i have an 89 5.0 tbi camaro, and its running exceptionally rich. its so rich if i stand behind the car, i smell like diesel all day. the issue is, its not throwing a check engine light.....any ideas why it wont throw a code? can i adjust the tbi?

 

My cars check engine light wasnt working either, so I removed the panel and discovered the bulb was missing. So if I were you try replacing the bulb. As for the engine running lean it could have something to do with the MAF sensor (I know TPIs have them but do TBIs) if so it might be bad or unplugged. Mine was unplugged causing it to have bad gas mileage and decrease in power (however the car still runs rich). Check that but I think that it is something else that is causing the problem. Im sure someone else knows what it more likely is.

 

TBI doesn't have MAF. Has MAP though. Does the SES light up at all when you flash the codes? If not - might be as suggested, a bad SES bulb.

 

Didnt think so thanks for clearing that up have never owned a carburated car.

 

Remove diesel from car, fill up with gasoline. Problem solved.

 

SES light is tested with a simple bulb check. Turn the key on, does the SES light come on? If so then it works. If not then the bulb is probably out or there's a problem with the ECM or SES bulb circuit. Rich running on TBI is most often an issue with the coolant temp sensor or MAP. TPS can also affect it.

Any of these can suffer an "in range" failure affecting engine performance without setting a code. The easiest way to diag this type of failure is with a scanner. Data will point out an inaccurate sensor signal. Without a scanner, we have to rely on testing the most likely culprit. In this case start with the CTS. Test it for resistance. It should read 3,400 ohms at 70F, 185 ohms at 210F.

 

where would i find the CTS, and can I check the map sensor?

 

CTS (coolant temperature sensor) is that thing sticking up right in front of the thermostat housing on the front of the intake manifold. Has a two-wire plug clipped on to it

 

You can check the MAP sensor for voltage at pin B of the connector. It should have about 4.5 volts with the key on, engine off. With engine idling it should have about 1.7 volts. Voltage should change with engine load. Should jump to 4+ volts on throttle snap.