M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: Crummy Cream on October 29, 2017, 10:27:01 AM
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Question: Why does my car idle at 1500 to 2k RPM?
New part list (things I have done)
1. MAF
2. ICV
3. ICV Upper & Lower Hose
4. TPS
5. spark plugs
6. intake boot
I've tried spraying brake cleaner on other vacuum lines, but i cant find if its a vacuum leak or something else.
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2 possible reasons, throttle cable is calibrate to having it more open or it getting caught. The other is the wrong coding plug connected into the instrument cluster. Of course everything you swapped can be directly related to it.
so first, was this issue happening before you replaced all of this? if not, it would be related to the work you did or the cable which is in the area.
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@monty23psk
I havnt domt anything to the throttle cable but i can tell u why i replaced all of that
Answer to your question is no
When i first got the car 6 months ago the car would idle from 800-500 rpms, but would even out after the car warmed up (but wouldnt have a high idle) i assuming a vacuum leak i found the icv vacuum hoses were shot so i replaced them. this made no change in the car... then i replaces the maf and icv. Still no change at all, but now even after the car warmed up the problem still existed . then i replaced the tps aye the car no longer changes idle like that, but it stays at a steady 1500. Now i did remove the instrument cluster to try and fix my speedo but gave up i no nothing about elecrtonics, ill have to check on the throttle cable, but how can i test the cluster.
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You can't really test the cluster. I am assuming the cluster is back in the car. Did you remove the cluster after the RPM issue started? if you replace a and b and your issue starts after that, it normally means its because of that. The ICV or an not connected ICV can give you an idle issue. Just take a systematic approach and you should find it because it wasnt happening before.
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I have not taken the cluster back out in a while ill check my the icv cause it was not east to get in
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Okay so i just fixed a small vacuum leak that i found and now the car is idling very steady but at 2k exactly... omg sometimes i love this car but rn im frustrated
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what happens if you leave the ICV unplugged?
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When i unplug the icv the car will start to creep up to 3-4k rpm
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Im starting to think maybe my tac is just reading the rpms incorrectly
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That would be the coding plug. It is specific to the engine. You can get to it without remove cluster, just need to remove the 2 from covers. Bottom right under the temp gauge. check out my member thread.
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Okay ill try that i work at a dodge dealer and one of the guys said there that the tps might be adjustable does anyone know this to be true?
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I was goiung to suggest adjusting the TPS.
http://www.m42club.com/forum/index.php?topic=16521.0
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Yea i just have no idea whatsoever on how to calibrate it
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Funny, that TPS thread is mine. I forgot about that. The adjustment is very little if any. You can try to move it to see if there is a difference.
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okay so can you guys give me the dummy version on how to adjust this tps I can't figure it out because the holes are not oval shaped to allow for movement of the tps... :( Here is a video of the car at idle on a cold start You can see how I went to the throttle cable to show it's not being pulled or anything at idle..
https://drive.google.com/file/d/0B0EwhfdQoPi2NnN4LVBVTlUwZE0/view?usp=sharing (https://drive.google.com/file/d/0B0EwhfdQoPi2NnN4LVBVTlUwZE0/view?usp=sharing)
so if you click that you'll be able to see that the idle is kinda high I'm just so confused, but it's a lot better than the car stalling on me all the time...
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And you said the MAF is brand new? Wanted to make sure the flap is not getting stuck open but its more about the throttle. Did you do the bypass of heater plate coolant hoses? do you have the hoses ran the correct way? I find this odd with a brand new MAF and ICV. From what I have dealt with, a vacuum leak while make the idle rough or low, never higher.
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Yes brand new MAF like brand new same with the ICV both are Brand spanking new lol so is the tps I Doubt a vacuum leak would cause this as u said this seems like a mad could cause this problem and I don't have access to my multimeter anymore so I cant even check the voltage >:
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is it possible that its because they're not oem their aftermarket because the oem ones were out of my budget
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also, i did not bypass the heater plate i'm almost pos it hooked up correctly too this is so frustrating I'm just afraid that because since it idles high that the motor won't be able to handle constant stress during running.
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OEM is the best, not sure about aftermarket quality. Do you still have previous MAF and ICV? If so, you can try one at a time to see if it fixes the issue. I also see you have that extra pigtail on the MAF connector from the video. Have you tried bypassing it? I forgot the reason for it. My car didnt come with it.
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Ill test this after work thanks man for all the help
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That sounds like a really high idle. Typically it's due to a vac leak. Does your shop have a smoke machine? If they find a leak it'll be the best money you ever spent, these cars have huge problems with vac leaks.
You re-connected all the vac hoses, right? The plumbing is all going to the right places? Is the blind plug back in the throttle boot? I'm not criticizing, just suggesting a way to eliminate possibilities. I'm only saying this because I've caused a new problem for like every three problems I've fixed. I've left brake parts loose, forgotten to plug the block drain, etc..
It's been so long since I've done this job, I can't recall where the hoses go. IIRC the ICV hose goes from the throttle boot to the manifold, the PCV hose goes to the lower throttle body, the FPR goes to the tee that also goes to the fuel tank vent valve. The brake booster hose fits in there somewhere too. I'll take a look at mine tomorrow & let you know.
Anyhow...other things I'd check:
Has anyone messed around with the TB plates? If they're stuck open at all, even a bit, your idle will be very high. There are two plates to check (and a linkage), they both have to close tightly so that the ICV can do its job.
Check the AFM for smooth door movement.
I don't think the later type M42 TPS is adjustable. The earlier ones had slotted holes so you could rotate them slightly.
Does the car idle high all the time, or only when it's warmed up? If it's only iding high when warm, What's the DME temp sensor resistance?
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the idle is high on startup only I almost pos i hooked everything back up ill have to take a look and I asked someone in service if we can perform a smoke test and they told me to bring it in after work this weekend to take a look so itll be free to test the vacuum line system thank god I hope I find my issue soon. I'll also take a look to see if the TB is slightly open do you have a way of testing the AFM Door to see if it will open?
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Idle should be pretty high on start up, mine runs at about 1500 for a minute or so depending on temp. Yours seems even higher than that, I agree that something is wrong.
The ECU/DME controls that setting by using the ICV and running a very rich mix. The DME detects temp with two sensors. Coolant temp (CLT) is in the cylinder head, air temp (IAT) is built into the AFM. They're really easy to test, just hook up a multi-meter in ohms (resistance) mode. A cold sensor will have a very high reading, like 9000 ohms (9 KOhms). As the temp climbs, the resistance falls. A hot sensor should only read out a few hundred ohms. Dean & I posted a pretty good thread about that here:
http://www.m42club.com/forum/index.php?topic=18012.msg123483#msg123483
I'd recommend testing it all to eliminate problems and save yourself some cash. I use a multi-meter more often than any other tool! I bought a good one on Amazon for like $40, it's paid for itself many times over. Don't replace stuff willy-nilly, test it all. You run the risk of swapping out a good part for an incorrect aftermarket part. Here's a good post I wrote a while back about the sensors and how they should be tested:
http://www.m42club.com/forum/index.php?topic=17926.msg124060#msg124060
Be aware that there are two very similar parts on the head. The CLT sensor runs to the DME, it's critically important. The coolant temp sender runs to the gauge cluster. It's relatively unimportant. The engine temp sensor has a brown case and two pins, usually mounted further forward. The gauge temp sender has a white case and just a single pin. If you swapped a few plugs around the wrong way when you did the hose delete, that'd cause some troubles. I've done it myself...the oil pressure sender, temp sender and CLT sensor all use the same plug, and the wires are long enough to put them together wrong. When I did the hose delete years ago, I mixed them up. I ended up with an oil warning light and the temp gauge never responded. Just like the crank & cam sensors...or the coil plugs for that matter...the same wiring connector plugs in the same locations make it pretty easy to mix them up.
I'll have to check my documentation to see which sensors the DME uses during the warm-up open-loop mode. I know that it ignores the O2 and many other sensors. A/C and O2 will also bump up the idle, but I don't think that happens until after the car warms up, when the DME switches to closed-loop mode.
Sorry about the novel I just wrote, LOL. I hope it's helpful.
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No thanks for the novel when i get off work im gonna send some pics of my vacuum lines and tb setup and im gonna borrow a multimeter from one of my techs
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Okay guys still havnt solved the problem, but now i need a new fuel tank
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why?
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My fuel tank has a hole in it but i just put some epoxy on it to patch it for now diy stuff but anyway o think i found my idle problem and its my throttle body i think one of the POS F'd with it because the new tps does not fit in perfectly right away i have to turn it about 25 degrees for it to fit in meaning the sensor thinks the throttle is being pulled about 1/4 of an inch even though its not correct me if im wrong because im going insane trying to find the reason behing this
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(https://lh6.googleusercontent.com/PtBuvf51wdFsbo-18SsdeXCxJS7poQlY_EQ2ezjXnPi55Tnj3vV6QiZI2vzjBiIEccYPevdeEWe_RCcRCwc6=w1601-h925-rw)
I think that this silver part that is sticking out here is misaligned
Here is a Video showing what I mean please don't pay attention to the music in the back
https://drive.google.com/open?id=16Fz5q4kmKBv5_I9N-0YawAOxIItZQdR6 (https://drive.google.com/open?id=16Fz5q4kmKBv5_I9N-0YawAOxIItZQdR6)
And here is another video of the idle in here I put the car in gear and slightly let off clutch to show RPMs drop, but then they go back to 2k
https://drive.google.com/open?id=1jUl3yX1pEWb-iPtEYIRCMK5yd-l1o0c3 (https://drive.google.com/open?id=1jUl3yX1pEWb-iPtEYIRCMK5yd-l1o0c3)
Shortly after doing this the car started rapidly changing From 1500 to 2k rpms however I wasnt able to catch this on video
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I think your part is good, the TB is supposed to put a little bit of pre-load on the TPS. The TPS isn't an on-off switch like in older BMWs, it's a variable-rate resistor. The DME (ECU) calibrates the throttle position automatically. So if the TB plates aren't adjusted to be fully closed at idle you're going to have some trouble.
I'll pull out a spare TB/TPS if I get a chance and double-check for you. I'm pretty sure the Bentley manual has a testing sequence for that part too, IIRC it has three pins, one is the 5VDC power in, one is the signal out, and the last one is a floating ground directly to the DME (ECU).
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Okay i think i found my problem after driving the car the tpsself calibrated so now on cold start the car iddles at 1k but after driving it starts to go back to 2k and fluxuates but its different everytime i push my clutch in. I also found thatif i go in the engine bay and give some throttle i hear a vacuum sound coming from the tb so i checked the bolts and 2 are stripped so im gonna get new ones. Hoping this solves my issue