87 raider won't pass emissions
pollutant
HC standard 3.0 reading 1.40
CO standard 25.00 reading 40.55 fail
NOX standard 4.55 reading 1.44
the solex mikuni was totally rebuilt by a reputable firm two years ago and all electronic features work. Had some trouble getting it to pass two years ago right after the rebuild and put a new cat converter on it and passed. any way to lean this thing out a little. this is the fourth test and on one with some tweaking i got the CO down to 25.71 but still a fail. the result shown is with a low tank of gas and a pint of denatured alcohol in the mix. also the advance is up to 12 degrees BTDC. does advance create more CO? can i change the jets? i need to lean it out just a little i think but don't know how. i think the only air fuel mix screw is for the idle only. correct me if i'm wrong. will a new cat help? this test is good for two years. i can put a new cat on pass the test and pull it for the next time if i have to. thanks
paul

There are 2 coolant temps on the stat housing. As well as the 02 sensor they all control stuff on the carb if I rember correctly. Swap em out cheap see if it helps.

Yes. Ground the black wire with a yellow stripe at the carburetor connector to the device box. Do so by soldering an extra lead to the black/yellow wire that you can ground with a ring connector. Doing so essentially grounds the MCS, causing the carburetor to go full-lean. You will have to back the mixture screw out quite a ways to get your idle back but it will lean your mixture down enough to pass emissions. Don't ask me how I found out about this fix, err..hack. But suffice it to say, it will get you through the smog test unless there is a major mechanical problem with the carburetor such a a sunk float or a ruptured gasket. On my vehicle the extra wire can be attached to the device box under the hood come smog time, and then as soon as I pass smog I take the wire off and stuff it down in the vacuum hose bundle to keep it from contacting a ground and then I re-adjust the idle.

Your other option is to remove one of the wires to the MCS(yellow and red wires..the small ones) from the carburetor connector and tape it off or otherwise isolate it so it cannot complete the circuit. Without a dwell signal to the MCS you will run as lean as the carburetor will allow.

Good luck with it.

Chris

Some have 3. On mine (I have 3..1988 SPX) one is a ground cut-out for the AC, if the coolant temp reaches a given point the ground path for the AC compressor opens and shuts the AC down. This one is mounted above the thermostat on the actual thermostat cover.

#2 is a single prong deal, feeds the temp gauge on the dash. Screws into the intake on mine, mounted very low under some vacuum related switches.

#3 is a two-pin thing that feeds the ECM. Also screws into the intake just below the thermostat, this one gets a coolant temp signal whether the thermostat is open or not.

Chris

the only black wire with a yellow stripe i see is coming from the temp sensor on the gooseneck at the intake manifold and it goes to the box on the fender well. is this the device box you refer to? i checked the list of 4x4 wire mitsubishi abbreviations and could not find MCS. what is it. is the device box the silver box on the fender well with all the vacuum lines and wiring input? also no one made reference to the advance setting. is the black and yellow wire connected solo or on a multiwire plug?
what do you mean two coolant temps? are you saying to put in a higher temp thermostat? the engine is running in the bottom 1/4 on the dash temp guage and this troubled me as it might not be hot enough to get good combustion. the O2 sensor was replaced when i bought the cat so it should be good and is an expensive pain to relpace on a guess $60

define MCS & device box please for a foreigner
can't find them in the manual or the 4x4 abbreviation list

MCS = mixture control system

Device box is aluminum colored box on dside inner fender with all the hoses.

Timing to 8*BTDC with vac removed from distributor and plugged, idle at 700-750.

Your prob sounds like stuck choke or bad float adj. or internal fuel leak. May also be bad mixture control solenoid valve in carb, or bad bowl vent valve. which is not in the rebuild kit.

PM me if you have continuing problem.

Mixture Control Solenoid. It is the primary fuel metering device that the computer controls during cruise/acceleration to keep your mixture in check. On my '88 it has a red and a yellow wire that enter the top of the carburetor, but you'll have to remove the air cleaner to see it. Your colors might be different. But either ground it out or remove one of the leads and you will force the entire system to go as lean as it can.

Chris