88 Burb Code 45-Wits End HELP!

:banghead: Hi All, Love The forum. I have an 88 burb 5.7 TBI 4X4w/ac front and rear. The engine I built,74 Camero motor ,30-over, RV 2 cam and alot of head work but mostly stock.I changed over everything from 88 on engine swap you would only notice the valve covers bolt pattern on looks. I purchased a Super Chip and 160 Thermostat to play ball with the computer and different engine combo. All works great cold but when it reaches closed loop vacume drops from 19 to 15 or so, Egr solinoid releasing egr a bit at idle I noticed. All new components connected to the ecm under hood wise. Idle 700, 65 tps on Holley Oem Replacement TBI unit, Timing I have curruntly 4 deg. BTC engine revs up nice and strong, sounds good but on casual accell and hold it stumdles or hesitates. Anyone have any suggestions other than tow it to the junk yard. "JK" Thx in advance any info i left out sorry a bit scrambled at this point. Will provide extensive info to any questions. THANKS!

What is your O2 mv reading???

(Stole the following off a website)
1.) Code 45 is set when the O2 sensor signal voltage remains above .7 volts for 30 seconds or more and in "closed loop".

2.) Engine time after start is one minute or more.

3.) Throttle position between 2 % and 20 %.


Diagnostic aides:

1.) The code 45 for rich exhaust is most likely caused by one or more of the following:

a. fuel pressure - system will go rich, if pressure is too high. The ECM can compensate for some increase. However, if it gets too high, a code 45 will be set.

Proper pressure for OEM TBI is 9-13 psi - DD

b. Leaking injector or rich injector - perform an injector balance test. Check for fuel contamination in the oil..

HEI shielding - an open ground ckt 453 may result in EMI, will result in induced electrical "noise". The ECM looks at this noise as reference pulses. The additional pulses result in a higher than actual engine speed signal. The ECM then delivers too much fuel, causing the system to go rich. The engine tachometer will, also, show higher than actual engine speed, which can help in diagnosing this problem.

d. Canister purge - check for fuel saturation. If full of fuel, check canister control and hoses.


e. MAP sensor - an output that causes the ECM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the ECM to set a fixed value for the MAP sensor. Replace the sensor if the rich condition goes away when the sensor is disconnected.

Will also cause rich if you have a vacuum leak, especially at the Throttle Body and/or Intake manifold. Spray joints with carb cleaner and see if performance changes while spraying. -DD

f. TPS - an intermittent TPS output will cause the system to go rich, due to a false indication of the engine accelerating.

g. O2 sensor contamination - Inspect oxygen sensor for silicone contamination from coolant, lead contamination from fuel or improper RTV sealant. Silicone contamination will be indicated by a Code 45 and lean drivability conditions and a powdery white deposit on the sensor. The ECM will then reduce the amount of fuel delivered to the engine causing a severe surge drivability problem.

Check for a leaking fuel pressure regulator by checking the vacuum line to the regulator. If there is fuel in the vacuum line, replace the regulator.

Let us know what you find!

:lol2: Thank you for the info. and you were on the money with o2 sensor it looks like. I replaced the map, pcv, egr and solinoid ah hell , last but not least today o2 and you are right about the tach reading being to high now it has dropped and thats a great thing after head banging myself for almost two weeks now. Thanks and hats off to ya DD! Sometimes you just need to hear it or see it another way ya know.Thanks and LOL! Yeee Hawww! I will repost the finishing touches tomarrow and post back. YYEESSS! thanxs again.