Engine Drivetrain 1st Gen Cooper S Most liked posts in thread: The mysterious power lag

Dan Z loaned me a spare TMAP - swapped it and still had same symptoms... but haven't tested the pre-SC MAP... do you know for sure if it was the MAP or TMAP they replaced, jnky?

 

NO codes typically. Occasionally a P0172 Rich Condition - happened pretty regularly when I first installed the RMW header - but maybe throws that code once every other month now (if that). Otherwise, no codes. But the symptoms are consistent.

Jnky - sorry - remembered you have a justa... so only on MAP sensor.

Keith - nope, haven't replaced wires yet. I'll try my almost-new-OEM ones first... then if that doesn't work I'll buy a new pair...

 

More clues perhaps?

Remember - the only symptom I see is this:


100% accelerator pedal input results in momentary WOT, then throttle closes to about 50%, then when I pass 4000RPM it opens back up to WOT.

While the car isn't producing any drivetrain P-codes, it DOES have some persistent CAN errors:


Just starting to dig into these as I only got a scantool that could see them yesterday. But I suspect they've been there a while, as Dan Z said he saw some codes like this when he scanned my car a while back.

Ideas? Related? Unrelated? Possible causes? Troubleshooting suggestions?

 

Yep - TMAP is on the front of the intake manifold.
MAP is on the SC inlet tube - you can see the plug between the airbox hose and the engine.

 

Soooo....

My flex joint on my RMW header broke. No worries - Jan is gonna fix it for me - so I took it off and put my OEM header back on. Guess what? The Power Lag issue is GONE. Car runs better than EVER - certainly better than the last 6 months. The pulley/one ball / intake / injectors / plugs / DT BPV / water-meth / RMW tune config ROCKS. I didn't have the meth kit installed before the header went on - so I haven't run this combination of mods before. I love it.

I'm thinking now that the car may have been running lean at WOT and midrange RPMs with the tuned maps Jan did for my car with the cam, due to the increased flow with the header. Car wasn't getting enough fuel, so it reduced throttle to compensate maybe? Not sure how or why if it was in open loop at WOT... but something like that seems to have been going on.

I'm pretty confident the car ran WELL with the cam+header for the first few months after I had it installed - because it rocked at VIR in November, then the lag seemed to develop with the yo-yo in December. So I'm going to have the header fixed but won't put it back on until I can have it re-tuned. And I'm keeping my current tune in case I want to revert back to the OEM header config - I'm also liking the reduction in decibels after several months of LOUDNESS.

Frankly, dealing with some exhaust issues has made me proficient enough at header swaps that I might even swap headers before and after track events, since I only do that a few times a year... and use Jan's flashloader to swap between the current tune and the header tune... it sure is nice to have a much quieter (and nearly as fast) car as a daily driver... and I can swap headers in about an hour now that I've learned some tricks.

 

Sooooo.... remember how I said this had resolved itself when I went back to the OEM header? Well, it had for a while. Then it started developing a *little* bit of lag that opened up at about 4000 RPM. Now it's doing it pretty much exactly like it did before I swapped back to the OEM header - and NOTHING has changed. So I'm having the exact same symptoms as before - can't hold open WOT until the car hits 4000 RPM - then the car goes like a batouttahell. There's a ton of power that I'm missing between 2500 and 4000RPM... GRRRRRRRRR...... WTF????

I'm gonna do some data logging, then put the RMW header back on in the next few days and get Jan to remote tune it and see what happens...