erratic timing question
Thread Starter
Racer
Joined: Aug 2006
Posts: 285
Likes: 10
From: South of Chicago Illinois
erratic timing question
2008 A6 - timing is jumping from 14 to 6 then to 20 degrees at idle causing an obvious erratic idle condition. Car has a supercharger and headers. Where would you start? Crank sensor? Tune has been reviewed and pretty much ruled out. Thanks.
Supporting Vendor
Joined: Sep 2009
Posts: 2,143
Likes: 169
From: Central Florida
blower install, and tune at the same time??
No offense, but who verified the tune?
If it was the person who did it, I might seek a second opinion.
If you told me the blower was installed and tuned, then it drive fine for a day/week/month, I'd say there is no way its the tune, but if it happened at the same time, and you have no clean driving experiences since the blower was installed (and presumably tuned) it is tough to say.
Generally, a broken or damaged sensor will lead to a check engine light.
No offense, but who verified the tune?
If it was the person who did it, I might seek a second opinion.
If you told me the blower was installed and tuned, then it drive fine for a day/week/month, I'd say there is no way its the tune, but if it happened at the same time, and you have no clean driving experiences since the blower was installed (and presumably tuned) it is tough to say.
Generally, a broken or damaged sensor will lead to a check engine light.
Thread Starter
Racer
Joined: Aug 2006
Posts: 285
Likes: 10
From: South of Chicago Illinois
Its a long standing issue since the install, original vendor didn't fix the car so I'm with a second.
Car was reflashed and tune started over with the second shop, found BOV spring keeping BOV closed at idle, 2 plugs and wires checked poor, now finally this erratic idle is all thats left. We see the timing changing when it shouldn't, hence going after things that affect timing. Its been a long year.
Car was reflashed and tune started over with the second shop, found BOV spring keeping BOV closed at idle, 2 plugs and wires checked poor, now finally this erratic idle is all thats left. We see the timing changing when it shouldn't, hence going after things that affect timing. Its been a long year.
Thread Starter
Racer
Joined: Aug 2006
Posts: 285
Likes: 10
From: South of Chicago Illinois
Learned that timing is moving around on the dyno pull as well. Changing the crank sensor wasn't it. Looking at the supplied injectors with the wiring adapters, (really loose) going to try some 65# FAST direct fit injectors today. Also learned that the miss travels around the cylinders using the tech 2 which is leading me toward this injector idea.
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Racer
Joined: Sep 2011
Posts: 452
Likes: 6
From: Pinson AL
just got this addressed on my blower install.
second tuner found that the burst knock setting was too sensitive and the duration of the retard was too many cycles.
My engine is noisy becase its all forged now so I was ready to pull my hair out because of the surging.
Burst knock is a prelude to spark knock so its a knock sensor - sensor if you will. Ask your tuner to look at this if he/she is willing if not get a better tuner.
The burst knock episode would trigger a timing retard that lasted to many degrees or cysles (revolution of crank) before it corrected itself. this variation is the surge you are feeling and seeing on the tach. good luck hope this helps
second tuner found that the burst knock setting was too sensitive and the duration of the retard was too many cycles.
My engine is noisy becase its all forged now so I was ready to pull my hair out because of the surging.
Burst knock is a prelude to spark knock so its a knock sensor - sensor if you will. Ask your tuner to look at this if he/she is willing if not get a better tuner.
The burst knock episode would trigger a timing retard that lasted to many degrees or cysles (revolution of crank) before it corrected itself. this variation is the surge you are feeling and seeing on the tach. good luck hope this helps
Thread Starter
Racer
Joined: Aug 2006
Posts: 285
Likes: 10
From: South of Chicago Illinois
Thanks I'll ask about this, so far the BOV spring was wrong, keeping the valve closed at idle, and the check valve for the crankcase was backwards, which caused issues on the dyno. Also installed a new inlet tube without the ECS radiator relief in it and that helped calm the MAF down. Getting better.....
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Joined: Oct 2004
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From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
Learned that timing is moving around on the dyno pull as well. Changing the crank sensor wasn't it. Looking at the supplied injectors with the wiring adapters, (really loose) going to try some 65# FAST direct fit injectors today. Also learned that the miss travels around the cylinders using the tech 2 which is leading me toward this injector idea.
I would be cautious with the FAST injectors, they are drilled out stockers, we will not use any drilled out injector here due to countless amounts of problems we have seen here from them.
You should have had brand new Motron's that came with the kit, we have never had an issue with one to date.
Premium Supporting Vendor
Joined: Oct 2004
Posts: 23,599
Likes: 1,224
From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
Thanks I'll ask about this, so far the BOV spring was wrong, keeping the valve closed at idle, and the check valve for the crankcase was backwards, which caused issues on the dyno. Also installed a new inlet tube without the ECS radiator relief in it and that helped calm the MAF down. Getting better.....
Thread Starter
Racer
Joined: Aug 2006
Posts: 285
Likes: 10
From: South of Chicago Illinois
Yes the pancaked area, with that tube removed and replaced with a round un-pancaked tube the maf settled down and the car idles fine at 550 rpm. ECS kit supplied injectors are on the car, the bov spring is changed to the green spring, and the check-valve is installed correctly now. Car is fixed, too bad I had to change installers to get it finally done. Thanks to Finishline Performance.