496 ho/headers to lean?
 

Has anyone experienced or heard of headers leanning out a 496 ho to the point that you loose power instead of gaining power.
Here is my situation, after installing headers I lost @ 700 RPM checked fuel preasure its 48lbs at idle 50lbs at 4000 RPM, it has a upgraded regulator because it has Raylar 525 kit,timing is 22@4000 RPM throtlle is 100% both visual and at scanner, fuel filter is good and clean.
I talked to lightning( HEADERS) and he thinks I may be too lean and the knock sensor is causing timing to pull back, but ray says 22degrees is normal @4000 RPM.
I only run at Havasu and live 300 miles away so I can't experiment to much. I will try a local lake with current situation and see if richening makes a difference, but they have speed limits there so it may not help me.
Any leads or thoughts are highly welcomed.:signs069:

BobL has dyno'd and worked with that exact setup and can assist you. I do know that there was no lean out issues however.
Try PMing him.
Dave

thanks ,I have seen that he has experience with 496.

More than likely your in gaurdian mode which will not allow it to go over ~4300rpm.
Do you have access to a scanner (Diacom)
You may have left a sensor (exhaust manifold temp) unplugged or something along those lines.
Dave

Dave's right. The lightnings won't lean it out that much. You're going into guardian mode. Get a scanner on it to determine what is going on. Probably an exhaust temp sensor or water pressure.

I do have Diacom and everything is OK no alarms no codes. Now,the plugs are real clean even with the 525 raylar kit it was just a little on the fat side. Now the question is if the knock sesor is detecting detonation will that cause the sam thing ?

You should be able to see any knock retard with Diacom. Check the %power available. I bet when you hit around 4300 RPM it is being reduced to 90% or less. If so you should be able to determine what is triggering it. From what I've seen it can do this and not set a guardian event in fault history, or audible alarm. I had a similar scenario that was triggered by an IAC that went bad. It would only go to 90% power above 4300 RPM.

That's one thing that puzzled me as well, it always said 100%.
Havin said that, even if it was pulling back on timing,fuel or what ever it does to lower the power the Diacom should have read less power.
I know that removing them and putting OEM back is one way to see if thats the problem, but it's some work to do that.

I have triple 496's and installed CMI's and now am having the same problem but the difference is it is only on one engine. I am convinced it is a sensor doing it but I too have not had a chance to find it. Throw out the idea of a lean condition as my other two engines are not having the same problem. Once I figure mine out, hopefully this weekend, I will let you know.

At least you got another motor to swap whatever you might think to be the culprit, but I can't put in the water untill next week and fatten it up and see what happens.

Most likely if you richen it up you'll lose more power. On the dyno, we played with a Raylar 525 kit, and started the fuel pressure at 52 lbs and worked it down to 47-48 (idle pressures) where it made the most power, and it was perfectly safe. (Raylar was there assisting in the project).

We had one boat that did not sound an audible alarm, but was shutting down on power because of excessive water pressure in the system. Once we free'd it up, off she went. It never sounded an alarm, or showed on a scan tool after the boat was on the trailer.

One tid bit per Mercury Marine c/o Dustin Whipple, the PCM555 ECU does not record knock events nor does it go into Guardian mode as a result. The PCM555 will only retard the spark if it senses a knock event. So a knock event will not show up in the PCM555 fault history. I did not ask if the PCM555 will record a reduction in power as a result of a knock event or sound an alarm but I would suspect not.

You touched on something that I'm curios about, my water preasure reads 2.5 lbs on diacom, but it's not overheating right exhaust is at 110 left 120 , engine temp is @ 175 which is normal. Now ,that could mean I have good volume and it's what maybe keeping it cool.

I sure would not reduce fuel pressure from the 50 psi that the kit is set up for unless you're capable of measuring the A/F on both banks. 12.5 A/F is generally reported as the prefered target for safe and optimum marine power with 13.0 the absolute maximum. Based on some lean A/F dyno numbers a 496 Raylar engine was leaned out in search of the max (dyno) HP by reducing fuel pressure which in the end resulted in a melted a piston. An engine can tolerate a lean A/F for a short burst dyno run that would kill it if used in the boat. Proceed with caution. Just my $0.02.

Your water temps are fine, the 2.5 lbs of pressure seems really low. Is that at idle? Any excessive pressure issue would have to be measured once the engine is up and running hard. At the 4300 rpm range where your motor shuts down, what is the water pressure?

If you hit record on the Diacom it will record all the parameters, including knock retard and water pressure. If your water pressure is that low (or has a false low reading) it will go into guardian.

The preasure was at idle with the hose on it, I can't recall if there was much change on the water. I will check it on Tuesday on the water.
I know that if I richen it the possibility exists that I may possibly loose power,but if infact it is running too lean I risck more than just power.
Now the motor does not shut down nor go into safe mode, it just won't go over 4300 RPM after fully trimed out.
That will be the next thing I have to deal with I suspect my X dimension is also off, but will be anothr thread for latter.
Not to confuse things,the motor did do 4900 RPM before the headers.

I have Lightnings and have no problems.

The problem is not the headers or fuel pressure.
Find your Gremlin. 4300 is the guardian mode.

I will retest and record and find that grimlin:angry-smiley-044:

Doing the basic math would point to the exhaust change. If the boat ran 4900 before and now only 4300 with only the exhaust change, you're most likely encountering a water pressure issue (possibly high or low). I'm assuming that the water temp numbers from the exhaust that were provided are numbers while the boat is running hard. If not, double check those numbers to insure you don't have excessive heat in the exhaust.

Good point DMP, sounds like you've been down this road...LOL. Hook up that Diacom and record a run, then go back and study it hard. I bet you'll discover the problem.

Could I have done anything that would cause a water preasure change, in this case lower, that I should check for?

I also have had a terrible season due to CMI ,s if your seapump is scared it puts air in the system makes steam pockets

How did you arrive at that conclusion?

Found my issue this weekend. Sea water pump pressure was at 43psi without engine running! Picking up the sensor today. Have heard there is a high percentage of these failing.

You should have someone scan the engine while running at the wot rpm. Watch your exhaust temps.. The port side is usually a bit warmer, but it should not be excessivley hotter. If it gets up close to 200* or more you are not getting enough water on that side. You will need to balance your waterflow.. Some exhaust systems allow for too much of a difference in waterflow from side to side.. We have seen this many times now with some aftermarket exhausts.. Also check your heat exchanger for cleanliness..

BTW a low seapump reading of 2.5-6psi at idle is sort of normal, for a true high or low pressure reading it should be checked at higher speed (preferably wot for an over pressure fault)..

:) Jamie / Lakeside

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all I did this year was the header my engines are Whippled making 806 hp I have no steam cruising around its at idle plumbed innercoolers back in to starboard side of exhaust new seapumps etc.removed all the blow off valves I just dont know what to do 412 781 0881 Bob looking for advise

You really should scan it & see what theheck you have going on.. Otherwise Its's kind of like having Ray Charles work on it.. What you should look for is inconsitancies in temperature from side to side on the exhaust and your sea water pump at all speeds.. Stuff that may be fine @ idle may not be ok in the upper rpm range.. Again being that you have a non stock exhaust & are running an sc, I would definitley pay attention to exhaust temps.. If need be you can engineer a valve to force more water to a side to even out the cooling temps.. Again assuming that, that is the issue.. Otherwise I recomend having a pro shop look into your problem.. We are on the other side of the state from you (about a days drive), but feel free to give me a shout if you need to bring it in.. :) Jamie / Lakeside

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Well I took it today,kindof difficult to hold wide open throttle for to long I would run out of lake (pond) .
Any way these are the readings:
RPM 4292 Aviable Power 100%
Coolant Temp 161.60 Sea Pump Preasure 22.5
Port exhst Temp 116.60 Starb Exhst Temp 102.20
Oil Preasure 47.92 IAC Duty Cycle 99.15
Throttle Position 96.83% Throttle sensor volt 4.49
Spark Advance 22 DEG Batt Volt 13.92
Manifold Absolute Pres 13.44 PSI Baro Preassure 13.81 PSi
Manifold Air Temp 110.2.
Can anybody see somthing wrong.
Is the IAC supposed to be all over the board. It changed from 0-99 depending on RPM.

OK, doesn't appear to be anything going on there. It could be a dead cylinder. Try killing one cylinder at a time and see if you've got one not firing. Broken spark plug while installing headers possibly? I found a grounded wire to a coil once that was killing a cylinder on a brand new boat. Customer kept complaining about lack of power/rpm. It still turned over 4200 RPM on 7 cylinders.

Thanks ,I will try that while its here at work I don't need to be in the water for that.

Make sure all the plug wires are fully seated on the plugs. I hate to admit it but I had a my engine running below par for just that reason.

:cool-smiley-011: I think I found the problem. Number 1 cylinder plug was wet with gas it turnes out that it had enough contact for system check, because I unplugged another coil and openned the key and alarm beep one short beep follwed shortly by two short ones indicating fault.
I tried unpluggin one coil at time but the motors idle did not change. So I tried one of those spark tester that goes between plug wire and plug. It was easier than try to reach each coil under the electronics.
I isolated plug, wire, coil, and after pluggin everything back # 1 fired like a charm. Found the grimlin.
Water retest coming soon

Thanks guys , coulndn't have done it without everybodys help.

Has anyone successfully put O2 sensors in lightning headers without getting the sensors wet?

Myself, Boatingbent and TX_Instigator all run Lightnings with 02 sensors. The Nordics use a custom low port exit header so the collector is pointing at a steep downward angle where the 02 sensor goes. They won't work on the standard lightnings. I learned that the hard way.

http://www.stealth316.com/2-oxygensensor.htmThose sensors on the 496 HO in headers are temp sensors, they atach to water jacket in the header and not exhaust. I noticed that when I put on the headers. I have replaced a few 02 sensors in my line of work and they don't resemble anything like this.
the sonsors were solid brass just like temp sensors, or am I wrong?

Your right, those are the temp sensors. What I want to do is monitor the A/F ratio while on the water, and that requires an O2 sensor(which CAN'T get wet!) at the header collector.
Thanks Bob, I was hopping that vertical collector was enough to keep the water off the sensor. I have a pyro gauge that reads the # 2 cylinder but really would like to know the A/F also. I will get the bungs welded in during the off season. For now I will just keep an eye on the plugs.

We added the 02 sensor bungs to the headers to monitor the A/F ratios.

found my issue bad seapump I guess a little sand smokes the brass pump, They dont make enough pressure at idle , the steam would go away as long as I was moving Im also running imco lowers