i put in a powerjection throttle body injection systemi in my truck and it works well. however im having a slight fuel issue im hopeing some of you guys can help me with. it starts and runs great but if i drive it for a while it gets to where it doesnt want to idle at stop lights. it acts like its running out of gas. it will still drive great but if i get caught at a light the idle drops and it will die is left alone. i can put it in neutral and give it some gas and it will be fine and if it does die i can start it right back. i think its a heat issue for a couple reasons. 1) it doesnt seem to happen much at night or early in the morning when its cooler but during the heat of the day it happens in about 20 minutes. 2) my temp gauge isnt working so that just makes me nervous in general 3) when i routed the fuel lines i remember thinking the line that goes into the rear of the throttle body was a bit too close to the headder. so i was planning on rerouting that one anyway but i didnt think it would cause me any problem. so ideas fellas?
i sent an email to the company and they believe its an idle setting issue. so im trying to tune the motor with my laptop. its messy.
just curious...sorry for the late answer... post how its going.. do you have the tuning manual.. its about 20 pages long... you need to find the idle air control info on page 15.... you will HAVE to use a laptop or if it has a display of some kind to look at the idle air control count .. IAC.. with the engine warmed up.... you will also want to look at the section on the TPS... so you can verify the TPS voltage when the engine is idling with the idle air control valve between 20 and 50 counts... that the TPS voltage is close to design spec for minimum TPS voltage.. or the computer will think that you still have your foot on the throttle and will not revert to idle fuel control.. the injectors pulsewidth will stay too wide.. probably around 2.1 to 2.4 Ms.. instead of at 1.2 to 1.4 Ms... IAC CONTROL - The injection system is equipped with an “Idle Air ControlMotor” that assists in start-up idle speed control and prevents engine stallon deceleration. The motor controls a valve that meters bypassed air to enterthe engine. The movement of this valve takes place in “Steps”. The totalnumber of steps the valve has is 130.C-TEMP BASED IAC BASE POS - This is the base position for the IAC at thegiven temperatures. This value should not exceed 23 when warm and the idleis properly set. (Butterflies)(A) IAC CRANKING POSITION - When the engine is in “Cranking” mode, theIAC motor will position itself to the value entered in the “IAC CRANKING POSITION”cell.It will then “decay” (reduce) the position in steps entered for each revolutionof the engine, after started, down to the value entered in the “C-TEMP BASEDIAC BASE POS”. The value on the C-Temp based IAC position table is thenumber of steps the IAC is open for the corresponding temperature.(B) STALL SAVER - This feature helps to prevent engine stalling. You canenter a value (RPM) that you want the feature to become active and theamount of steps you want it to add to prevent stalling when the throttle platesrapidly close. The decay value is the number of steps per revolution to reduceback to the IAC position on the C-Temp table.NOTE: The above parameter usually does not require change.(C) RPM FOLLOWER - The RPM Follower lets the IAC motor control the engineidle speed automatically. The follower can be used to make up for differentloads applied to the engine while idling such as A/C and putting anautomatic transmission in gear.RPM must be less then…: RPM must first be less than this value for the RPM Followerto activate.NOTE: Throttle Position must always be less than 2% for RPM Followerto become active.IAC Control - With our new and improved IAC controls you easily changefrom two different modes: RPM Target and Step Target. RPM Target meansthat the EMS will attempt to automatically control your engine idle RPMbased on coolant temperature. You just need to enter your desired idle speedfor each coolant temp displayed. Further IAC control is found under "RPMFollower" where you can set minimum and maximum step limits based oncoolant temperature. Always be sure to set the RPM threshold 500 to 1,000RPM higher than your maxium target RPM. In the RPM Target mode theStall Saver setting becomes inactive because it is not needed. The further theactual RPM is away from the target RPM, the faster the IAC moves to compensate.In the Step Target Mode, the IAC motor will stay in the position you commandas long as the Stall Saver and cranking positions are not needed. Inthis mode you must manually set each IAC position based on coolant temperature.When using Step Target, the RPM Follower parameters are notused.After entering your desired values you must click Send to update the profile.The bottom portion of the window allows you to see the status of theIAC motor.• Close Position: is active when the key is off.• Cranking Position: is active when the RPM is 400 or less.• After Start C-Temp Decay: active for the amount of time in the decay table.• Temp Based Operation: IAC function is active when Step Target is selected.• RPM Follower: IAC function is active when the RPM Target is selected.• Stall Saver: is active when the EMS reads the parameters entered in “StallSaver”.• Manual Mode: This is used for troubleshooting purposes only.
if you don't want to play with the lap top....try backing off the idle stop screw .. what... yea.. just try it.. then shut off wait 20 seconds and restart the engine.. the idle air control valve needs to handle the idle air bypass.. if you look around the many forums.. you will find that i know OEM fuel injection quite well.. and this is just a version of GM fuel injection.. with roots back to bendix and bosch fuel injection systems.. the idle air control counts are the amount of steps back from Zero... closed passage... 130 counts is as much opening as the idle air control motor can back out.. at normal operating temps.. the idle air control is somewhere in the 25 to 30 range... if your idle air counts are lower.. the throttle is open too far... and the ECM is trying to slow the engine down... if your idle air counts are above 35.. and the engine is at operating temp.. your throttle may be too far closed.. if your TPS voltage is too high because the throttle minimum adjustment is too far open.. or is BINDING and not returning to the exact same fraction of a volt when the throttle is closed.. this can fool the computer into keeping the fuel control ready for power... cause you all kinds of issues..
havent been on in a long time but wanted to update this. i was able with a combination of laptop tuning and mechanical adjustments to get the truck running great. i have put several hundred miles on it since correcting the settings and its very good. its turned out to be one of if not the best upgrade i have done.