Back on the Dyno
 

I just returned from the dyno, tried the new ECM, same results.
Tried the new 2 bar MAP sensor, same results. Unplugged the knock sensor, same results.

Results:
Engine runs up to any RPM you like and when you hold it there for 20+ seconds, the motor starts seems to lose power and then you can watch the EGTs decrease dramatically. Bring the throttle back to idle and it clears up and is ready for another run.

Is there anything mechanically that could be causing this? I've been advised to do a pressure test on the block to verify that at high RPM, the higher water pressure isn't leaking into the cylinders.

Since I'm now grasping at straws is there anything else that would potentially cause this? Anything you can come up with I will check, this really sucks!

I looked back at your previous post. You have some patience! Are you sure it is in electronics? If you have a carb and intake laying around, why not throw it on and run the motor to isolate the procharger and fuel system? If all runs well with a carb, then you would know it is definetly in the fi system or procharger.

Patience? This is killing me!!!! I have tested, changed or looked at nearly every part of this engine.

What methods are left in troubleshooting the EFI system on the motor? I believe I covered everything. Is there anyway that we are putting a load on the engine incorrectly on the dyno to cause the engine to reat the way I described above and in my other posts?

Are you detonating and the computer is pulling the timing back and then resets the timing when you back off it. Try taking some timing out of it to 28-30 degrees. What is happening to your fuel pressure at 20 secs? Do you lose some?

I also have gone back and re-read your first post although I don't have anything to add that has not been suggested I am going to show the link so maybe someone else will have a idea. I hope you find the answer soon.

Link to other post

My timing is set at 30 degrees. I could lower it just to try it.

As far as detonation, I assumed that if I disconnected the knock sensor the ECM would go into default and wouldn't cause a shut down. But even with the knock sensor disconnected I get the same result.

Scott, thanks for posting the link. I'm sure people are getting tired of my begging for help, but I really would like to be boating this year!!!!

Oh, sorry, fuel pressure is solid at 52 PSI while at boost!

Are you sure you have the correct batt. voltage. You say it runs good at idle and quick revs but start's breaking up under a long load you may not have the right voltage too much or not enough.

seems like alot of fuel pressure ,no its not the dyno,turn off yhe motor when the egt drops a good bit and check the plugs ,is it rich ?? lean?? or water ? ,,I doubt water but maybe
I love fuel injection don't you ?? sorry for your grife !

I'm sure you already checked for valve float? weak springs are a broken inner?,- maybe to much oil in the top end and passing the valve seals? you got us stumped also, what kind of leak down do you have on the engine % ? sometimes on high boost you have to add some more seat pressure to your valve spring's,

The part I do not get is how are you loosing temps on one side of the motor? I thought I read where 2 would drop then 4 etc.???

Pantera, Sorry to here about your problems.
Does the temp drop on the cylinder and then the ignition starts to drop out, or does this happen at the same time. If the ignition is dropping out, I would think the temp. would then drop because of no fire. Somehow you need to determine if the ecu is causing the problem or something else is wrong causing the ecu to shut it down. Sorry i'm not much help.

Battery voltage is 14V, before during and after the cylinders drop out.

Plugs have been checked 4-5 times after this has occurred and look normal, light brown on the insulator down in the plug. Does not appear to be a lean or rich condition. I'm looking into the water issue tomorrow - going to pressurize the system to 15 psi and check for leakage or leak down.

Valve springs have been replaced and upgraded to avoid a problem with valve float or the boost issue. Unless they were incorrectly rated this should not be an issue, but I will bring it up at the dyno session tomorrow.

If you run the engine from idle to 3000 or 4000 RPM and hold it under a load, after 20+ seconds the engine missed and then the EGTs on the # 2, 4, 6 and 8 cylinders go cold. However the other night, we ran it up from idle to 5,500 RPM under load and it appeared that the # 1, 3 5, and 7 cylinders went cold.

I have tried a new ECM, no change, it does not appear the the ignition drops out, as we have a timing light hooked to #2 and it continues flashing throughout the situation.

Thanks for the input, I will and do check everything that people recommend and will post the results here. You know there are going to others with this situation and it will help them also!!

Thanks Again,

Kirk

Kirk, one easy thing to look at would be to mark the crank for #2 cylinder and hold the timing light on the mark and see if the timing is doing something wierd when it starts to mess up. Something has to be causing this.
Just throwing ideas in the air.

The ECM is a MEFI3

I'll try the timing mark idea today.

Thanks

MEFI3 should be 1999 and up

I have not read the first thread but could it be the coil is overloading or geting hot & thus reducing the voltate to the plugs. The timming light will still fire but when motor is under load, plugs need more voltage to fire. What gap are you using on plugs & what kind of plugs? Have you tried changing the plugs

Good Idea Turbo, It's something easy to change and I have had coils go bad and they do some really wierd sh$t.

Thanks Turbo, I will try the plugs today. I did run another set in the begining and I'm sure there was the same result, but its cheap and easy to try. I'll see if I can dig up a coil also.

I'll be trying the items listed here later today.

Thanks Again,

Kirk

What injectors are you running? Are they the same impedence as the original? Could the ECM injector drivers be overloading?

I'm running Lucas 42# injectors:

http://www.racetronix.com/product/In...s/621031a1.jpg

These injectors are 15.9 ohms

Since we are not seeing the plus show lean I would guess problem has nothing to do with fuel. Is there a distributer? If so, have you changed the distributer cap & rotor

New cap and rotor as well as plugs.

The engine is definately going into safe mode. I need to trace the wires and see if anything is grounded, it is the only thing I haven't done!!!!!!!!!

Anything else I should look at before cutting the nice wire looms and tape job I did?

:confused: :confused: :confused: :confused: :confused: :confused: Stumped

Three things: 1.compression ----good

2. Fuel----quantity (pressure and pulse length)

quality (octane requirement) {BLOWER
boost?}

3. Ignition------secondary voltage

timing at rpm

The ECM,s can alter 2 and 3 however some of it is observable with the right testing equipment...

Per request, John B

I understand your greif.I went through a nightmare with a procharger set up on a carberated version all because of a faulty fuel pressure gauge.Through all my research and calls I heard alotta grief on procharging fuel injected versions.I am just curious if you are using the whole shooting match from procharger...Fuel system,computer,etc.My wild ass guess is you might be loosing volumne of fuel delivered..seems to have all the symptoms(perhaps #2 has the path of greatest resistance for fuel flow?).I had a 454 built specifically for a Procharger....balanced,full roller,did everything but blueprint it.To give an idea of how much fuel it likes I have 84 jets in the front and 99's in the back.I certainly hope you get it figured out...even after my months of grief I am still thrilled with my setup! Best of luck!

Thanks Pachanga,

I'm pretty sure my fuel pressure is good. I have a 2-1/2" gauge at the end of the fuel rail and it reads 32 at idle and 52 at boost.

I was hoping to pull the engine off of the dyno and take it up north this past weekend, but I had a rocker loosen up at the stud. So we are repairing this and then hopefully getting some professional attention!!!

Pantera...So I don't sound dumb! :-) I had ta make my post in a hurry as I had somewhere ta be! The one thing that sticks in my head procharger preaches is the type of burn they like on a plug...at least when feeling out the engine...as we all know a blown engine running too lean is sure disaster.Procharger likes a black ring with a white center...I thing you said yours were the typical light brown? Could it be your knock sensor is doing it's job because maybe you are detonating a little? I am no expert...and have hardly any experience whatsoever with fuel injection and computer stuff! But I do know the basics of what makes an engine go. All had given up on my problem...ended up solving it myself.Procharger's tech support was no help at all. I would like all ta tell me how a holley carb handled this! My initial setup was putting somewhere around 40 PSI to the carb at idle! My problem was too much fuel but we were thinking the opposite because the faulty fuel pressure gauge was showing very little boost reference(very important on a blow through carb setup).What I am about to say is what I heard in passing trying to figure things out...Isn't 32 PSI a bit low for idle fuel pressure on an EFI set up, Bear with me as you maybe teaching me too! :-) especially on an engine which is blown? Pressure doesn't necessarily mean you are getting the volume you need....I have duel 1/2 inch fuel lines running to my carb.Also,If you have the competition procharger fuel system...the pump doesn't like to draw...needs to be as low and close to the fuel tank as you can get it.Maybe while the engine is on the dyno still you should try elevating your fuel source and see what happens.Curious as to my results? This is not GPS...My original setup was an old 450 horse crate LS6 turning an alpha!(LOL) Got screwed by the dealer...ran it without water and I shortly lost #8...so I figured I would go for the bang! The best she ever did on the speedo was 68....(teleflex 80mph). I haven't had the guts ta push it all out but glanced down once and saw the needle straight down on the MPH! My boat definitly has more power than it needs as far as topend is concerned...but man does it kick after she's out off the hole! Last comment...Man...that's a scary thought having a rockerarm loosen up that quick.(especially if it was the stud!)