POLL: Keep tbi or go back to carb

[chakaD460]

Not to hijack, but how do you get to the FI site?

I keep getting this error: PHP has encountered an Access Violation at 018B51CA

[shimniok]

Vacuum leak - I have resealed the tbi and adapter. The intake I have is a used Edelbrock Performer. Can these things warp? If it was an internal leak is it possible that I would be burning oil?

My new Performer manifold was warped, so, yes. Dumb question but doesn't the GM ECM tell you status of sensors as it's running?

Does a carb idle better on it?

Michael

[AlsChopShop]

have you replaced (or checked) the TPS? sounds like a TPS problem to me.

Al

[Bill USN-1]

Did you see something in his data log file that shows it bad?

[Rogue]

I've had "rolling" idle problems in the field be caused by too large an exhuast - but that is usually on Fords. I have also recently at work had two OBD1 systems with dead 02 sensors doing things I'd never encountered before. In one instance the when the computer switched to closed loop the computer would jump up from 128 BLM to 168 BLM, the engine then would stumble and remain in limbo for a minute while the computer tried to figure out what the heck was going on. No I haven't read your datalog - I'm just adding two cents based on what Mark ( DieselSJ ) said about your 02 readings. I've seen a lot of weird things in 15 years on the job and like I said - I would have never guessed an 02 sensor was causing the problems I was having with a few customers cars, yet.... they were. Good luck, Steve.

[Bill USN-1]

Maybe he dumped the FI system by now???

Been a while since he replied.

[crispyboy]

*UPDATE*

I was finally able to get back to the project.

• Intake manifold - had it planed - warped about 7 thousands of an inch.
• replaced throttle position sensor as a recommendation from Howell. Still idles at 3.6%. IAC is approximately 28.
• Got one more chip from Howell - 6 total chips - whew...

The last chip seems to be the best so far. The blm's are at 128 at idle through 1200 rpm - jump around a bit at higher rpms. Range from 99 to 146 but these where the extremes - seemed like spikes - mostly it stayed in a window of 120 through 135 throughout the rpm range.
It does not stall anymore. I can put it in gear, make quick stops etc... Rpm dips some but seems to rebound quickly.
I will now put a license, insurance and tires on the vehicle and start driving it on a regular basis. I have not ruled out a trip to Howell as I think the idle is only fair - seems to range from 675 to 750.

[82Waggy]

I wonder what your vacuum reading is at Idle.

I also wonder if the high overlap of the cam you are using is causing your TBI idle troubles - intake dilution, low vac, etc.

[crispyboy]

Vacuum at idle is 15 inches.

Cam spec:
Edelbrock 2132
Advertised: int 278, exh 288
@ .050: int 204, exh 214
@ cam: int.280, exh .295
@ valve: int .448, exh .472
intake: open 3 deg atdc, close 27 deg abdc
exhaust: open 42 deg bbdc, close 8 deg btdc
lobe seperation: 110 deg, intake centerline 105 deg

[82Waggy]

Vacuum seems high enough but overlap is 68 degrees, which may be a lot for a computer controlled motor.

Edelbrock recommends a 112LSA for use with their EFI systems.

Anyway, the high overlap could be giving your system fits - just a thought.

[Bill USN-1]

I would recommend performing an initial set up procedure for your TB.
You need to set the min idle speed and adjust the TPS. Sometimes you need to elongate the holes in the TPS to allow more adjustment.

I would also like to see a BLM log if you are using winaldl for your data.

A single BLM reading at any given time is not useful. It needs to be an average over a drive. The longer the better, but at least 30 mins.

[crispyboy]

Bill,
this is a non adjustable tps. Idle speed is built into the programming - if this is what you are asking.
The throttle body on the GW is from about a 1993 gm vehicle - found this out when I had to purchase a new tps (round connector).
The throttle body on my truck is older - but the tps is also non adjustable (rectangular connector).
PM me back with you email address and I will send you a log file tonight when I get home - I use winaldl.
thanks,
Steve

[Bill USN-1]

You can slot the screw holes enough to get the TPS reading where it needs to be once you make the min idle speed adjustment.


Idle speed is controlled by the IAC.
Minimum idle speed is set by the screw on the drivers side of the TB.

Go to the BB and look at the injection forum FAQ for the procedures.

You may find that after you back the min idle screw out some, the TPS will be much closer to 0%=.54V

scoutii76 at hotmail what else would it be!!

[tndonor]

None of the above......PROPANE!!!!!!!!!!

[FSJ Guy]

You shouldn't have to adjust the TPS on a GM TBI. I have a Howell system and I've NEVER adjusted the TPS.

I suspect your cam is not TBI friendly.

Hopefully the latest chip will work well for you.