88' crew cab fuel injection

Hey guys i need some help.
1988 chew cab 454 w/turbo 400
I know when i bought my truck that my lovely 454 would suck down gas. Wasn't worried about paying for gas but the other day i had my intake cleaner off and had the truck running and saw a ton of fuel spraying into the throttle body. It does smell like its running rich and the plugs say I'm running a little rich but I dont know what to go off of or what to check to see if something is wrong.

Any ideas would be great. I live in the bay area in california and as far as I can see I am the only lowered dually in the land. thank you for any help you can offer.

If your truck is starting out cold this is normal to run a little rich. The reason is because of the one wire O2 sensor. You can change it to a 3 wire O2 sensor to fix that problem (hook up switched power, ground, and the sending wire). The newer trucks have them. All a 3 wire O2 sensor does is heat it self rather than using the exhaust to heat the one wire O2 sensor. They tend to run rich until the truck is warmed up. If it is rich all the time check the EGR valve and port in the intake. They get clogged up with carbon and will cause it to run rich all the time. Just some things I found on my 93 454.

Good advice on the three wire O2 but to add to that, I've also read that it's best to stick with the AC Delco brand, Bosch seems to be the most common replacement and allegedly* it responds slower than the Delco.

The TBI systems also can be bad about falling back into open loop at idle, even when warmed up, so they may idle a little rich but go back to normal while driving. If it's showing rich on your plugs though that's not good.

It's really easy to test your CTS (coolant temperature sensor, some people call it the ECT engine coolant temperature but whatever, CTS I like better) to see if it's lying to the computer. When these fail, they almost always read colder than normal, and that'll cause a rich mixture because it's forcing open loop. I personally had one that was so bad it would flood the engine and stall it. When I tested it, the reading equated to about 40 below zero, when it was a nice warm 70F day.

The CTS is the sensor next to your thermostat housing. Unplug it and put an ohmmeter across it. Here's a chart of values and the temp they equate to. Helps a LOT if you have an IR thermometer so you know for sure what your actual coolant temperature is, instead of relying on a gauge.

Coolant sensor approximate resistance specifications: (thanks to Chevytech)
177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C.

Also, don't overlook a possible sticking or incorrect temp thermostat. A lot of people install colder thermostats to boost power, well it just makes it run rich. Proper temperature stat for your engine is 195F, you need the right one for the computer to operate correctly.

Richard

Richard has a big brain.

Well, ya know what they say. Smart is sexy.

Richard