I have an '83 Camaro 305 TBI Crossfire F/I. Its running like SH*T right now. When I first got it I started putting 93 octane and fuel injectior cleaners and stuff in it, well, just last year my cat was clogged, my shop teacher said it was from the car running rich and we discovered the timing was off and still is, so we gutted the cat, and it was perfect, ran good. Now the car has a rough Idle and is shaking like it has a cam, Now it happened 2 times before...... the first time all i did to fix it, I didn't know it would fix it, but it was raining and i backed up and spun the tires and caused the car to hop a little and it fixed the problem, So I guess there is stuff building up in the cat???? and the last time it happened i had to hit the cat with a hammer to bust up the stuff. Now its been like this for 3 days and I can't fix it. Im not 100 percent sure its a clogged cat because the cat was gutted! When i put the car in drive it idles at like 500 rpm like it always has but realy luggs it seems. and when i drive it feels like its bumping like a duh duh duh duh duh realy quick. Need help, and i can't take off the cat because its welded on and i don't have a welder and i cant realy drive the car anywhere. Please Help!



Also I recently did a full tune up, No egr valve if that matters, but im pretty sure something is jammed up in the exhaust because the engine seems smooth, then right when i go down by the cat i can hear its rough and when i gutted the cat, my buddy welded it on at his shop and there is a leak at the top and it seems like alot of air is being forced out of that hole so that tells me that theres a clog after that part of the cat. When the car is cold should i hit the cat with a hammer to bust up the stuff inside if thats the problem??

 

Look for a vacuum line that has a leak or has come off. You can spray carb cleaner around all vacuum lines while it's running, if the idle surges or smooths out for a second, that spot you sprayed has a leak.

 

Thank you for the Reply, Yea, I will try that, Tomarrow I will take off the air cleaner and check all the vac lines and the spray pattern in the throttle bodies, I have a feeling something is jammed up in the exhaust tho, It just scares me a little because the cat was gutted so what could be clogging it? I forgot to mention that I recently did a tune up so its not that or a fuel filter.

 

The problem just seems to violent for a Vac Line problem, It really runs like Sh*t.

 

A gutted cat shouldn't do a thing in the world unless it wasn't completely gutted. But even then it can't plug up that much. You would be suprised how much exhaust will escape out of a leak even with low to no backpressure. How bout the MAP Sensor or the TPS?

 

It was all clogged up with the "honey comb" looking catalyst inside, after we gutted it out I could see directly to the other side meaning it seemed hallow. How do i check the Map or TPS

 

The Cadillac convertor is fine then. Good move on gutting it in my opinion. Usually by back probing with a volt meter to see how many volts each of the sensors if putting out. When I was doing my rebuild, the Throttle Body had sat in the weather for about 2 weeks...OOOPS. fired it up and hooked my laptop to it cause I couldn't figure out why it was running so rich, turned out at idle it was telling the computer it was at 83%.

I will get on shopkey when I can and check what the voltages should be and more specific instuctions.

 

Ok, cool. My shop teacher said that my car was running rich when i brought it into my school. I would have just done everything there but they told me i couldn't bring the car in anymore. and i forgot to mention one of the times i tried to drive the car i had it in drive and held my foot on the brake well I heard a rattling somewhere, not sure if it was the exhause, but theres a cover or heat shield that i did take off, that may have been the problem

 

Is your check engine light on? When you did the timing did you cut the Tan/Black wire that is connected to the ECS Module. You have to have that wire disconnected to put the computer into Bypass mode so it doesn't fight your adjustsments.

 

A few things to check for/check out:
-vacume leaks,check the vacume hoses and all the bolts
that hold the upper plate to the manifold.
-IAC valve problems-there are 2 on the C/F,if one hangs
up can cause nasty running
-ignition problems-bad plug wires,plugs etc.
-engine problem-bad valve,etc.-do compression test.
-CEL working?-sensor problems will light the CEL.
-both injectors working?-next time it runs like sh*t
take the air cleaner off and observe: if one is not firing
there is a wiring,ECM,or injector problem-wiring problem is most likely,ECM problem rare,injector prob.
very rare.

 

Ok, now heres the thing, When I had it at my school, My shop teacher said "he didn't know how to fix the timing" but we did discover that it was off and the car runs rich, ( i think thats the problem that happened to the cat in the first place, from it running rich it deteriorated the cat) so we left it at that. And I honestly think it has to do with the exhaust because the engine is running healty, so when I was hitting the cat with a hammer, not hard enough to damage it, the engine stumbled at idle and the check engine light went on for a minute and went out, So im thinking that theres a clog by the A.I.R hose in the cat.

 

Ok, Theres a small vaccume leak at a hose by the fuel canister just from cracking, I plugged it with my finger and it still ran the same. I didn't check the bolts, not quite sure what bolts your reffering to. The IAC Valve im not sure where that is, The Throttle bodies seem to be in sync and make a good cone pattern, even when i rev it. I did a tune up before summer with new plugs and wires. The Check Engine light does work and lit for a minute when i was hitting the catalytic converter with a hammer to bust up any catalyst thats inside (if any blocking it), then the light went out, when it lit the cars idle lowered or stumbled. There is one grey wire that has a clip that is just hanging from a harness on the passenger side of the engine, It seems its been disconnected for a while, There is absolutly no other connector where it seems it would go. Im still very convinced its a clogged exhaust somewhere. There is a leak that air comes out of, well since the problem started i Hear more air coming from the leak where it wasn't welded, So in a way it makes sence that if its clogged the air would be forced out the hole, but theres a good amound of pressure from the exhaust tips behind the car

 

If you're concerned about exhaust a Sawsall will fix it in about 2 minutes. Hitting the Cat could resonate enough to trigger excessive knock counts and the computer added fuel and pulled timing. I would blame the idle change on that. You need to get the timing dialed in before you explore anything else. The Timing directly relates to fueling. Set the timing then get concerned about about your exhaust. If you can see through that Cat like you said, that isn't your issue. If you are still concerned I don't know what your states laws are for cars that old but lose the CAT completely if you can.

 

check what code was set when the CEL was lit-that will
give some clues.
There is an IAC valve on each throttle body-they have
a large hex on the end with a 4-pin plug,are wired in
parallel and are suposed to operate in unison,but some
times they don't.
If you feel exhaust at the back of the car, i really doubt
there is a plugged exhaust.
Timing is very easy to check and set(need to get or
borrow a timing light)

 

In case nobody's mentioned it, you need to check your fuel pressure. If a CFI motor allows you to see the injectors at all, you need to see what the spray out of them looks like. If it's more droplets than a fine spray, that may be your problem with stumbling and rich fuel condition. This could be a bad pressure regulator or a bad gasket on the injector pod which is causing fuel to leak and drip in. You should know what's going on pretty quickly after looking at them while it's running.

And check timing too. Those are my two best guesses.

EDIT: Also, if the exhaust is plugged or clogged somewhere, that section of the pipe is going to get RED hot after running for a few minutes because of the trapped hot gases. I've seen clogged catalytic converters and crushed pipe glowing red hot, it would be hard to miss or mistake.

 

I agree. If your car shop teacher doesn't know how to check your timing than he should not be teaching. You need to check your timing. Any shop should be able to do it for next to nothing. Start with the easy stuff first. if your cat is truly gutted than that is not the problem. Put your hand over the tail pipe and rev the engine. If you feel a significant amount of exhaust flow, it is not your cat.

Things to Check

Timing
Fuel pressure
Spark

A shop should be able to test each of these for next to nothing. If you are not sure how to check these, a few minutes with a timing gun (less than $20 at sears), volt meter, and a $20 haynes/chilton's manual will give you enough ammo to test stuff yourself.

 

I wasn't going to bring up the Shop Teacher...hehe.

 

Yeah, the thing with the exhaust is i don't have a welder to put it all back together, and if i cut it i cant just clamp it.

 

ok, I will check that, What am i looking for, just a damaged iac valve?

 

The injectors fire a fine spray in a cone pattern, and accually when my cat was clogged before it didn't get red at all, the exhaust was still able to pass through it though, just barely

 

Ok, well i know im getting spark and the timing is definitly off, Thats as far as i got at my school and its supposed to be like 6 degrees tdc and its at 24 tcd, and i asked ok well how can i fix it and he said idk and got 2 other teachers and they didn't know, unless they didn't want to help me. Fuel pressure is also good, i checked that on my own last year when my cat was clogged

 

Again I appreciate everyone helping me out with this, Im tryin to get this car runing well before i get my licence, I got my permit and im driving a dam pick up truck for now.

 

Nothin wrong with a Pickup Truck Bud. Then again my friend that races says I should quit hot rodding a 5400 LB Truck. Oh well, I'll get it into the low 14's high 13's someday.

 

Your timing isnt off, in order to check it you have to disconnect the tan/blk wire under the dash, without doing that the computer still has control of the timing and it should be up where it is, the ONLY time you can check it with a gun is with the wire disconnected! THATS THE ONLY TIME IT WILL BE A WHAT THE STICKER SAYS!

Hell no there's nothing wrong with trucks! mines only 2980lbs, none of my buddy's cars are a problem for her.

 

Yes, I know theres nothing wrong with pick up trucks, The one im driving is a piece of crap thats all.

 

So, After I disconnect that wire (if i can find it) should i leave it unplugged for a few seconds then plug it in? How do i set the timing accually, The distributer doesn't set it does it?

 

What kinda truck you got anyways, if you don't mind my asking?

 

Oh, and by the way, I pulled the air cleaner housing off and looked everything over and The engine is running smoothly, The engine accually feels like it always did, just when I rev it, Its hesitant, I mean, it revs but its sluggish.

 

Low fuel pressure can cause hesitation and sluggish
revving-fuel pressure is not all that easy to check on a
crossfire,there is no schrader valve like on a TPI,you
have to tap into the pipe between the 2 throttle bodies
the pressure is suposed to be around 11-13 psi(they
actually run better if pressure boosted to 14-15 psi)
if low pressure is found,it is possible the foam rubber
coupler hose between the pump and the steel pipe
(inside the tank)has turned to mush and blown out.
Lots of other stuff to check 1st,check for any stored
codes yet?
BTW i have a hot-rodded 350 CFI in my car

 

Yea, Im thinking it might accually be a bad fuel pump or something inside the tank, The fuel filt is newer but ive ran the car out of gas 2 times within 2 years and who knows how long ago before ive had it the fuel pump was replaced..... I'm just getting so discouraged over this, I wan't to fix it up to where it runs like a top but I cant do it myself. I didn't check for codes yet, i don't have a scanner. And about the fuel pump, Ive noticed, well heard, for about a year now, if i start the car and shut it off quickly after starting it cold, I will hear some kind of noise coming from the pump i think, after the car is off it will be a low growling noise. Its wierd. can you put up some pics of your CFI? I wan't to try to get a vid of what my car is doing up on youtube for yall to see, exactly what im talking about. Tomarrow its guna rain i think so hopefully within the next week it should be up there. What makes your CFI hot rodded?????

 

no scanner needed to check for stored codes,just jumper
terminals A+B on the diagnostic plug under the dash
with a piece of wire,bent paperclip,etc. the CEL will flash
a code when the ignition is turned on(do not start car)
first it should flash a "12"(one flash,pause,two flash)
"12"indicates the computer diagnostic is working,this
will repeat 3 times,then any other stored codes will flash
if no other codes will go back to flashing "12"(you will
find lots of info on the codes on this site)
the fuel pump used on the C/F is long lived and very
reliable,so probably still good. Hearing the pump run
for a few sec. after shutting off cold is normal as is the
described noise
Back in 1994,i installed an '84 vette "L83" crossfire
350 in my z28,it was decent but i felt it wasn't up to
what i thought it should be-power really tapered off
above about 4200 rpm,etc.
(most of the problem was the intake runners are small
cross section and cast with a sharp edge at the runner
intakes) So in 1995,took off the intake manifold and
using a TIG welder,built up the runner intakes and
using a die grinder reworked the runner intakes into
an enlarged "bellmouth"shape,hogging out the rest
of each runner about 1/8" all around, then added a
1/4"lid spacer for more clearance above the runners.
Pulled the heads and did a mild port job,modified
the fuel pressure regulator,tweaked up the fuel press
a bit(i already had headers/3" super single exhaust
on car before engine upgrade) all this work resulted
in a dramatic increase in horsepower,torque increased
a bit too now easily revs to over 5500 rpm. Nearly
15 yrs later,still delighted with the performance
-for an early '80s car it flat rocks!!,faster than my
porsche 928(4.5L v8)

 

Dam, that sounds nice man, you ought to get a vid up or something, I'd like to see it, I want to get my car running like that (even though mynes a 305) and show up some kids at my school talking Sh*t, Saying how third gen camaros are slow and it didn't help that my shop teacher said that a stock 87 Camaro 305 TPI will run a 17. But anyways, no updates today, it was raining and i didn't want to mess with anything in the rain, my shop teachers saying he MIGHT let me borrow the scan tool to get some codes and see what the problem is Exactly, But I think im better off just taking it to a shop, because even when i do find the problem, i may not even be able to fix it by myself, But before i jump to conclusions i am going to scan it first. But i did have my car running today, i let it warm up just idleing, and i went to take it for a quick drive down the road and after it was warm i put it in reverse and it idled at 500 rpms and it was lugging, It REALY did not like that, I just held my foot on the brake while in reverse and it felt like it was stumbling, Thats how its been the whole time since the problem started but i never noticed until today.

 

Probably saw it on a TV show or something. There was one a few years back where they hopped up an old 3rd gen that was horrible out of tune (or horribly driven) and held it up as an example of how they all run. My 91 Camaro 305 TBI with an auto and 2.73s turned 15.7s with over 200,000 miles on it. Just had all of the cheap TBI mods and some computer tuning, and there are people that have gone much faster than that on the old 305, especially TPI.

 

these cars arent slow. and if your car is bogging down... buy yourelf an 8.00 can of throttle body cleaner ( or carb cleaner I cant remember which you said you had)and go to town. you would be suprised all the gunk you come up with. but it dramatically improved gas mileage and throttle response on my old 2.8. what do you have to lose?

 

Lol i just remembered i was in the TBI section. so of course you have throttle body. lmao its 1:00 in the morning. Im not thinking clear. :P

 

Yea, well he said that a Stock 87 Camro 305 TPI From the dealer will run a 17, He made me look like an A$$ in front of the kids with honda civics that I told i could beat.

 

My car doesn't bog down Its just hesitating when I rev it and drive it, Its sluggish, I will try some carb cleaner and see if that works but i doubt it, It was kinda cold this morning and I started the car up and It didn't realy sound like it idled up like it should when the choke is on.... Another thing I thought of also, is that the distributer rotor i replaced when i did the tune up ended up going bad, and I threw the old one back in that wouldn't tighen down all the way, so im thinking it could be something like that, but Ive had the old one in for like 3 months now, so I doubt thats the problem unless something hapened when its missing or something, I will check it out, and I should be able to get a vid on youtube tonight for yall to hear what im talking about

 

There are articles on this website from 80s car magazines (Hot Rod, Car and Driver, etc.) that tested these cars when they were new, and they were running much better times than that. You ought to print one off and take it in to him. He's just ignorant, that's all. :P

 

You're fuel injected, dude. You don't have a choke. But it will idle high when it's cold, like a fast idle or choke on a carburetor does.

Bad dizzy rotor would definitely cause problems, and with your car being older I'm wondering if it has a separate bolt-in ignition module like the HEI setups, which can cause this. Some of the other guys should know that one.

 

Yes, Thats what I mean, Sorry, Its a fast idle, but this morn when I started it up it didn't really Idle high, Its not that cold out but it should have gone a little higher, It does have the seperate igniton, Me and my shop teachers got into an arguement, about the vaccume advance, Its not on the distributer like a traditional HEI, Its seperate, well controlled by the ecu or ecm i forget,

 

Yes, I know, Wasnt the mustang fox body the chevy camaros competetion and although the camaro was faster, (top end and 0-60) they both would run like a 13-14 I think, Correct me if im wrong.
and i think irocz.com has those articles

 

After you disconnect it leave both ends hang and start the car, hook up the timing light and turn the disty to set the timing so that it matches whatever the emissions sticker under your hood tells you to set it to. With the wire unhooked the disty is setting it, thats the only time though, whenever the wire is plugged in the PCM controls it.

It will have the CEL on when its running and the wire is disconnected, dont worry about that, just set the timing, shut it off, plug the wire back in and restart, that code isnt stored so it will shut of a few seconds after restart once the wire is connected.

 

Ok, Thank you, I'm going to wait untill I fix this little problem I have now, then I will try to bring it to my school if my shop teacher lets me.... But I let the car run today, and I heard a rattling in the cat, and the check engine light came on, so I wonder if its like a blocked A.I.R pipe or something. I have't had much time to realy look at it because right after school I work untill dark.

 

Ok, well instead of me borrowing the scanner, he said to tap the muffler

 

YOUR SHOP TEACHER IS A DOUCHEBAG. (just for the record)

 

ya, your telling me, but its ok for the black kids to leave their crown vics there to completly restore the whole school year. Anyways, its been realy shitty weahther for the past few days so, when i get a chance i will take off the A.I.R hose from the cat and take a look inside if I can, then if thats ok I will check the rotor under the distributer and try to eliminate the easy things first before i start trying to get a scan tool, The check engine light hasn't come on for a while so maybe thats a good thing. I'm not realy woried about doing the timing right now as much as im worred about getting the hesitating problem fixed.

 

your shop teacher seems to be a real basterd and has favorites

 

need to see what code was set when the CEL was lit.
-no scanner needed,heres how to check for stored codes
-to the right of the steering wheel,on the drivers side
of dash,lower edge, you will find a 12-pin plug,2 rows
of 6 contacts,on the upper row of contacts,jumper the
two contacts on the right together with a piece of wire
or bent paper clip and turn ignition to on-CEL will flash
stored codes,those will give clues to the problem

 

Good News Everyone! I havn't been driving my car since I posted this thread, but I have been letting it run, because of the cold, I just didn't want to let it sit untill I fixed the problem, So the last time I started it was 2 days ago and I let it run for like 5 minutes, well today I started it and It was the same, its been realy cold here so it idled up as it should in the cold to about 2000 RPM and I walked in my house to get my jacket and I came out and the problem was completly gone. It had idled down and It was smooth when I revved it, I walked over where the catalytic converter is and I didn't hear that noise that sounded like all the exhaust was being pushed out the leak. So I let it run for like a half hour, I put the heat on. I havn't driven it yet, I want to get a gas can and put 5 gallons in it, It's pretty low. Thats whats wierd though, I guess it was a clog in the muffler then, but my gas mileage was sh*tty. Seems ok now, But next week I'm gunna take it to my dads mechanic and let him set the timing and check everything over and replace anything nessary to make sure this don't happen again. I will probably have him check the fuel pump and change the screen out, I'm sure theres alot of gum in the tank. But again, I thank y'all for helping me!