Got a real problem with my 85. I have done some work on it, but it still runs BAD...had a fuel line that had been squeezed shut, so I had to replace it. Rebuilt the distributor, and put on a new intake, added a 52mm throttle body, replaced the wires and plugs, and added a pertronix coil and module. Car runs like it has a dead miss.....checked the wires, they're all good, they all get spark, and the spark stays steady as the rpm'a are increased...replaced the fuel filter, it had some CRAP in it...set the timing to 6 BTC....car starts as soon as I touch the key...in park, sitting in the garage, car revs great, but as soon as I try and drive it, it spits, sputters, and wont gain any rpms....checked the cat, it's brand new, and did a pressure test, everything ok...engine vacuum holds at 17, steady as a rock. Checked the injectors with a noid light, they all pulse. Fuel pressure is 41 and steady, no fuel in the vacuum line. Alternator puts out 14.2 volts.
I have a feeling what it is, but I'm gonna wait and see what you say first.

Thanx guys

Cheers,
Michael

 

My experience in the past is that if it revs good with no load on it and you get the miss under a load it is probably the distributor cap or rotor. Take the cap off and look for carbon tracking inside the cap. Hope this helps.

 

Try Adjusting your Throttle Position Sensor.

If you still have the original TB, try re-installing it. Unless you have extensive head and intake work, anything over stock will only hurt you.

Is it throwing codes? Did you pull the rocker arm covers to make sure all the vlaves are opening and closing?

Sounds like a bad MAFS, or mis-adjusted TPS.

Try unplugging the MAFS and see if it changes anything.

Also, you may try and put it in Feild Service mode by:

Taking a paperclip, bending it so that the two ends are next to each other. With the car off, insert the two ends into the A and B terminals of the ALDL box (under driver side dash, and those are the top, right-most terminals) Click key on and start car. Car should now be in Feild service mode. It will Ignore readings from MAFS and O2 Sensors.

Im pretty sure thats how its done. If you have a Haynes or Chiltons manual, they will tell how to get it to Field Service mode too.

Anyways, the SES light will flash code 12 (3) times, then it will flash any recently set trouble codes. Then it will flash 12 ( Blink--Blink BLink) 3 more times to signify that there are no more codes. It deos this only in Feild Service Mode.

I just cant recall if your supposed to start the car while the 2 terminals are still grounded or not...maybe someone will chime in.

Good luck!

 

I am having similar problems with my 85 as well. Same symptoms as above. I replaced the cap and rotor, wires, plugs. Rechecked vacuum lines for second and third time after I replaced water pump a few months ago. Was throwing a 32 code but has not again since rechecking the lines. I did notice, however, that #8 spark plug was caked with sludge when I pulled it...that was the ONLY one. Car ran just fine with new plugs for about 50-60 miles, then went right back to running poorly under load. Maybe valve or valve guide seals? Could this be a similar problem to the one mk842766 is having? Just a thought.

 

have you done a plug reading????

 

Have you checked your ECM. Three years ago had a similar problem. Replaced the rotor, rotor cap, wires -- still had the problem. Checked compression, fuel presure -- fine. Checked for codes -- none. After three days of trying to figure it out, I swapped out my ECM unit and bingo, cars been running great ever since.