How do I test the MAF?

mongoosetoo

New Member
Joined
Oct 19, 2005
Three wires, I assume one is volt in, one is volt out and the black is the ground. What are the voltage values that I am looking for? I remember most Bosch systems look for .60-.80 with ignition on and engine off. Is that right??

The car is flooding, bad. I know that if a MAF doesn't throw a signal to the ECU, it will increase the injector pulsewidth roughly by four times what it should be. SO I assume the MAF has gone bad, but I hate to just throw parts at a problem without checking it out as far as I can first.

Thanks, Brew
 
Check Engine light?? Codes?

Can you scan the MAF readings?

6-8 at idle

Somewhere over 200 at 15PSI.

Numbers should go up smooth with throttle/power.
 
You say check the coolant temp - you mean to make sure it registers toturn on the input from the sensors, right? On a GN, what temp does it need to be to trigger the ECU to start "listening" to the sensors?

No check engine lights, no codes. The car floods like I'm gonna need a life preserver. I have a book on Bosch injection systems and it says if the input from the MAF is not registering, the injectors will pulse 4x thier usual bandwidth.

I don't know. Tonight I installed a brand-new MAF and compared the numbers to the old one - identical. I also installed a brand new TPS, and set idle to .55 v and WOT registered around 4.6 or more, so I know the TPS is good. But the battery is dead from trying to start it the other day, so I have it on charge tonight. I'll change all the easy spark plugs tomorrow and give it another shot. Thanks, Brew
 
mongoosetoo said:
.......... I also installed a brand new TPS, and set idle to .55 v and WOT registered around 4.6 or more, so I know the TPS is good.

Brew,
That could be part of your flooding problem. Try setting the TPS in the 0.40 - 0.44 V range with the engine off.
 
"Brand new MAF"?? Most replacements suck, at best.
Where did you get it?

.55 will make car idle a little higher, but I doubt it would make car run pig rich. I almost say no way.
 
turbo2nr said:
............ .55 will make car idle a little higher, but I doubt it would make car run pig rich. I almost say no way.

Well,
You may be right and we both agree "it does not help the condition".
As stated in my post "it could be part of ........" Agree? At this point, I feel it is time to set the TPS where it "needs to be" to get on track. This is a good start to get the car running. Nothing to loose right?

Well, I am NO expert, but ........ the TPS set at 0.55 may throw of the computer since the MAF is reading idle and the VSS is at 0 thus effecting the load variable. (Experts correct me if I am wrong) ........ So the computer "thinks" you stepped on the gas and need to go into enrichment mode.
 
Reset the TPS to .44, also replaced MAF with aftermarket. Changed the two easiect plugs (1 & 3). Fired up, rough idle, warmed it up and then beat on it. The car runs really good now. Still some popping at the higher RPMs, but really running well.

My fuel pump has a dedicated circuit coming right off the battery. I used a 30 amp radio shack relay and used the grey wire from the original fuel pump relay as a trigger. The pump is pretty loud, and since it's the original that has been sitting on my shelf for eight years, I'll replace it soon. I have the correct pressure at idle, but have not monitored it at high RPMs - I'm thinking the pump has pressure but lacking volume. Either way, the pump is ancient and is gonna fail pretty soon anyway.

Thanks, Brew
 
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