ok, not sure, but 'sometimes' when i start my car it hides fairly high (lil over 2000rpm) for a few seconds then drops back down to like the 1200rpm range, its odd, anyone have any clue what's up? i have a '91 camaro (305 tbi), 5sp, open element k&n, mallory ign, some other crap.... thanks. ALSO, not really a tbi question i guess, but this is the only car i've ever driven with a stick and the thing sometimes doesn't really want to shift unless i hammer her, is this normal? maybe new tranny fluid? ok, thanks all.

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91RS open element K&N, dual flows, mallory ign, AR 89-92 camaro big block hood, dark red, some mods.

 

mine is a 92 RS and it does the EXACT same thing. The rev's I figure are normal when it's cold and the shifter...seems to be a car 'mood' thing. Sometimes it's smooth as butter and other times...'wham!'.
I asked this question before and nobody feels like answering it. If you find out anything let me know,
Jay

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92 Camaro RS Anniversary Ed.
Open Element

 

lol, alright man, will do, i'll ask around here as well (goose creek, sc, near charleston, on a naval base but i have buddies who use to be car mechanics before joining the navy, maybe they know if no one else on the board does). i just thought it was weird cause it doesnt always idle high after i start it, only on occasion, some days more that others, and for no apparent reason, hmmmm. anyways, thanx .

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91RS open element K&N, dual flows, mallory ign, AR 89-92 camaro big block hood, dark red, some mods.

 

I think (not %100 sure) that it's just burning the highly rich air/fuel mixture. The O2 sensor detects that and it raises the timing (since it can't open the throttle plates) and that increases the idle speed momentarily. The ECM basically floods the engine in open-loop mode just to get the engine to fire. It uses the MAT to get an idea of how much fuel to add while starting, and to keep it running after it starts.

Have you ever seen how much fuel pools up on the butterflies if the car won't start? You could light it with a match. I just had a starting problem yesterday, and at first I thought it was water. Then my friend said it smelled gas (I can't smell anything ). Then I watched the injectors as he cranked it. I guess I'm just used to carbs. I never saw gas on a carb unless the accelerator pump squirted gas on the plates.

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92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford 2ch. to 2 MTX 12" subs

[This message has been edited by AJ_92RS (edited July 07, 2001).]

 

Opps. Sorry edin. I forgot the shifting part. Yes you need to change the tranny fluid. After a while the fluid looses the slickness and causes the gears to be stubborn. Once had a 91 RS 5spd that did that. I had the fluid changed and it was fine after that. That was also the first time I found out it was auto-trans fluid in there.

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92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford 2ch. to 2 MTX 12" subs

 

AJ_92RS, ok, i do sometimes smell gas right offhand.... is this bad the whole startin it up thing?? should i increase timing? what would be good timing for me to set with the mods i have?

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91RS open element K&N, dual flows, mallory ign, AR 89-92 camaro big block hood, dark red, some mods.

 

No it's not bad. Sorry. I should've said that. It's just the way it works. The TBI doesn't have a choke, so this is the way it richens the mixture. The O2 sensor tells the computer the mixture. If it's below 12.7:1 (which it will always be at first), then the computer is programmed to burn that as quickly as possible, and get the mixture more around 13.2:1 (from what I can remember anyway) in open-loop mode. Then after a certain engine temp, or time period (which ever comes first) it goes into closed-loop and tries to maintain 14.7:1 A/F ratio.

If you've ever adjusted the idle mixture on a carb then I'm sure you noticed that the richer you set the screw (up to a certain point), the faster the engine idles without even touching the idle speed screw.

It's a whole combo of parts that work together on EFI in this process. To many to list and explain, and this is only the basic idea. And I have to say that I'm not sure that the ECM has no control over the throttle plates. I think it does, just not very much. Kinda like when it raises the idle speed when the a/c is on.

[This message has been edited by AJ_92RS (edited July 07, 2001).]