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  1. #1
    FEP Super Member PaceFever79's Avatar
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    Default E-Quadrajet runs very rich only on cold starts

    '89 Olds Custom Cruiser wagon (Caprice) 5.0L with E-Quadrajet

    When the temp goes below 50 it starts but floods badly for about 30 seconds
    then it clears up and runs fine. It's not the choke, it's working fine, and it will
    still flood on cold start if I deactivate the choke. If the temp is over 50, or the
    engine is warmed up, it starts fine and doesn't flood.

    To the best of my knowledge the only thing "electronic" is the mixture solenoid
    which is connected to a temp sensor. But I'm not sure exactly how it functions
    or if it could be causing my cold start problem.

  2. #2
    FEP Power Member MAD MIKE's Avatar
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    Default

    Quote Originally Posted by PaceFever79 View Post
    '89 Olds Custom Cruiser wagon (Caprice) 5.0L with E-Quadrajet...
    To the best of my knowledge the only thing "electronic" is the mixture solenoid
    which is connected to a temp sensor. But I'm not sure exactly how it functions
    or if it could be causing my cold start problem.
    OLDs 307 I presume?(often mistaken for as a 'Pontiac' as the heads have 'PMD' cast into them) I'm familiar with the CCC system as my '87 Olds Cutlass uses an earlier variation of the system. The difference is that the later '88-'90 systems had a knock sensor and different ECM.

    GM called it Computer Command Control(CCC) not to be confused with the Corvette C3 system. The carb is computer controlled on the primary side, the secondary side is still mostly the same as '70s non-CCC Q-Jets. There is a blue connector on the top of the carb that controls the mixture control solenoid(MCS), and a milky white connector on the front of the carb that is the output for the throttle position sensor(TPS). There is also a differential pressure sensor(DPS) mounted on the inner fender, this has the same function as a MAP sensor but the voltage readout is inverted from typical GM MAP sensors. A BARO sensor is located under the dash, near the ECM. There are two temp sensors, one is for the dash light/gauge, and the other is for the ECM.

    If you have a scanner with the GM connector, you can actually watch the input and output from the ECM. Pretty advanced for the time, I don't think you could do that with Ford until EECV on the 4.6 Crown Vic.

    tl;dr, http://tech.oldsgmail.com/emis_ECM.php

    The most common issue with cold start flooding is the maladjustment of the choke plate. On the passenger side where the choke coil is located make sure that the choke linkage is free to work, crud can built up and impede its operation. Make sure that the choke spring is correctly set if it is broken, lazy, or maladjusted it can cause bad cold start running.
    Your car should have a VECI label under hood, either on the shroud or upper radiator support plate. This has all the steps and settings for the carb and engine. Verify that the two steps for the high speed idle settings are indeed correct. The choke cover(black plastic disc) if never tampered with, should have 3 rivets holding it on. If the rivets are missing and replaced with screws, then most likely the carb has been tampered with.

    On the CCC E-Qjet, like older Q jets, their are two idle mixture screws at the base of the carb. With the CCC system these idle screws should not be adjusted, they have tamper proof caps on them. If the caps are missing and you can see the screws, someone may have changed the idle mixture, causing an overly rich condition with the choke fully engaged.
    The biggest problem with adjusting these screws is that the CCC system will compensate for any changes by changing the amount of time(dwell) that the solenoid is on(LEAN) or off(RICH). If someone backed these screws out further than they should be, this also could be the cause of the foul running. The CCC can compensate for quite a bit, but if the mixture screws are backed out slightly more than need be, at cold idle the engine may run very rich with the choke on(open loop)

    You can check for codes by jumping the A and B terminals on the ALDL connector, with the car ON and engine OFF. http://tech.oldsgmail.com/ecm_codes.php

    To set the timing, the engine needs to be up to operating temp. Turn the ignition to ON, jump A and B terminals, start the car. On the Olds 307 base timing is 20* @ 1100rpm. You can usually get the engine to run 1100rpm by setting the choke on the first step manually, and adjusting the screw to maintain a steady 1100rpm. If the timing is off, the dist needs to be adjusted. Plan on soaking the distributor base in PB Blaster for a week before attempting to rotate the distributor, unlike the Chevy which goes through the manifold, or the Windsor that see direct oiling, the Olds distributor does not see direct oiling, the main body can become seized in the block. It's a right PITA. Let the PB blaster soak, and try jiggling the distributor, keep at it with PB blaster or KROIL and small increments of rotation. If you force the dist too much too fast you can shear it off in the block. Patience is key.

    With the engine at operating temperature, verify that the MCS dwell is withing range. Using a DWELL meter, set it to 6cyl scale, and connect the terminal to the loose wire with the green connector. This should be located somewhere near the front of the carb near the fuel filter housing and the thermostat housing. Make sure the dwell meter you are using does NOT affect the engines running condition. If the engine speed changes when hooking up the dwell meter, you will not be able to verify correct operation with that dwell meter. If no changes in engine running occurs, monitor the dwell meter. It should swing back and forth around 30*. It should not swing wildly from 0-60* and it should not be stuck on any specific degree either. If it stays on a specific degree there is something wrong with the system, or ECM.

    Some of the issues with the CCC system that occur, broken, missing, leaking, incorrectly routed, vacuum lines, loose intake manifold bolts, loose carb/carb gasket, loose carb horn(top plate), broken/loose ground wires(there will be two main CCC harness grounds on the P side of the second to last intake manifold bolt near the heater control valve). Missing/loose ground straps from engine to firewall(D side behind Dist).

    Things you will need to check for proper closed loop running.

    O2 Sensor.
    Delco/Delphi, Denso, or NTK O2 sensor brands. No other brands! Bosch one wire sensors blow ass, they are lazy and cool off too quickly. If the O2 body is shaped more like a beer can than a pencil its crap. Get a proper O2 sensor.

    Vacuum hose.
    You will need 60 FEET. I am not joking, this is how much hose is used on the 307. I *think* its 3/16". Also forgo all those rubber boots on the TVS and that solenoid assembly on the driver side rear of the engine. Those boots become very sloppy over the years, just directly plug into the port, or(as I did) cut 1" sections of hose to mate the devices to the orange vacuum tube couplings and then to your new vacuum hose.
    To make it easier on your back, have the nose of the car on a down angle. Either put the rear wheels on ramps, or park on a hill, the steeper the better as you will be able to see and not strain your back.

    EGR.
    The 307 is very sensitive to it. Only use DELCO EGR valves, cheap brands do not use the correct spring pressure on the diaphragm which causes the valve to oscillate. This causes random pinging.
    Of course none of this matters if the 'injector stacks' that are screwed into the manifold on the primary side, or the EGR passages in the intake are clogged. I do not recommend removal of the injector stacks, especially on the later 85-90 'Y' 307s with 7A heads. Pinging will occur without them.

    Timing chain/Cam sprocket.
    The Olds uses a AL sprocket with nylon coated teeth. The problem is that the chain stretches way too much. On engines with 50K miles its common to find anywhere from 15-20* of slop. When the chain stretches, the flat links(which are 'C' shaped) open further, they no longer create a single tooth, and this digs into the nylon coated teeth breaking it apart, causing further timing retardation. The stretching is so severe that the misaligned links actually chew into the steel crank sprocket. If you can catch this early you may be lucky enough to just get away with replacing the timing chain and sprockets with steel pieces. But if the nylon teeth have fallen off, they promptly get jammed into the oil sump pickup. This will require an oil pan R&R.

    IMO if you find the base timing off, before you adjust the distributor, check to see how much slop is in the timing chain itself. If its how far off your base timing is, save yourself a headache and replace the timing chain/sprockets. I actually did this on another Olds engine I had AFTER I already reset the timing. With the new chain/sprocket, I had to go BACK and reset the distributor to what it was a few months prior. Karma can be a right one at times.

    I think I covered the basics.

    The CCC system is very robust, and the 307 Olds will last hundreds of thousands of miles with little to no complaints, there are just a couple of silly things(crap timing chain) that need to be addressed.
    -Michael
    '79 Fairmont 5dr 'car guy safe' MM Tech Tips StopTech Brake Bias StopTech White Papers

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