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Rough Idle

S

souljasmooth

Active Member
I have a rough idle on my TTA. Its kind of weird, as it is not a misfire, but more like a deep bass rumble coming out of subwoofer. It shakes the whole car. It happens only at idle. I had a mechanic look at it, and he doesnt think anything is wrong with the car. He said possibly a mild cam. My TTA is suppose to be all stock. When you step on the gas it completely goes away, but as soon as you stop, the rumble comes back. I have a friend who has a 91 Firebird, and his car does the same thing, but just a lot worse. Of course his started happening after he tore the car apart. Anyone have any ideas?
 
the TTAs idle pretty rough stock, especially on cold starts. If the mechanic didn't think that it was a misfire you should be fine as long as your rpms are staying right around like 800 at idle.
 
souljasmooth said:
I have a rough idle on my TTA. Its kind of weird, as it is not a misfire, but more like a deep bass rumble coming out of subwoofer. It shakes the whole car. It happens only at idle. I had a mechanic look at it, and he doesnt think anything is wrong with the car. He said possibly a mild cam. My TTA is suppose to be all stock. When you step on the gas it completely goes away, but as soon as you stop, the rumble comes back. I have a friend who has a 91 Firebird, and his car does the same thing, but just a lot worse. Of course his started happening after he tore the car apart. Anyone have any ideas?
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Same problem with mine. I have only had it a few weeks, but it appears to be all stock. I started replacing vacuum lines and that has helped a bit. I also borrowed a friends MAF and that helped considerably, but I had to give it back. I will plan on a MAF upgrade in the not to distant future. It currently has a NAPA MAF in it. It idles pretty good until it warms up enough to go into closed loop, then it fluctuates about 100 rpm every 10 seconds or so. Like it is going to die, then it plips the throttle.
 
at t 2d -

About 4-5 years ago, 2 of my turbo buick buddies were both working for napa at the same location. Needless to say, it took quite some time to find a "decent" NAPA mass air flow that would idle well and peg 255 gps in a hopped up turbo buick.

I would just go straight to the LT1 mass air flow and translator, or at least borrow one, and then install a turbo tweak chip.. His idle quality is pretty darned good if you ask me.

If you plan to purchase a chip, i would highly suggest upgrading injectors at the same time so you dont have to upgrade down the road.

BW
 
at t 2d-

I also forgot to mention, your probably on the right track tracing down all those vacuum leaks.
You might also pull the idle air control motor out, and scrap the carbon build up off the pintle end and see if that helps your idle.

BW
 
Stock prom'd TTA's don't idle well as they are closed loop idle. I bet if you watched it go into closed loop(on a scan tool) it would be earlier than you think. Meaning that the ECM has set enough flags to go into closed loop in just a couple minutes, while you, the operator, thinks the car isn't warm enough yet.
I think closed loop idle is too lean and causes erratic, wierd, idle patterns. Even in similar generation V-8 GM cars.


...
 
You are right, we can watch it on the scan tool and as soon as it hits closed loop - the idle gets bad. I have already ordered the Turbotweak chip and I can't wait to get it in! Next up will be an LT1 MAF sensor.
 
One thing I discovered, that I'm sure allot of fellas here already know, is don't underestimate the ECM's need to "learn" the new mods you do.

Especially the upgrade MAF and TT chip. Almost everytime I lose power to the ECM, or change a setting on the translator the car runs like a turd with wierd idle and off idle stumbling and couging,sputtering. But a good 15 miles of regular driving and a couple on/off start ups and it gets back to where it was or even better(in the case of the LT1 maf I put on).
So, don't get discouraged if it runs funny after a change. It should clear up after the ECM relearns.

..
 
WS6 said:
One thing I discovered, that I'm sure allot of fellas here already know, is don't underestimate the ECM's need to "learn" the new mods you do.

Especially the upgrade MAF and TT chip. Almost everytime I lose power to the ECM, or change a setting on the translator the car runs like a turd with wierd idle and off idle stumbling and couging,sputtering. But a good 15 miles of regular driving and a couple on/off start ups and it gets back to where it was or even better(in the case of the LT1 maf I put on).
So, don't get discouraged if it runs funny after a change. It should clear up after the ECM relearns.

..
Click to expand...

I kid you not, i just installed that chip earlier today. I started it twice, then shut it off after 5 seconds of run time. Then started the car for a third time and let it run for 10 minutes. Went out for awhile and started it 4 hours later and thats the video i made.

I totally agree that some cars do idle weird while learning, and even worse if the cars out of tune other than the chip. That open loop idle is smooth as silk with Erics chip.. No tip in issues on any of my cars. I put the video up just to help anyone here see how steady smooth these engines can be.
It would be a bad thing a year from now if everyone thought all the TTAs had a bad idle issue. :explosion:

Anyone want to buy some red armstrong chips for 50's??? LOL
 
From memory here...I think the first start up after a TT chip install Eric has them set up to utilize a closed loop idle to enable learn quicker. After that, they use an open loop idle with a richer A/F. So much so that when it's really humid and hot, and my IATs are getting up there, the car will load up after 5-8 minutes of steady idling(800 rpm). So, to combat that I put it neutral and idle it up to 1200 or so to get it into closed loop and clean it out.


EDIT; but then again I was running a cam with 3 worn exhaust lobes, so maybe I wasn't getting good cylinder evacuation.DontKnow: If the weather stays hot here for a couple more weeks I'll have a chance to test my theory.
 
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I wish my car idles like that. I am going to try the LT1 MAF. What is the closed/open loop that you guys are talking about? My car idles rough at all times cold or hot. Is there a specific TT chip I should order?
 
There is a guy selling rebuilt stock MAF sensors. Would this be a good option, or will I just be wasting my money? Should this fix or help my problem, or am I better off with the LT-1 MAF?
 
One other thing.....Is there a specific LT1 MAF sensor to get? I know there are a bunch of different ones. Can I just plug in the LT1 MAF sensor and call it good, or do I have to do any mods to make it work?
 
souljasmooth said:
I wish my car idles like that. I am going to try the LT1 MAF. What is the closed/open loop that you guys are talking about? My car idles rough at all times cold or hot. Is there a specific TT chip I should order?
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I would hold off and upgrade injectors first, no reason to buy a chip now, and then in 3 months or 3 weeks be replacing it with another chip for bigger injectors.


Id search tb.com for a set of 009 injectors, heck you might find a set of 009s and a Turbotweak chip for around 140-150 bucks.

Or 289.00 new TurboTweak - Turbo Buick Custom Chips and Parts

I run 009s in 2 cars, both low 11 second cars.

BW
 
souljasmooth said:
One other thing.....Is there a specific LT1 MAF sensor to get? I know there are a bunch of different ones. Can I just plug in the LT1 MAF sensor and call it good, or do I have to do any mods to make it work?
Click to expand...

Everyone has been down that road of trying reman/rebuilt mass air flows, its hit or miss and just not worth all the hassle unless you have multiple cars and parts you can swap around trying out used/repaired mass air flows.

You must use a translator box to convert the signal so just installing the LT1 maf will not work.

BW
 
Thanks for the leads. I might just buy a new set from Turbo tweak to make sure I get the right chip for it. Well see.... Where can I get a MAF Translator box. Is there a specific one? What about a specific LT1 MAF sensor?
 
The dealership has two MAF sensors:

1.0 air meter AC delco part# 213-353
1.5 air meter chevy part# 19207203

which one should I buy?

thanks
 
souljasmooth said:
which one should I buy?

thanks
Click to expand...

In my opinion? Neither...go to fullthrottle.com and order an LT1(3.00") maf and translator as a package. Or go gonzo and get the LS Maf (3.5").

I don't have a great way to explain open loop vs.closed loop, but I'll try...The ECM(computer) controls various functions from air/fuel mixture to torque convertor lock up,etc. It does this running in open loop mode or closed loop mode. Basically, stimulus=response, but at the speed of light. It collects data from sensors and reacts with commands to various controlled funtions based on preset data programmed in it(cells or blocks) or by driver input like mashing the pedal or turning on the AC. Now to do this effectively and balance as clean as possible emissions against driveability. In open loop operation the car is generally either cold or full throttle(ish). So the parameters that usually are used in closed loop are ignored so as to allow the operator to get in, start up and drive away with out any stumbling or wierdness. Think of it as running with the choke on,sort of... now this is HC rich and not acceptible to the EPA so as soon as possible the ECM looks to get the car into closed loop and accept all data and react to it keeping the 14.7:1 AF ratio...or leaner sometimes(EGR).
In closed loop the ECM uses data collected and looks at the cells and figures which cell will provide good driveability and maintain clean emissions. Open loop ignores data and just uses a handfull of sensors to keep the engine running good, emissions be damned! If you have a datastream scan tool you can drive the car and watch it go in and out of closed loop operation. Like when it's cold and warms up or when you mash the gas pedal.
TT chips utilize an open loop idle and use the O2 sensor to richen up the idle mixture and stabilize the idle. And it's interesting to watch how much more the ECM goes open vs. closed with a TT chip.

I know this is a convoluted explanation, and maybe someone can explain it more clearly. But there are some good books out there to explain ECM controlled vehicles and how they work. If you are going to tune then you need to get a basic understanding of how CCC3,OBDI,II systems work.
 
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