Weird 2000 rpm sputter.. help???
 

As a background, i just bought a 86 turbo, automatic. Since ive had it, theres been a werid sputter in the engine.

Idle seems to be pretty smooth, maybe not perfect, but pretty good. But then if you give it maybe half throttle, or quarter throttle, the car sputters at any speed under 2000rpm. It feels the worst at 1700rpms.

Recently ive replaced the belts, fuel filter, spark plugs, wires, cap, rotor. After doing all of this, i fired it up and it ran PERFECT!! for about 10 mins, then back to normal.

Im out of ideas, does anybody have any suggestions??

Mine does the same but only at 1700rpm not any higher or lower. It sounds like when a tractor grinds. And mine is a 5 speed.

Sounds like it might have something to do with the MAF. Does it matter if the engine is hot or cold?

How does it run under a load above say 3000RPM's?

Keep in mind the only sensors that really matter are the MAF and Crank angel sensor. The others help fine tune the mixture, FTS, CHTS etc.

It didnt seem to matter if the engine was cold, or hott. But after I did the tune up, and the engine ran great..... it was cooled.

At 3000 rpms it seems to run fine, but.... its sounds like its straining alittle? And even though its a auto, if I floor it.... I dont think ive ever seen it rev farther than 4500 rpms

Is this some how all related??

Read through the FSM and do all the test they have in there. You check most all the sensors with a meter.

You can get a copy of the manuals here

http://www.xenonz31.com/reference.html

Also you can unplug most of them and see if things change any. The Cylinder head temp sensor (CHTS), Fuel temp (FTS) and O2 sensor can all be unplugged and should not cause a big difference in the way it runs. Like I said before those are used by the ECU to fine tune the mixture. Also pay some attendtion the the Idle up and FIDC valves. Check for vacuum leaks and test your fuel pressure too. It would be best to T a pressure gauge in the line and run the RPM's up. The FSM has a section on what the pressure should be.

Before you start unplugging things check the ECU for any codes.

If you just bought the car you might double check that it has the right ECU in it.

Goto this site, it has a link to the part numbers

http://www.redz31.net/pages/fuel.html

http://www.redz31.net/pages/eculist.html

Who knows someone might have already messed with it.

I know for sure I found in the FSM where it says that if the Mass Air flow Meter is bad the ECU will not allow the car to go above 2000RPM's before it shuts the fuel off.