Author Topic: 93 e36 higher rpm crazyness (Read 3546 times)

Max55 · « **on:** October 03, 2010, 07:48:08 PM »

Hey guys, 1993 318is 5spd here. This has just started happening within the past month or so. Here is what happens

While getting up to speed 50% of the time when the rpms get above 3k, (usually just under 4k) the rpm gauge goes nuts and engine seems to cut in and out sporadically and like crazy. Especially when its maintaining highway speeds right under or at 4000 rpm. The car bucks and jerks. I thought it was fuel filter however the car actually did while i was decelerating while in gear going down a steep hill.

What would cause this? It seems to be getting worse and doing it more.
Could it be Fuel filter? I have heard possibly a crankshaft sensor.

This car is my daily Driver and I love it, Help me save her!

here is a picture of her

DesktopDave · « **Reply #1 on:** October 03, 2010, 08:17:51 PM »

I'd check the crank & cam sensors for resistance. Crank should be around 640 ohms, cam about twice that, 1250 give or take a few ohms.

Have you done a stomp test yet? Turn the key to position II (don't start the car) and stomp the gas pedal five times within about five seconds. If you do it right the CEL will blink codes out. It takes a bit of practice to get the timing right but those codes can definitely help out. I'm just guessing that the ignition timing is jumping at high RPM, but it could be a lot of things.

Max55 · « **Reply #2 on:** October 03, 2010, 08:47:50 PM »

Hey Dave, well I have a CEL but have been trying the stomp test for a long time and it does not work on my car anymore. I was able to do it quite easily this past spring but now it does not work at all. I even unplugged the battery and the CEL was still on. idk what is wrong, very frustrating

DesktopDave · « **Reply #3 on:** October 03, 2010, 09:51:27 PM »

Could be an O2 sensor - they'll set a CEL and you won't be able to read the codes easily. I wonder if you unplugged the sensor & tried again? You can take it to a dealer, but what would be the fun in that?

Your model also had a history of DME troubles from water flooding it after a deluge or pressure wash. Maybe check the drain on the passenger side firewall to see if it's functioning.

Max55 · « **Reply #4 on:** October 04, 2010, 11:04:13 AM »

Hey Dave, thanks again for the response. I just checked the DME compartment and it had some dust and small leaves but nothing that looked like water had ever been in there. , although there is no telling.

I am really irked by this, i have to run to my mechanic to get it on a lift for the o2 sensor.

I will report my findings

DesktopDave · « **Reply #5 on:** October 04, 2010, 02:59:56 PM »

Let us know. Hopefully it's just one flaky sensor or an odd vac leak.

azrats · « **Reply #6 on:** October 04, 2010, 04:58:01 PM »

I was having this same problem recently (it would start cutting out around 4k rpms) and it turned out to be a dirty (oily) cam sensor, simply take it out and clean it with a rag. Its held in with 1 allen bolt. Try that before you throw money at it.

PS: I think you need lowered Eibach springs or something you wont regret it.

Max55 · « **Reply #7 on:** October 04, 2010, 10:41:05 PM »

Well I took it to my mechanic, and we checked it all over. We found that the valve cover gasket was leaking a lot of oil into the spark plug "holes"? and that all the spark plugs themselves were really loose in there. So he cleaned the plugs up and put them in good until i can go back and get a tune up on Wednesday.

It did seem to run a lot better on the way home but still did it a little bit as i neared my apartment and was going on a roundabout off the interstate

azrates, I have a Bilstein H&R suspension on the car now, It lowered the car a good bit, the car is my DD and I drive in Atlanta, I would be worried about going too much lower

Max55 · « **Reply #8 on:** October 06, 2010, 08:37:17 PM »

OK UPDATE! for all those wondering and for "some" closure

Did a tune up on the whole car, new plugs, oil change etc and cleaned the crank and camshaft sensors. Still had the rpm issue, then did the "wiggle test" on the TPS sensor cable, car would almost die and rpm would change even at idle.

Pulled back the boot covering the cables, sure enough only one of the 3 wires was even connected and then only by a little bit. So as a short term fix until I can find the right part/cable with clip, we spliced some wires onto the broken ends. and electrical taped it up to the ends on the TPS. CEL light immediately went off and the car does great, it still does it but barely.

Will update again and continue to check the thread