bsboss

Trying to chase down issues with this single 08 525 not performing. Looking at numbers on laptop and was wondering if it is normal for engine temp. @ 158 to drop 12.6 degrees from idle to full throttle. Also looking at the MAP sensor readings on the laptop are in psi and correspond with Baro pressure w/engine off, at idle MAP reads only 2psi lower, once we full throttle it read close to Baro pressure and slightly higher. This doesn't seem correct to me but would like other opinions. There are no codes, beens chasing this problems since we purchased boat this year.

bsboss

Anbody? Suggestions?

Dave M

The temp reading sounds normal. At higher RPMs you are getting higher sea pump pressure, thus higher water flow.

As far as the MAP, I'm seeing the same thing with the engine off. I don't have my recording files handy so I don't know what it reads when running.

bsboss

Thanks Dave for your input, I would appreciate your info from your recordings. I'm starting to think maybe I have a internal vacum leak. Would like to know what kind readings you have to help determine my low performance.

stevesxm

i can't speak to the map readings... the factory workshop manual will have that curve for you to refer to... but the water sounds cold to me. and if its cold, then its rich and if its rich it will not only run average and all the other parameters will try to adjust to deal with it. i don't think 158 is warm enough to get the injection to lean out where it belongs...

Dave M

Funny you should mention that. I've owned this motor for less than a yr. and thought the same thing. I believe this motor has a 160* t-stat. Every other EFI motor I've owned ran about 170-175* regardless of air or sea water temp. My motor typically runs around 150*.

The motor runs great, no codes, no soot, or fuel smell. I do have pretty high water pressure, around 35 PSI depending on speed and trim. I'm running a DWP XR w/ITS.

stevesxm

there won't be a code... the motor doesn't think anything is wrong... it just thinks it hasn't warmed up and keeps everything at FA ratio that it thinks a cold motor wants... none of which is good for a motor if its run that way for a long time and those settings are certainly no good for performance.

i would fix whatever i have to fix to get the temps where they belong , put a fresh set of plugs in it and see what happens. if you put a new tsta in it, don't go drilling holes in it or anything. leave it stock

bsboss

I also was thinking the same way, I believe somewhere I read it should have a 160 stat. Maybe previous owner drilled holes? Does anybody know for sure what temp it should be?

stevesxm

i ran my 502 mpi's at 175 and would have gone to 185 if i could have figured out how to do it repeatably... and you have to know if your gages are good. the other thing i discovered was that the electric gages ( mine were gaffrig) are absolute scrap. you get 3 dif ones w/ 3 dif senders and throw them in boiling water and get 3 different numbers 10 deg apart... what WAS accurate was the scan tool.

stevesxm

i ran my 502 mpi's at 175 and would have gone to 185 if i could have figured out how to do it repeatably... and you have to know if your gages are good. the other thing i discovered was that the electric gages ( mine were gaffrig) are absolute scrap. you get 3 dif ones w/ 3 dif senders and throw them in boiling water and get 3 different numbers 10 deg apart... what WAS accurate was the scan tool.