TooSlow

Hi all,

My 99 1.8 has been sitting in the driveway for over a year due to engine problems that I'd yet to diagnose. Money problems prevented me from working on the car last fall, and I'm finally getting to it this summer.

Last year a friend hooked his vag-com to my car and diagnosed a faulty camshaft position sensor. So I replaced the sensor today, replaced the plugs, and now the car starts up but idles really low (say 500-600rpm). If I give it just a little gas, the car begins revving up and down between 2200 and 1000rpm repeatedly until I let off the gas. If I give it more gas, it will rev to any RPM I desire and stay there.

Any ideas? I'm going to check the main hoses now, but could it also be a sensor? Anyone else have a similar issue?

Thanks!

TooSlow

Made a little bit of progress, and I'm pretty sure the MAF is defective but I also think I have more going on.

After some reading on the forum I went out and disconnected my MAF. I could start the car, but it still idles very low and slowly the RPM goes up and down (only 100-200RPM variance). If I press the gas, the engine instantly stalls.

I also unclipped each coil pack and disconnected them one at a time while the engine was running. The car would stumble equally each time I disconnected one and ran fine when I plugged it back in. Would this in combination with the smooth running at high RPM tell me that the coil packs are OK?

In summary, with the MAF plugged in I can rev past the stumbling at low RPM and drive it (like a bucking bronco) around the block. With the MAF unplugged, it stalls instantly as soon as I press the gas.

Vacuum/air leak? Another sensor? Any help until I can find someone with a vag-com to read codes would be very helpful. Thanks!

4Driver4

Just get a generic code reader, clear whatever is there, drive the car for 20 minutes, and scan again. VAG-COM is great tool, but anything is better than guessing.

TooSlow

Thanks. Wasn't sure if a standard code reader would clear the codes properly like a vag-com would. Is there an alternative that is "good enough" if I don't buy a vag-com? I'd love to buy one, but I'm most likely going to sell the car once it's fixed, so it's tough to spend so much on a tool that I won't need 3 months from now.

TooSlow

PS: Noticed the Miatas in your sig... I have a 91 which I eventually plan to prep for track days. Only downside is that everything else feels like a huge SUV when I drive it!

4Driver4

Heh. Try going from the Miata on the track to the Suburban with the Miata on the trailer behind it. The first turn coming out of the paddock is always a doozy!

Read about your local club rules before you start working the Miata. Unfortunately the world is becoming less friendly to open top cars. I just retired my 1995 with Hard Dog roll bar in favor of the 1999 with full cage. Good luck!

4Driver4

Buy a generic scanner. I love my VAG-COM, but I reach for the little scanner even for the Audi when I need to know quickly. Anything you get will clear codes too.

TooSlow

Hahahahaha! I can only imagine. I jumped from the Miata to a GMC Jimmy one day, and my first turn had everyone grabbing for the oh sh$t bar! It certainly takes some getting used to.

Thanks for the tips, I'll grab a standard code reader and provide an update.

I'll also read up on local track rules... I always planned to go with a hard dog bar and a hard top. Thanks for the heads up!

onedayonly

Force a TB adaption via vag-com, and don't drive it with the fuel that is in it.

TooSlow

Bought the scanner and ran it last night. Before clearing: P1545, P1338, P0102, P1544, P0123. Since those codes, I've replaced the CPS, spark plugs, and cleaned the MAF.

Cleared the codes and ran it again. Now I only get the P1545, which I believe is throttle position. Did a bit of reading and it suggests a throttle alignment with a vag-com and/or cleaning of the throttle body.