engine not idling correctly after tbi conversion

[Tyree]

Gentlemen,
We finally got the ecm and TBI engine up and running. Again on a 94 stock 350 with automatic tran. for rock crawlwer apllication. The engine is running but we do not have the diagnostic port tied into the harness yet. It only seems to want to idle while the gas is held down a little bit to keep from dieing. And when it is running it, it seems to be slightly throttling back and forth like in some kind of loop.? Does any body have any ideas on this? After reading some of the posts, they say that the EGR valve could be sticky or also the I.A.C may need some type of calibration?
Is this the right direction to start troubleshooting?
Thanks for any info on this.
-Tyree

[buddrow]

EGR stuck open usually causes rough idle condition. I would lean more toward the idle needing to be adjusted. That said, without knowing what the computer is seeing or trying to do it's a crap shoot as to what the actual problem is. Might try placing a matchbook between the throttle screw and lever and see if that changes the idle.

[notime2d8]

Yeah, this can be a number of things...on my conversion i had a vacuum leak, bad spray pattern on my injectors, and my distributor internals were rusted...After this it was purring nicely. You can easily test all of those, also make sure your timing is right at 0*, if you're using all stock parts you shouldn't need to adjust the idle position screw. Also here's a link to IAC cleaning - http://www.thirdgen.org/techboard/po...221-post6.html

[EagleMark]

Is this the right direction to start troubleshooting?
-Tyree

No! Right direction would be the ALDL port and checking error codes and getting a data log. If you don't do that first it's just a crap shoot in all directions.

Basic maintence could be the issue. Maybe it was running that way before you got it? Distributors on these are OLD at this point even if they've had new cap and rotors, the other parts are way past service life as are all other parts. Engines could still be in a very good condition depending on miles and maintenance.

[Tyree]

Gentlemen,I just wired up the diagnostic connector according to the schematic for the 1227747 and I am getting information off the A8 serial data connection pin on ecm(I checked it with my oscilloscope). But my obd reader will not acknowledge for whatever reason. Does anybody know about this.? Thanks for the continued help to everybody.

[Tyree]

ok. so I jumped a and b together on the diagnostic connector and was trying to read the A5 pin which is also pin D on the diagnostic connector directly for SES codes and saw nothing.. I am lost on this. I also notices that when in the key is in the accessory position the IAC is vibrating a little bit.?

[EagleMark]

When you jump the A and B it will flash the CEL. The check Engine Light coming out of ECM is ground and it needs to go to Key On Power.

Without the jumper and the key turned on the CEL should come on, blink once and stay on till engine is started, then go off.

[Tyree]

Thanks eagle mark, I will try that. I must have been interpreting the schematic incorrectly. I will connect the aldl pin D to ignition power and try again. thanks