This is the 2.8.
When the car sits at idle, the RPM's will drop a few hundred for about 1 - 1.5 seconds. Then bounce back up to normal.
I pulled it apart and found a tear in the lower intake boot which I replaced.
I also thoroughly cleaned the ICV which had a LOT of buildup in it.
I cleaned the CVV just for the hell of it, not sure if it did anything.
Put it all back together last night and things were completely unchanged.
Any suggestions as to what's next on the list of "usual suspects?" Clean the MAF? Air filter is new and the enclosure is clean.
She pulls great and is torquey at speed. Really, the engine purrs - it's just this interesting little fluke at idle.
Last edited by CoconutPete; 03-04-2019 at 08:48 AM.
Zed's dead baby. Zed's dead.
Rebuild your VANOS. One way to confirm is to unplug the connection to the VANOS. If your idle dip goes away, your seals are bad.
http://www.beisansystems.com/procedu..._procedure.htm
I have the same idle dip when cold. I have the seals, just not the time at the moment.
Last edited by s8ilver; 03-04-2019 at 09:05 AM.
Nathan in Denver
1999 M Roadster, VFE V3 S/C, Randy Forbes Reinforced, Hardtop, H&R/Bilstein, Apex PS-7, Supersprint
1999 Z3 2.8 Coupe, Headers, 3.46, Manual Swap, H&R/Koni, M Geometry/Brakes, M54B30 Manifold, Style 42
Interesting thought. I hadn't given it any thought due to not experiencing loss of torque or the bogging/surging at 3K. I also felt the power distribution is smooth.
I'll give the "unplug test" a try though.
Zed's dead baby. Zed's dead.
I had the same doubt about this; had a barely noticeable step in power at around 3000RPM - I did the Beisan seals and anti rattle kit last weekend and was surprised to find how much torque I was missing below 3000. Delivery was quick, instructions are good, results are impressive.I hadn't given it any thought due to not experiencing loss of torque or the bogging/surging at 3K
Honestly, it feels like this engine woke up from hibernation.
Brad Cushman
2002 Z3 3.0
1973 450 SL
1967 Camaro SS/RS
I think it's due to the gradual degradation. The loss is very incremental I imagine as the seals go south.
I need warmer temps and time to do mine, but excited to get back any power lost. Can't hurt, and what's it cost, maybe $120 if you do it yourself and replace VCG and a few other bits while you're at it?
Nathan in Denver
1999 M Roadster, VFE V3 S/C, Randy Forbes Reinforced, Hardtop, H&R/Bilstein, Apex PS-7, Supersprint
1999 Z3 2.8 Coupe, Headers, 3.46, Manual Swap, H&R/Koni, M Geometry/Brakes, M54B30 Manifold, Style 42
All good points. At 18 years old and 145K miles, perhaps it's time not matter what.
PO loved FCP Euro and AutohausAZ......
Valve cover gasket and radiator hoses were un-opened in a box in the trunk when I bought it. I smell a day off when it gets a tad warmer....
Zed's dead baby. Zed's dead.
+1 for the Beisan seal kit. Don't go with the other brands, his is the real deal.
Be sure to also get those little valve cover rubber grommets that are not included in many valve cover gasket kits. If you reuse the old ones, it'll still leak but in different spots (don't ask me how I know).
https://www.fcpeuro.com/products/bmw...er-11121437395
Count on your current VC how many you need, if I remember correctly you need 15.
Last edited by me77; 03-04-2019 at 03:30 PM. Reason: Added number
I had the same problem with my TUB28, rebuilt the VANOS and it solved the problem.
96 320i Touring
98 Z3 2.8 Roadster
01 PY M Coupe
96 Z3 1.9 - DASC
95 318ti Clubsport
94 Miata M-Edition
13 smart fortwo
I had what sounds the same issue with my S52. At idle rpms would drop dramatically then go back up. It ended up being the throttle position sensor. Replacement solved the problem.
VANOS issue throws no codes to my knowledge. Have you unplugged the VANOS solenoid to see if the dip goes away? If it does, it's absolutely your VANOS seals. I started at the ICV just like you did. Mine was frozen solid. I cleaned it with carb cleaner to get the rattle back (the rattle should occur) with zero change in idle.
My issue does go away when the temp needle reaches the middle of the gauge, but I'm sure I'm still down on power.
Last edited by s8ilver; 03-08-2019 at 09:50 AM.
Nathan in Denver
1999 M Roadster, VFE V3 S/C, Randy Forbes Reinforced, Hardtop, H&R/Bilstein, Apex PS-7, Supersprint
1999 Z3 2.8 Coupe, Headers, 3.46, Manual Swap, H&R/Koni, M Geometry/Brakes, M54B30 Manifold, Style 42
Only threw a code at the very end, as I was driving to the shop to do a "just replace the darned sensor, nothing else has worked, and I saw someone on BimmerFest forum solve it this way" That was in 2005 or 6. Before that no codes. The code it threw was - throttle position sensor.
Bill
2002 M Coupe. Steel Gray/Black.
Experiencing similar symptoms with my 2000 Z3 2.8.
Looking to do the troubleshooting suggested to unplug the connection to the vanos and see if the problem goes away.
From the rebuild procedure at the above link, looks like there are several connections to the vanos, and looking at the Z3 nothing is jumping out at me as the connector.
Can someone provide a little help -- where is the connector(s) that should be unplugged for the vanos to verify the symptom?
Thanks.
Steve
Alexandria, VA
2000 BMW Z3 Roadster 2.8
2020 BMW 230ix (Convertible)
2015 MINI Cooper S (Convertible)
2015 Jeep Grand Cherokee Limited
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