hey everybody im a new member to the forum but if visited the site many times before and got some great information. My current situation is i just built a 5.9 motor for my truck (a 96 ram 1500) it has KB pistons, indy MA-X heads, comp 210/220 cam, hughes air gap intake, 24lb injectors, fastman throttle body, long tube headers, and an sct tuner. the engine is in front of a PATC mega viper trans with an 1800 stall converter. just got the engine together recently and im in the process of working out some problems with the truck. I have not yet had the fuel sync set so that could be the reason for some of the problems im experiencing. I am also waiting on a set of adjustable rockers i ordered from hughes because i believe that with the comp cam having a different base circle then the stock cam i might not be gettin full valve lift or might have a valve being held open. anyway the main problem that im trying to tackle right now is the idle. The truck does not want to idle at anything below 600rpm which i dont find too odd considering i have a larger cam thats a bit choppy. but everytime i try to set the idle with the screw on the throttle body it doesnt "hold" its adjustment. meaning i can get it set to idle around 900-950 in neutral or park which is ideally where i want it. i can then put it in gear and it drops to maybe 650-700ish. however as soon as i burp the throttle and then take it out of gear the truck will idle very high at about 1500-2000rpm then if i try to put the truck back in gear it sputters and shuts off. i tried 3 different IAC valves one was brand new, and one was off a working truck, the other is the original IAC valve on my truck. with every IAC it does the same thing. i just can not get this truck to idle well at all, and if i wiggle the plug at the IAC valve the truck starts to die then idles back up very high. so i think that maybe the pins in the electrical connector could be lose possibly? just want to get some input from some other people as to what might be going on. thanks

 

it could be a bad IAC plug but it sounds more like your fuel sync is off. i just had a problem similar to this one and the fuel sync was 13* advance. WAY off. hook it up to a scanner that can set sync (i used an OTC genisys) and see what it says. if you messed with the dist. at all then the fuel sync is probly off. it doesnt take much at all to throw it off. counter-clockwise is retard and clockwise is advance, just for reference.

 

i did mark the distributor and hold down for reference during reinstallation, i know thats not accurate really when dealing with the fuel sync but its all i could do really to get a base setting. just out of curiosity how did your truck run when it was 13* off was there a noticeable difference when you set the fuel sync properly? im going to go out later and examine the IAC plug and see what it looks like make sure theres no corrosion and such. I also took some vacuum readings not really sure if its gonna help with this issue or not but i am curious to see if it is "within spec" because im not exactly sure what a normal vacuum reading is anyway here are the MAP HG readings taken off my scanner

1000rpm - 10.6
1500rpm- 8.6
850rpm - 12.5

 

marking the dist will get you in the ballpark but it still could be off by quite a few degrees. the dist is EXTREMELY sensitive. when i set it to 0* and then tightened down the hold down it was already 4* advance. just the pressure from the clamp alone was enough to throw it off.

when my sync was off it would misfire alot. it also had idle issues and would occasionaly bog and die kind of like whats happening to your truck. and any time i would rev it up while it was parked, the rpms would dip down to almost 400 rpms, almost to the point of dying (there were times where it would dip far enough and die) so it does kind of act like a bad IAC. when i set the sync to 0* with a tolerance of 1 or 2 degrees (you wont get it to constantly stay at 0*, it will fluctuate but as long as its not much and i stays in range its fine) the problems went away. it would not dip so far down at an idle and wouldnt bog and die so yea it made a big difference. i also did notice a small power gain since it was firing properly.


im not sure what the normal vac reading is but i do know that a vac leak can cause odd engine performance like missing, high/low idle, bogging ect. check vac lines the make sure theyre all connected and not cut or cracked.

when you built up the motor, i assume you did all new gaskets. did you replace the steel plenum plate with and aluminum one? if not, do that. it will prevent that gasket from breaking apart like in normaly does with a steel plate.

 

Does your SCT take into account the changes you have made to the engine? You are in serious need of a custom tune there....

Not sure exactly how to set base idle..... on the GM's, turning the key On would drive the IAC all the way in. At which point, you could disconnect it, and use the screw to set base idle. Keep in mind, you also have to have TPS unplugged as well. You probably want base idle around 500 RPM, if you can set it that low, and keep the engine running...... Once set, disconnect the battery for a few minutes, and plug everything back in. See if it behaves any better. Having fuel sync set FIRST would be an extremely good plan.

 

sam priem - i have the hughes air gap intake so the plenum pan is not a possibility. i dont beileve there is a vaccum leak everything seems ok. and the IAC valve plug looks good but it is very odd that the idle changes and sometimes kills the truck when i wiggle that plug around on the IAC valve.

Hey you - i originally planned for a much less mild build so the sct tuner is set up for a different cam, stock heads, stock injectors, shorty headers and stock intake. i agree i think it needs to be reflashed for the other new parts on the engine i talked to hemifever about this and he claims that the tuner should be fine even for my MA-x heads, bigger cam, bigger injectors, hughes intake, and longtube headers none of which were programmed into my current tune

 

Well, I would trust his opinion over mine.

The wiggling the connector causing funkyness though, THAT is something I think you need to address.

 

Usally stock injectors are good for past 400 hp , you may wanna switch back to stock and see if it runs better

 

connector locks onto the IAC valve like its supposed to though and none of the pins are bent and no corrosion. not really sure whats going on there or what to do about it. Hemifever told me that as long as the air fuel ratio is within a certain spec at WOT i shouldnt need a reflash

 

lastrights - cant hurt to try i suppose