M42 issues....please help!

[Guest]

Ok so the other day I am going to meet up with a friend to hit up some local junkyards. On the way to the residence I see out of the corner of my eye the check engine light flash breifly.

fastforward 6 hours...

I am sitting at a light and my idle starts surging between 800 and 1200..800 and 1200...an so on.

Then the check engine light comes on again. (will do this periodically)

Today 6-3-08 on the way to and from school when I was shifting to 5th there was hesitation and lost power when I let off gas everything was fine. And every so often i lose power..

Have any of you guys had this problem and what could it be?

Small list of my i thinks..

Throttle position switch?
MAF sensor? or whole thing?
Crank position sensor?
Idle control valve?
Fuel pressure regulator?

I am hopefully going to Run a code reader on it tonight if he gets here:)

any response is appreciated
THX guys

[wagonizzle]

Tps... sounds like no signal in the closed throttle position. It can be rotated until it works. See Bentley but use an ohmmeter and make sure it's sending a signal out.

[BBY1104]

ok, I will cheack that out...looking for the ohm meter

[BBY1104]

Bump for additional support and help

[kenika65]

when you start it do you have to give it gas, or when you are idling do you have to give it gas to idle it up, if so then yo u have a vacuumed leak. I would pull of all your boots and hoses and give them a look, an easy fix is electrical tape or rubber tape.

[BBY1104]

No it is only when I am drivnig, I replaced a number of hoses prior.

maily when I am driving i will lose power and have to let of gas off or shift down.

[smonkbmw]

lol, oh yeah thats right, didnt you take off a bunch of hoses and T them together and call it a hose reduction mod or something like that? maybe thats the culprit?

[BBY1104]

yea I did but I used hose clamps. i will check them Only one hose I didnt clamp I will check it

[Cobra Jet]

Sounds like an ICV issue, as the ICV regulates the "idle" and air into the engine... AFM regualtes air as well, but when the ICV starts to go bad, you will experience idle fluctuation and/or "flat spots" while idling or driving.

Turn the key to "on", touch or feel the ICV. The ICV should be humming or buzzing and it can be felt when touching it. Remove the ICV. Get a multimeter out and test the ICV conection at the bottom of the ICV and see what ohm reading you get. If the ohm reading you get is above or below that of the Bentley specs, you need to clean the ICV. Take the ICV and soak the internals w/ either carb cleaner or brake cleaner. Let it sit and dry out completely. Then soak the internals w/ WD40. Retest the ICV w/ your multimeter, you should get a reading now that is closer to or right on w/ the Bentley spec. Reinstall the unit after cleaning & lubing it. Once reinstalled, your engine should idle nearly perfectly and you should not experience any "hiccups" while driving or sitting at idle.

The inside of the ICV is comprised of a spring & plunger mechanism. The movement of the spring & plunger mechanism regulates the idle/air into the engine while @ idle or while driving. Due to miles, wear/tear and carbon build up, the spring & plunger mechanism become sludged, which decreases the ICV's normal funcationality (ie: sticking or high idle, low idle, hard starts, idle fluctuation while driving, abnormal acceleration, etc). Usually w/ most ICV cleanings, you can get the ICV working almost 100% again.

IF the ICV is NOT buzzing or humming, do the above cleaning method but also grab a small hammer and tap the outer casing of the ICV. You don't want to "smash it", just tap it hard enough around the entire outer casing so that you might dislodge the plunger/spring from sticking. After tapping the outer casing, then do the above cleaning again, test it again, etc. Severely sludged up ICV's will require some persuasion. If the persuasion method does not work, then you will need to buy a new ICV.

:)

[BBY1104]

i can fell it vibrating/moving so...

[BBY1104]

Nightly ump for help. Had a friend use codereader and it gave a somewhat quick signal and then there was nothing.

Only when using gas. Could it be the TPS?

[smonkbmw]

Could it be the TPS?

ummm yeahhhhh im gonna need those TPS reports mmmhmmmm yeahhhh and im gonna need you in on saturday yeahhhh.

wtf chuck i thought it was fixed? can you be a lil more descriptive cause the post above makes barely any sense. alls i get out of it is "is there somethinbg wrong with my tps sensor.

[DCColegrove]

Note: M42 (DME 1.7) TPS is self learning. Not adjustable.
If / When you replace it you need to disconnect the DME for lets say 30 seconds then plug it back in and start the engine without touching the throttle.

[Gray S.]

You sound like your having the exact same problem I was when I first got my m42. I would be cruising at part throttle constant speed and the car would start bucking and sputtering, let off the gas it would stop, give it gas and it would start again.

It did this periodically, would do it for a day then not for a few weeks. I took it to BMW and they diagnosed a bad AFM. I replaced the AFM with a known working one and havent had the issue since, that was 4 or so months ago.

It also might be a combination of that and your old plug wires or your ignition system needing a tuneup.

[BBY1104]

it has new plugs and I will look into replacing it with a known working AFM. I will also look into borrowing some plugwires that work fine.

Jeff: Curt plugged that Codereader in, something very quickly popped up and then it was gone again so the codereader was almost no help. -thanks Curt-

I am wondering if it would be something like the TPS because when the car is sitting it is 100% fine. I drove it for 10 min after reseting the codes and it starrted acting up again. Sputter and stalling with my foot in the gas.

I have 230 to fund fixing it so until i know what it is I wont be getting anything. I was going to replace things like air/fuel filter and such just a routine maintanance.

Do you guys think it could be the fuel pump at all?

Just looking at a bunch of possible scenarios.

thx for all the input

http://www.koperformance.com/online_ordering/make_n_model_search_catalog4.php?make_select=BMW&year_select=1991&model_select=E30318M|||70f23384c1acbedcaf5727021c405148&model_select_text=318i%20M42%20%28E30%20chassis%29&3flag=Y&group_id=F2&group_text=Fuel/Air%20Intake%20System&group_log=4493792&cat_select=822&cat_text=Air%20Flow%20Sensor&cat_log=4436856

Does anyone know if the AFM is worth my time if infact it really is the problem? Has anyone used that one? thx