rdssk8rcs1

could a crack in my intake manifold cause my car to run lean?

The other day when i was doing some pullson the highway i noticed my car was running lean, not terrible but about 12.5- 13 on my wideband, so i pulled over to check everything out, nothing really noticable was wrong under the hood but when i started looking at my honda logger i noticed my map sensor was reading about a pound or more less preasure than normal with my turboed car so i checked for boost leaks and found a pretty nasty one in the intake manifold

Turbo-LS

iTrader: (4)

if your map sensor is reading less boost then it could make it run lean but if there is a boost leak then the engine isnt getting more boost then the map sensor is reading so if its that lean as you stated then you have a tunign issue. was it tuned on a hot day and you ran it in cooler weather or vise versa?

rdssk8rcs1

it was an average day, jeff evans tuned it, i trust his work, and i noticed is running noticably slower now im getting nervous

Turbo-LS

iTrader: (4)

do a leak down test, i wouldnt be boosting it if the things in the 12's and 13's for a/f you need to be in the 11's. if you keep boosting it like that your goign to destyroy that motor if you havent already

rdssk8rcs1

no i havent since this happened, yeah thats my only worry i hope i havent messed anything up yet, i already ordered a new intake manifold....how do i do a leak down test?ive heard of them all the time and i have an idea of what it does just have no idea how to do one?

thanks for teh help

Turbo-LS

iTrader: (4)

get a leak down tester and they come with instructions, or you can do a sinple compression tester, it wont tell you where the problem is but it will tell you if you have a problem

rdssk8rcs1

yeah i was going to do one first thing monday, so if nothing shows up wrong when i do a compression check im good?


but still what could be the problem with my car?

rdssk8rcs1

anyone else

alpha

Running leaner partial throttle? Checked battery voltage?

rdssk8rcs1

leaner at partial and open throttle, no i havent checked the voltage...
also my injecter duty is lower than it used to be

alpha

Check your battery voltage and post back

rdssk8rcs1

battery voltage can really effect duty cycle?

alpha

Examples. My own car. For one reason or another my battery voltage dropped to low 11's. My A:F went from 11.5:1 11.7:1 to 12.5:1 - 12.7:1. Recently tuning a car we lost an alternator belt. A:F went from 11.5:1 - 11.6:1 to 12.5:1. Had to add about 10% fuel to get it home

rdssk8rcs1

wow alright ill check that thanks

OBRJosh

Check your fuel pressure if you have a adjustable regulaterthe tighting nut couldv came loose

dunkd

What leak did you find in your intake manifold? Wouldn't that cause some nasty surging?

rdssk8rcs1

its a crack at the bottom of the runner near the injector