wide open throttle at start up?

[josh1095]

ok, so a member on the forums here and i dropped in my engine..... finally.
fresh rebuild, all the internals forged..etc.etc.
any way, at first car wouldnt spark or fuel. so, knowing that when i dropped the car off to this horrible mechanic, it DID run fine, i deduced it could be either the cps or ecu. ecu unlikely so i tested the cps, it was bad. they had cracked it when reinstalling it. SMH. so today i installed a new cps. starts up for the first time and goes wide open throttle! i immediately shut it down, this is a brand new engine here.
i tried disconnecting the iac motor, checked throttle cables and then ran out of time to troubleshoot further.
this sounds to me like a classic case of unmetered air entering past the throttle body. a hose disconnected or something on the intake mani.
sound right to u guys? i dont see how any sensor could magically sneak air past the TB. its trying to peg to so its alot of air getting past.
i just want to double check with u guys and make sure im looking in the right place to solve this problem. without air, an engine can NOT rev up. ive seen this before a few times but just need affirmation basically

 

[96 420a-t]

Sounds to me like you are on the right track. BLT time.

 

[josh1095]

BLT? acronym im not familiar with

 

[TSi Kid]

Your tps isn't set properly.

 

[standard235]

My buddy's GST, he left the washers on the intake mani studs before putting the manifold on.. THAT made things interesting haha

 

[98mitsubishigst]

I got you on this one kid!

http://www.dsmtuners.com/forums/newbie-forum/422316-high-idle-rev-start-up-round-2-a.html


Should always read up on the forums by searching first.. Because MY thread comes up first.. i replaced my Thottle position sensor, Idle air control, and the Thottle body and i still had this "HIGH REV" at start up..

First time, it was my THROTTLE CABLE wasn't adjusted properly..

SO FIRST OFF, i would disconnect the throttle cable and start the car, see if it still does it..

If it does do it, you must then do a BOOST LEAK TEST, chances are your intake manifold gasket is shot or the wrong one, thats what was wrong with mine and I'm assuring you, if your throttle cable is right then its your intake manifold gasket.. lemme know if this helps.

Edit: noticed you already did throttle cable thing, so yes its a Boost leak, trust me on that

 

[Boost_freak_87]

^^^^ bingo!

 

[josh1095]

ill check the IM gasket. thats my worst fear. it was brand new felpro but i didnt install it so i cant vouch for it. rlacasse, a member here, installed it. and from watching the guy work, he knows how to put a box of bolts back together. guy is pretty good. but still, mistakes happen, thats ok. plus, oreilly could have messed up the p/n and gave us the wrong one. shit happens.
im also going to look up the vac hose routing. if we misplaced one of those lines, its drawing in unmetered air as fast as it can causing the rapid rise in rpm. i think once this is ironed out im gonna have a great car.

its the first time its been running since july, when i bought it and dropped it off to the incompetent mechanic. this is a minor problem ill have solved in 30 minutes when i get time. ill check everything and report back. thanks guys, love this forum

98mitsubishi, read that thread u linked. good reading. will check everything out. btw, this car is a ###ing frankenstein. the further we got the more we noticed. it was originally an auto, the engine is either a 95 or 96 7 bolt. gound that out the hard way today when i ordered a 97 cps. got to oreilly and said "wtf??" totally dif. so out of curiosity i asked to see a pic of a 96 gst cps. perfect match!
so, if the IM gasket is dif from those years..... theres my prob. luckily, rlacasse told me to leave off the IM to block bracket. that will make this job way easier if it is indeed the im gasket.

 

[98mitsubishigst]

ill check the IM gasket. thats my worst fear. it was brand new felpro but i didnt install it so i cant vouch for it. rlacasse, a member here, installed it. and from watching the guy work, he knows how to put a box of bolts back together. guy is pretty good. but still, mistakes happen, thats ok. plus, oreilly could have messed up the p/n and gave us the wrong one. shit happens.
im also going to look up the vac hose routing. if we misplaced one of those lines, its drawing in unmetered air as fast as it can causing the rapid rise in rpm. i think once this is ironed out im gonna have a great car.

its the first time its been running since july, when i bought it and dropped it off to the incompetent mechanic. this is a minor problem ill have solved in 30 minutes when i get time. ill check everything and report back. thanks guys, love this forum

98mitsubishi, read that thread u linked. good reading. will check everything out. btw, this car is a ###ing frankenstein. the further we got the more we noticed. it was originally an auto, the engine is either a 95 or 96 7 bolt. gound that out the hard way today when i ordered a 97 cps. got to oreilly and said "wtf??" totally dif. so out of curiosity i asked to see a pic of a 96 gst cps. perfect match!
so, if the IM gasket is dif from those years..... theres my prob. luckily, rlacasse told me to leave off the IM to block bracket. that will make this job way easier if it is indeed the im gasket.

Haha lemme know man =) it drove me nuts! because my talon is also a frank stein haha, Its a 2g with a 6 bolt swap.. well i used the 7 bolt intake manifold gasket for the 6 bolt head // 6 bolt intake manifold gasket. That was a big no no!! leaked under the intake manifold when i did a boost leak..

Let us know what the problem is, or if it's not this, post back and ill try to help

 

[BurrowZ]

My buddy's GST, he left the washers on the intake mani studs before putting the manifold on.. THAT made things interesting haha

I actually did this, but it was a pain to start up. Once it started though it bounced off the rev limiter.

I really doubt your TPS is set incorrectly because you would still need to get AIR from somewhere, if your throttle isn't open and your TPS reads WOT, your ECU sees this and it's going to dump fuel and you'll run rich, causing a potential idle problem but not like this.

 

[josh1095]

ya burrowz, it doesnt want to start but when it does..... holy sh!t. all i keep seeing is blowing up a very expensive engine in 5 seconds. sunday its gonna be nice around here: in the 50s, so ill have it nailed down then. will post back

 

[Rockyp]

BLT? acronym im not familiar with

Bacon, Lettuce, and Tomato. You may ask yourself what a BLT has to do with with the problem. In any situation where there's a question, Bacon is ALWAYS the answer my friend.

Boost leak test...

 

[BurrowZ]

ya burrowz, it doesnt want to start but when it does..... holy sh!t. all i keep seeing is blowing up a very expensive engine in 5 seconds. sunday its gonna be nice around here: in the 50s, so ill have it nailed down then. will post back

50s!? You lucky son of a..

Okay you have your problem completely narrowed down, now to just find where the leak is! Speaking from experience you COULD have washers in between your IM and head. You would be able to see that, because they are the studs which are right on top of either side.

If you think about it it's a pretty easy mistake to make. You don't want to lose the washers and if you're like me you put them back where you got them.. ie: the studs. So not even thinking about it you put the IM gasket on over it, completely covering it from view and the rest is self-explanatory.

Just grab your flashlight and take a looksy there. I'm betting something of the nature is keeping it from sealing fully. Your gasket being bad wouldn't cause THAT bad of a leak, as least I don't think so, but it would be significant.

EDIT: The above statements keep saying to do a BLT. Make sure you do it properly from the throttle body if you chose to.

 

[josh1095]

yes, TB and manifold is where im suspecting the leak, anything before the TB wouldnt make it do that. i cant wait to find the NEXT problem , im sure there will be boost leaks, bad sensors, etc etc. but its sooooo close now.
and ya, ive been to wisconsin ONCE in the winter, last time i ever go . so cold thought my eyes would freeze. i do have a hospital in sheboygan but luckily only have to visit there once a year. and hope itll be in the summer.

update: SOLVED
problem: throttle cable adjustment. thing is, i could have sworn i saw the guy i was working with adjust it. but neither of us took the TB off to check for sure. i did this time and found it open atleast 10 degrees , that will make an engine idle just a tad bit high, dont ya think? haha

first drive on new engine. heard lifter tap at first but went away after 5 minutes or so. clutch slave cylinder leaking. found oil dripping AFTER the drive but not during the initial 15 minute warmup, so it leads me to believe when i pushed the clutch in while driving, it leaked, and blew that oil to the rear of the engine compartment.
otherwise, i could have a leaky half shaft seal or maybe over filled the tranny. not sure yet. ill have this one figured out by sunday i think.

 

[98mitsubishigst]

yes, TB and manifold is where im suspecting the leak, anything before the TB wouldnt make it do that. i cant wait to find the NEXT problem , im sure there will be boost leaks, bad sensors, etc etc. but its sooooo close now.
and ya, ive been to wisconsin ONCE in the winter, last time i ever go . so cold thought my eyes would freeze. i do have a hospital in sheboygan but luckily only have to visit there once a year. and hope itll be in the summer.

update: SOLVED
problem: throttle cable adjustment. thing is, i could have sworn i saw the guy i was working with adjust it. but neither of us took the TB off to check for sure. i did this time and found it open atleast 10 degrees , that will make an engine idle just a tad bit high, dont ya think? haha

first drive on new engine. heard lifter tap at first but went away after 5 minutes or so. clutch slave cylinder leaking. found oil dripping AFTER the drive but not during the initial 15 minute warmup, so it leads me to believe when i pushed the clutch in while driving, it leaked, and blew that oil to the rear of the engine compartment.
otherwise, i could have a leaky half shaft seal or maybe over filled the tranny. not sure yet. ill have this one figured out by sunday i think.

Told ya to check that first =)

 

[josh1095]

leak fixed too. i broke it in yesterday per motoman. it lives!!!!!!! just rides extrememly harsh and has some shakes. thanks 98mitsu, much appreciated. i thought i checked that but must not have loosened screws up all the way, soon as i did, bam, butterfly slammed shut.