94 bravada code 23

[pete123654]

HI all, I've got a 94 bravada 4.3 automatic that's spitting out a code 23. IAT sensor I thought. I've got 5 volts to the sensor, have replaced the sensor and reset the computer, but I'm still getting that same SES code.
Its (or something) causing it to be really hard to start when warmed up.
Any ideas?

[MT-2500]

Good ground on ground wire?
Voltage should change with engine cold to hot.
What is the engine scanner read out on sensor?
What engine code.
Do not confuse the IAT sensor with the engine CTS.

[pete123654]

The IAT is in the air duct, so I know I'm working on the right sensor, well it may not be what's wrong, but that's what the scanner said and what I replaced. Warm I have about 18ohms, room temp around 30 (tested with a multimeter) so it seems to be in range ya?

[MT-2500]

Have you checked the wiring?
Good ground?
With the sensor pluged in does the referance voltage change with air tempt change?
Your ohm reading is off some what.
70 degrees tempt sensor should read around 3400 OHMS.
Check another sensor

What is a scanner reading from computer say on IAT tempture?
If it is reading -30 degrees your wiring is bad or pc has gone bad.
MT

[pete123654]

I only have an OBDI scanner, glorified paper clip. Its cooled down some now (won't start again until completely cooled down) and is reading 5 v when I test either side of the thermistor. Ground seems good, but how can I tell if its not? Once I get it started again, I'll let it come up to temp and test sensor again for voltage. (resistance does change with temp, so I'm thinking voltage would to.)

[pete123654]

So I'm back to working on the Bravada (vin "W")again. Here's the skinny: nut kit, fuel filter, plugs, wires, dist and rotor less than 100 miles on. Checked fuel pressure at the schrader valve and had 80 psi with a rapid drop to 30 in about 15 secs. tested just pump (at the filter) 75 with the same rapid drop down. Replaced fuel pump and since the regulator was under warranty yet replaced it as well. Now pressure at 68 and holds between 68 and 55 for 20 mins. Still no start. tablespoon of gas into plenum starts up and runs for a sec or two. Pull plenum, cycled fuel pump a half a dozzen times, no leaks or puddles, 12 v at the injector plug with key on. Place plenum back on without bolts and only vac lines hooked up, no sensors. Started up. hooked sensors back up, died mid bolting plenum down, won't restart. Checked for codes and had a boat load (cause I had everything disconnected!) Cleared codes and tried to start, no joy. Pulled plenum again, no leaks or puddles, 12 v at injector. Placed plenum back on without bolts, but with vacs and sensors. Started let run a few mins, bolted plenum down, let run for 10-15 mins ran great. test drove it (up and down the drive lol). Parked it and shut it off, restarts great. Let cool half way down, trouble starting, when it did start, I had to rev it to keep it going and it ran rough even while reving. Pressure steady at 58 or so. only code is 23, because I have it disconnected yet (IAT) as I have the air cleaner off. So, while I've replaced some parts were not funtioning properly, I haven't solved the no start/hard start problem. What am I missing? spider assembly? Long post, but good advice comes from good data.
Thanks.

[MT-2500]

You need to get it on a engine capable scanner and see what the VCM/PCM computer sensor readings are at.

[pete123654]

Well I finally got it going! Turns out it was the injector. Every time I pulled off the plenum to check things out, I would push down on the connector to make sure it was snug. I tested the wiring with a multi meter and wiggled the wires no change in the voltage, so replaced the injector and all is well. Probably a bad connection inside the injector. I did find out one thing though, not only can you buy just the pressure regulator by itself, but you can also get the injector by itself. Thanks for all the help, this forum and the people on it really helped me solve this problem.

[MT-2500]

You arer welcome and.
Thanks for posting back the fix and how it went.
Glad you got it going.
MT