Need Help with Diagnose!

[ryan242v]

I have a 79 242, with a 89 b230ft and 89 M47 trans. Everything is stock. The engine will not rev over 5,000rpm with any boost. I checked this last weekend and the fuel injectors are cutting out at 5,000rpm with any boost. I checked the mass air flow sensor and when I blipped the throttle, in neutral, the reading on the MAS was almost maxed out at 4.88 volts ( I am 90% sure the MAS is a 0-5 volt setup). So, I am maxing out the MAS in neutral, I put a 100ohm resistor jumping the signal wire to ground ( the #3pin I think? The volt wire) and this reduced the overall voltage. Now the engine will rev to just about 6,000rpm, but idles very bad and has bad part throttle drivability, but makes it to 6k rpm.

Now for the main Question. Could the MAS be bad and have these symptoms? without the resistor the car drives good, but seems slightly low on power and will not rev over 5,000rpm.

I have had experience with older N/A cars with bad MAS, but they drive terribly, they miss sputter and you can only barely hit the gas. I had heard that Volvo redid the limp mod to be more driveable, but I do not know what is considered driveable, in limp mod.

Again if anyone has any tips or ideas that could help I would appreciate it. Could the MAS be bad and have these symptoms?

Thanks!

[ryan242v]

Thanks for all the great help so far?

[dl242gt]

There is no way that the airflow demand revving up the engine in neutral would max out the AMM. So, I'd say that does seem like a bad AMM to me.

[ryan242v]

Thank you very much for replying!

But, as I do agree with you, do you think that if the MAS is bad that all other driving conditions seem alright? The car does seem low on power, but it does not stumble, miss, or anything. So I was not sure if the MAS would actually be bad.

Thanks for the input, since I dont have money for a new MAS I will have to try finding another at the junkyard.

Thank you for responding dl242gt I apreciate it! Thanks!