may cut this back.

Be willing to pay for proper diagnostics that will indeed identify the problem.
Then and only then, proceed via a written work scope "Quote" that states the work will correct the problem.
Otherwise..... you're letting them haphazardly spend your hard earned money.

.

Click to expand...

I am doing all I can with what we have here. There are no Crusader dealers here any longer. The ones that are left never messed with TBI engines it seems, Only Carbs. The TBI injectors are no longer available for these engines and is a issue. The guys are decent but I could tell they were a little hesitant on even using the computer to put it in base time mode. So I am doing my best to educate myself on these engines so I know they are not bending me over. Just really frustrating b/c we have hand full of techs here in town and all are so busy. Is timing suppose to be set under load? Or I guess it can be checked under load I assume. I just do not know enough about it so I am willing to pay but finding right guy is proving tough.

Mccoy38 said:

Is timing suppose to be set under load? Or I guess it can be checked under load I assume. I just do not know enough about it so I am willing to pay but finding right guy is proving tough.

Click to expand...

Non-EST ignition advance timing does not require the engine to be under load in order to set BASE advance, or even to check the progressive or TA.
However, an EST ignition system that acquires engine data to appropriate the advance, may require certain conditions.

Find out if you do indeed have an EST ignition system.
Find out if the EST advance is influenced by engine data.


.

Check your spark plug wiring on the Port engine, for maybe a crossed wire!

RicardoMarine said:

Non-EST ignition advance timing does not require the engine to be under load in order to set BASE advance, or even to check the progressive or TA.
However, an EST ignition system that acquires engine data to appropriate the advance, may require certain conditions.

Find out if you do indeed have an EST ignition system.
Find out if the EST advance is influenced by engine data.


.

Click to expand...

From everything I see it is EST ignition by the looks of the 8 pin module and remote ignition coil set up.
How the advance is influenced is another story as I do not completely understand this system.

I read where ECT sensor, MAP sensor and knock sensor all influence fuel delivery by the MEFI1 ecm and I guess the TA is controlled by the Distributor module? These engines being sea water cooled have 143* thermostats in them and I have confirmed this is correct with Crusader. Closed cooled engines have 160* thermostats in them. I never see over 145* on these engines.

I have owned boat for 1 year so I am not sure what has been replaced over the years since 1997, either automotive parts or correct OEM parts. The mechanic called earlier and wants to try and replace the entire distributor as this was advised by Marrysville marine to him. I see I can buy the parts loose as well but they said we had to buy complete.... I do not mind doing so if it fixes it but now I have to get them to agree to remove it if it is not the problem which is now throwing parts at it and not what I wanted to do b/c they will want the labor paid either way.

I will go over plug wires again but did that already but will make sure. Runs so much better than it did at idle and at lower RPMS but now is only giving me 60% power if feels like. Just really confused how it could run worse at higher RPMS when timing was set to Correct degree. Starting to wonder if it was a patch to cover up a problem.

Do the simple stuff 1st! like I said firing order: clockwise at Dizzy: 1-8-4-3-6-5-7-2 Front Rt side plugs 1-3-5-7, Frnt. Lft. side 2-4-6-8

A Delco ESt V-8 module will only have 22 degrees of advance....

8pin module - as long as they are split into 3 connector; 2 pin internal (pickup), 2 pin external (coil) and 4 pin for computer.

The advance is changed by the module based on a signal from the computer...and the computer determines "how much" based on the inputs received from the sensors monitoring the engine

makomark said:

A Delco ESt V-8 module will only have 22 degrees of advance....

8pin module - as long as they are split into 3 connector; 2 pin internal (pickup), 2 pin external (coil) and 4 pin for computer.

The advance is changed by the module based on a signal from the computer...and the computer determines "how much" based on the inputs received from the sensors monitoring the engine

Click to expand...

Thanks Mark, So then how are we reading 42* at dock? Distributor looks to be original as rusty as it is under the cap, Could barely get new rotor on. I am buying complete new distributor and hope to have someone install it this weekend and time it. Will see if that does anything.

With this type of distributor, the driven gear, the upper shaft and rotor all rotate 1:1 with each other.
Other than the indexing to the camshaft and relationship to the crankshaft, the EST distributor offers no mechanical or other type of advance.

So basically, this type of distributor is a triggering device only.
It also distributes the spark to the correct spark plug cable poles within the cap.

If the triggering device is working, and if the rotor distributes the spark correctly, what is there to go wrong with one?

I'm speaking of the distributor only.


Apparently this particular module offers only 22 degrees of advance via electronics algorythm.
Add BASE advance, and we have our progressive and TA.

How is this system able to provide 42* advance... unless the module is not varying the the spark event delay correctly?


I agree...... you should not pay for parts that do not solve the problem.
However, you'll certainly owe for diagnostics if they are effective.



.

RicardoMarine said:

With this type of distributor, the driven gear, the upper shaft and rotor all rotate 1:1 with each other.
Other than the indexing to the camshaft and relationship to the crankshaft, the EST distributor offers no mechanical or other type of advance.

So basically, this type of distributor is a triggering device only.
It also distributes the spark to the correct spark plug cable poles within the cap.

If the triggering device is working, and if the rotor distributes the spark correctly, what is there to go wrong with one?

I'm speaking of the distributor only.


Apparently this particular module offers only 22 degrees of advance via electronics algorythm.
Add BASE advance, and we have our progressive and TA.

How is this system able to provide 42* advance... unless the module is not varying the the spark event delay correctly?


I agree...... you should not pay for parts that do not solve the problem.
However, you'll certainly owe for diagnostics if they are effective.



.

Click to expand...

Well we will see what happens. Got new distributor kit with plug wires, coil, and complete distributor. Will go ahead and throw plugs in as well. 17 year old distributor may be the culprit (if even original) as I have read a few others on here that have gone through similar issues and distributor fixed the issue. The TA is what is puzzling me. Both engines are reading 42* TA at 3500.

I did lose a ECM last year and had to get a Mercruiser MEFI1 ecm and had Crusader program it for me but other engine is original so I feel that it is programmed correctly.

Mccoy38 said:

The TA is what is puzzling me. Both engines are reading 42* TA at 3500.

Click to expand...

Yes.... that puzzles me also.

Questions:

• How are you seeing and reading this 42* TA at 3500?
• Are you actually strobing your timing marks as you increase RPM?

If not..... mark off your harmonic balancer up to approx 35* in the direction that you would use to see ignition advance.
Strobe these markings dynamically with a Non-Advancing timing light, or an Advancing light while in Standard Mode, so that you can view this in Real Time/Real Degrees.

Do this... and you'll have WYSIWYG.


.

RicardoMarine said:

Yes.... that puzzles me also.

Questions:

• How are you seeing and reading this 42* TA at 3500?
• Are you actually strobing your timing marks as you increase RPM?

If not..... mark off your harmonic balancer up to approx 35* in the direction that you would use to see ignition advance.
Strobe these markings dynamically with a Non-Advancing timing light, or an Advancing light while in Standard Mode, so that you can view this in Real Time/Real Degrees.

Do this... and you'll have WYSIWYG.


.

Click to expand...

I watched from fly bridge on the throttles, I will have to ask techs these questions, Yes they were using timing light but I am not sure what type of light they were using. They had a laptop on it as well.

I can change parts out and do normal stuff but I am not a detailed mechanic when it comes to timing or rebuilding engines etc. Feel kind of ashamed b/c I quote and sell engines for Cummins Marine but I am no tech. I am reading up, watching videos etc b/c I do want to learn but feel I will dig a hole, burn up a ecm or something. Just want my engines done right to be able to use it as it is intended and on stuff I am scared to tackle on my own its money well spent if I get the right tech.

makomark said:

A Delco ESt V-8 module will only have 22 degrees of advance....

8pin module - as long as they are split into 3 connector; 2 pin internal (pickup), 2 pin external (coil) and 4 pin for computer.

The advance is changed by the module based on a signal from the computer...and the computer determines "how much" based on the inputs received from the sensors monitoring the engine

Click to expand...

I thought I read the Delco EST big block module provided 32* advance, plus the static 10* advance, but I'm not sure? It does seem a bit much though.

MikDee said:

I thought I read the Delco EST big block module provided 32* advance, plus the static 10* advance, but I'm not sure? It does seem a bit much though.

Click to expand...

32* progressive plus a BASE/Initial of 10* = a potential 42* TA. Yikes!


Marine engine loads are quite different from automotive. Detonation is a huge concern.
Detonation can be caused by several things:

• Poor fuel octane rating
• Lean F/A
• Excessive cylinder pressures
• Excessive cylinder temperatures
• Excessive spark lead

The last one noted can be refered to as Ignition Induced Detonation... of which is a real concern if the system is not functioning correctly.

(don't confuse Detonation w/ Pre-Ignition)


.

Here's an interesting, informative link I just found:

http://www.marinemechanic.com/site/page229.html

Update. My tech spoke to crusader and they told him that TA should be at 40. I know many seem to think this a lot but they assured us this was correct and the timing is done in the ECM on my engine. I do not know if that is correct so I can only go off what they say.

I went back to fuel. Replaced all filters. Tightened all fittings, pulled return line and blew air through it and it was a little clogged and freed up so got me thinking and put gauge back on. It was fluttering and dropping from 13 to 9. So I pulled fuel pressure regulator since that return line was a little clogged. Backed screws out and spring had no tension at all and was broken in 4 places. Finally!!. It was returning fuel back to tank at higher rpm's making me lean. Replaced with a 10 psi from napa and then engines would die when put in gear. Pulled it back off and put a quarter in FPR to tighten the spring up and fuel pressure rose to 15. She pops up on plane and runs great again, I'm not seeing 4400 I want to see and only see around 4100 at wot so I may play with the fuel pressure and get another spring rated at 18 psi and see if she likes that better.

You may want to check your props for pitch to see what they are able to do for wot rpm