OK, finally got it running! Runs smooth too. But just after startup, about 5 seconds in, the check engine light comes on. Code 33, MAF high. I reset the computer, and looked at the MAF. Wire is ok, and never had codes before the cam swap. I can tell you it's a 305, TPI, Siamiased base, ported plenum, Vin F. Just put in Crane CompuCam2030, for flat tappet hydrolic lifters. The car runs good, yet lacking in the low end now. Seems a little to sluggish. After 3000 rpms, it really wakes up now, yet I think it would do a lot better of course if the MAF was working properly. Also have the base timing set at 10*, just like I use too.

 

What do you mean by looked at the wire and its okay? Do you mean you checked to make sure the maf was plugged in? Check to make sure the wire inside the maf is still intact, maybe it got damaged somehow during the cam swap.

 

Sorry, I meant to say I looked at the little wire inside the MAF, and it was still intact.

 

That would be the heated-wire sensing element, and breaking that will set a DTC '34', not a '33'. A '33' is for higher than expected intake air flow. That's likely good news, since it means the MAF is probably still mneasuring intake air.

The '33' is typically generated when the TPS voltage at the closed throttle position is set too low. The ECM bases the intake air computations on engine RPM (distributor reference pulse rate) and throttle position (TPS voltage). If the TPS is set too low, the ECM will presume that the throttle is closed more than it is, and that the engine cannot possibly be using as much air as the MAF is reporting. Make sure the TPS is set to 0.54-0.61 VDC. (Oops - I changed verb tense in mid-stream. Too friggin' bad...)

There is a remote possibility that you still have the original "bugged" factory EPROM in the ECM. There was a TSB issued in late 1986 regarding all 1986 model TPI engines. The replacement EPROM is reporgrammed to allow a wider range of inputs before setting an error code, and addresses several other operation problems, like TCC lockup being too low, low idle RPM, etc.

Start by checking the TPS voltage and setting the throttle minimum air position as per the correct procedure. That cam grind should not cause any operational problems with a MAF systems whatsoever - it just isn't that aggressive.

 

Funny you mention that Vader, I was just thinking of trying to up the voltage setting. Currently it is at 0.53, I was thinking of around 0.65.

And, A couple years ago I saw your post on the bugged prom chip, I replaced it then.

I'll let you know how it goes.

 

OK, I've set the TPS to 0.65 volts. Still sets code 33. I have noticed though, that my idle is around 900-1000 rpms. So tomarrow I think I'll reset the IAC, and then redo the TPS voltage.

I also noticed that the code sets about 5 seconds after startup. This is with the engine cold. I also undid the neg battery cable for 2 mins to reset the computer. My understanding is the computer is on "open loop" when cold, so it shouldn't even use the MAF untill it warms up and goes into "closed loop". Whats with that?

 

The MAF reading is used as soon as the engine starts, just like the distributor reference pulses, CTS, TPS, etc.

 

Found problem! When I pulled the wires on the relays, I must have reversed the MAF relay with one of the others. Switched them around, works great!

 

The relays are the same for both of them, so...

 

Some cars used the same relays for both functions, while some models/years had a different part number for each relay. The FP is usually a little different on most cars.