mitchberry

iTrader: (1)

91 camaro RS 305 tbi (tough but inadequate)


before i type this explanation, i'll say up front that i think it's a vacuum issue, but i'll let you guys be the judges.

long story short, when i pull up to a stoplight like you would in any normal car, it boggs the motor down and can ultimately kill the motor. and if i don't let the car roll forward before i hit the gas it will stall out, which REALLY sucks because i have to stop and put it in PARK before i can start it again.. nearly been rear ended a few times already from this.

i have further tested this by slamming the brakes harder than normal, like an abrupt stop, and it stalls the motor. this mostly happens when the motor is warm, moreso than when it's just getting started. which means that i'll think everything is fine until im several miles away from home driving across town.

here's what's been done so far..

new:
plugs
wires
distributor cap
rotor
TPS
mass airflow sensor (or whatever their called on these cars.. the thing that hangs off of the firewall)
injectors
air filter.

given that it doesn't stall at idle, and only happens when i apply the brakes, like i said, i think it's a vacuum leak, but i've been over -everything- several times and 1. it's difficult to see every vacuum hose and connection 2. what i do see seems to be in good working order.

i did get some hose clamps to clamp down the hose connection that goes to the brake booster through the little filter looking thing back to the motor, but i haven't test driven the car since then to see if the problem has been solved. i'll try to do that later on today.

given that i've replaced just about all of the normal stuff to replace, what else could it be?

i hate to say that i think it's a vacuum leak because people tend to see an answer and agree with it v.s. thinking about what it could be and coming to their own conclusions, but.... that is what i would like...... let me know what you think it could be..

i have not changed the fuel filter or fuel pump in the car. (not looking forward to changing the fuel pump. )


also worth noting, i just got this car into my possession 1 week ago today, and it had horribly old gas in it, so i filled the tank up, and put seafoam in it, and i have yet to go through the entire tank. i know a lot of things will get worked out once i have a few tanks of gas put through it, but i don't think this is one of them. the car hasn't run for over 2 years and the person we bought it from was convinced that it was dead and would never run again - so we gave 200 bucks for it - and now im driving it......... but some of the underlying issues they were having still exist. this being one of them.

ex-x-fire

Remove the iac valve, clean the tip & the air passage, Its located on the throttle body.
I'd disable the egr valve, then drive it a couple days, the valve could be sticking open causing the stall.
If your car is an automatic, it possible the torque converter is staying locked up, shift it into nuetral & see if it still does it.
Most vacuum leaks cause high idle issues.

mitchberry

iTrader: (1)

its an automatic, it seems to shift fine when driving, and puts it into 1st at a stoplight, if i put it in neutral, it does not seem to do it. and it does idle a little high at times low at others depending.. usually when you cold start it, it idles up like normal, then after a second idles down, and is pretty much normal from there. it's hard to tell exactly what it's idling at because it conveniently has the "3rd gen tach problem" that requires resisters n crap to fix....

where is the egr valve on this thing?

ex-x-fire

The picture shows the egr, it means exhaust gas recirculation valve. The iac is just to the right of the egr valve.

mitchberry

iTrader: (1)

oh yeah... forgot to mention in the original post that i also put a new idle air control valve on it too weeks ago as part of getting it running.

mitchberry

iTrader: (1)

wow your setup looks significantly different. mainly a lack of hoses on yours... phone battery is dead or i would take a pic...

but yeah, i replaced the other deal, will check out the egr..

ex-x-fire

Thats just a picture I took from the web. It might be a v6.
Yeah, just plug the vacuum line going to the egr & drive it awhile.

UnderCover89TBI

iTrader: (25)

yeah my car did this for the longest time. i changed to ebl and it stopped. then it reared its ugly head again when i started tuning. i think it is either a lack of fuel or too much fuel. i am leaning towards too much fuel because my car idles rough and smells rich.

zenish

and if i don't let the car roll forward before i hit the gas it will stall out, which REALLY sucks because i have to stop and put it in PARK before i can start it again.. nearly been rear ended a few times already from this.

it can also be restarted in neutral while rolling.i do that when mine cuts off.

mitchberry

iTrader: (1)

what's an ebl?

and.. neutral.... hmm. not sure if i've tried that yet, i guess i just assumed it had to be park considering almost every other automatic car i've owned had to be in park.. it makes sense to be able to though.

i wouldn't have any of these problems if i stuck a 5 speed in there though. at least, i wouldn't notice them as much. lol

UnderCover89TBI

iTrader: (25)

yeah i restarted mine in neutral too it sucks and you dont want to make a habit of it. ebl is a computer flashing program. i recomend it for even stock cars it makes the car run really smoothe.

NeNick95

(Didn't want to make a new thread)While attempting to go to the emission center.My camaro cut off on me in traffic and highway. I did a complete tune up. A while back I've changed the fuel filter and pump and lots of crap and rust came out by now it seems like the same thing.Looked in the tank and no rust and the little shoe thing for the fuel pump was still on, so now what could be the problem.Also ecm through a 42 and 32 trouble codes. CAn anyone add more to this for help

mitchberry

iTrader: (1)

lol... yeeeehhhhh

well, that reminds me, i need to update my thread.

me and my mechanic stepdad (certified in every possible b.s. mechicy thing you can get) found an intake leak in it and replaced the gasked, so now along with everything else i've replaced, add that to it..

there is absolutely no way there's a vacuum leak in this stupid car, i've tested, re-tested, re-re-re-re-re-r-e-re-re-re-re-tested and then tested again, and replaced damned near everything on the outside of the motor i can think to replace,

and it still runs like absolute petrified dogshit.

when i start it up, it gurgles n spits n farts and acts like crap, and if i put the brakes on and put it in reverse or in drive, it tries REALLY hard to die but it wont..

i pulled the plugs (by the way, WOW what a pain in the *** to change the plugs on these cars) and gas actually poured out of one of the cylinders...

all 8 plugs are getting spark, that has been tested and re....... yeah you get the point...

i replaced the plugs and it ran better for about 10 minutes...

the car ran absolutely PERFECTLY each time i changed something and begins to degrade as soon as i park it for a few days...

when i drove it home from the shop after fixing the intake leak (by replacing the gaskets ) it ran at 95% of what it SHOULD run... it will never run 100% considering the mileage on the car etc...

then i parked it and started it up a day or so later and it had the exact same issue...

pull out of the drive put it in drive hit the gas

VROOOOO-bbbbbbbbbbbbbbbuuuuuuuuuuuhhhhhhhhhhh VROOO---bbuuuhhh VROO------buuuhhhhhhhhh


and the more i hit the gas the less it wants to run....


i'm SERIOUSLY considering pulling this piece of crap "fuel injection system" and putting a damned Holley on top of it AND BEING DONE with it....

MSD ign, Holley carb, plug off all the freakin vacuum lines,

end of problem.......

if not, i yank that pos 305, and use it as an opportunity to blow a sbc apart in my garage and take it to the freakin scrap yard to make a few bucks off of it before i replace it with a honda motor or something RELIABLE for the love of god im sick of dealing with this car, i've NEVER had so much trouble with a SBC or ANY old car, and i've had tons and tons of old cars...

this car is just in the right area for age to where chevy was experimenting with crap and got it wrong more often than right....

LT1 awesome motor...
LS1 even better

305 THROTTLE BODY INJECTION............................. seriously???? one of the crappiest motors GM ever produced, you can argue with me all you want, but it's a fact.... otherwise every 3rd gen on the road would have one in it instead of people using them for paperweights..


as for the last person who posted, notice that this thread has been up for a long *** time, no one has been able to answer yet, i lost hope and stopped trying.. it's the same answer on every thread, and are all things i've done for the most part....

---aside from maybe replacing the freakin computer or finding someone who can flash it... and if im going to do that i'll put a damn MSD on it as previously stated, rather than Richarding with a 20 year old computer that an original gameboy 1.0 trumps in processing power....

sorry i'm slightly bitter about this car it's cost me way too much and is now taking up garage space, i needed a car for the winter and haven't been able to put more than 100 miles on the DGMFSOBF'ing car since OCTOBER.... i miss my 4th gens... they never gave me issues and had over double the power..

UnderCover89TBI

iTrader: (25)

for teh record EBL is a different ECM for the car that you can tune. it sounds like your getting too much fuel. bad injector, bad Map sensor or something.

RFmaster

Too much fuel could be due to intermittent or a flaky TPS. Getting any codes when it runs like poop???

//RF

mitchberry

iTrader: (1)

well, i have 2 brand new injectors on it, but i guess thinking about it, maybe the idiots at autozone gave me the ones for a 350 instead of a 305.. idk... their not all that intelligent where i go.

"305 TBI"

v6?

333330000005

350???

33333333300000000000055555555555555

5.7???

THREEEE OOOOO FFFIIIVVVEEEEE 55555...0000000

TPI?

NOOOO

TBI!!!

t..............pi???

TTTTTTTTTTTTTTTBBBBBBBBBBBBBIIIIIIIIIIIIIIIIIIIIIIII

tpi.

THROTTLE BODY INJECTION FOR THE LOVE OF GOD!!!!

oh ok yeah we got that here....

eeehhh.....


anyway, also brand new map sensor,

brand new EGR

brand new distributor

brand new plugs

brand new idle air thing

brand new idle position sensor

brand new wires

have reset the computer multiple times

fixed all the vacuum leaks

put new intake gaskets on it

put new gasket on the tbi

maybe the tbi needs a rebuild

maybe i need to throw it in the trash and put a 650 holley on it... couldn't be much more or less than buying an EBL, software, chips, figuring out how to program it etc...

but..... who makes ebl's for this thing?

mitchberry

iTrader: (1)

no, there are zero codes on it... the only codes it throws are from the thing you have to unplug to check the timing, and the air temp sensor from the air cleaner being popped off, but i clear those out..

nothing aside from that

tps was replaced brand new

mitchberry

iTrader: (1)

ouch... 430 for an ecu and ebl......

650 holley, intake, MSD ignition, screw this lol

3318RS

Hey Mitch I feel your pain. Mine IS doing the following:

1. Turns on & stutters a little before the idle smoothes out.

2. Runs fine for about 20 to 30 miles (perfecty fine, accelerates well, etc...)

3. When I have driven it about 25 miles (just like you when I'm far enough from the house to make it a PITA) it starts stuttering under hard accel, the harder I put the pedal down the worst it runs/sputters.

4. It has tunred off a couple of times, but I've been lucky to put in neutral & start it (mine is an auto as well).

5. I changed the coil, but this actually led to the carppy idle at start. It started perfect before the NEW coil.

So my problem sounds just about the same as yours. Oh yeah, to make it worst, sometimes when I restart it, it runs fine again for another while, then the problem comes back?????

mitchberry

iTrader: (1)

yeah that's pretty close, only difference is mine does it when it's cold, but if i let it warm up for about 30 minutes before i take it out, it runs fine and doesn't stall out on me (anymore)... but yeah damn close.. i guess it's common.

i just wish it was common enough for someone to be like

"OH.. yeah, that's definitely the XXX(insert abbreviated part name here)XXXX" fix that and you're golden

mitchberry

iTrader: (1)

nice vette by the way, i cant tell, is that monterrey red?

3318RS

Thanks man, It's anniversary red.

mitchberry

iTrader: (1)

damn that's beautiful... i've yet to own a c5, every time i get close, something happens and i need the cash more than the car. but i'm definitely partial to the LS1 LS3 ... ls anything, and a T56.... which i think is a huge source of my frustration over this

305 T.ough B.ut I.nadequate with a 700r4 / 4L60 ... my old cars could give this car a 10 second head start to a mile and still beat it to the end lol.

whatever though... i like my 3rd gen but i can tell it's going to be a freakin money pit, and can tell i'm going to have to save for an LS1 swap... but... for not much more i can buy a wrecked C5 and throw money at that...... instead of a 91 camaro

eeh.... toysssss

Caveman305

iTrader: (8)

im really not good at reading through a full thread before posting

was your issue resolved?

i second changing out the ECM if it has not been changed

get a re-manufactured unit from the auto part store, swap your Prom chip in it, and see what happens,

i had this exact problem 4 or 5 years ago, and i did absolutely everything to fix it, go figure the last possible thing i could change without actually changing my stall converter was to swap the ECM, and i havent had a problem since

mitchberry

iTrader: (1)

mine hasn't been fixed, how much is an ecm???? how much is the prom, and what do i have to do to program the prom or is it programmed already? yeah i know there is a lot of literature on this site about it, but to be completely honest, i have a lot of other things to read up on and figure out right now with my websites. a quick rundown would be more than appreciated!!!

mitchberry

iTrader: (1)

i answered one of my own questions.... either 72.99 or 78.99 for the ecm depending which part number i have (assuming he knows what he's talking about... i have little to no faith in the autozone nearest me)

and they don't have a chip but they sell them for 69.99 order only... whats the price on yours and what are the advantages over one i'd get from autozone specifically for this car (which is bone stock)

that's the problem though... "see what happens"

i hate the "throw money at it and see what happens" idea.. i'd rather have a specific diagnosis, which is something that not even well qualified certified educated no bs mechanics can give me about this car apparently.. i've taken it to a few aside from my stepfather who has been doing this since 1978, has every certification known to man etc and has owned about a dozen of these cars in his life.. if HE can't figure it out i think i'm screwed lol........... and he cant figure it out....

it dumps gas so bad that when i pulled one of the plugs gas poured out of it... its obvious something isn't right...

Caveman305

iTrader: (8)

i remember paying around $70 for mine, you have to take your prom chip out of your current ECM before you give it to autozone as a core, then you just plug it in to the new re-manufactured one, its already programmed to your needs, i would swap the chip on the counter at autozone so their is less of a chance of it getting erased or shocked(which still isnt very likely but that's what i did)

their may be someone in your area that has a spare ECM you could try out, that way you could know for sure its gonna fix your problem, after i had to go through trial and error fixing mine, i lent my ECM to any friend that needed to test if theirs was bad, helped a few people out

the only other problem is your prom chip itself could be bad, but that's pretty unlikely

mitchberry

iTrader: (1)

hmm... well i guess if it's unlikely, then that helps a bit, and i'm only out 80 bucks or so, and i guess it couldn't hurt to replace it either way of course of the 3 numbers the guy gave me, none of them match my car..... so i'm fairly certain he was looking up the wrong car as usual.

i tried to buy an injector harness and i asked them 5 times to verify that it was the right one. they ordered it and it was for a TPI.... so i had to have them send it back, refund me, and had to go to napa to get one... eeehhhhh..

i wouldnt doubt if my injectors are off of a 350... that would be my luck... gave me the wrong ones or something... i need to get a job there strictly for the reason of looking up my own parts when i need them...

Caveman305

iTrader: (8)

lol yeah i feel ya, they will hire anyone at a most part stores and trust they can look up a part in a computer without any knowledge of cars in general

and yeah, the Prom thats in your ECM is more than likely good

ive since set my ECM up for Tuning so i can burn chips whenever i need it

its definitely worth a shot to swap your ECM, I believe all the later TBI cars used an 8746(which is the last 4 digits of the service No.)

your prom is under the metal cover that has 2 screws holding it to the ECM housing, it should be in a plastic carrier that allows you to only plug it in one way so you cant screw it up

when you plug everything back into your car and hook the battery back up, do the key on engine off test and watch your SES light to make sure it flashes the SES then stays solid, this tells you the ECM is reading your PROM and it is safe to start the car

mitchberry

iTrader: (1)

hmm.. cool.... yeah since the first message i've already yanked mine out of the car and it's sitting on my dryer... i'll take a look at it to see what numbers are on it. the 3 he gave me over the phone were 7730, 6349 (or 6347 i cant read my own writing) and 8262 / which he has in stock....

so since he said those are the only one that fits my car, i already know he's an idiot lol...

mitchberry

iTrader: (1)

ok here's what i see on it...

serv. no. 1228746 which means you're right, and also means that either autozone doesnt carry them or, he looked up the wrong car........ those are probably ecm's for a 350...

for the record, the camaro never came with a 350tbi did it????????? i think it was either 305tbi or 350 tpi.... may be wrong...

Caveman305

iTrader: (8)

well 7730 is for 305 TPI, and the other one i have no idea what its for,

but yours should def be 8746, i just looked it up on the autozone website, everything matches same as mine

.......
just saw your reply

yeah the 305 TBI was the highest option for an RS, TPI was only on Z28's(non IROC) and Iroc-Z's which could be 305 or 350

sounds like hes just looking at 91 camaros in general on the computer and not selecting RS W/5.0 vin E

UnderCover89TBI

iTrader: (25)

www.dynamicefi.com but it will not fix any mechanical problems.

too much fuel. Could be a bad MAP sensor. Too much fuel pressure or something of that nature.

mitchberry

iTrader: (1)

again.. the map sensor is brand new... as for fuel pressure, i don't know, i dont have a gauge to check pressure. i've been meaning to change the fuel pump and filter but that goes back to the "throwing parts and money at it on a whim" thing i'm trying to avoid doing until i know for sure...

i'm broke as hell ans buy on a need to buy basis.

lectric80

iTrader: (1)

I can think of 2 possibilities, but I haven't personally dealt with one.

1. Fuel pressure regulator is bad, and not responding appropriately to changes caused by reduced fuel needs for the engine. This is one I haven't dealt with, but is a possibility, you would need to check pressure to verify.
2. Fuel pump is weak. The turbine pump delivers a pretty decent lifespan, but can grow weak. I have experienced this myself on 2 different GM TBI setups, and both were solved by replacing the pump. Both did exactly what you are describing, except that mine would do it even when warm. I actually had it die as I was slowing for a bridge by Lake Powell, and let me tell you that is a scary feeling.

I think it is unlikely that it is dumping fuel, more likely that cylinder wasn't firing, since TBI doesn't directly inject to any cylinder, you would have seen fuel in every cylinder, or at least in more than one. Fuel pump is my guess, they were barely enough for the engines anyway, and now it has a lot of miles on it and has probably gotten pretty weak.

mitchberry

iTrader: (1)

thanks lec,

yeah i guess i did say that it poured out of one cylinder, in reality, all of them were way wet, 2 of them poured out, all of them were soggy, all 8 plugs were fouled

as for fuel pumps,

how does the excess gas get returned to the tank on these cars? does the fuel pump send the excess back to the tank as well, or is there another unit for that? one of my thoughts is that the back flow is weak.

aside from this post, the next thing i planned to do was to change the fuel pump and filter, as soon as i get the motivation to drop the gas tank (which will be a while)...


then again, maybe i don't need to drop it..... but something tells me i do.

lack of fuel pressure would definitely cause it to bog down when you hit the gas if it's starving... and maybe because it is lacking fuel pressure the computer is trying to compensate by riching it out / or maybe i'm giving this little watch calculator of a computer too much credit for what it does.


but i guess to be more specific for those who are just joining within the last day or two

when i fire it up in the garage it pretty much throws raw gas right out the tail pipe, and the fumes are horrible... like.... burn your eyes and throat kinda horrible after a few seconds (yes even with the garage door open lolol)

that never goes away no matter how warm it gets.

but if i fire it up and immediately back out of the drive n take off, as soon as i hit the gas it attempts to die, but the computer seems not to let it. but if i let it warm up for about 30 minutes and try to drive it, it STILL DOES IT but nowhere near as badly.... i attempted to drive it up to my dad's house to work on some stuff, in december and got about 15 miles into it, turned around and came back because it was starting to act up.... haven't really driven it since except to and from my stepdad's shop.



the last time we did anything to it was to replace the intake manifold gaskets and other associated ones, and it drove almost perfectly.. even had a little bit of power to it! next day.. ran like fermented ***..

i guess i'll start with the fuel pump because it needs to be done regardless. im sure it's the original one to the car. almost everything is original for better or worse.


so fuel pump / filter
then probably the computer after that.. and if that don't fix it, idk......

UnderCover89TBI

iTrader: (25)

well the fuel returns via the other line going to throttle body unused fuel goes back to the tank. deffinately too much fuel

mitchberry

iTrader: (1)

yeah, i guess what i was asking though, is it pumped back via a second pump, sucked back by negative pressure in the tank, pushed back mechanically via tbi, or does it rely on fuel pressure from the pump pushing it to the tbi to push it back, does the fuel pump pump to and from, or is it gravity, or magic that puts it back to the tank?

if the fuel pump handles both to and from, then it's pretty obvious that i have a fuel pump problem, if there's a second pump, it may be the return pump, if it's a mechanical return pump in the tbi or on the motor, that needs to be replaced, if it's gravity, maybe i have a clogged return line.

either way the pump's gotta be replaced i'm sure, but just want to make sure that whatever i do is accounting for to and from.

UnderCover89TBI

iTrader: (25)

only 1 pump in tank

lectric80

iTrader: (1)

It is returned as excess pressure from the pump in the tank. Basically, the pump puts out say 15 PSI, the regulator is set for 12, the extra 3 pounds flows out of the regulator back to the tank. No second pump required.

mitchberry

iTrader: (1)

ah... yah, forgot about the regulator... wonder where that is on this car

lectric80

iTrader: (1)

The regulator is part of the throttle body assembly. You have 2 lines going to the TBI unit, one pressure and one return.

mitchberry

iTrader: (1)

so then it is possible that the regulator could be out disallowing the return flow of gas to the tank equally as well as it could be the pump itself...... which would also make sense considering it has too much fuel at idle and not enough fuel at rev.....

mitchberry

iTrader: (1)

i do have a fuel pressure gauge that i could in theory plug into the system so i could get a reading, but i don't have a diagnostic tool specifically to test pressure, so again it sounds like i'll just have to buy all of it and eventually something will fix it..

but... that will add up quick, and considering i dont really have money for the gas to make it run in the first place, i can see it being a while before i get this thing running. $60 part here $200 part there, etc etc eventually yet very quickly, i'm looking at putting more into it than the car is worth. which is inevitable, but i don't have it to waste lol.

dang... i wish i had a fuel pressure diagnostic tool.

lectric80

iTrader: (1)

If you can watch the guage you can get a pretty good idea of where the problem lies. If you hook up the gauge, start the car, then work the throttle while watching you can probably find the issue. If you rev the engine and fuel pressure drops dramatically, your pump is bad. If fuel pressure remains constant, it is probably going to be a regulator issue. That is the way I would test it for now, unless you can find someone with a pressure diagnostic.

mitchberry

iTrader: (1)

that sounds like a good idea. i'll have to see if i still have all the stuff for the gauge. i just sold my AEM UEGO wideband sensor, that would be useful about now too lol. damn

lectric80

iTrader: (1)

I certainly understand not wanting to throw money at the issue, most people can't afford to do that, myself included. At least this should give you a baseline to work from, and hopefully allow you to quickly figure out where the issue is.

mitchberry

iTrader: (1)

yeah, i think that'll work, i'll look at my gauge tomorrow morning and see what i need to adapt it to fit my car / if anything....

http://www.ebay.com/itm/190601359657...ht_2602wt_1163

too bad that would tear that old 4L60 to shreds....

lectric80

iTrader: (1)

See and when I can get to it my plan is an LSX 454 and a T56, but that is serious $$$. The 383 goes in my Blazer.

Good luck, post up with the results.

alexquade

iTrader: (2)

any news?? curious if you got her runnin yet?