1989 Project Update

Been a while since I've popped in.  Since i have been working on Bronco, I completed full tune up.  Got all vac lines figured out, replaced brake booster and master cynlinder, checked EGR valve and cleaned out IAC.  Also tested voltage to all sensors.  Motor is running very good.  Still has a cold start, but rough idle is no longer an issue.  After about 15-20 minutes of driving the CEL comes on.  After shutting off and restarting it won't come on until another 15 or 20 minutes of driving.  Still getting codes 33 and 41.  Today, i found a rather large leak in the exhaust right before the cat which houses the Oxygen Sensor.  Could this be allowing excess air to pass through the cats and throwing off O2 sensor causing the lean code?  I'm really hoping this is the last issue i need to fix.

Paul

yo Paul,
DTC 41 for HO2S Failure Or Fuse \"E\" Inoperative, ABS Light On, Back-Up Lamps Inoperative, Daytime Running Lamp (DRL) Inoperative, MIL On, Inadvertent Self-Test, Speedometer Inoperative & Trailer Battery Charge Relay Inoperative in TSB 95-5-21 for 92-95 Bronco & F Series; "...the HO2S wires in the 12A690 (subassembly of the 14B060 battery cable) harness may become chafed and the vehicle could exhibit any one of the following conditions....Lack of proper HEGO operation may cause, or be the result of a rich or ***lean fuel condition***, which could cause additional heat in the catalyst. Perform self test KOEO and KOER, service any codes. CHECK FOR PROPER HEGO GROUND. If the HEGO ground is good, the following areas may be at fault: ..."

DTC 41, Common Locations for Short Circuits TSB 95-02-11 on 94-95 Bronco & Trucks; "the HO2S wires in the 12A690 (subassembly of the 14B060 battery cable) harness may be cut on the lower right engine mount causing improper signals to be sent to the PCM. Damage may be under the electrical tape.

DTC 33 is triggered when the EVP sensor is not closing;

This code could be caused by several different factors. If the pintle position sensor (Ford calls it the EVP sensor) is shorted or open, you could have a code set. If the EGR valve becomes carboned up and does not seat fully, the EVP sensor gives a high reading and a code is set. If the diaphragm of the EGR valve is bad, then it, too, is flagged..."
Source: by Harry G

so EZiest & cheapest checks are to inspect & repair/replace repair any bad vac lines. for a <$ vac line test; I pull em off and use the straw sucking test; one finger over one end;

You can use a local auto parts store loan-a-tool program to "borrow" a hand-held vac pump/meter and accessories for a fully refundable deposit.
read more if you didn't see this in a prev reply to you @ http://broncozone.com/topic/24352-89-bronco-302-self-test-codes/