I have a 91' RS 305 and when it is first started in the morning it surges real bad and stalls out but once its warm it seems to rum fine although it still hesitates some what could be causing this problem, have had numerous mechs look at it replaced o2 sensor, replaced brain box, replaced TPS , please help

 

How's the CTS?

 

I don't know anything about the '91 305 setup, but my 2.8 was doing the same thing. The air temp. sensor was telling the ecm that the air was 180* all the time, so the cold start system was disabled. Replaced the sensor and it starts fine now, 15* a few days ago and it started right up and idle was smooth.

 

I will change the CTS and let you know if that fixes problem and i am also going to change the air temp sensor for good measure, i let you all know if it works, thank you

 

Nope, 2 different compents. The CTS (coolant temperature sensor) is one of the inpust sensors for fuel determination. Using coolant temperatures, it determins how much fuel to dump in. The colder the temps, the more fuel it dumps.

 

yea i realized it was two different sensors, i replaced the coolant sensor and still have the same problem, i have to drive to the next town over to get the air temp sensor, this is really becoming a pain

 

okay replaced both of those, and no change when i pull the plug on iac it dosnt surge anymore just idles real high so im going to replace that next i guess, can anyone think of anything else, im ready to pull my hair out.........

 

Take the IAC out and clean the carbon off and try it again.

EGR stuck open?

Have you checked hoses for a vacuum leak?

 

yes i checked all hoses and cleaned the idle controler the best i could is it supposed to be so hard to push in and come out icant bearly move it when pushing with my fingers and i dont see a way for the plastic to come out from metal sleeve so i guess i will just replace it, this is getting rediculous, will a computer at the chevy center tell me anything that i cant see for myself by doing the check engine light trick with the paperclip??

 

I am at my wits end on this thing i have replaced so many things and i still have the same problem I have replaced the TPS, CTS, air temp sensor brain box, AIC checked for vacume leaks and can find none this car is running so bad, im ready to sell it but cant when it runs so bad, I dont no what else to do to it I have very little money and have spent alot and have had no results.....please help im desperate !!!!!

 

Can't tell you what to try next. Try searching for engine surge , there are a lot of posts here from people with the same/similar problem.

 

yea ive been searching and searching, tried it all remeber the good ole days when it was always something simple, ha if anyone else can help please give me some pointers

 

look for a vacum leak.

 

found no vacuum leak how do i check the fuel pressure and would fuel pressure be an issue just at cold temps? or if i had bad fuel pressure would it run bad all the time, or just when giving it gas?

 

Check the EGR system then datalog would be the best bet.

 

When i unplug the egr there is no difference in the running of the engine so i guess i will pull this out, can i clean it or do i need to replace it? there is alot of blue smoke coming out of exuast, is this a symptom of the egr valve? also when i replaced the brain box they had me take the original chip out of it and place it in the new box, what if the chip is bad? should that be by next move and also what is datalog? i have no scanner so if it involves that i guess im stuck taking it to the chevy dealership, i dont know anyone who would have one....let me know if the blue smoke will help anyone diognose the problem?

 

ok i took out the egr and it seems to be working just fine, when i put my mouth on it and suck it would easily open, so i completely bypassed the solinoid and it ran the same and the check engine light came on so im asuming that since i did not get a code before bypassing the solinoid, that it is working fine, hooked vacuum lines back up the way they are suposed to be the motors runs fine when its warm and the blue smoke is gone, but when i put it in gear and hold my foot on the brake and give it some gas it dies, i guess i will check the fuel filter the mech said he put one in but maybe the new one is clogged up again, if anyone can offer any more suggestions that i havent tried, it would be greatly apreciated

 

Have you checked your PCV valve & hoses. Surging Idle is often caused by a vacuum leak. Try closing off the vac. hoses one at a time & see if it changes. The vac. hoses that go to the HVAC system are hard plastic that breaks easily.

 

Make sure the filter is on the right way too. Putting the fuel filter on backwards would be the same as a clogged filter. The element collapses and blocks flow.

 

well i changed the filter yesterday, my hand still smells like gas, what a pain, anyway i still have the same problem, i am at a total loss here, i really want to sell the car but theres no way i can with it running so rough, i just dont know what to do from here i have taken every suggestion and i still have the same problem

 

Start checking things you haven't looked at yet. Write up a list of what you have done so far. It is easy to overlook something when you get frustrated.
I don't see in your other posts any ignition parts. plugs, wires etc. have you checked any of those?

 

Throwing parts at a problem is an expensive and ineffective way to repair a car. Try doing some diagnostic work before replacing parts. Get some basic tools like a digital multimeter, vacuum guage and a service manual.

 

yea live and learn, im new to this...duh !! and i apreciate all the help im going to replace all plugs and plug wires and see what happens they all look ok, but might as well its ben about 30,000 miles since its been done

 

OK Here is a list of all I have done to try in fix this problem

new brain(computer) same chip
TPS
CTS
O2 sensor
air temp sensor
idle controler
fuel filter
new cap and rotor
new plugs and wires

after replacing the plugs and wires and cap and rotor it runs alot better, but its still rough idle at start-up and has a hesitation when you give it gas from a stoplight or even if i am already moving there is hesitation.........im running out of ideas here

 

Good to hear someone else is having same problem! Mine started almost 2 months ago and I have done all the fixes you have, or ran tests on components, except for ECM. When first start it (89 camaro RS w/305) it has to warm up for like 10-15 minutes or else it sounds like it is missing real bad and will barely go and/or stall. Once warm it goes fine but will hesitate on moving from a stop and when at highway speeds I notice a loss of power. It has me and a mechanic baffled! It is definately a component that has gone bad and all the obvious ones have been checked or replaced. On christmas day it finally threw a code 44 which is lean exhaust at the O2 sensor, replaced that sensor just to be sure and problem still continues. CTS was replaced as soon as problem started with no luck, checked connections at ECM for that sensor also and all checks out fine. This all started one night when I was heading down a 25mph speed zone road which I always drop the car into second so I won't accidently speed on cause of the speed traps on this road. When I came to end of road and light turned green the car stumbled through intersection like it was out of gas, it was low on gas so I made it to gas station and refueled and problem remained. There is only one thing I haven't checked and that is the fuel pump and the reason for that is how difficult it is to get to and the fact I just replaced it a year ago. I suppose it could be faulty but I would like to make sure before I pull the tank again!

I will watch this post to see if you figure it out and if I get it fixed first I will let you know.

 

Its Fixed !!!! heres what I did i had a mech shoot some fuel injection treatment directly into the fuel lines to clean the injectors and now it runs like a champ, thank you so much for all the help on this forum and i hope this helps someone else who is having the same problem

 

Glad to hear you got it fixed! Did your problem come on all at once or was it a gradual decline situation? Mine came all the sudden..within a mile or two of driving. I have been eyeballing the injectors but haven't messed with them yet.

 

yes mine came all at once too

it cost me 99.00 for the treatment but it was worth it

 

i am having the same problem what type of fuel injection cleaner is this and where can i buy it

 

What he is referring to is a treatment that mechanics do at shops. I have looked around for this treatment to buy and do myself but haven't had any luck, so my problem still remains!

 

I've looked at buying setups to do this treatment. Expensive! Just the can of cleaner is $8 - $25 each, then you have to buy the hose kit with all the adapters.
If you are only doing 1 or 2 cars it is cheaper to pay a shop to do it.
http://www.etoolcart.com/browseprodu...-Kit-2510.html
http://www.etoolcart.com/browseprodu...--OTC7448.html

I had injectors cleaned by Rich at Cruzin' Performance. You have to take them out of the car to do this. I got a set of injectors off ebay and sent those to be cleaned and swapped them out when I got them back.

 

Hey I did a search on engine surge and I came up to this post and it sounds like I am having the same problem. Yesterday it was a lil warm out 40's now its in the 20's windy cold like hell. Anyway my car doesnt want to start up I have to put my foot on the gas to make her start once shes warm shes ready to drive. However when I would get to a light she will seize out and die.

I have to start her up the same way I did the first time so I can be on my way. As I read on in the thread some of you mentioned that it just did this out of the blue mine did it cause of the fact it was cold. Also when I turn off my car the RPMS goto 1000 . Could it be the injectors need to be cleaned and if so how much did you have to pay for that to be done ?

EDIT: Ok I did a lil search on EBAY for Fuel Injector Cleaning Kit I found one thats a bit cheaper take a look here.

Injector Kit

Any suggestions what do you guys think should I go for it I already emailed him and ask him if it would work on my car.