lc tpi

i have found that my vehicle has an idle problem that seems to be intermintent. it runs great idles good hunts alittle on the idle but not much. the real problem is when i take it for a drive the idle seems fine when i come to a stop-manual trans. once in a while the idle will come up to around 1200 and stay. dont know why. the only way i can get the idle down is to unplug the tps sensor and plug it back in . this is wile the vehicle is still running. if i shut it off and restart it it is fine. this is not the only tpi with this problem. i know of two other tpi motors with the same exact problems. one is sd an mine and the other is maf. they are all three in non smog vehicles with no catlylitic converters. tpis told one of the guys to try and run a heated o2. because these vehicles dont have cats the exhaust may not be getting hot enough for the o2 to work properly . the guy who contacted tpis has been fighting this problem for some time and dumped alot of money into this problem including time. used a number of custom proms has a snapon scanner. to no evail. i would like to see if this could really work. i am somewhat new to this tpi stuff but i can learn quick. and would rather try and fix this thing without having a 100,000 $ tpi system. any info on this would be great. just about everytimg on my tpi is new. done the minimum idle reset a zillion times ,iac reset, new iac all sensors, wiring injectors, fuel pump,prom.whats next heated o2?

Zepher

iTrader: (1)

mine would do that and it was a bad wire on the TPS connector.

lc tpi

the harness is brand new. and im not the only one having this problem, my uncle and a guy he met through a friend also have the same problem. i know it could be just quincidental that we all have the same symtoms and all could be differnt problems. but i seriously believe it can be fixed but finding out what it is is going to take some time . i will check again., but i dont think i have a bad wire.

CreepingDeath94

iTrader: (4)

Possible cracked vacuum line that is ok enough to only cause a surge when it gets jossled? Mayeb you move something when you mess with the TPS? Just an idea. Also, where did you get the sensor? I have had an issue with a couple sensors from NAPA from time to time where the sensor was actually just faulty or wrong from day one.

JB22

I have been having a similar problem with my 350 install. Will idle sometimes perfectly when coming to a stop, othertimes around 1200. My issue however I think revolves around the IAC sticking because I have not cleaned/replaced it.

I did the IAC Reset a few times, as well as the IAC voltage check, so I know those are good. Car idles around 600 normally, but always seems to be after I drive a little bit it will stick around 1200.

lc tpi

i dont believe the tps is bad when the idle stays at 1200 i check the voltage to it and it is .54 volt exactly.the throttle blades are not hangig up either. the only vacume on the thing is the egr and fuel press reguletor. if i un plug the tps the idle stays, as soon as i plug it back in it drops back down to normal. i have read that the coolant temp is the same part as the air temp sensor. is this true. i used the same sensors in both. brand new from autozone. i put a brand new pcv in it . i can unplug the pcv when the idle sticks and plug it with my finger and doesnt make a difference.i have sprayed it with eather. nothing.i run a 180 thermostat. electric fan comes on 195 off at 180. no power brake booster on this car either. pulleed intake off when i had my injectors cleaned and flow tested to make shure of no leak around the intake gaskets. used all new gaskets. felpro. there has to be a fix for this .keep the replys coming i know you guys can help , its just a matter of time.

lc tpi

jb22 this is exactly what mine does. i can count on it to do it every time , just dont know when. the other day it didnt do it at all. weird. i have a brand new iac from kragen auto parts. it is a nieoff ,cost me around 46.00$ there were more exspensive ones. i dont want to buy another and not be able to take it back if it doesnt work. weird?

JB22

well, mine seems to have gotten better the more I have driven the car. but I Only have 200 miles on it right now. I am going home to work on it some this weekend, so we'll see how it acts then.

I am far from an expert at this, so I really dont have the answer. I guess its always possible your IAC is sticking even with the new module. Maybe someone else can chime in any experience with this.

CreepingDeath94

iTrader: (4)

Well, I didnt know it was a brand new motor still. I would keep driving it for another few hundred miles and see what its doing. It is possible that it is still breaking itself in and finding where it likes to run before it will smooth out.

dave-92gta

iTrader: (1)

hey, sorry i am sort of new to this web sight, but it is super cool, you can chat and do w/e, i know for a fact it is not this issue, all cables are fine, and i have checked the throttle body, it is clear, i will explain the situation to you better.

when i start my car cold:
the car starts in high idle, which is around 1100, and as far as i know thats normal. when it starts to lower due to engine warming up, it falls to 1000 or 900 rpm and then climbs right back up to 1100. since it is like 30 degrees here, the car des not need to warm up very long so this prosess talkes 15 seconds to start.

when i start my car already warm:
it starts and holds idle at 1400 rpm, that is, nothing elce

some of the side effects of this is hard to stop, there is increased power all the time, just like in high idle, but its more. it also jumps when i take my foot off the break. it also down shifts hard and is really jsut a big problem. i thought i would explain some the symptomes even though you probably already know them, every thing can help me right now.

i dont like talking my car to a garage if i can help it, but i phoned one and he said it could be a vaccume leak, does that sound right?

lc tpi

ok so i put a heated o2 in the vehicle and the idle is pretty smooth and stable, so i think the heated o2 is a good thing. but i still have a problem with a high idle that seems to only happen when i put a load on the engine at a low speed near idle. say for instance when i start to take off in 1st gear and lug it down pretty good. i am wondering if not running a vss ,if that could be part of the problem . the vehicle thinks its going to stall so it ups the count on the iac and since there is no pulses from the vss it does not know that it has not stalled. i have been reading alot on the gm mefi4 that this has been a big problem with guys running a ramjet or any mpfi with the mefi 4 system. when they put a load on the engine at around 1400 in high gear and let off the gas the engine keeps going for up to a minute before idling back down, and in some instances the have to shut it off and restart to get the idle back down pretty much the same typ of problem. so im wondering if going back to closer to a factory setup excluding the smog crap, like adding the vss and see what happens.

magus92z28

I have the same problem, and i had to fix other things before, and now im im about to tackle this problem, my car is 5spd, person before took out the org tranny, and its been idling high and when i just roll in neutral it stays idling high which annoys me and been killing my gas mileage. would be great if you can post any additional info on fixing this. as well my car has no smog equip as well it was gutted out.

JP86SS

iTrader: (1)

That is the reason for your stalling problem.
There are settings in the program that take into account the car slowing down that effect the IAC. Installing one will probably correct the stalling.
The flaring idle could be noise on the VSS line (just a guess)
Try jumpering the connection and see if the problem goes away.
You should install the Park/Neutral indication switch wire as well if you do not have that connected. IIRC not having it grounded indicates "in Gear" but wouldhave to double check that.
Just some thoughts.

89Nighthawk

Okay, the guy that told you the oxygen sensor wasn't getting hot enough because their is no cat so put a cat on it...................
The exhaust gases are not going to get hotter by adding a cat since the sensor is upstream of it. The distance from the head, the A/F ratio and whether your headers/manifolds are coated will determine when the oxygen sensor gets hot enough.

I've had this problem in the past, did a real good cleaning of the TB and then reset the IAC and TPS and that took care of it.

My idle does hunt at times, sounds like a top fueler, surging when sitting still, it seems to unnerve people. Of course it is kinda loud, people close to my car when I start it usually jump a couple of feet.

GTA350VORTEC

"The flaring idle could be noise on the VSS line (just a guess)
Try jumpering the connection and see if the problem goes away."

When you say try jumpering the conection, do you mean the conector that attaches to the trans or another area? I have the same problem with my GTA the idle will surge and surge and surge when stopped, sometimes it will even stall. Any info on this would be greatly appreciated. I have the same setup as the rest of the previous posters TPI w/ no smog/cat/egr 5spd the only difference being that I have vortec heads.

3.8TransAM

Try puncuation and splitting up those massive messes of words

+ spellcheck

It hurts to read

lc tpi

well i found out my problem and the thing that pisses me off is the fact i trusted the guy who burnt me a new chip and the whole time i fought this it was the program. im not shure if i can post any names but i will tell you he works at howell. i bought the moats apu1 and used tunerpro , iused this site to track down stock bins and i used the flash cip with adapter. i programed the chip with an 89 350 with man trans bin and changed injector size changed the flags to disable vats and ran the chip in the cruiser and it seems to run perfect. now im not very good at this yet and have a lot to learn but i was so mad because i spent 285.00 and spent even more on parts trying to fix this. i have not figured out how to go about this whole thing and try and get my money back. the fact of the matter is this guy also burnt my uncle a chip and he spent 285 + 100 on the programing after he sent it back and the guy supposedly changed some things. it ran worse after he got it back. i burnt him a chp for an 89 vette 6 spd changed injector size and vats. it actually runs very good. his motor would never come down from 1100 rpm. and on the cat making the 02 hotter im not 100% on that but when i put the heated o2 on my notor it smoothed the ide. thanks guys ive been so wraped up in every thing i havent been on the forum. ill keep checking back.