Bob Boberson

iTrader: (3)

Please don't treat this as a tl;dr thread, I am giving as much information as possible so it won't require posting back and forth to check if essential things were done....I have a 91' NA btw.

My car runs fine and doesn't appear to be in limp mode. I failed my emissions test for HC's barely and replaced the cat and it got worse. I just replaced the water thermosensor and o2 sensor, hoping to retest the car tomorrow. I also seafoamed, replaced the plugs, and changed the oil 2-3 weeks ago.

Besides not passing emissions, the car is very hard to keep started in cool weather and runs pretty rich(as in you can smell it, thus the high HC count), which I'm hoping the new thermosensor will take care of.

I have had voltage problems in the past, and it is also inconsistent in cold weather and under electrical load.

I tried to pull the codes tonight just to make sure everything is ok and noticed that when I turn the key to ON (of course after jumpering the green test connector to the car), that the MIL light comes on, turns off for a few seconds and stays on subsequently. Does this mean I just don't have any codes? I think it may mean that there is some connection error between the ECU F1 terminal and the green 6 pin connector. I don't think its just the ECU b/c the car runs fine otherwise.

Thanks ahead of time to anyone who will read this very long post and give their thoughts. You guys have always been a huge help.

jjwalker

Sounds like the ECU is bad, based on the fact that the MIL comes on and just stays on with the test connector attached. The mil should just stay off unless it is showing codes.

Bob Boberson

iTrader: (3)

Thanks for the quick reply. Is it possible that some pins just need to be resoldered? I would just be surprised that the car would run well with a malfunctioning ECU.

HAILERS

I'd go to the FSM. Fuel and Emissions section and check out the ACV/airpump for functioning right or not.

If the MIL light stays on without the jumper in the initial set coupler, then the emissions guy would have failed you on that light staying on. So I guess it come on when you turn the key ON but goes out like it should after a couple of seconds like it should.

Do you fail emissions during a 15mph check or the 25mph check? Both? Or do they do another type of check that does no involve driving on rollers?

Also try the things I underlined in RED in the attached jpg.

Bob Boberson

iTrader: (3)

Thanks for the reply HAILERS.

The MIL is not normally on. When I jumper the green 1 pin connector and turn the ignition to ON the MIL flashes, then goes out for about 3 seconds, and finally comes back on permanently.

I actually passed the 15mph test the first time around and only failed the 25mph. Then I replaced the cat and failed both tests. Then I replaced the water thermosensor and o2 sensor and failed worse. The test is the standard sniffer test on the rollers. I don't have the papers with me at the moment, but I'm pretty sure that I'm within 20 HCs of passing on both tests. I didn't have a cat welded on with an air tube, which I am very much regretting now, b/c I think I would probably pass with that in place. I think I may use J-rats ethanol method to pass b/c we have a go-kart shop right down the street.

I would still like to fix this MIL problem though, hopefully it will fix my cars problem with the idle in cold weather. Its a pain giving an automatic gas at a red light. I was actually going to try to do what you highlighted in red when I get home to work on the car next. Except I was just going to check all of the pins as described on page 80 I believe. It describes checking (1F) the Self-Diagnosis Checker, is there anyway I can use a 12V led to accomplish the same task, or should I just verify the voltage hits 12 after about 3 seconds? Also, for checking the secondary injectors (3X and 3Z) it says ground time is very short. Does this mean to just not test it with the voltmeter too long?

Thanks again HAILERS, you've now helped me on numerous occasions.

Bob Boberson

iTrader: (3)

Thanks to my new found friend, EtOH, this matter isn't as pressing, yet I would still appreciate any feedback that anyone may have concerning this issue. Shameless bump I guess.

HAILERS

You don't need a tester for the pin 1F. You do need a digital meter. You leave all plugs connected and backprobe the 1F with the positive lead of the meter and observe. I'm talking about the page called something like CONTROL UNIT.

As for the remarks outline in RED above.......you disconnect the plug at the ECU, then put the meter positve lead on 1F and the meter neg lead on a known ground point. Then meter set on ohms, touch the wire in 1F. There should be no reading if the wire is correct. If it's touch gnd somewhere, then the reading might be something like 1ohm or so and that means that wire is touching gnd somewhere. Shouldn not be doing so.

The remarks in the FSM are goofy to me and I don't care to make sense out of that. IF you backprobe the plug at the secondary wires , they should read batt volage. That's all there is to it. Secondarys only work while driving and under LOAD so there is no way to check them out in the driveway. You can while driving though. Back probe a secondary wire and it will show batt/alt voltage til you hit 3800 under LOAD whereupon the voltage will fall to 7-9vdc or some other figure. Depends on how much LOAD as to how far the voltage will fall. IF it stays at batt/alt voltage, then something is Seriously wrong. Bad wrong. Expensive wrong.

The remarks in RED where you supposed to be finding out why there is a problem with the MAL light has you also checking secondary fuel injectors. What bs. Not related to a MAL light. Too lazy to figure out why anybody would put that there.