jmoore1225

iTrader: (1)

Is your cmi exhaust new? Pressure checked before you put it on? Had the same issues @ idle & now in need of a rebuild because the exhaust was dumping water on a piston!

stevesxm

am glad you coaught this before you killed it. well done.

don't forget to change the oil now that you have some time on it. as for the idle ... it could be a million things but try to think horses and not zebras...

idle is a function of tiny pulse widths at the injectors and small carefully metered amounts of air. if the idle can be maintained correctly static and its smooth then you can make some assumptions from that. it doesn't take much... the fuel and air flows are so small at idle that it doesn't take much to make them " wrong " and turn your idle to sht. and if the idle is shabby and weak then i would go looking for vacuum leaks from a cracked line or something you forgot to put on.

failing that i would have the injectors out and clean them. flow cleaner backwards thru them and pulse them with a scanner until they fan correctly.

on mine i found that a couple of things were common... first that they get rusty and dirty pretty easy and the fan gets shabby and the other is that it takes nothing at all to clog the screens.

a good spray pattern is really crucial to making an injection system work properly. for me it was a simple matter of taking a pump and a can of very aggressive cleaner and with a hose and a clamp pumping fuel to the injector from both directions while pulsing it with a scanner. you could see the pattern clean up immediatly and the junk that would come out of the screens was significant.

i suggest this to you because your boat has been sitting around while the motor was being done so the tank has some junk in it and the lines might...

you have two things to remember ... first that you have had everything apart there is to have... so touch and rub all that stuff again... and second, things like filters and old fuel and all manner of forgotten stuff will consire against you from the boat sitting... make sure all that is correct first... and have another look at the iac and make sure ir moves smoothly and that the seat and port are clean. and if you don't have a scanner , buy one. it is a crucial piece of equipment for you. i have one if you need it

horses... not zebras

Griff

Have you checked the timing????? It should be set at 8* when put into base timing mode.

MikeScarab28XLT

Short question to the experts.

MEFI 1 502EFI 1993.

Diacom read over 3100RPM to WOT only 29,53 Spark advance.
Base time are set so 8°.
EFI dont make 34° at WOT is it nomal?

Thank you.

stevesxm

well... a few things...

first you have to look at which ecu you have and what the total timing is supposed to be in that unit .

second, make sure that no one has " reflashed it" and changed whatever they could have changed.

third, check the diacom numbers with a proper jumper and timing light just to make sure you are actually interpreting your diacom data properly ... i useded the much much older diacom systems on oldsmobile motors and the data was often "raw" and did not actually answer the quetion you thought you were asking...

and fourth... i suppose you could have something triggering the knock sensor and backing the timing off...

MikeScarab28XLT

Hello stevesxm,

thank you for the info.

I have the first MEFI 9550 two ECM´s and two ECM´s reprogramed.

If i drive with 2500 RPM i see in diacom 37° and with the timing light i go with -37° to 0° with the light. At WOT diacom shows me 29,53°, but i have not read it with the light.

Now what make me confused. I have Base Time 5° for test.
Diacom Show 37° and timing light shows 37°, but not 34° at 0 ore 37° at -3°. Where are the 3°.

I have test base Time 0° and 10° all the same. I have no Crankposition sensor.


All other people have say to me. Diacom shows only the Table and i have to add the 8°.

Diacom 29 + 8 = 37 ???

ore is it

Diacom 29 = 29 real with base 8
Diacom 29 = 31 real with base 10
Diacom 29 = 33 real with base 12
???????????????

I have no Table from the ECM 9550 so i can not say what the timing shout do at 4860 RPM.

MikeScarab28XLT

"and fourth... i suppose you could have something triggering the knock sensor and backing the timing off... "

Can the flappers in the Imco Endtips can do this ??

stevesxm

i'm sorry but i simply don't know. i understand what you are saying and i understand your confusion but wiythout seeing the screen and the understanding the current diacom data, i would just be guessing in an area where it is not smart to do so. i think if i am standing where you are i am going to just make absolutely certain that i understand the timing marks i am looking at and i would use a very simple timing light... one without the advance dial... and make sure i wasn't running 37 degrees or anything like that...

beyond that you need someone genuinely familiar with whatever version of the software that diacom is running now. and i apologize but thats not me. have you tried contacting diacom ? when i was using their stuff you could just call them and talk to them...

MikeScarab28XLT

OK good idea, i ask Rinda. What the Spark Advance Show me.

I can use the timing light with 0 like a light without the advance.

I see in Base time 8° with light at 0°
I see in Base time 0° with light at 8°

I see in Rinda 29,53 at 3100RPM with timing light 29 i see at 0° the light.

I ask Rinda.

stevesxm

[QUOTE=MikeScarab28XLT;3679117]OK good idea, i ask Rinda. What the Spark Advance Show me.

I can use the timing light with 0 like a light without the advance.

I see in Base time 8° with light at 0°
I see in Base time 0° with light at 8°

I see in Rinda 29,53 at 3100RPM with timing light 29 i see at 0° the light.

I ask Rinda.[/QUOT

they are or were a very good company. when i
" knew " them they were actually making all the oem test equipment for GM ... a GM factory scanner was actually a rinda designed and manufactured piece... so they aren't some aftermarket outfit... they have been around for very long time and have ( or at least used to have ) the inside track at GM ... so i would start there.

but first just make sure you don't have TOO much timing in the thing and do some harm before you get your answer.