TBI (i think) causing rough idle and SES light on
 

hey there, I i have a 1990 Camaro RS with a 89 350 IROC engine bought it a few months ago.. well just a few days ago i buring way to rich i could stomp the gas and blow smoke like no tomarrow well i fiddled around with my IAC plug and TPS plug to see if they needed to be replaced. well after i unhooked and re hooked them back up at engine start i get a low low rough idle like the car is going die then in about 3-5 second it kicks up a little high, but still sounding normal and my SES light pops on.. so i still got a issue with the wierd idle and a little black smoke still coming out, but not nearly as bad.. if anyone can give me a hand with this id really appreciate it.

Re: TBI (i think) causing rough idle and SES light on
 

I don't think that IROC-Z 350 was originally TBI... could be wrong.

anyway it sounds to me like the IAC valve, was it gunked up really bad with carbon or did you even pull it out??

Re: TBI (i think) causing rough idle and SES light on
 

thats what I thought it may be and no i havent pulled it yet i just wanted to make sure my thought was right before i run off and start pulling stuff apart lol.. Thanks

and yes your correct the 350 didnt originally have TBI so im guessing the person i bought it from put it on there.. i did think it might be a 305, but the car has to much torque and HP (havent dynod it yet) but i could also be wrong there.

Re: TBI (i think) causing rough idle and SES light on
 

you'd be better off running the casting numbers to figure out the ci's. do a search and you'll find how/where to look for these.

Re: TBI (i think) causing rough idle and SES light on
 

alright ill do that, but first you know where the casting numbers are on the 89 iroc engines? tried looking around last night couldnt find it

Re: TBI (i think) causing rough idle and SES light on
 

found the casting number under the valve cover well turns out it is a 5.0 305.. which is no biggie to me i still got ALOT hp and torque lol.. but yeah if you got any other ideas throw them at me ( casting number 14102187 )

Re: TBI (i think) causing rough idle and SES light on
 

You definitely have a 305 TBI motor (at least assuming the heads match the motor), the motor that car is suppose to come with. I hope the guy selling it didn't tell you it has an IROC 350 motor. Well, actually he wouldn't only be half lying because you could get an 89 IROC with a 305 TBI motor.
Did you pull the SES code?
If I were you I would pull the TBI unit off and give it a thorough cleaning.
You also might want to pull a spark plug and see how it looks.
When is the last time the car was tuned up? Plugs, wires, air filter, fuel filter, pcv valve, TBI gaskets/cleaning, injector cleaner, etc.?

Re: TBI (i think) causing rough idle and SES light on
 

im still some what new to the car deal so not really sure how to pull the SES code.. i do know how to do the tunes ups and all i just changed out the distributer cap and rotor i pulled the plugs i have the bosh fuzion 4s they were a little black but cleaned them up and put them right back in.. (i had bought bosh platinum 2) i will deff. try working on cleaning the TBI out completely.
I did also know that the IROC came with a 305 TBI thats why i checked for the casting numbers.

Re: TBI (i think) causing rough idle and SES light on
 

Go to an AutoZone and get one of the free pamphlets on emissions stuff.
It'll tell you where to put the paper clip, and how to do it, and how to count the flashes, and list what they mean.
I'd be doing that long before pulling anything apart.

Re: TBI (i think) causing rough idle and SES light on
 

alright ill do that today thanks for the info

Re: TBI (i think) causing rough idle and SES light on
 

There is just one thing you need to know.

EVERYTHING you will ever need to know about your car is already somewhere on this message board. IT IS GREAT!!! The "search" button can be your best friend.
When I owned my 90 RS (RIP) I went from not knowing how to change the oil to installing headers, full suspension, a transmission, engine modifications, etc. just by doing research on these boards.

Re: TBI (i think) causing rough idle and SES light on
 

If I were you I would put some regular copper AC Delco plugs in the car, those seem to work the best and are only about a dollar or two each. All those crazy spark plugs are just a waste of money in most people's opinion.

Re: TBI (i think) causing rough idle and SES light on
 

thanks for the responses. I already know the basics plus a little on cars there is just **** like hard core engine or tranny work i know nothing about and most electrical besides wiring in speakers and a headunit, but who doesnt know that already... I will deff. use the search button more i just joined the forums to hope i get some good advice on my car.

also how exactly do i match the numbers with my motor and my car to see if its the original motor?

Re: TBI (i think) causing rough idle and SES light on
 

the cylinder heads are definitely heads from a 305 TBI motor. I believe the block casting is somewhere near the back of the block, not sure if it's something easy to see. I would assume you have a 305 TBI motor, im sure if the guy put in a 350 he wouldn't use these crappy flowing heads unless he was really on a budget and you are running a very high compression.

Re: TBI (i think) causing rough idle and SES light on
 

well i went on and replaced IAC sensor bcuz its original and its atleast 18 years old cant hurt having a new part and that seemed to fix my idle issue i still got a small surge in park or neutral but very very small nothing big to notice.

and yes i heard the heads on my engine were the worse ever made for 87-91 the swirl ports =/

Re: TBI (i think) causing rough idle and SES light on
 

Alright guys thanks for all the help my baby is finally 100% normal now.. so i went to autozone and pulled the code it was code 33 aparently it was for MAP sensor so i looked at it pulled it out bought some cleaner cleaned it up and now its normal and actually better than before.