2002snortbird

Ok IAC's have come down to approx 32 at idle and warm engine(thanks to blade hole). Hot and cold starts need help(feather the gas). And the dam thing still has a stumble down low(under 2000rpms), and dies (sometimes)when reved up and let to return to idle. And sometimes the thing idles great??WTF <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> I'm thinking it my be the bbk, but didn't have problems prior to cam install??What do you guys think?? cam is 224/224 .561 112 thanks

2001CamaroGuy

iTrader: (6)

This is the TR cam right? if so its the same cam I have. I also have the BBK TB so I can tell you its not that.

Have you tuned the car (LS1Edit or something like that)? If not that is going to be the problem. The car is so far out of tune from the mods that it can't compensate.

I tried really hard to get my car to idle at 800RPM but it just would not work (had the dieing after reving). I now have the idle set at 850RPM and have almost no problems.

10secondZ

iTrader: (24)

the only thing i can tell you is if you can get the idle to sit right around 900 or so and it's still not fixed...then all i can think of is pull the timing cover again to see if the cam was installed correctly "dot to dot" and if all is good serious tuning is in order thru an ls1 edit session with a reputable tuner...good luck

carter

Slowhawk

iTrader: (12)

I run the same Cam.No problem on cold(5 degrees) or hot start.I drilled the stock TB a few sizes bigger and kept the idle at stock 800 rpm.I would say it's the TB or if you have a ported MA that could be causing the problem.

Raven

I have the same symptoms with my car right now - surging idle, stumbling/stalling engine if I take my foot off the accelerator too fast, etc <img border="0" title="" alt="[Frown]" src="gr_sad.gif" /> <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

I have a hotcam and bolt-ons, but I didn't have these idle problems until I had a Vig2800 installed a couple weeks ago. The shop that does my installs has been adjusting things with some improvement, but my car still surges pretty bad while warming up and will still die on me if I take my foot off the accelerator too quickly after short, part throttle acceleration. <img border="0" alt="[cry]" title="" src="graemlins/gr_cry.gif" /> BTW, I do have custom tuning, a raised idle, and a drilled throttle blade idle hole.

I'm bringing my car back in tomorrow to have the guys adjust things some more (3rd time in 4 weeks), so I hope things finally get dialed in. I'll post what it took to resolve the problems. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Sorry I don't have any answers for ya, but at least you know you're not alone when it comes to those type of tuning issues after a new mod <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

-Bradster <img border="0" alt="[burn out]" title="" src="graemlins/gr_burnout.gif" />

HITMANSS

I have a relatively mild 218/224 cam on a 114 LSA, plus a MAFT, plus LS1Edit tuning. My idle is lousy, even at 1000 RPMs. I have all the classic symptoms --- very rough on cold starts, surging, part-throttle hesitation and bucking, etc. I now have my MAFT set 20% lean for the base setting, 2% rich at WOT. So far, that has worked best.

I guess I need more LS1Edit tuning, but I'm thinking that still won't make it idle right. I might just pull the cam out & go back to stock.....

ARTY99z

Can fouled 02 sensors cause the car not to run right. After doing a major cam swap I would think that fouling the 02s would be possible since the tuning is so far out of wack. I might be wrong just a thought.

2002snortbird

I had the computer tuned by raging motorsports. Mark seems to know his ****. I think it may be the throddle body, but won't have a chance to swap it out till next week.

Colonel

"Can fouled 02 sensors cause the car not to run right."

Most certainly. If they're fouled you will see that they read about .450mv at all times.

You guys with idle problems, make sure you Ltrims are close to zero. If they're not then it may be indicative of a vacume leak, and exhaust leak, an O2 sensor or MAF sensor problem. You shouldn't need major changes to the MAFT base settings to get the Ltrims right assuming you're running stock injectors.

Pro Stock John

iTrader: (34)

I think it's fuel related, but the causes may vary.

To me, surging and an off-idle stumble is indicative of running too rich at idle... The surging is potentially the IAC trying to compensate for the rich AF. The off-idle stumble and poor gas mileage could be plugs that are fouling out due to running too rich.

Then again you could have a bad plug or wire. If one cylinder is running bad the car will run through fuel like crazy.

It can also be related to having fouled o2 sensors. Basically if the car runs too rich it can foul out the sensors and the plugs.

A quick and easy experiment was noted above. Plug in a MAF-T and lean out the base setting by... 2-5%. If the car I tried that on was running too rich at idle, it usually cleaned up the idle within a minute.

A lot of misfires at idle, are just that, misfires. Plugs that are not getting good spark, getting fouled etc., will misfire.

Take that all for what it's worth but borrowing a MAF-T is a quick easy test.

Here's my suggestions on the sequence of tests:
-Fill up and run new fuel through the car, maybe bad gas
-Check all plugs and wires. Brown color is best, white is lean, and black is rich.
-I rarely see plug wires cause problems.
-A-Tap and if the Ltrims are +15 thru 25%, the car is adding fuel for some reason. -25 means it's pulling out a ton of fuel, like if you ran uncalibrated injectors.
-Adjust tuning as needed.
-Drill out TB hole to add air to help reduce IAC counts to below 50.
-Make sure you did not suck a leaf in and it's against the MAF wires.
-.450mv O2 readings that don't change indicated dead o2 sensors.
-go for .050-.060 plug gap, .045 and less is too tight and can cause misfires.

HITMANSS

I have a MAFT, and have tried several settings, from 5% lean up to 25% lean. Very little effect on idle quality, surging etc. I now have the idle up to 1000 RPM, by adjusting the idle set screw. That has eliminated most, but not all, of the problems. That's too high an idle level for the street though, IMHO. Put it in gear (M6) and the idle speed actually goes up to 1200!

I think it needs the timing cut back a few degrees.

Colonel

That's not an idle set screw. Your idle is programmed into the PCM. If you've actually managed to raise your idle to 1000 with the screw then your IAC counts are no doubt pegged at zero. In effect, your IAC is no longer working. This is making your problems worse.

Return the screw to normal and set your idle with programming. You can adjust you IAC counts by cracking the throttle just a little (don't want to go too far) or by drilling the TB idle air hole. Get your IAC counts to about 30 with the engine fully warmed. Make sure you O2 sensors are working properly and that your Ltrims are good.

2002snortbird

HHHHMMMMM when I had atap hooked up the Strims would vary with maft adjustment, but the ltrim would stay constant at 13.3??? does this mean bad o2 sensor <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Colonel

A constant O2 reading of ~.450mv means a bad O2 sensor. Ltrims don't adjust immediately. Drive it around for a little while. They'll change.

Colonel

Let's move this to Computer Diagnostics and Tuning...

2002snortbird

Ok guy's I spent all day tweaking this thing to no avail. Ok here we go, I removed plugs and cleaned them up with wire brush, and regapped to .055. Checked all plug wires and reinstalled. Went and got fresh gas 94 octane. Got short and long trim to approx 0. The car would run great somtimes and others die. Still has that dam stumble below 2000 rpms(somtimes)Idle seemed ok, but would die somtimes or rev to high, IAC's zeroed out on me. Changed to the stock throddle body and would not idle high enough.Used shim to bring idle up, and IAC's zeroed. Still hot start needs the gas feathered <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> I'm soo sick of screwing with this thing <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" /> NOW WHAT???? Oh yea forgot to tell you I also changed 02 sensors, and still problems??

Smoke_ur_5.0

iTrader: (2)

Hey Jeff, have you tried using the stock throttle body and using a different sized hole? We had a local guy with a 383 that had a BBK on his car like you do and it wouldn't idle all that great either until he drilled a fairly big hole in it.

Try that or maybe even play with your MAF translator base settings.

98TAauto

iTrader: (2)

glad to see im not the only cam guy with friggin issues <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

i fixed most of my warm start surge by adding 2 degrees of timing to park and drive...

But my car still sreaches for idle on cold starts for about a minute then it smooths out.

LTRIMS at idle for me are -7 to -3 and my IAC is around 0 to 10 in this cold air when warm.

BAD 02's will make the car act like friggin CRAP! Ive replaced 3-4 of them already because my AF guage was shorting the drivers side 02 out for some reason. My passanger side just went bad yesterday because of age i guess. <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

but the car will surge like hell and if you drive it the car will flood with gas BAD! Sputters like crap!

good luck

2002snortbird

thanks for input guys, I going through things now with a fine tooth comb, and I'll keep you posted. The computer is going back to have the programming checked. It's a long shot but we'll see. <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

<small>[ January 28, 2003, 03:49 PM: Message edited by: 2002snortbird ]</small>

FASST

Ok, here's a different idea...do you have the cats installed, or are you running ORPs? If you're running ORPs, did you delete the rear O2 codes, install O2 sims, or delete the cat over temp protection. I've heard that if you don't turn off the cat overtemp protection, your computer will just randomly dump in fuel because it's not getting a signal from the rear O2 sensors. This will seriously kill your ability to tune A/F ratio...thus affecting your idle stability, etc. Just a thought. Take a look.