987Krab

I made a thread not too long ago but didn’t receive anything very helpful so I’m gonna give it another go. I have a 987.1 with a 987.2 swap in it. I have a jumpy idle or sometimes it gets low and stalls out. When it gets low enough and wants to stall out, hitting the gas pedal does nothing. It won’t rev and it doesn’t force it to stall right when I hit the pedal it just simply doesn’t do anything at all. I can’t drive the car because it won’t even hold its own idle. It’s throwing a code P1095 and the only thing I’ve replaced so far is the MAF and it did not change anything. I’m stumped, anything helps. TIA

harveyf

You are in a tough situation. Unlike large parts of the internet, I think most followers here will say nothing if they have nothing to add. You are in a vexing situation. The 987.2 platform is relatively rare (versus the 987.1) and thus there isn't as much group knowledge. But even for the 987.1, these kind of issues don't lend themselves to simple solutions.
Did you port over the entire 987.2 "operating system", including the ECU, relays, etc.
Did it idle correctly after the swap? For how long? Does it happen all the time?

Remember, the throttle on these cars is electronic. When you push it down, you make a "suggestion" to the ECU that you want to speed up the car. Having just gone through a 987.1 engine, there does not appear to be any separate idle circuit or plumbing, like on say 80's fuel injected cars. So I can only assume that the position of the throttle valve and the amount of fuel injected is totally controlled by the ECU, as required to obtain a stable idle. You really need a very sympathetic 987.2 owner that would let you plug your ECU into his harness for a minute to see if the problem follows the ECU. Easier said than done.

I think I already sent you the workshop manual page for the P1095 code. The important part is linked below. You need to make sure all the sensors in the Diagnostic Conditions section are reporting correct data to the ECU. Also easier said than done!

Diagnostic conditions
I Supply voltage 10 V ... 16 V
I Engine start
I No faults detected for throttle valve adjusting unit, ambient pressure sensor, intake temperature sensor, speed sender
K NOTE
J In this context, please also observe the function description.
Possible fault causes
J Hot-film mass air flow meter faulty (battered)
J DME control module faulty (ambient pressure sensor at fault detection threshold)

Shark Attack

Are you running an air filter that requires oil? The oil will ruin a MAF very quickly. The oiled air filter / re usable "race" filter will ruin your entire motor over time. they are meant to go in cars for the track where you run them 500 miles and rebuild. Not for the street. Have you pulled out your air filter and looked at it? Have you made sure nothing was left in the air ways when the motor was swapped. A rag perhaps?

Go to wal-mart, buy the hyper-tough Bluetooth ODB reader. It will stream live data to your phone. You will be able to look at your measured air-flow, O2 sensor readings as well as a ton of other things. I love mine. I leave it plugged in all the time.

Ubermensch

You've replaced the MAF. So that's likely working correctly. If it's still giving the same code it's probably that the measurement the MAF is getting isn't matching up with what the engine/DME expects or is experiencing. I'd look for vacuum/air leaks. There are a lot of lines that can be disconnected or missed when replacing things (including the MAF). Any unaccounted-for air in is going to throw off the AFR and cause issues.