New user, new to BMW, high idle m42, I'm lost

[TheNoteTaker]

So yea, as the title says, kinda new to the bimmer world but it IS just a car and the same rules apply. Mine is 1995 318i with the 5-speed.

I'm having issues with it revving straight up to 5k+ rpm on start, and no, it doesn't wind down.
I've been having problems with this car since I got it. At first it didn't want to start, but got it started after I zip-tied the CKPS in place, people I bought it from snapped the head of the allen screw off trying to tighten it and the steering rack is in the way, so that can just wait. It was running extremely rough, massive surges and just turning the running lights on it'd die. Finally got it to where it would run and didn't bounce the idle around too bad, then it would rev between 2k and 3K rpm, and that's what it was doing up until a few days ago when it decided to rev between 4K and 5k at idle.

Now if I try to start it, it'll go straight to 5k.
Also, it burns black from the exhaust and smells of raw fuel, so it's running rich. Oil level is fine, planning to do oil change if I can get it fixed, has burned through a half tank with about 5 idle sessions and 3 or 4 1-mile trips around the block.

I saw on a different thread somewhere on this site that their IAC supposedly had problems with the windings, causing it to idle super high, I'm going to attempt to disassemble mine soon to check it. I've checked for vacuum leaks the old fashion way - with brake cleaner or ether - the bottom of the IAC was sprayed and it revved up shortly (before it was staying at 5k), took gasjet maker and sealed up the bottom of it to make sure it wasn't leaking, replaced the PCV hose with some heater hose of the same size, fits snuggly. the pass-through tube from the intake to the IAC and the injector tree had cracks where the joint line is at each end, took rubber cement and sticky duct tape and fixed that, zip-tied the hose to the IAC. The intake boot doesn't have any cracks or tears in it.
No codes.

I replaced the TPS and the CMPS(cam sensor). The old TPS was original and was going out(stomp test didn't work, new one did).

I'm just completely lost, if I check the IAC windings and they look fine then I don't know where else to look. I really need help with this, I'd like to be able to get this car legal and road-worthy.

[Eric93se]

Check for vacuum leaks (smoke test it).

Verify that the throttle cable is not bad, have someone press the gas (car off) and someone under the hood verify that the throttle plate snaps shut, so press gas peddle quick on/off and under the hood you should hear the throttle plate snap shut. Use you hand to check the throttle plate operation and that it is closing.

Check that the alternator is operating properly, use a volt meter, it should be either 13.8V or 14.4V with the car running.

You could have a bad fuel injector, consider having them serviced (remove them from the car and send them off), or if you handy you can learn to clean them yourself.

After all that then replace your oxygen sensor, but only after you've fixed all the problems.

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Oh yeah, welcome to the forum!

Also use the search feature, set it to the e36 subforum.

[TheNoteTaker]

Thanks! It seems like a good forum.

I'll remember that, I did an advanced search within the e36 subforum earlier before just posting another thread but nothing I had seen sounded remotely similar.

I guess I'll just have to re-rig up my smoke tester to check it. Hadn't thought about the alternator, but I just recalled that it didn't quite want to start the other day(dying battery style, the battery was completely dead a couple weeks after I bought the car, the trunk light wouldn't turn off because the plastic liner wasn't seated right). I didn't want to mess with the injectors but I guess I will here sometime, might have to put this project off for a short while (college freshman, have 3 papers due before the end of the semester which is Dec.12, go college!).

I hate these o2 sensors, they're just a pain.
Correct me if I'm wrong, but this car only has one right?

[Eric93se]

yes just one, pre-cat.

[TheNoteTaker]

^ cool, just wanted to make sure, thanks.

ok, couple of developments.
1. got it idling at about 3k rpm, MAF/AFM off of car completely
2. plugged intake hose for ICV that comes off of intake boot, dropped to 2k rpm
3. I've seen several threads saying that the MAF or AFM (whatever basically the same) across pins 1 & 2 or 2 & 5 should ohm out at ~11.5kOhms.
-mine tested out at 3.5kOhms and 4.5kOhms, respectively. and they didn't change when I moved the door.

anyone have any thoughts??

[Eric93se]

So the MAFS is bad (so long as you tested it correctly ) There's a good price at rockauto.com, there should be a %5 off coupon at retailmenot.com There's also a sweepstakes for that particular part brand to enter and maybe win a '66 chevelle! lol

While it was idling did you try to plug the main air intake (put your hand over the air inlet at the MAFS), while this might stall the engine, if there were a large vacuum leak the engine would continue to run.

[TheNoteTaker]

I did, it almost died and sucked my hand in very violently.
Note that the idle set screw for the throttle plates is MIA so I have a long self-tapper in its place atm.
After i plugged that hole and got it down to 2k, I loosened that screw and it started to slowly bounce between normal idle and 3k, I turned it off when it was at a low point.
But I took a screwdriver and pushed the cruise-control plate into a more closed position (the spring fought it and put it right back) and it started to die, I only did this because I noticed a very visible gap along the top of the plate, I have the cruise-control module unplugged atm as well, and I did check that the throttle cable int hanging, I lubed the springs, pins and down the cable with Kano AeroKroil so it's nice and free-moving.

Tomorrow I think I'll try using some cardboard to completely cover the main intake up and plug he ICV hose too and see if it'll still run. I try to spare my neighbors too long of hearing it run lol.

[Eric93se]

If you haven't already, you need to smoke test it to find all the vacuum leaks.

Also remove the IACV and clean the inside, make sure the valve weight on the inside swings freely.

[TheNoteTaker]

It'll be a little while before I can smoke test it, but I have cleaned the IACV insides up really good. Used brake cleaner, and outdoor A/C system coil cleaner. The weight moves pretty freely, if you quickly rotate it you can hear the valve opening and closing back.

[jc43089]

The throttle plate should be closed/sealed when idling. The stop screw is just to stop the plate in a certain spot so that it doesn't rub or pinch inside the throttle body. No air is intended to come through the throttle body at idle.

[TheNoteTaker]

That's what I thought. I took the throttle body off and cleaned it in some aluminum-coil cleaner, got all the black deposits off of it.. not sure how the got there but whatever. The cruise control cable was too tight and was holding it open as I said. Loosened it, it stayed completely shut.

Took the MAF off, plugged the intake hole for the ICV, readjusted the throttle cables and it ran better than it ever had, took it on a quick drive and it ran perfect, but got it back and it was idling at around 1500rpm, gonna try it again today, see if the idle went back to normal but I'll try to keep this thread updated.

[TheNoteTaker]

Ok, had a chance to start it today. It revved up to 2k then dropped to normal idle but was having a hard time staying running. I was out at a junkyard yesterday and saw a '97 318ti, robbed the intake temp sensor from it, pulled a good chunk of its wire too. I wasn't sure if I could even use it but hey i didn't get charged for it so whatever. I shoved the two wires in the #2 and #3 pins on the MAF connector while it was still warming up, immediately started idling better. Still not sure why it's running so rich though. I mean it doesn't have the cat anymore, it's gutted = straight-piped to a magnaflow dual-exit 2.25" muffler. But it smells strong of unburned fuel. It was doing this before the MAF decided to completely give-up-the-ghost so it's nothing new. Any suggestions??

[TheNoteTaker]

So, in an attempt to fix what I believe is the vacuum reserve for the DISSE Valve, i took the entire lower intake manifold off yesterday, WORD OF WARNING, it is EXTREMELY challenging to remove this because of the wiring harness.
Once I successfully got it off, I was easily able to pull the fuel rail out, injectors attached, and noticed that all of those vacuum hoses were spilt down their centers.
I purchased some replacement hose and plan on fixing that this weekend, along with rerouting the wiring harness and reconnecting the DISA vacuum reserve.
Also, two of the injectors has black sludge on the nozzles. I cleaned them up. Hopefully that's all they needed.
I'll keep this thread updated.

[Eric93se]

Replace ALL the vacuum lines. While the injectors and rail was out you should run the pump to pressurize the injectors to see if any leak.

[TheNoteTaker]

Well there are only a few. Those 4, the few on the vacuum reserve and the one for the crank case ventilation. I bought a couple feet of 1/4 inch hose to do the vacuum reserve ones... It'll be simple enough. Just got to be careful with how much I use.

[Eric93se]

Also use new gaskets, the old ones can leak.

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Ghetto rig a smoke tester, use a cigar and a shop vac, use a hose small enough to hold the cigar, put the small hose in the shop vac air intake and some duct tape to seal it off, pipe the exhaust into one of the cars vacuum leads or intake.

[TheNoteTaker]

Yea I'm going to have the main intake gasket sent to my parts store tomorrow so I can go pick it up when I go, yet again, to get more hose. It's only $9.99 at O'Reilly's apparently, cheapest gasket I've ever seen.
The one I took off looks original, and it also looks to be made out of a cork material. New ones are composite.
Pulled all of the wires from the harness out and plugged everything I could back in, going to run the wires under the backside of the manifold... how it SHOULD have been done.
Got the vac. reserve hoses re-ran, just have to put the manifold back on to finish the job.
Once I get it all back together the only thing that'll be missing is the MAF but it should run without it, besides I'll be getting a new one from RockAuto soon enough.

[TheNoteTaker]

Got the whole manifold back on, started right up last night. It didn't smell as rich as usual so maybe that helped replacing those hoses. I've got it set where the throttle plates are completely sealed and the DISA/vacuum reserve stuff is all hooked back up. It'll probably be a month before I can get the MAF though. But that doesn't matter, it's just my project for the time being.