CCC system and E4MC Questions....

[oxide80]

So I'm looking to pick a few brains here, I'm messing around with the semi-rat 87 442, the car is just a hobby car I've having fun with..

Little back ground when I purchased the car the CEL was on and found no fuse for the ECM in the fuse block. Put in a fuse, CEL went out.

Any ways I'm getting an intermittent CEL at over 50mph ish, when the CEL comes on the TC disengages and fuel economy goes down the tubes. I'm assuming it kicking into limp mode. Slow down to under 40ish, CEL goes out and everything returns to normal. I checked codes with Key On Engine Off by jumping the top 2 terminals on the OBD 1 connector, I got a code 12(its not running anyhow) and a Code 45 Rich Exhaust... I also noticed that I don't hear the MCS clicking with Key On Engine Off... I'm guessing the O2 Sensor has been saturated at this point and should be changed regardless... (only OBD1 scan tool I have is a Bosch it shows no codes and in closed loop gives me some funky readings not sure if its the car.. or the meter)

Should I be thinking bad ECM... or start with O2 sensor and MCS?

 

[Canon_Mutant]

Sadly, this is impossible to debug remotely. Rich exhaust is likely rich exhaust period. Doesn't mean the O2 sensor is not working. Why it is logging rich exhaust can involve a number of things in the CCC? TPS, Solenoid, Something deeper within the primary side of the CCC. Also, the car goes into what is called lean burn mode when you are light throttle, in 4th, and in lock up which leans out the CCC and advances the spark enough to counter it so it still runs good and gets those mpgs up. It sounds like something related to this is wrong to me. Keep it out of drive and just light throttle it in 3rd at highway speed to see what that does?

 

[oxide80]

Well messed with it for a bit tonight. I have 12v at the grey/pink wire on the MCS.. but no clicking in KOEO. From what i read and understand the green spade connecter infront of the carb is the MCS diagnostic port, please correct me if im wrong.

At KOEO i had 5 degrees with my dwell meter off that port. Running and warmed something between 30 and 40, i cant remember for sure now. But still no clicking from the MCS.... i noticed the MCS connecter lock clip had been broken off and someone zip tied it in place.

How noticable is the MCS clicking? I seem to remember it being noticable with the key on. Its been a long time since ive worked on a ccc system.

Any info is appreciated.

 

[86MCSS86]

You should be able to hear the clicking from the solenoid. The green connector is used for checking dwell. I am by no means an expert but I think dwell should be between 28-32 when warm. 30 is the sweet spot. There are a few ccc gurus here hopefully they chime in.

 

[Canon_Mutant]

Well, unfortunately, my car is still scattered so I cannot try some things for you [otherwise I would]. But, KOEO, with the diagnostic terminal grounded, you should get a code 12 check engine [which is normal] and the solenoid will click for about 25 seconds at a rate of 10X/sec. When running, the solenoid will always click at that 10X/sec rate [while in closed loop] regardless of conditions but it is a matter of how long the plunger spends in vs out that sets the primary mixture rate. This rate or dwell can be measured with a dwell meter. When it works, it is surprisingly accurate. Frankly, though the solenoid or how it is set up could absolutely be at fault, if it was not working at all, the car would literally not run hardly at all.

Since you originally described this problem as occurring in high gear, lock up, I still suspect this is a lean burn mode problem. So, the ECM thinks it should enter lean burn mode, has leaned out the mixture, has altered the timing accordingly for a lean mixture [this will go clear to like +60], but then notices a rich condition from the O2 sensor. It then latches a code and likely exits lean burn to avoid anything catastrophic and there you are running WAY too rich down the highway. Now, that could also mean the O2 sensor will not show a lean condition but you can check that easily enough with the engine or consequently O2 sensor warm KOEO vs running. The O2 voltage should vary from about .1 to 1V as I recall. There are a number of dwell checks that can be performed on the solenoid. A good scan tool and manual would be good.

Just curious, have you changed altitude recently?

 

[83hurst#1812]

I fought the code 45 for a while after I got my H/O...Tried new 02 sensor ( an original AFS-20) .. no help.. My problem was the carb.,,which ,definitely sounds like you have carb issues as well.. You should definitely hear the MCS clicking when you put the jumper in with KOEO. My carb still had all the factory plugs in it and had never been off the car...A quality carb rebuild, with all new electronics ,,timing set ,,and mixture needle adjustment to get dwell right ,,and the code 45 has never been seen again.

Sounds like your car is working correct..By that I mean ,,after 2 mins or so at a part throttle setting while in closed loop,,it will set the code if the condition exists.,,and when you back off the throttle,,the condition goes away ,the ecm doesn't see it anymore,, and cel goes out ,,but the code remains

 

[airboatgreg]

No clicking can mean somebody has mis-adjusted the rich and lean stop. 45 is rich and the o2 sensor is working. Remove top carb vent hose from carb and accelerate hot engine to 2k RPM. If you feel vacuum on the hose the canister purge valve is bad and sucking fuel from carb bowl. Next are plugs for ALL carb adjustments out? If so carb will need to be properly set up. I still have the tools to do that if you are close to me I can show you how. I built hundreds if not thousands of these carbs back in the day when I was a drivability tech. A lot of things are going on and we know the carb is rich so we will start there. We also had some funky throttle position sensor issues on that carb as it would get dirty contacts if someone drove the same way all the time. Turn engine off, key on and depress accelerator to floor about 50 times. This will wipe the contacts. I have fixed many weird issues on injected and carbed vehicles over the years doing this. The anomaly happens so fast it doesn't meet the criteria for the ECM to set a code. With the dwell changing that is good. Also the vacuum hose to the MAP sensor should not have a dip as vapor can form and skew the signal and will not set a code

 

[jiho]

I have 12v at the grey/pink wire on the MCS.. but no clicking in KOEO.

There should be no trouble hearing that thing click. Check resistance across the two terminals in the connector on the MCS, that is, across the solenoid itself.

 

[airboatgreg]

Rare for the solenoid to fail, but there are getting old

 

[oxide80]

Rare for the solenoid to fail, but there are getting old

I just got home, went and checked.... both security plugs have been removed from a/f mixture screws... so someone has been into this thing. tomorrow im going to check the canister purge valve and check the soleniod to see if it clicks with battery power/ground.