Bogs under moderate to heavy accelleration between 2k and 2.5k RPMS only in 2nd Gear.
10-23-2016, 03:04 AM
#1
Bogs under moderate to heavy accelleration between 2k and 2.5k RPMS only in 2nd Gear. 99 Z28.
So she has 206k on her, motor and trans Im 90% sure are all still original, never rebuilt and I'm well into the grey area as per the lifetime / reliability of anything mechanical, meaning I'm aware it can give up at any time at this point. The motor still seems to be strong but I've run into an issue.
When pulling out into traffic under moderate to heavy acceleration, she gets up to about 2.5k RPMS and then it just bogs down and the RPM's drop back to 2k before she wakes up and then accelerates. This only happens in second gear. In first gear it revs through it swiftly, likewise third gear. Second gear seems to want to hold the car back before letting it accellerate though. The transmission thumps pretty hard too. No codes or SES. Does it sound like my A4 is about to bite the bullet and I need to be prepared to replace the transmission?
So she has 206k on her, motor and trans Im 90% sure are all still original, never rebuilt and I'm well into the grey area as per the lifetime / reliability of anything mechanical, meaning I'm aware it can give up at any time at this point. The motor still seems to be strong but I've run into an issue.
When pulling out into traffic under moderate to heavy acceleration, she gets up to about 2.5k RPMS and then it just bogs down and the RPM's drop back to 2k before she wakes up and then accelerates. This only happens in second gear. In first gear it revs through it swiftly, likewise third gear. Second gear seems to want to hold the car back before letting it accellerate though. The transmission thumps pretty hard too. No codes or SES. Does it sound like my A4 is about to bite the bullet and I need to be prepared to replace the transmission?
10-24-2016, 01:45 PM
#3
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I agree completely with wssix99. That sounds like a classic sign of a dirty/failing MAF. That's where I would start.
As for the transmission "thumping", you weren't very clear about how/when this happens, but my first thought would be to inspect the trans mount. Probably needs to be replaced, and sometimes you can't see that they are cracked without removing them.
As for the transmission "thumping", you weren't very clear about how/when this happens, but my first thought would be to inspect the trans mount. Probably needs to be replaced, and sometimes you can't see that they are cracked without removing them.
10-24-2016, 02:11 PM
#4
Clean the MAF, as mentioned, it costs like $6.00 for a can of MAF spray. Also spray the IAT sensor in the lid.
I've had these exact same issues before...years ago. It was a failing 02 sensor. And no, they do not give an SES code until they get really bad or completely fail.
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I've had these exact same issues before...years ago. It was a failing 02 sensor. And no, they do not give an SES code until they get really bad or completely fail.
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10-24-2016, 06:07 PM
#8
Just noticed that, I replaced the driverside O2 alittle while back but the passenger side O2 still needs to be replaced and come to think of it I did see alot of smoke coming out the exhaust. I actually have the O2 sensor just never bothered putting it in because I wanted to wait till I did headers but I might try this first.
I honestly can't remember for sure but I want to say that it did have this issue as I have always remembered when pulling out into traffic it would slightly bog / hesitate before really accelerating unless I went WOT. It's just now its pretty noticable and kind of worries me. At first I thought it was the trans slipping but I guess my transmission may still be good. I'll install the O2 sensor when I can find an O2 tool.
I honestly can't remember for sure but I want to say that it did have this issue as I have always remembered when pulling out into traffic it would slightly bog / hesitate before really accelerating unless I went WOT. It's just now its pretty noticable and kind of worries me. At first I thought it was the trans slipping but I guess my transmission may still be good. I'll install the O2 sensor when I can find an O2 tool.
10-24-2016, 06:10 PM
#9
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Was the trans mount an OEM replacement or aftermarket parts store version? Just because it's only two years old doesn't mean it's not broken. 
OEM ones usually last a lot longer though.
OEM ones usually last a lot longer though.
10-24-2016, 06:22 PM
#10
Its the $10 one from Napa Auto Parts. I can't remember specifically but I came across a thread where people were using a mount from Napa Auto Parts that were supposed to work on all A4 F-Bodies and I chose that over OEM since it was cheaper / not Polyurthane. It actually had a Poly mount on there but it rattled like no tomorrow at anything above 55 MPH
10-24-2016, 06:44 PM
#11
Just noticed that, I replaced the driverside O2 alittle while back but the passenger side O2 still needs to be replaced and come to think of it I did see alot of smoke coming out the exhaust. I actually have the O2 sensor just never bothered putting it in because I wanted to wait till I did headers but I might try this first.
Swap it......maybe thats the issue.
Could also be a worn spot in the TPS sensor since your bogging is happening at the same RPM and in 2nd gear each time only.
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10-25-2016, 08:10 AM
#12
Just noticed that, I replaced the driverside O2 alittle while back but the passenger side O2 still needs to be replaced and come to think of it I did see alot of smoke coming out the exhaust. I actually have the O2 sensor just never bothered putting it in because I wanted to wait till I did headers but I might try this first.
10-26-2016, 02:44 AM
#13
This is a BIG problem and you should do this ASAP. The O2 sensors gradually degrade over time, so you have one good one and one not-good one on the car. One is telling your PCM the truth, the other is lying, and they are fighting for attention. The car can make fine adjustments for subtle differences side-to-side, but if the PCM is getting two radically different stories from the sensors, odd things can result.
10-26-2016, 09:37 AM
#14
I recall that I had to use a wrench on that one, due to the clearances. I'm not sure I've ever used an O2 socket on this car at all, now that I think about it. (I've never replaced my post-cat sensors, where that type of socket would be most convenient.)
