92 camaro rs 305 tbi, put a air gap intake on it with tbi adapter and now when you start the car cold it runs really rough and when you drive it it has bogs and sputters, when it gets warmed up good(bout an hr of driving around) it seems to come out of it. woundering if it is realated to the intake swap or somthing different. i checked and double checked and everything is hooked up, and also there was no codes in it. could it be a sensor issue?

 

I would verify your AFR with a WBO2, but it's probably just very lean now.

You may have been on the edge of having some lean cylinders before the swap and just pushed it over the edge. The TBI system relies in part on high intake port velocity (small intake runner + swirlport heads), AND heat in order to provide atomized fuel or fuel vapor to the cylinders. The quality of your fuel delivery may be suffering now due to the changes. To make the new combo work well, you might have to try multiple tuning tricks.

Taking control of the calibration will probably be the most important step. You can adjust your VE, AE, and SA in the chip calibration to improve the tune. You may find that raising fuel pressure can help in combination with some tuning changes in the chip, - maybe not.

Before digging into the tune, I would check very thoroughly for any other problems like a vacuum leak, a fuel pressure problem, or an ignition problem. It could be that you just have a fouled plug or two.

edit: The air-gap intake normally has a space connecting the two plenums right at the carburetor flange. Did you leave this as an open space or have you divided both plenums?
Keeping them divided will increase signal to each throttle bore, and may possibly improve your running condition.

 

they are divided between the two. were would i go about getting the chip tuned?

 

You are experiencing exactly same issues I had with a air gap style intake and without chip compensation as 305sbc has suggested. Not sure how effective a tune will be with that manifold. Lets say it will be partly effective. I believe car will always run poorly until that manifold develops some heat into it. I see you are IL. I am WI. Similar climate. Might try raising fuel pressure before you attempt tuning. I recall Holley may have sold a coolant spacer to place under TBI to help preheat. You may want to consider a non air gap manifold such as Edel Performer.

 

Im sure this isnt what you want to hear, but an airgap intake is one of the worst intakes to use with a stock TBI setup. They can be made to work well in my experience, but it requires extensive compensation that the stock ECM isnt capable of.

The problem is that the cold plenum allows the fuel to settle out and stratify at low temperatures. This is probably why it runs poorly when cold. AE can also be a real issue as those airgap manifolds need tremendous AE when cold, but none when fully warmed up. That, and the manifold temp constantly changes when you drive.

There are some things you can do to make it run well. First is run an open element with no cowl induction or any cold air. This will feed warm air to the manifold and keep it at a constant temperature. This is real important with TBI. No CAI or anything like that. The next step is to get into prom burning. Youll want to add more AE and retune the VE tables to get the fueling back in line.

 

You can do it yourself, find an experienced tuner that can do it, or you could swap to the EBL system which makes it easier to do yourself.


http://www.sallee-chevrolet.com/Edel...ages/7516f.jpg


See the dip in the divider between the two plenums? What did you do to seal this off?


In the mean time you could run a factory air cleaner housing and force all the intake air to come from the heat-stove on the exhaust.
I would still look for other problems. The TBI should be able to perform no worse than a carburetor of similar size on that intake.

TBIs are notorious for having extremely low spark advance calibrated into the factory system. You "might" find some improvement in idle and drivability by increasing your initial spark advance at the distributor temporarily until the chip can be recalibrated.

One common trick to improve idle and drivability with the TBI is to increase the throttle opening - or minimum air rate setting of the throttle body, and then decrease the amount of IAC steps (done in the chip calibration) so that more of the air has to go past the throttle blades for better fuel shearing/atomization.

 

thanks for the help guys, i decided that i am going to put the stock one back on for now until i do some more research. then i would like to do a motor swap in it.

 

305 sc,the dip between the two sides, i took it to a local shop and had them weld it shut then smooth it out.

 

Keep in mind that TBI cannot see teh actual airflow like a carb can since its speed density. This causes the fueling to drift as the intake temp changes.

I did run this intake for a while, and it can be made to run quite nicely with TBI, but it will require a good deal of tuning.