Miller MAF and/or Misfire issues.

[Pocket Chant]

So, I recently put in a Miller MAF. At first it ran fine, then, if the car was very cold, it'd take a while to start. I'd have to hold the gas a bit, otherwise it'd just stall out right after it cranked over.

Now, the engine has started shuddering. It happens intermittently, when I hold the throttle in one place for a period of time, or if I let it rev high enough. Other times I can go for a drive without issue.

I just replaced the spark plugs, have a new TPS and Coil on the way, I haven't found much in the way of help though on what this is. Any ideas?

[jlevie]

The first thing I'd do would be to have the intake smoke tested and fix the leak it reveals, replace the ignition wires, distributor, and plugs using NGK ZGR5A's if you used something else, replace the O2 sensor, check rail fuel pressure, and adjust the valves. If that didn't help I'd revert back to the AFM configuration to see if the MAF conversion was the cause.

[Pocket Chant]

Those are actually the exact spark plugs I put in today, so that's one thing down. I also have a new intake boot on the way with the TPS, just because I was unsure if this one was okay (Especially after running an M30 AFM).


The cap, rotor, ignition wires and plugs were all replaced around June, But when I looked at the plugs (Bosch Copper) they looked similar to "Too Hot" on this chart.


EDIT: Shit, I just re-read what I put, and I'm an idiot. I didn't mean surging, I meant shuddering, like in a misfire. Using the wrong terminology doesn't help. The revs drop slightly and and the car lurches. Don't know if that changes anything.

[Pocket Chant]

Bump.

[Pocket Chant]

So, TPS and intake boot come today, new coil tomorrow. Yesterday I drove the car and it only shuddered once or twice, and softly.

[LJ851]

Hopefully you bought an OEM CPS. I had issues with my CPS when i put Miller PSIK on, wouldn't rev past 5k even though the CPS was only 2 years old (it was aftermarket).

Bought an OEM one from Blunt and problem gone. Apparently aftermarket E30 CPS are pretty lousy.

[Pocket Chant]

I replaced it with an OEM one- or at least, one that looks exactly like OEM. Though that was a while ago.


The TPS is Bosch though, and it seemed to have fixed the problem. I replaced it, it was rough at first, but after a short bit it sorted itself out, and now I've been unsuccessful in my attempts to recreate the problem. Fingers crossed, I'll update again if the problem resurfaces.

[Pocket Chant]

So, a short while ago, I took a fast corner and the car flat out died. Would crank, but nothing would happen. Got it towed to a shop.

Called me the next morning, apparently a belt had chewed through the CPS. They replaced it and re-routed the cable, and now it runs perfect.


Updating to help anyone with the same problem.

[manjambles]

there's rewiring you have to do at the ecu to send the voltage output for your new miller maf. 12volts I believe is the original output for the air meter and 5volts for the maf

[Pocket Chant]

there's rewiring you have to do at the ecu to send the voltage output for your new miller maf. 12volts I believe is the original output for the air meter and 5volts for the maf

Yeah, I know. Checking that connection was one of the first things I did when I was troubleshooting.

[manjambles]

cool beans, I didn't see anyone mention it.