RSCamaroGuy92

Hey guys, just finished my 350 tbi swap-in, in my '92 RS(stock 305 tbi). I changed the ESC module, Knock Sensor and put in 350 injectors like your supposed to do. I had a chip made for the car, and I took off the smog sh*t. Checked the timing and I'm at 0. I put the car 8 degrees advanced, 'cause that's where it ran the best without backfiring through Throttle Body or exhaust. The Idle question comes later but here are the vitals....

These are the modifications I made to the 350
EXHAUST:
- Hooker Headers w/ 2 1/2in collectors.
- 2 1/2 exhaust: y-pipe, and exhaust with a 80 series flowmaster.
- Eliminated C. Converter
IGNITION:
- MSD Coil, Cap, rotor, and distributer.
- Taylor Spiro Pro 8.8mm wires
- Splitfire Plugs
Replaced entire cooling system (rad; fan; hoses, thermostat. ect..)


Now, my question. Why am I idling at 1700 RPM?
The car runs like a raped ape, great throttle responce, very quick.
When I retard the timing, my idle decreases, but the car will backfire and run like sh*t, so this can't be the problem.
I check and no vaccumm leaks
The check engine light flickers with the idle of the car (brighter & darker)
I replaced the throttle position sensor, it didn't do anything.

I was told that possibly I didn't have enough backpressure for the O2 sensor to operate correctly so the car goes in a out of loop.
What the heck does that mean, and is that my problem?
I'm not real knowligible on the computer stuff, so this is not my specialty. Any ideas that may help would be greatly appreciated.
Thanks.

JPrevost

Min idle screw is way out of adjustment or you have a vacuum leak somewhere below the throttle blades. Timing and fuel can raise and lower an idle but nothing in the relm of 1700rpm.

TBI305Camaro

Look near the throttle linkage. There is a screw that determines the idle. You can back it out and that may lower your idle. Just need a little tiny torx bit.

RSCamaroGuy92

I've determined that I don't have a vaccum leak, I sprayed ether along the hoses and base of the TB. I was told that the idle screw was inside the TB blocked by a plug that had to be drilled out. So, if the plug is still there, why would the idle screw be off?

TBI305Camaro

with the new motor and everything it may just be running way different. Plus the chip may not be perfect. There was nothing blocking my idle screw. I messed with it so it would idle at 750rpm in gear. Used to be around 500.

RSCamaroGuy92

I punched out the min idle screw tonight, and backed it off. It only went a half turn or so before it moved away from the linkage. The rpm only decreased 100ish. Now I idle around 1500-1600 RPM.

If my distributor was off a tooth, but I was still able to set timing to 0*, could that be my problem?

Also, I seem to think that I have too much fuel pressure. If the regulator went bad, could too much fuel pressure be the culprit?

Any other ideas guys? I'm really banging my head on this one.

RSCamaroGuy92

ANYONE???

JPrevost

If it isn't a vacuum leak then I don't know what to tell you. The motor is OBVIOUSLY getting more air than through the throttle blades. I doubt it's an intake manifold gasket leak so look at the vacuum fittings in your center console (climate controls). Try switching around the climate controls, watch the rpm and listen for the leak. Another easy way is to unplug each vacuum fitting on the intake manifold 1 at a time and plug it up with your finger. You could just kink the lines (not the hard plastic ones).
When you find the leak, let us know what it was.
The rundown list of vacuum leaks to test for;[list=1][*]MAP sensor (back of throttle body just above fuel fittings)[*]Bad PCV valve (comes out of valve covers, makes a 90 degree bend an inch up and goes into front of TBI)[*]HVAC climate controls line (passenger side of intake manifold, hardline)[*]Evac canister (under alternator along with fuel lines, hardline)[*]Powerbrakes (the boaster line to a fitting in the intake just below the TBI facing the drivers side headlights, metal line at the intake manifold)[*]Stock air cleaner thermac system aka Heatriser control[*]EGR (hardlines going to the #8 cylinder vac fitting)[*]Last, but not least, check the bushings on the side of the throttle body[/list=1]

RSCamaroGuy92

I'll try that sometime today or tomorrow before work.

headhawg7

I had that same problem after swapping my 305 tbi system to my 383 stroker system using the same tbi setup off of the 305 (until I can get a new intake and tbi). What I had to do was clamp(pinch) off the return fuel line, replace the O2 sensor and replace the fuel pump and lines. This took care of the problem immediately and let me tell you, even with the stock intake and tbi that this car flat out runs. Its funny because I put headers on it and ran a single 3" pipe down the side, over the axel, and into a single in single out muffler and does the air ever flow. I pulled up beside a new cobra on the interstate and I know he had to be thinking my RS was a V6 and when he stepped on it, then I stepped on it I beat him by a bout 5 car lengths doing 120 before I let off, but anyways clamp off the reutrn fuel line, replace that O2 sensor and you can get away with the stock fuel pump and lines as long as the return line is clamped off until you can replace the fuel pump and lines. Hope this helps. Danny

RSCamaroGuy92

nothing, vaccum isn't the problem.
I saw the post about the return fuel line, I don't know if I like the idea of having to pinch it off. Even if I plug it up, that still seems scarey. What exactly is it there for? I mean, really, will it hurt anything to get rid of it(pinch it off)?
If I do "pinch it off, I think that I'ld just plug the line at the tb, so not to hurt the real fuel line in case that doesn't solve the probem. Any feedback guys???

JPrevost

If it isn't a vac leak somewhere remote then you've gotta tell me what the problem is!!!
Don't plug the return fuel line unless you don't mind stressing out your fuel pump with crazy amounts of psi at the injectors. I repleat, do NOT plug the return fuel line or be ready for more serious problems.

ShiftyCapone

iTrader: (7)

I had a similar problem but with my 305. it ended up being an internal gasket leak thru the intake manifold. Air was being sucked into the crankcase thru the bottom of the intake gasket. It cracked for some reason, I am the first person to ever have this happen I geuss. I never figured out the problem and it took a dealer 7 days to figure it out and cost a fortune.

RSCamaroGuy92

I'm gonna try the ether test along all sides of the intake gasket. I think that I may have a leak somewhere along it. Its the only thing that I can think of.
The only other possibility could be the chip?? I had some guy program it for me, is it possible that he messed up the chip that badly?

RSCamaroGuy92

I checked for the hundreth time, no vaccum leaks.

I pulled codes 51 & 53. Do you guys think that either of these codes could be my problem?? I know that 51 is bad prom and 53 is either EGR (which could explain my idle) or security prob. Could the bad EGR or a no-good chip do this???

racereddy20

sounds like a bad chip to me. I bought a hypercrap chip online. When I installed it, it made the check engine light flicker rapidly. I didnt even bother moving out of the driveway because of the way it was idling. I took the chip out and installed the stock one and viola it ran fine. Put your stock chip in just to see what happens.

BTW i got my money back for the hypercrap chip.

Low C1500

I will assume that you have an IAC in your TB,

The only way to fix this is to put limit to the amount of IAC steps. This has to be done in the prom, The industrial term for this happening would be "reset wind-up", where the computer saturates its output at 100% to the IAC (full air), hence the 1700rpm idle. This usually only happens in high performance engines, because the acutal gain of the engines proccess is very high at idle compared to a stock motor (ie: a change in input fuel causes a large change in O2 output, since HO motors have low VE at low rpm, and gain = output / input) So to compliment the higher than stock engine gain you need a lower than stock ECM idle gain.

But if your IAC count is low or normall, it sounds like a vaccum leak, a tiny leak will cause a big idle.

RSCamaroGuy92

That makes great sense thanks, I really didn't understand what the IAC did, but I know how they act when they go bad. I'm gonna try putting my stock 305 chip back in and seeing if the idle clears up, if it does, then I know that the chip is crap.

RSCamaroGuy92

With the new chip I keep getting code 51. I broke a pin off of my stock chip somehow, so that gives me a code 51 also. Is it possible that my ECM is bad maybe? Or just the chips on a 51 code.

RBob

iTrader: (1)

Code 52 is a bad checksum of the EPROM. Broken pin on the EPROM
will cause this. The guy that buned the EPROM probably forgot to update
the checksum once the changes were made.

RBob.

(EDIT: Sheesh, lets make the above a code 51, NOT 52).

Thanks.

Aaron91RS

iTrader: (2)

The chip is not making a good connection. It is running in limp home mode, plain and simple.

Soak the chip prongs(only) in vinager and wipe them off.
Get a better connection and everything will work right.

RSCamaroGuy92

Tried vinegar, didn't help any....doh! Is it possible that I am still not making a good enough connection between the chip and the ECM? Also, what if the ECM went bad? Could that shoot code 51 only? Is there any way to check either the chip or ECM in that case guys?

Hoochz42o

Did you ever get this figured out? The thread stops at #22 and I can seem to see if it continues lol. I’m having the same problem with my new 350 tbi. Idle in park/neutral at 1700rpm and 1000 in gear. Same same. Changed damn near every sensor. Cap/rotors plugs/wires. TB spacer. Short headers no cat. 1 into 2 flowmaster. No chip. Idle screw backed all the way out. Seen that the tps could be adjusted. Haven’t tried this yet. Real question is. Would the high idle harm the engine? Can I still operate vehicle until I can figure this out?

henryd3

iTrader: (128)

Here's a little tip from the How Tos section on here. Have you done this?
IAC and TPS Adjustment - ThirdGen.Org

Schurkey

You dug up an ancient thread, I wasted twenty minutes with an extensive reply to a post that is near twenty friggin' years old.

Fast idle isn't going to hurt anything except the transmission when you put it into gear. Given a choice, I'd fix this without driving it more.

Verify fuel pressure, verify base ignition timing with the ESC wire disconnected. Shut off the engine, reconnect the wire, and then verify that the ignition timing advances. Typically "about" 12 degrees, but that's dependent on the computer programming.

Connect a scan tool. Find out what the computer is trying to tell you. Verify EVERY sensor, verify the computer outputs, particularly the IAC commanded position. If your computer allows, use the scan tool to command different idle speeds, see if the IAC reacts.