MuRCieLaGo

iTrader: (14)

Unfortunately, I don't feel like driving the car around at 1,600 RPM. Can't afford it!

DaleClark

iTrader: (55)

Can you get a picture of the sensor check screen with the engine not running?

Also what does the boost/vacuum say on the commander with the car running?

Dale

MuRCieLaGo

iTrader: (14)

Yes!

Sensors screen: car wasn't running, took it just before starting the car.

I understand vacuum is very low, but could it be because of the rich mixture, preventing the engine from building a decent compression?

OR,

Could it be because of the (known) exhaust leak between turbo and wastegate?

Bimmer_Tyler

iTrader: (1)

Correct me if I’m wrong guys but -251 on the map sensor OFF is fairly out of wack right? Maybe the map sensor needs to be Calibrated? I know I had to do the scaling in the Datalogit to correct it before tune
*EDIT- I’m dumb I see rpm right above it*

MuRCieLaGo

iTrader: (14)

-251 mmHg = -10 inHg, that's about what my gauge reads (gauge reads -12 inHg).

BUT. I've had a failed map sensor before, and honestly, maybe it feels like it. We all know what happens when you unplug the map sensor hose (it runs very rich, and that's also what is happening now). I'm thinking about buying an used one locally.

Bimmer_Tyler

iTrader: (1)

What does it read not running? I totally didn’t see that it was running, quick glance and was looking for something hahah

MuRCieLaGo

iTrader: (14)

Of course it's running now!

Key ON, haven't started the car in the last 3 hours:

Red94fd

iTrader: (5)

Did you run the car before all this mess with these ports?
Do you have a pic of the exhaust ports?

MuRCieLaGo

iTrader: (14)

Last time I ran the car was 4 years ago, it wasn't ported.

I never really took pictures of the porting, but here is an example.

I would like to add that I've got full confidence into that rotary shop, they've got a pretty much undented reputation.

zweetz32

iTrader: (2)

Your vta1 and vta 2 are out of spec. You have to adjust the tb and adjust the tps. Max range for vta1 with throttle close is .70 and vta2 is 1.25

DaleClark

iTrader: (55)

VTA1 and 2 are out of wack because the throttle is manually opened with the throttle stop screw.

Murci, you may want to close the throttle and see what VTA1 and 2 read to rule out a misadjusted TPS.

Dale

DaleClark

iTrader: (55)

AHA!

We got something going on with the MAP sensor.

I just turned my car on, stock map sensor with stock map sensor calibration. It's reading -25mmHg - yours is reading .23 kg/cm2 - that's showing with the car off about 3psi of boost!

Do you have a stock MAP sensor? Go to the PIM volt screen and make sure it's set to Normal, option1.

Also my sensor check screen shows 2.65v for PIM which is really close to yours - I'm damn near sea level elevation BTW.

Dale

Bimmer_Tyler

iTrader: (1)

That map sensor showing positive pressure while off likely effects the vacuum reading while it’s running as well yeah? So he’s likely pulling more vacuum than it’s currently saying correct?

DaleClark

iTrader: (55)

My guess is the PFC is configured for an aftermarket MAP sensor like a 3-bar. Yeah, if it's that far off with the engine off (atmospheric pressure on the sensor) it will be off all over the place.

MAP sensor is one of the primary inputs on the ECU, if it's that far off the car is going to run very poorly.

Dale

MuRCieLaGo

iTrader: (14)

​​​​​​
I unscrewed the idle bolt in front of TB and I managed to get VTA1 and VTA2 within specs, open and closed. However, I screwed it back in, because otherwise it will not start.

It was set to "Option 4". So I selected "Normal". Stopped, it now reads -35mmHg (warm, right after the engine has been running for 5 minutes).

Car started, ran much better. I couldn't hear the street port idle! I even managed to get a steady idle of 930-1,010 RPM.

At this point, I really thought it was time for a road test... not yet.

I gave the engine some gas (went up to 4,000 RPM)... Then the idle got like before. Had to screw the idle bolt up to 1,600 RPM to get it steady. I stopped the engine, restarted it... Still no luck.

DaleClark

iTrader: (55)

Good! Well that's one problem down!

The -35mm hG when off is correct, that's what it should be showing. That's most likely why the car is running so rich.

Didn't you reset the PFC to defaults at some point? I'm baffled as to why the MAP sensor was on the wrong setting, resetting it to defaults should have wiped that setting out.

Dale

MuRCieLaGo

iTrader: (14)

I did reset it a couple of months ago, however I'm pretty sure I selected the "Option 4" myself (I am still learning how to use the Commander).

I did another reset today. I turned off O2 feedback. MAP sensor's default setting is "Normal" so I kept it there.

Tonight, I started it again. Steady idle at 1,300 RPM. I decided it was time to go for a test drive... Then the bouncing idle came back all by itself (I wasn't touching anything).

It seems like the bouncing idle happens when the engine reaches its operating temperature... I've got to fix that before going for a test drive. The vacuum is much better now, -400 mmHg/-16 inHg, that's a relief!

Mrmatt3465

iTrader: (10)

You’ve been trying forever to get this thing to run but you’ve probably never even had the PFC learn idle yet. Takes like 25 min for it to learn idle. Look up PFC idle learn on here and you’ll find some threads about it. IIRC it’s like run it 10 min, 10 min with rear defroster on, and 10 min with AC on or something to that tune. The fact that you’ve been playing around with the wrong throttle plates doesn’t help. That screw you adjust shouldn’t ever be fussed with really. You adjust idle speed using the air bleed screw at the bottom of the throttle body. Initial setting of the PFC, it should be 3/8 to 1/2 turn from closed IIRC. As for other idle related things, I imagine you don’t have an air pump anymore, which would effect idle. Do you still have the ISC? A tune will greatly help your idle after you do the idle learn procedure.

Matt

zweetz32

iTrader: (2)

The screw you are playing with is the throttle adjusting screw and should be 1/4 turn after touching the lever. You should use the air adjustment screw under the throttle body for adjusting idle. I have that screw 1.5 counter clock way out. Do you still have idle air control valve?

DaleClark

iTrader: (55)

Nice! First drive, woo hoo!

I agree, you will have to do the idle learn procedure. Also if the ISC is dirty it can create a bouncing idle as well.

The idle learn procedure is well documented, read up on it. I like to do it with the car warmed up. Get it warm, then do a full PFC reset and restart the car and start the process.

Dale

MuRCieLaGo

iTrader: (14)

Yes I still got the IAC! It used to make some noises sometimes before when the key was ON, now it's quiet...

Your procedure is bang on, that's the way to do it. Here is what I did:

1. Brought the car up to temperature. Bouncing idle only started when it was warm, again (at 70°C (158°F) on the Commander).
2. Turned the engine off. Adjusted the screw to get VTA1 and VTA2 within normal specs.
3. Unplugged the battery, pumped the brake pedal for a few seconds.
4. Plugged the battery back.
5. Started the engine, can't idle (I had to tighten the screw and to go over normal VTA1 and VTA2 specs. I went as close to normal specs as I could).
6. Started the engine, instant bouncing idle. Waited for 11 minutes, no change whatsoever. That is a where I took the following video.
7. Tightened idle screw to get constant idle of 1,900 RPM (can't get it steady under that).
8. Turned the engine off.
9. Unplugged the battery, pumped the brake pedal for a few seconds.
10. Plugged the battery back.
11. Started the engine, instant steady idle of 1,900 RPM (can't get it steady under that).

And that's where I am. Do you guys think it's time for a smoke test, to check for vacuum leaks (I never did that before)? Or is it time to send the car (on a towing) to the tuning shop?


I didn't even know there was a screw at the bottom of the throttle body... Hmmm... Yes, IAC is still there and plugged in!

Temptation to go for a test drive as it is is very high!!

Dirty ISC (IAC)? Wait, what? I'm assuming that the UIM was sucking some oil from the filler neck, so for sure everything got dirty in there... But I like the idea. As I said before, that IAC used to make some weird noise sometimes (electrical noise), but now it's always quiet. I'll search!

EDIT: I removed the IAC. It is dirty, but working fine.

Narfle

iTrader: (16)

Yeah a bouncing high idle is a classic sign of a vacuum leak. Good to rule it out, if nothing else. Probably good to zero in the throttle body adjustment as recommended, too.

zweetz32

iTrader: (2)

If you have a pfc and you try to start the car and it won't after awhile, it will buzz the iacv. It's normal. Nothing wrong with the iacv. You should look up how to adjust the throttle body and set the correct tps settings before trying to dial in any kind of idle.

DaleClark

iTrader: (55)

The ISC can move and look OK but be dirty inside. Spray the inside of the ISC with carb or brake cleaner and get it clean - you will probably get black crud coming out. Once clean, spray some WD-40 in there and use 2 wires to hook the 2 terminals to 12v and ground and click it open and closed a few times.

Also that gasket is the old paper gasket, the new version is a metal gasket. Probably not a leak but something to know about.

There's also the idle adjust screw below the entrance to the throttle body. With the PFC you typically screw it all the way in and then back out a half turn.

Dale

H_M

iTrader: (7)

I had the bouncing idle on my old street ported motor when it got above 70*C. It happened out of nowhere. Parked it one night and then had the bouncing idle the next morning. I spent months tracking it down but did not find anything wrong. No vacuum leaks or anything like that.

What I found helped was a combination of adjusting the various throttle body screws (I think there are three) and lightening the electrical load. One of my radiator fans was stuck/fried and when I unplugged it, it helped settle the bouncing idle a lot. It didn't 100% cure it but I was able to resolve the rest by adjusting the various screws on the throttle body. After that, I was able to comfortably idle around 900rpm.