Mysterious Timing Retard at WOT
 

As the title says the car is retarding timing it feels like when throttle position is greater than ~30%.

I've tried replacing the throttle body, spark plugs, checking injector connections, serp belt, checked compression and installed DT BPV.

I originally (pre - tb replacement) got a p0300 code for multiple misfire and a code for a bad throttle body. The only code that I've gotten since replacing the TB is P1498 for vacuum leak. I rearranged the IC boots and re-seated the TB and it hasn't come back up.

I'm absolutely stumped. after I replaced the TB today the car drove and pulled perfectly, but later on in my commute the original issue occurred.

Car is an 05' R53

Mods are:
17% S/C reduc
Megan 4 to 1 header
Stock Cat
JCW Exhaust
MSD Coil pack and wires
NGK Iridium heat area 7


Thanks for any suggestions in advance.

You using 93 octane?
Sparkplugs...are they recent, and JCW temp?

Yeah everything mentioned was replaced this month. JCW heat range is 7.

Might be time for a tune...
Bet the 17% with a header makes it a bit lean....

Its most definitely time for a tune, but those mods have been on for a year or more so I dont think that would be it.


I will mention that the old tb opened to 88.7% and the long term fuel trim was -6.2 while driving.

With the new tb from a gp it opens to 87.7% and my LTFT was -7% while driving.

Did you reset the throttle adaptation values? It's a necessary step when replacing the TB. Clearing the codes alone will not do this.

I reset the Ecu. Does that reset said values?

What octane fuel are you running? With 91 I will get some pinging/timing retard every now and then. I have to run 93...then I'm good to go.

Also...have you tried getting fuel from a different place?

Sorry for late response...thought it got posted a while ago.

Anyway, Yeah I travel to different parts of the state frequently so i'm always filling up at different stations. I only run 93 octane.

I can't quite tell if it's a fuel cut or a timing retard to be honest. I've been looking at short term fuel trim vs throttle position and it seem that around 32% throttle open it stops adding fuel and goes to 0.0. I haven't seen what it is normally but I thought it would be at 0 only during WOT...not at 30% throttle. Car doesn't appear to be running lean according to 02 voltage.

Also, I caved and brought the car to New country MINI for a diagnostic.

I told the mechanic to drive the car on the highway in 6th gear and go wot. He said he did but didn't feel anything out of the ordinary....

Anyway they performed a dry and wet compression test revealing the compression was slightly higher during the wet test, but only by 5psi at most...

I don't think it's a valve issue, but they told me that taking the head off and replacing valves would be the best option, or to get a tune and hope it goes away.


Basically, I paid for a very expensive car wash and compression test....

Nothing like wanting you to jump in with both feet!

lmao they wanted $3000 just to take off the head. I was like are you ****ing high m8?

Solved: I replaced my injectors with st 225 380's and it runs a lot better. I still have 4 codes for vacuum leak and 1st o2 sensor malfunction. Car runs fine though.

It's possible your problem was a bad injector but that shouldn't through a vacuum leak or o2 code.

If the car still throwing a code for a vacuum leak. I would chase that down your throwing gas and power out the window if your sucking air. And the "problem" is likely to come back after the computer gets used to the 380's.

Yeah its weird because the vacuum leak code appeared after I replaced the tb, and the o2 sensor code came within the last 2 weeks. None of my codes came originally when I had the issue. I don't think they are related but regardless I need to fix them.

Check for cracks or a loose fit on the vacuum lines to the TB, but maybe more importantly the vacuum line from the intake to the fuel regulator, don't forget, fuel pressure on our cars is completely regulated by vacuum, a loose, bad or disconnected line will cause the car to run lean under heavy throttle only, but may not actually be noticeable as a leak at idle, ie. rough idle may not occur, or under normal driving.

It sounds like a similar problem that I was having. I tried EVERYTHING that you tried. It turned out that it was the timing chain tensioner!

Things I tried:
1) Replaced knock sensor
2) Tried Octane 104 Booster
3) Tried a bottle of seafoam engine treatment (In gas tank)
4) Replaced spark plugs (NGK IRIDIUM)
5) Replaced Ignition coil (MSD)
6) Replaced Ignition wires (MSD)
7) Tried gas from other stations
8) Installed DT BPvalve

Things that worked:
1) Timing chain tensioner

I was completely stumped aswell.

I would clear the ECU adaptive settings, if you haven't don't that yet. (This may be what you did with the mentioned "ECU reset".

And worse case you could replace all the rubber ...

Best of luck.

Motor on!

It seems to have mostly gone away. Rarely feel it, but a new tensioner is needed for sure.

Fuel regulator vacuum line.
 

You might want to check your vacuum line to the fuel pressure regulator. I had a similar issue and the vacuum line had come loose at the intake end. It's really hard to see but you can see it where the vacuum lines join the intake below the left side of the inter cooler.
To be honest my smog guy found it. I had to zip-tie the end back on though as it was loose and kept popping off under boost as the rubber is so old. I should just replace it but I can't be bothered removing the intercooler right now.

It may also be the cause of my pinging under load when I had a 17% pulley and just ended up going to 12% - as I say it's hard to spot :-|

Cheers,

Andy

Andy, were you getting any codes?

No, no codes at all, which I wasn't too surprised by as I don't think there's any way the ECU could know if that line was loose.

I figured it out.

While installing a boost Guage I realized a vacuum line coming off the left side of the intake mani had popped off giving me a boost leak.

Codes for the 1st o2 sensor, boost leak, lean mixture, and map sensor are all gone.

Glad to hear you've got it all sorted. I take it you're talking about the vac line that runs to the fuel pressure regulator under the I/C. I was looking at mine when I was dealing with what worked out to be my bypass valve issue and it kept slipping but not really popping off easily. A small hose clamp did the trick to make me feel comfortable I wont ever have to deal with it.