1991 Camaro RS 3.1 V6 AT. 190,000 miles running strong as ever... can still smoke the tire to oblivion... rumbles along with flowmasters. few hundred miles later...damn. The engine decides to max-out at 36-4000 RPM. Horrible gas mileage. gets about 10mi/gallon! used to get a good 15,16. Running really rich. When 100% throttle, engine fluctuates between 36-4000 rpm and just surges. In idle and in drive. Takes a good hill to hit 70mph. Heard i may have a bad PROM, decided to pull one from a junked Firebird so i dont waste money on a brand new chip in case that was the problem. 'bird's chip in...nothing. May be a bad ECM, swapped with the 'bird's... nothing. Changed 02 Sensor to try to pass smog, no luck, changed Coolant Temperature Sensor (activates ECM) no luck. ECM was remaining in open loop for a looong time. even at and beyond operating temp. Thought it was a clogged Cat. pulled exhaust manifolds.... nothing. was clogged but problem still existed. Had a bad injector. replaced, made little difference. Last week driving along on the freeway slow down for traffic. traffic moves, give it gas, hear a tapping in through the exhaust from the engine. pull over, check under the hood, hear a tapping from the valve cover. think its a loose rocker arm. WHAT ELSE CAN WRONG WITH THIS F'IN CAR! Starting not to care since I've got a 350 waiting to take over for this sucky tired 6 cylinder, thats taking up space in a nice third gen f-body. Anyone ever have this problem... Can anyone help?

 

how's your oil pressure/MAP sensor?

 

Map sensors running fine, oil pressures same as usual

 

You check the timing? I was getting awful mileage and no power, and it was because my timing was off 10 degrees. Youd be amazed how much different it felt after I fixed the timing. You didnt say if you checked it or not, but Id check that first before I went into other things.

 

maybe it senses that you want to swap in an 8

collapsed lifter?

 

maybe it senses that you want to swap in an 8


yeah maybe it knows its death is eminent
im not as worried about the valvetrain as the drivability problem. i havent had time to look in there so im just guessing with the rocker arm. but ill check that out too.

 

You check the timing? I was getting awful mileage and no power, and it was because my timing was off 10 degrees.
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Yeah I checked timing before all of this started (couple months ago) first thing i did was turn it back about 10 degrees.. helped a bit but here i am. stuck

 

When you want to repeat what someone said, click on the button.

Hows your 02 sensor, when was the last time it got a good tune up, how's your fuel filter, fuel pump, injecotors, coil, spark plugs, How's your spark, Theres many ways to test your spark. I like to use a paper clip in the spark plug wire boot and hold it up to the tip of the spark plug. Is the spark white bright, orange? How's your air filters, oil filter? Those are just some of the things to check. Also do you have an exhaust leak? With my car running in near tip top shape I'm getting 26.1 mpg.
And welcome to the boards

 

Check timing. 10 degrees back?? You mean 10 degrees retarded? First, set it to 12 degrees advanced timing. Then swap the timing chain.

Next, new ignition system - Distributor rebuild, ignition module, cap, rotor, wires, plugs, and maybe new MSD coil.

Do those, and you should be set.

 

Tune-up has been done only a few thousand miles ago. The timing was pretty advanced to begin with, yeah i meant i had to retard the timing, so theres no point in advancing again. the spark advance is fine. tuneup included module, coil was done like a month before the full tuneup.

 

tuneups only a few thousand miles old. O2 sensor is new. no exhaust leak. spark advance is right on. Have white spark from all wires

 

Fuel filter?
Is it cold outside ( worse milage)

 

Fuel filter included in tune-up. Gas mileage not an issue.

 

Sure you're getting spark on all cylinders? A cylinder not firing will cause an injector tick, which sounds a HELL OF A LOT like a screwy rocker arm or something. I know from experience.

 

Sure, got spark on all cylinders

 

I am going to try all the obvious stuff first.

When you timed your car did you unplug the computer control wire on the distributor? If not your timing would be screwed.

Are there any large vaccum leaks? Is the vaccum line on the brake booster cracked? Is it on tight?

Is your EGR valve opening and closing properly?
Have you cleaned your IAC?

What are you idling at? Have you ever tampered with the throttle screw?

 

Ok, lets see #1) i unpluged the wire for the timing. the timing seems fine. #2) No vaccum leaks. #3) Havent checked EGR or IAC. #4) Its idling at around 900 rpm. #5)As far as i know no when has messed with the throttle or any of its components.

 

Anyone else think they have the answer?

 

dude i don't know what to say... the 3rdgens feelings are hurt... i remembered when i swapped my 3.4 in and the 2.8 out... my car was angry(decided to change the original word) with me. It took awhile for my car to like me again, and now we're best friends again. No i'm serious! our cars are alive, and have a big sensitivity problem. it took months before my new spirited thirdgen liked me again.
maybe cuz it had a 4gen heart in a 3rd gen body?

good luck with the v8 swap...

try everything!!!!
new spark plugs, spark wires, cap and rotor, flush some of the old liquids out. ADDITIVES!!!! anything... just so it can hang on till the v8 says hello

just hang on a little longer

 

Just buy used where you can!! You don't wanna spend too much money on life support when the old geezer is just gonna die anyways. Eep, did I just say that??

 

Yeah, thats pretty F'd up man. Well i just wanna squeeze a few more drops outta this V6 and run it til it dies. Its been good to me so far.... Anyone else got any tips? Anyone?

 

no one else huh?

 

Did you remember to disconnect the EST when you set the timing?

 

of course

 

so does anyone out there think they can solve my problem?

 

I'd have to go with the timing chain... my firebird was running real rough and stalling when I shifted... and I was getting about 13 MPG (this was an LG4) it still had most of its top end power... but I couldn't figure what was wrong for the life of me... and this all happened over night.

So the day my friend and I were going to fix the problem, I had it idling and all of a sudden there was a clackity clackity sound from the front of the engine, we both looked at each other and said "timing chain!"

So when I got in there, one side was nice and taught and the other side of the chain had a good 2" of freeplay...

Other reasons for timing chain theory:

You've tried everything else'

You get a ticking sound

Your car has 190k on the clock

You're getting poor gas mileage

The engine is acting like the timing is WAAAy off... you might not find that the timing is off at idle, but a slipping chain is just that... it's slipping, and therefore giving you random timing at high speed.

If you've changed the chain recently then it's not worth the effort to check, but if you haven't it's probably a good time to do it now... you don't want it to break while the engine is running... that will mean new motor time.

 

for starters.... as far as i know a timing chain doesnt slip. its a chain on two gears with teeth. like a bikes chain. it may jump... thats not impossible... but very difficult. If you think about what your saying, it is difficult to fathom the possiblilty that a chain would "slip" only on high rpms not affecting idle timing. if the timing is thrown off at all it doesnt just reset at idle. These camaros dont have variable timing. once the timing is off its off for good til you reset it. I reset timing about 3 mounths ago and its had the same timing and spark advance since... so highly doubt that that is my cars problem thanks though... oh and that ticking sound... its not from the front of the engine.. and doesnt occur intermittently... and the ticking started about 4 months after the original problem ive been working on

 

v8 the bitch, say **** it and put in a real engine

 

Have you taken the valve covers off? Maybe one of the rocker arms is loose...

 

Ya know my original intention with the car was to throw in a couple more cylinders but with new CA smog laws... its not practical to put in that carbed 350 i wanted. dont really have the money to get some crazy 5.7 tpi... i could probably get another z28 with the money id spend...

 

yeah i heard that would be a likely cause.... but when i got to the valve cover.... i couldnt get to one of the bolts so i said **** it. im not too worried about that though... im just trippin about the whole RPM thing... (chk the first few posts.)

 

alright valve covers off.... doesnt look like anything is too loose or somethin... i dunno... it started to rain so i came inside... but not much play on any valvetrain parts

 

That's straaaange.....so it fluctuates between 3600 and 4000 rpms...will it get past those fine?

 

You broke a spring.
It's dead Jim.
Go buy a V-8 car.
Or swap in a 3.4
Good luck.

 

Whos Jim?

 

it hasnt gotten past 4000 in a looooong time

 

What's it do, hit it and stop, or struggle like hell up to it and then just cant push itself farther? Does it shake/vibrate? Sounds like something in that car is deaaad...

 

well... aside from the whole valve problem... the car runs fine, pretty much without a hint of a problem... until it reaches that 35,36,3700 rpm area.... (when i give it more than 3/4 throttle) thats when it cuts... the best way to describe it is as if theres a limiter... if im goin 65 on the freeway and give it more than 3/4 throttle, its almost as if i get off the gas... in the sense that it doesnt accel. and begins to slowly decel. as if its in neutral but... its still revin... the tach bounces between 3000 to 3600 and you can hear the engine surging as if im just givin gas and lettin go-seesaw like... uppp dowwn... best way i can describe it....

 

What valve problem are we talking about here? Did I miss something, besides Karl telling you it's a broken valvespring? Is he right?

 

i think theres a loose rocker... no broken spring... but its got nothin to do with the fluctuation

 

Stupid longshot 'might be worth saying' statement here. This is completely un-technical and is probably highly improbable and/or impossible, but I'll throw it out for debate anyways!

Maybe your distributor is way out of whack and once it gets to those rpms it starts cutting spark because it can't keep up or something? Like, maybe a pickup coil problem, or something physically bad?

It's 4:30 AM and I quit my job tonight...so excuse me if I sound a little out of my mind!

 

Not so far fetched... I was browsing posts and someone had a similar problem... a member told responded with the same problem which he solved by changing his ignition coil... i think... but ive been to caught up with school and crap so i havent had the time to try it.

 

When this problem occurs, ATTEMPT to pull over & see if you can isolate the area where the ticking is occuring.
IF it is the ticking you mentioned & the lack of power, yep a valave spring broken can cause that.
Electrical, sure.
But gotta try to isolate better the symptoms when it occurs.
With the milage on the mill, it could be valve spring (common) or electrical.
I'd say valve spring & you should be able to hear it upon start up & a spirited drive, too.

 

First thing I did when the problem occured, was pull over and try to isolate the problem so i could be sure that i could drive home... (i was about 20 miles out) its a bit hard to tell right away but if you listen closely its defin. coming outta the valve cover. amd ot doesnt make the sound everytime i start it.. i can go day and night demanding the most the car can give and it wont tick at all... as far as the whole lack of power thing... like i said before this problem isnt attributing to my original problem. i cant see how it is linked... im more worried about the original problem (read the first few posts) than the valve thing... i do appreciate the input though... ive got the valve covers off.. and ill take a closer look later today or early tomorrow

 

I don't know much about automatic transmissions, but if you have an auto, could it be something with the torque converter?

 

Well if the converter clutch was engaging prematurely or staying locked, he'd know it..the car would buck on deceleration and turn too low rpms in 2nd gear and up or so....but it wouldnt limit the rpms like that. I suppose it's possible that there's something physically broken in the converter that COULD be doing this but....I really can't imagine how it would do this. Makes my head hurt just to think about it. [Singing to self] Flexplate connected to the converter, converter connected to the input shaft, input shaft connected to the----thats as far as I can go.

Here's a thought. Does your car have the original catalytic converter on it?

 

Thats exactly what my car did when the KNOCK SENSOR went bad woulnt acelarate past 70 no matter how hard i tried ran like crap try replacing that 20 bucks at AZ. it is a bitch to get at tho gotta take off the starter.

 

went that route too... got the car on the hoist and pulled the exhaust from the y-pipe down... no solution... still had the same problem.. only loud as hell!

 

yeah... im looking at sensors right now... im thinking of replacing IAC valve and Knock sensor... TPS is fine... but i dont see a MAP sensor on there....

i can bury the needle at 115 if i wanted to, just cant punch it to get it there

 

MAP sensor, look on your firewall, on the passenger side. It's like a little box, and it's mounted on the sill over the firewall. It's got a thin plastic vacuum line running to it that attaches to the back of your plenum. If you have no MAP, then you've got a vacuum leak unless the line is plugged, and your car probably runs like *** because the computer has no idea whatsoever about how much air the car is getting.

IAC valve shouldnt have anything to do with it. WOT the valve isnt going to change position or anything...