91 Camaro RS V8 - Low RPM dead spot???

[Relik00]

Hey there everyone... First off I wanted to say that I've read many of the forum threads in the Camaro section and it's so nice to see so many dedicated fans as well as so many helpful people in one place. Just wanted to say thank you in advance for any time or suggesting given to me.

This is my first post and I will get to it... so as not to bore anyone...

I have a 91 Chevy Camaro convertible... RS V8... it has about 300k miles on it... I know... it's alot. My problem is ... when I have it in gear and I accelerate very slowly... my car runs in to a VERY distinct dead spot or flat spot... where the car chugs and loses torque and almost wants to die... but always comes back to life after a few seconds of this. I can make it do this at will by putting it in gear and holding down the brake... and then just barely giving it gas... It will just continue to sound like it's choking or sputtering... (best I can describe).

I have no check engine lights on... already changed the fuel filter and the TPS sensor... It runs perfect and strong on the roads or highways... just happens when I'm going slow... like tooling around looking for a parking spot or going over a speed bump really slowly. It shows up... then snaps back to a normal steady idle.

I have no idea what it is... and haven't found anyone that knows. I figured it couldn't hurt to give it to you here and see what happens. If you need more info or have any suggestions... leave a response or email me... private message me... instant message me... call me... whatever you want... but I can't figure it out...

Thank you in advance for any consideration to my problem.

[DaMoNe6969]

hmm.. tough to say without looking at it.. I'de suggest taking it in for a fuel system flush to clean out the injectors..
Does it do it when the car is cold? warm?
how does it idle in park?

[DaMoNe6969]

it's a 305 correct? is it TPI or TBI?

[Relik00]

It idles perfect in park... I can give it gas in park... goes through the rpms just fine... never skips a beat... Only when there is force applied in drive, like going over a speed bump slowly from stop or holding the brake on while giving it a lil gas... but it happens while backing up.. going forward... either way.

The fuel system seems fine... I don't have any clogs that I can see and it gets plenty of fuel.

[Relik00]

It is a 305... and as for the TBI / TPI... I'm not sure of the difference... but there are two "injectors" under the air filter... you can see the fuel easily... comes out in lil cone shapped spurts.

Hope that helps some.

[edit]

Oh I forgot... it does it when it's cold or warm... doesn't matter... but more noticeable when it's all warmed up and at a steady idle.

[DaMoNe6969]

My best guess is the Idle air control valve (ICM)
Pull the connector off, and screw the valve out (really big wrench) Check to see that you can move the little tip in and out.. if you cant, clean it all off with carb cleaner or similiar.. even gently tap on the end with a hammer to try loosen it up.. (worked for me)

[Relik00]

I will for sure try that out... haven't even heard the ICM being mentioned before... It would be so nice if it was something so simple as carb cleaner ... I will put that on the list of possibilities.

[DaMoNe6969]

Oh, then it would be a TBI

(throttlebody injection)

[DaMoNe6969]

Ive got a pic of a throttlebody with the ICM
if you want it, i could e-mail it to you..

[Relik00]

Yeah that could help out for sure... thank you...

[89IROC&RS]

get an induction service done. what is problyhappening is that there is carbon build up or other fuel deposits that are clogging the air intake linkage, and idle air controls. i would start with the induction service, and go from there.

oh yeah, the RS is the 305 TBI engine. VIN code E.

[Relik00]

Is that a service that I can do on my own... or is it a shop service only type suggestion??

Thanx for all the feedback so quickly by the way.

[DaMoNe6969]

Not something I would pay anyone to do.. A can of carb cleaner will work just the same

Just pull out the ICV and clean the end and spring real good with carb cleaner (careful not to get the electrical plug or componant wet) and make sure it moves in and out with a little resistance.. if not.. As i suggested tap on it with a hammer to try to loosen it up.. careful not to break anything If it simply will not move, its garbage and needs to be replaced..

[89IROC&RS]

pretty much, although the shop can preform a BG service that smells horrible, and does work. but i wouldnt do it in your neighborhood, the people next door wont like you for a while you could try the carb cleaner deal. but i suggest the BG service.

[Relik00]

I did remove the IAC valve... is this the same thing that you are talking about??? Has a little spring with a 4 prong plug on the end??

If this is it in fact. I pulled it out and there was some oil on it, it did look old and I could barely move the thing on the end unless I pulled very hard. I went and bought a new one... Idle Air Control Valve... I think it's right... looks the same except the spring looks a bit more flimsy and not as tightly wound. I'm guessing it is the same part, but probably a little different over the years. I also got some TBI Cleaner instead of carb cleaner. I was thinking this might work pretty good. I'm going to try this out and try to get rid of any carbon deposits inside the IAC airway.

I'll do this tomorrow and let you all know how it goes.

Thanx again.