innovative induction

Ive been into the lt1's for some time now, (94 firehawk) but I found a deal on a 99 z28 I could not pass up, but now Im having some probs with the idle,
Who ever owened the car before me was a complete jack ***,
the car has SLP long tube headers, Y-pipe and GUTTED high flow cats, and a flowmaster cat back.
The EGR system has been removed completly.
the O2 sensors are cut
the AIR pump system is gone.
Im not sure why they did all of this when we live in an emissions state, but what ever I will just tune it out with HPtuners.
My Questions are, will all of that removed would that cause a high idle?
Ive put 4K miles on the car since i got it and the high idle just started.
At First I found the IAC motor was leaking, so I replaced that, and it seemed to help, idle was perfect until the motor got hot and it went back to 1200-1500rpm.
so I thought It may be the TPS so I re-set it by un hooking the battery, let stand for 5 mins, then hooked it back up, cranked it back up, let it idel for 5mins, then put it in gear for 5min. then back to park. did i do this right?

Ive checked for vac leeks, found none. but when I spray starting fluid around the throttle body i get a slight surge, very slight, and I have to spray alot.

The car will idel fine (800-900rpm) until it gets hot, then the idel runs around 1200-1500

next question, since the o2 sensor wires are cut, and the cats gutted, would it be better to hook them back up or just leave them alone?

Also the automatic trans is shifting hard from 1-2nd, My first thought was the valve body, but could it be related to the high idel? like a vac leek?

thanks for your help!

Onemeanbird

What o2s are cut the front or rear?

waldershrek

iTrader: (1)

Well I'm assuming the rears were removed since the car would not run without the front ones. Do you know if the previous owner ever had the car tuned after doing all these mods? Is the check engine light on?


As far as the transmission shifting hard from 1-2 I thought that about mine when I first got it but apparently it's normal on these cars within reason.

Onemeanbird

Hmm... yes it will run with the front o2s cut it will stay in open loop which will cause it to... idle high

waldershrek

iTrader: (1)

Well yes, I guess I mis-spoke. It will run, just not very well

Onemeanbird

Running in open loop would cause the problems hes describing fairly close just need more info to give as accurate as possible internet diagnosis.

02 BLK WS6

iTrader: (11)

Make sure the front O2's are good. Clean the MAF (a dirty MAF can mess with line pressures). Take TB off to clean and inspect and reinstall with new gaskets.

waldershrek

iTrader: (1)

I'm guessing the previous owner never got a tune after installing the headers and stuff

innovative induction

like i said the previous owner was a jack *** redneck, that believes anything computer is bad for your car, ALL o2 sensor wires are cut, front and rear. and no he never got a tune, I was just happy to find out he did not put the headers on him self, from what I have found out, the car came from a casr lot in GA, they fixed it up, that put groundeffects, ss hood, zo6 wheels, the SLP headers, and the complete exhaust, they did not do a tune. it did not need it since they spent the extra money for the high flow cats. they sold it to this stupid half *** redneck, he owned the car for just 4mos before it was repo. this guy did so much to the car, that the car lot no longer wanted it and sold it to me for $1300. he stole the wheels,ground effects, hood, the LM rear exhaust, and even the air filter! when I got the car it woulod not even start, after looking around I found he had cut allmost every wire under the car, fuel pump, coolent level, oil level, o2 sensors, ect it was a mess. he also removed the egr system, and removed the AIR system, and get this ! duct taped the AIR system hoses!... oh and he guted the high flow cats, Ive got everything back in order now but the o2 sensors and the egr/air . its sad the car only has 62k miles.

I just did not know if rewiring the o2 sensors would be good or bad. guess it would be good?

SIDE NOTE: the car has an aftermarket air box on it, and he stole the filter. I can not see who it is that makes it, but its made of fiberglass, and says somthing like modern BLANK & race on it, anyone know what company that is? thanks

Onemeanbird

Man that sucks and depending on where he cut the o2s you might be able to get new sensors but sounds like thats your problem front o2s not working will cause you all kinds of bs problems. If they are cut on the harness side and you have to repair it be very careful and you must solder the connections any off resistances will goof up the readings the rears aren't going to do you any good anyway if he gutted the cats so i wouldn't worry about them for now just get the fronts fixed and the vacuum leak at the throttle body and see how it does.

Onemeanbird

You will still get a check engine light with the rears not hooked up but it wont affect the running of the car it wont cause it to stay in open loop just gonna be a catalyst inefficiency code telling you that the cats aren't working..

waldershrek

iTrader: (1)

Wow that sucks. That sounds like an absolute nightmare.

innovative induction

its not been to much of a nightmare yet, the hardest part was welding up the bottom of the headers, The car is lowared with long tubes
I had 3-4 little holes in each header, I welded them in and welded a plate to the bottom of them so it will protect them until I get some factory springs.


So any Idea who makes the air box? I went to audozone and had to mesure all the filters til I found one that kinda fits lol I would like to get the replacement k&n filter for it, But I cant seem to find who it is that makes it.

at one time it had stickers on it that read "modren BLANK & race" the last owner spray painted it red and I can not read the other word.. it could be like a local shop or person who made a sticker. the box looks just like the SLP air box, but it has a gloss black fiberglass radiator cover that has a k&n sticker on it.


EDIT::: Allmost forgot to say thanks! for the help! I will find out tomarrow if it is the o2 sensors, but reading about it, sounds right on the money !

Brian M

iTrader: (1)

good luck did you find out if it will pass code for your state if not let me know i just took off all my egr and air pump. depending on your headers they might hook up. my car is a 99 also about the air filter from what i have seen with just a lid it should use the stock filter let me know i have an extra one of those to pm me if you need Brian

innovative induction

you guys are good, I found out only the pass side o2 sensor was cut, the driver side was hooked up and the rears where just unhooked, I had to add wire to the factory harness for the LT headers (pass side only, the driver side had an extention) but now she runs like a dream, idel is right at 600rpm
thanks alot for the help! the car will not even come close to passing emission testing. I prob just going to have the egr, AIR and rear o2 sensors tuned out, but PM me price for the egr/air setup.. I may be interested.

I found the air box info I needed it's made by a company called "Modern street & race" its a full intake set up that pulls air from between the radiator, I was not able to find much info on it, the only info I could find was from a magazine install guide.
I did find out it uses the same size filter as an 92-96 lt1 corvette or a ramair TA
here is a link to the ad http://neptune.spacebears.com/cars/stories/airbox.html

innovative induction

Oh more more question since you guys are so good at internet diagnostics, On my 94 lt4 firehawk, the tempture is going crazy, (keep in mind I have an 165* stat and the fans are programed to come on at 180) the car will run at 165-180* for a long time, and all of a sudden it will start to climb quick, it gets to 220* and the "check gauges" light comes on, it will stay on 220* for aprox 5secs then it will drop real quick back to 180*
after it does it the first time, it will keep doing it until i cut the off and let it cool, but it will run for 30-45mins before it starts to do this...
could this be an air pocket? or maybe a t-stat sticking?

I can not seem to find this one.
thanks

Onemeanbird

Sounds like your stat is sticking. There cheap buy a new one and when you change it make sure to purge the system good.

TheBlueKnight

iTrader: (4)

glad you found out the problem. Your temp. really sounds like your thermostat sticking

waldershrek

iTrader: (1)

Change the stat. If that doesn't work it's probably the temperature sending unit.

innovative induction

well I changed the stat, drove fine temp stayed at 185. been running everyday for the last week 40 miles a day, and today on the way home temp went to 220 so I pull off the interstate and cut the car off, and herd something under the hood, lifted the hood and the oil dipstick had been blown out, and coolent/oil was spraying out of the dipstick tube! watter is all under the valve cover. crazyness guess something big is broke. I will find out tomarrow. But it looks like RIP..........