Troubleshooting M52 Idle Issues...

[BBDirtbiking]

First take a look at this video...

http://youtu.be/BkEOSKJ7hJo

So at first it would jump way up, then way back down, but now it sticks around a good idle but just randomly dies... Also my lights stay on on the dash.

Another thing is when I just barely push the throttle it rockets up in the rpm... Just might be something to take getting used to...

Here is a schematic of my vacuum lines for reference.


The only vacuum leak I could possibly have is the throttle body to the manifold as there is room for a bigger gasket then what I ordered.

So what are your thoughts? I need to make this a reliable car as soon as possible as it won't be long till school starts again...

[cormier]

What is T-ing off by the FPR?

Edit again. Read your diagram wrong the top clip thing is coming beneath the manifold, gotcha.

[BBDirtbiking]

Wanted to add some more information...

The O2 sensor is plugged in, but just hanging, not in exhaust.

The HFM is plugged in, but also just hanging.

The car is OBD1 and I am running a custom tune created by a friend, starting to think this may be a DME issue...

[jrdeamicis]

Ummm..

Are you serious home boy?

First, get your MAF in the intake boot, clamped. No filter is OK, but just hanging is stupid.

Unplug your O2 until you get an exhaust.


Once you have fixed these massive offenses you can try to get it to idle.

[cormier]

Hang on.... Hanging as in it's still hooked up to a filter and to your intake elbow right? Not just ....hanging?

May be an idea to remove the chip and revert to stock for now to get it going

[BBDirtbiking]

Haha, seems as though I have broken a cardinal rule by just having the MAF hanging.

Today I was actually going to hook it up...

[jrdeamicis]

Haha, seems as though I have broken a cardinal rule by just having the MAF hanging.

Today I was actually going to hook it up...

Both are crazy.

The engine is trying to run while having zero information for AFR

[BBDirtbiking]

So I hooked up that extra wire on my alternator, see X6524 pin 1, and it turned off all my warning lights when car is running, all except my brake hydraulic light.

As far as idle goes, we unplugged the MAF and it will actually run and somewhat idle!

Going to clean it as well as try and borrow Stephens (Yes...? Haha), I think it is in good enough running shape for a test drive real soon.

[BBDirtbiking]

So the first thing I did today was actually hook up the MAF with the intake boot to the throttle body as well as unplugging the O2 sensor completely.

New video time! http://youtu.be/k7poJvee074

I go to start the car and it fires up, then dies. Try again, same thing. Only way to keep it running is to manually open the throttle body.

I then get my Dad to unplug the TPS, and the car starts then dies. We plug the TPS back in and unplug the MAF. The car fires up and bounces around until it achieved idle at around 800-900 rpm, it is a rough idle however. (All this is in the video!)

I took the car for a drive shortly after the video and as it warmed up it seemed as though the idle got worse, the throttle was extremely touchy and I need to bleed my clutch as it still isn't perfect. (touchy throttle might be because the clutch was releasing fast...)

What wasn't shown in the video is when the car was running, we plugged in the MAF and it died instantly.

One thing that I didn't try was unplugging the TPS when the MAF was off... I will try that tomorrow if I remember.

So basically the question I have now is: How can I test the MAF to see if it is truly the thing at fault here... Is there a way to use my multimeter to ensure it is bad, instead of dropped cash on a new/used but known to be working MAF? I was going to try Stephens but his is the 6 prong for non vanos cars. I will be looking online for specifications to test it...

Another issue I have is my temperature gauge isn't reading. I will test that sensor/wiring though, that I can figure out easier then my idling/running issues.

Also, here is the first drive video! http://youtu.be/DDqr7hljEH8

[BBDirtbiking]

I got a M50TU MAF that is known to be working to try out. I hope this solves my problems! I will know at my lunch break.

[rightcoastbias]

Not related to your issue:

Don't mount the intake air filter directly to the MAF housing; the air will be too turbulent for the MAF to acquire accurate air flow readings. Place ~4" section of 3" OD tubing between the air filter and MAF.

Typical set up is Air filter with 3" ID outlet, 3" OD tubing, 3" ID silicone coupling, and MAF inlet (3" OD).

[BBDirtbiking]

^I know about this. In the driving video there was no MAF on the car at all, so I just put a filter over my intake boot to ensure the air wasn't super dirty going into my intake. And I would personally use 3" ID ABS as you aren't reducing the intake size more then you have to. I already have my intake setup, just been waiting for it to idle write, then I need to make a bracket as it just hangs there. This bracket will be my intake and power steering reservoir holder.

Now for an UPDATE!

Installed a working MAF. Starts, dies, same symptoms.

Unplugged said MAF, car starts, dies. WTF.

Unplug TPS now along with the MAF, car idles perfectly at 600 rpm.

Going to test my MAF on a working M50TU and ensure it is not at fault, then going to put a known working TPS on my car and see if that helps. Will post back tonight!

[BBDirtbiking]

Just confirmed MAF is working properly. Time to switch out TPS with a working one.


Also check engine light is throwing a IAT sensor error. Going to investigate.

[BBDirtbiking]

...

I had the IAT sensor and the oil pressure sensors mixed up with the wiring... I took off the IAT plug and was like WTH!? Only one wire going to it...?

Went back to some of my resources and sure enough, that was oil pressure and sure enough on the oil pressure sensor was the plug for the IAT sensor...

Fired it up and it had a rough idle at around 500-600 rpm, where it is supposed to be. This, remember, is with no O2 sensor, so that might smooth it out I am thinking.

Now where it gets a little weird, I unplugged battery as the check engine light was still on, when I went to fire it up again it had a REALLY bad idle jumping from like 500 to 1500... This seems pretty drastic for an O2 sensor missing, or does it...? I put our computer on it and erased all faults as that usually helps the computers, but I didn't start it again, will probably do that at lunch as it was getting late and I knew my neighbor was already asleep.

Any ideas for the rough idle? One thing I want to mention is my ICV is horizontal... Does it have to be vertical to work properly? I have a throttle body gasket coming tomorrow so there will be on in the intake and one in the throttle body, making sure there is no leak there.

[R3Z3N]

I had EXACTLY the same problem as post #9.

Problem was the ICV needed cleaning and a vacuum leak in the ICV lines. ODB1 scanner told me the MAF was the problem, yet it was not in the slightest.