hypforlife32

What’s up guys. So this may be a long one, but anyhow. I bought a boat back in may that had a cracked block on the port side. The starboard side runs fantastic. Smooth responsive no codes, service mode with a paper clip method works well. Even with a scanner too. I verified in service mode I have 8 degrees BTDC. Engine runs like a champ. Looks original with boat saying 440 hours but ecu reads 280.

now, onto the port side. Removed the engine. Found out it is a 383 already with the WRONG compression. Was upwards of 10.3/4:1. Luckily I did some math to find that out before getting a new block, piston combo. Had the machine work done and they assembled the long block. I did lifters, intake manifold and dressed it. Compression is 9.1:1 now which factory is 9.0:1.

I am have a very hard time trying to set timing on the new engine.

key on. Insert clip. Start, try to get base time where it needs to be. Even 5-6 the more is very responsive BUT out of service mode the idle increases?? I can only get about 1 degree and idle stay at 750 fully warmed up out of service mode. Is there any reason why increasing timing would increase idle?? I’m thoroughly confused. I’ve tried swapping throttle bodies. Map sensor. All from the good engine that runs. Similar results.

I did forgot to mention that I had to have a cam custom made to the original specs which I found same lsa 114. Same lift etc.

vaccumm on good starboard engine is 16 at idle

new engine is 10-11 at 0-1 degree BTDC.

VOLTAGE is 13.x

the map sensors read at 5hg diff as well. Would this maybe be a vaccum leak im chasing? To cause this issue??

when I get timing to 7 degrees idle is now up to 1500ish.

maybe I am doing something wrong?

Any and all advice would be greatly appreciated.

SB

iTrader: (1)

Within reason, no other changes, adding initial timing adds idle rpm. However, the ecu should see the increase in rpm and close the IAC (idle sir control) valve further to msintain facttory commanded idle rpm.

Therefore, check IAC first. If it fully closes it’s passage, their is an air leak somewhere. Remove throtttle cable from tbidy first and make sure blade closes down to it’s screw stop.

Less initial timing is going to reduce idle manifold vacuum. Also, a air (vacuum) leak will also.

Even on new motors, if it runs incorrectly, check fuel psi and compression first. Without good #@s you’ll never get it running right. Never ASS-U-ME anything.

hypforlife32

Would initial timing setup being off cause the ecu not to go into service mode? the motor itself runs great minus this. lol. the throttle body does fully close.. I have checked fuel pressure at idle and up to 3k rpm on the engine stand. Fuel pressure was right inline with the service manual. I guess i can check IAC by advancing timing and increase intial rpm to see if the IAC compensates? Everytime i have have taken the Throttle body off the IAC is in the same spot. about halfway in the hole. No where near closing it.

This is my first " distributor" setup.

SB

iTrader: (1)

Ck your service manual, but most things I work on close the iac when you turn key to on. This references closed position every ‘trip.’ As most IAC’s don’t have a sensor within it to know exactly where it is. So, I turn key to run, wait 20 seconds and then unplug iac. Turn key off. Then take a look to see if actually closed. This is if my scan tool diesn’t have a IAC function test for the certain vehicle.

So, look in your manual for procedure.

SB

iTrader: (1)

You just aged me and many here Lolololol :wink

hypforlife32

I do know the ecu displays "counts" but i havent seen the iac move period, and i have moved them from engine to engine. they end up in the same spot..i will pop it off this evening real quick and relook. Its almost like there is a bad signal wire or something. I have swapped ecus, ignition modules, throttle body, map sensor. tps. all same result

F-2 Speedy

iTrader: (6)

you have not installed a distributor or timed an engine before ? are you looking at the correct timing marks ? you cant time it without being in base mode

EDIT: by cycling the key on and off the IAC should move in and out

hypforlife32

Really? I dont remember this IAC moving at all if i recall correctly after key on and run cycles. no ecu error code for it either.

sadly no, i come from a late model gm LS background. ive done many ls engines and no issues. I did verify TDC mark on the balancer as research shows they can slip. With the GM Est Distributor is there an intial timing setting? I thought it was just service mode and 8 BTDC? Sorry for my lack of knowledge on this..

hypforlife32

haha, It happens, im so close to ripping in the water but this dang issue is hanging me up.

SB

iTrader: (1)

counts are assumed by the signal to the iac and by ecu commanding iac closed each ‘new trip’ ie engine iff .key On.

say iac is stuck half open. When you turn key to on, iac is commanded to close. ECU assumes it closed and assigns it’s position as 0 . “Closed” . Again, most iac’s don’t have an actual position sensor.