Idle surge?
 

My Baja with a 454EFI has a "surge" at idle, it only surges a couple of hundred RPM's but, its kind of annoying, last spring I had the boat checked over and the mechanic said he "cleaned" some Idle valve or Idle control or something like that [sorry, I cant remember the exact name] but, he also told me it would need to be replaced in the next little while, anyone know what he was talking about? LOL, I would like to get one and swap it out before I splash the boat, Thanks for any input!

Michael

1. Throttle cable to tight - no slack
2. Timing is wrong

try cleaning the backside of the throttle plate,,,its easy and should help,,,let us know

Throttle cable and timing are fine. How do I go about cleaning "backside" of throttle Plate? I had the top end of the motor rebuilt last year, runs great other than the slight surge at idle. Thanks!

Michael

Fixx
 

non chlorinated brake cleaner and a tooth brush,while your at it clean the idle air control motor also,,if that don't do it check the tps voltage with a ohm meter,should be under 1.0 volt,,,but more like .40 to .60 volts,,if you turned your idle up that would do it to...if none of this works then you may have a vacuum leak..

Idle surge
 

yea mine does that too.. both engines??? I have contacted the cam manufacture. :evilb::evilb:

Probably needs a new IAC valve.

IAC Valve and Idle control motor BOTH sound very familiar, are they easy/cheap to fix? or clean? I have no idea where they are, so, if you can Email/post/PM me and let me know where they are and where to buy them I would GREATLY appreciate it!

Actually when the boat first starts the idle stays "stable", but, if I give it a "shot of gas" [in neutral] the idle starts to surge, I am not sure if thats relevant or not? but, figured it coudln't hurt to let everyone know, like I said, other than that it seems to run great!

Thanks!
Michael

Your idle issues are from one of 2 things. Either the IAC motor (idle air control) is not seating properly any more or the throttle position sensor is bad.

The IAC motor should be on top of the motor either behind or in front of the throttle body and the TPS sensor will be on one side of the throttle body on one end of the shaft that goes straight through the throttle body.

The IAC motors will run you approx $100 and you will have to get these from a marina that sells merc parts and the TPS sensors are approx$30 or so from auto zone if I remember
right.

Either one will only take you approx 5-10 minutes to replace.

I had the same issues with both of my 350 mags last year and said screw it and replaced them both on both motors versus trying to clean them again.

My boat has the "454EFI" motor, which is similiar to the 454/502 Mag, the plenum is "flat" and the air cleaner faces the right side of the boat, do I need to remove the top of the plenum to get to either one of these parts?

Thanks!
Michael

Fixx
 

# 32 tps & # 35 IAC...

its easier to remove the throttle body to service,get a new throttle body gasket also..

http://www.marinepowerservice.com/CO.../300x20149.gif

I am not 100% sure on what you will have to remove to get to them. I have a buddy that has a 502 in his baja but never really paid much attention to where things are at on it.

Do a search in the general Q&A section for Merc manuals. I did this about 2 years ago and I was able to down load and print out complete parts and schematic manuals for my motors and bravo drives as well as the ECM book for free!

These manuals will tell you everything you need to know about your motor.

I believe I found them all on Iboat or Iboats.com and they have come in real handy!

I also bought the scan tool and between that and the books, I have my motors under control and always no whats going on with them when they decide not to play well with each other!