Okay, after days of searching the (possible) issues I keep coming up with the same 2 results, either A the thread just dies with no results or B it does not really apply to my car.

So, here we go again.

Car is a '85 Z28, 305 TPI

Problem developed out of nowhere of sputtering and coughing itself to death. Immediately presumed it was a fuel issue, filter replaced, pressure checked no dice.

Car would run, but horribly, backfiring through intake at idle and load in drive, NO MIL or soft codes.

Moved on to ignition. Plugs and wries barely 2K miles on them for the summer, no wires are burnt either. Timing is set. Cap and rotor are in decent shape (seen worse, spark is desired blue), cleaned and put back.

After checking ignition sytem out and disconnecting bettery to clear codes I caused by disconnecting MAF and TPS for testing, it seemed to run normal for a brief few seconds, then get worse than previously (EXTREMELY rich).

Now, if MAF is connected @ startup, will start, run about 800 rpm, then boggle around 450-550 then sputter and die.

MAF disconnected, it will stay running but lope severely. After closed loop is achieved and idle begins to search, if I shut it off and reconnect the MAF, it still searches but will not die and lowest rpm is 550 where it whould be (still rich).

Checked for vauum leaks, none to found. TPS is at .54V. Checked and repaired some leaks in intake duct. CTS is only few months old. O2 recent as well.

I'm thinking I have a bad burn off module active at all times?

 

Id take a closer look at the MAF.

 

I would think so too right off the bat, but shouldn't it throw a code (33 or 34) at that effect? Given it's running so rich your eyes start to burn I would think it's out of operating perameters?

 

Ok, now thigns are little more confusing.

This morning it won't run unless the MAF and TPS are disconnected? I was under the assumption that one backs up the other in event of a failure?

Looking into it, there is bum spot at 2/3 throttle or 3.3V where the voltmeter goes O.L. Why would this make a difference at idle speed?

Obviously if does make a difference, I feel much better tossing a low buck sensor at it versus a high dollar. But, is it safe to assume that if the TPS is bad (and throws no codes yet), my MAF may also not be the best since it doesnt' seem to be able to do that 'back-up' job?

 

I'd pull the TB, clean it real good. Clean the IAT and remove the bottom TB plate to clean it's passages. Vader has many good posts on that along with pics. Use a new TPS since yours has a dead spot. Then see how it runs.