29scarab

96 502mpi engine.

I finally got my engine in the boat and running. Took a few tips from the guys here on the board and everything seems to be working. To get some of the surge out of the blower I started with a small hole in the throttle blade and drilled it a little bigger at a time to get the surge out. I finally got the surge under control, but when I go to stick it in gear it dies everytime.

The engine did go on a dyno with the fuel pressure set accordingly and Mark at Precision did the tuning on the ECU to get the mapping right. Of course, when you go to put it in the water everything changes as far as the torque on the prop in the water.

Is there anything else I can try before having to pay someone to get the thing tuned right? I only have a couple of small options here in Houston as far as knowledge. If all else fails I guess I will have to set something up with Mark in Louisiana.

Any help would greatly appreciated.

Thanks,
Shawn

tomcat

Get a Merc scanner tool on it and see what it reads for "counts" on the Idle Air Control. This solenoid controlled air valve is what opens to allow more idle air to maintain desired idle RPM when you add the load of being in gear. Simply put you want the IAC to be floating sort of half open so that it has the range to open even more when you go into gear, or close when you take it out of gear. The ECU controls how quickly the valve moves, also controls idle spark advance and fuel if necessary. Do this before you call Mark and it will help him advise you.

TylerCrockett

iTrader: (1)

You also need to make sure your TPS is set at .500 and your throttle is closing all the way. If the ecu see's anything over 3
% throttle opening it won't go into closed loop Idle control. You also have a spark stabilizer at idle that is programed into the ecu.

Turbojack

two very good things to look for. Do you have it timed correctly?

29scarab

My marine mechanic came to the race shop with the scan tool to set timing up on it which, I beleive is 8 degrees. I was in the engine compartment when my buddy put it in gear on the lake. It changes position as soon as the engine is started and doesn't change when I put it in gear. I have the primary throttle set all the way where the blade is what I beleive completely shut. I tried to adjust the secondary to let some air bleed by. It brought the RPM up idle but it died as soon as putting it in gear.

Where can I get a scan tool?Is there one I can rent or is it something I'm going to have to buy?

Exactly what is the name of the scanner? Brand ect???Thanks

I appreciate the input from you guys!

tomcat

Since you're in Houston, why don't you take the boat over to Victory Marine. They have the scanner and went through this adjustment on the HP500EFI engines we supercharged in a 32 Skater.

Dave_N

www.rinda.com

If you can justify the extra $$, the Diacom software is far better than a hand held scan tool. You can record data on a run and then analyze it later. Another nice thing about Diacom is that you can email the files to a tech anywhere in the world (that has Diacom) and they can look at it and advise accordingly. Just in the last month, I have helped guys in South Africa and Sweden by recieving and reveiwing their files and sending them files from known good engines to look at. It's well worth the additional money.

Dave

29scarab

Is there a way to tell if the IAC motor is working properly without the scanner? I'm going to start checking things today.

Thanks

Turbojack

I had to do some searching for this but I found this thread. Hopefully it will help you. If not to late.IAC Tutorial

In searching for this I had found a lot of threads with the same problem. Solutions were IAC and setting the timing correctly. It will not hurt to check the timing again to verify it is correct.

If you want to talk, just email me and I will get you my cell number.

OK, fixed the link

29scarab

Turbojack,

Thanks,

I'll see if I can find it. Your shortcut went to another thread, but it didn't have the shortcut to the thread for the tutorial. I'll see if I can find it.

I did order another IAC motor with my race mechanic. After talking with Mark at Precision marine, and considering my IAC is 10 years old I opted to order anther one just to make sure. It was only 65 bucks.

Thanks,
Shawn