First time here and need some help. Put on a new micro tech MAF and the car is way rich on startup. Installed the MAF because of cough on tip-in and little popping out exhaust. New MAF cleaned up original problems. 85 coupe, 406, TPIS mini, TPIS headers, 165 ECU, TPIS prom, 6sp Richmond. thanks Mike

 

The Adjustable Micro-Tek MAF? What is the ambient air temp? The adjustable MAF seems (in my experience) to do a poor job of air temp correction, I was constantly fiddling with the adjustment to keep it "right" , or even Livable, as things changed. I don't know if this is a Micro-Tek problem in General or if it is Only the adjustable versions that do it. Or only the example that I had..

On a daily driver here in New England that rapidly became more of a pain than it was worth, and the thing went in the trash. The gain in possible air flow (if there actually Was any - I didn't notice anything huge happining) wasn't enough to justify wearing out the hood hinges playing with the adjustment.

For what it's worth I did try editing the PROM program to reduce the fuel at low air flows, that way in open loop (when cold) it at least wasn't super rich (as you are complaining about). It sort of helped, didn't have to wind the adjustment on the MAF itself as far down to get it to idle better when started up cold.

That adjustment on the MAF seems to effect the output signal across the whole range, if you have to turn it down at Idle the readings are then skewed lower All the time. This can be compensated for in the PROM, but why go there - you Know what the actual air flow numbers are (within reason, anyhow) at a given point (rpm/load) and that Should be what the MAF tells the ECM, not something off by a large percentage.

In any case, if the ambient air temp was always the same (if I was in Hawaii, or someplace) then I could have lived with the Micro-tec unit, but here in the Real World the thing was junk. IMHO.

 

Thanks for the reply and opinion, it's appreciated. The micro tech is not the adjustable unit as from information I have read the calibration should be able to trim fuel if info from the MAF is apples to apples with stock unit. I will say that the new MAF really gave the engine better throttle response. I drove the car on and off for a year with the 870 ECU and a over the counter Hypertech chip and it ran ok but not as good as the engine should have. Changing to the 165 made me realize just how blind I was and the performance gain was minimal even with the costly TPIS chip ( I didn't really want to get into burning my own chip but it looks like I might have to try going there). The only sensor I haven't replaced in the last month is the IAC but it isn't that old (came with 58mm BBC throttle body) I just hope to get some direction from guys that have been there done that. thanks again

 

Cool. Keep in mind that the MAF "tells" the ECM how much airflow there is, the ECM in turn runs down a lookup table of Airflow vs. Fuel to determine the "baseline" amount of pulse width for the injectors.

If changing the MAF made it rich then the new MAF is telling the ECM a bigger air flow number than the old one was, probably incorrectly. This is making the ECM choose a higher pulse width and adding more (too much) fuel to the motor.

The ECM will not do anything to Correct the fuel flow, from the lookup table, until it goes into closed loop, and looks at the O2 sensor. This means that when you start it up it'll be fat (rich) and stay that way until closed loop happens. Your BLM table ought to show this happening.

The only way to fix this, if the MAF isn't adjustable, is to edit the airflow vs. pulse width tables in the PROM. OR - you could drop the fuel pressure (adjustable regulator) to lower the fuel flow That way, the ECM doesn't know about That possibility. Changing the injectors to a smaller flow rating is another possibility..