Kevlo911

iTrader: (36)

Under heavy acceleration the car sometimes feels like it hits a wall. say I got wot in 1st gear, the car will feel like it hit a wall, it just stops accelerating. it can be at 3k or 4k/any other rpm. it happens under boost and not under boost. i let go of the gas and drive normally and all is well again, i can go WOT w/o problems.


Anyone experience this? I have not logged this with the EU but i dunno if it is related.



Also under WOT, when i shift, the car doesnt accel smoothly right after the shift. say I redline first and shift into 2nd, it will hang around 4600 for 1-2seconds and then start going. could this be related?

thanks

EDIT:

So the shifting thing I finally logged the weird shifting thing:

http://i17.photobucket.com/albums/b7...funnyshift.png

Don't look at the attachment, it is too small. I assuming the tires are spinning but I'm not noticing?

Flava_24/7

iTrader: (46)

What are your plugs gapped at? When I had spark plug blow out it was very similiar. It only did it at full throttle.

Kevlo911

iTrader: (36)

iirc, .036ish

I need to take um out and recheck.

OC_Nooby

iTrader: (11)

I think they are gaped way to much, you also have Meth kicking in right?

Kevlo911

iTrader: (36)

yes, but it kicks in at 2psi. it has happened premeth as well. it is random, might happen multiple times a week or once a month

Specd_out

Seems to me like its detonation. If that knock sensor picks up something it will just kill power.

Kevlo911

iTrader: (36)

well i've felt knocking, and it doesn't make it stop accelerating

Specd_out

It will signifigantly reduce power. You said it feels like you hit a wall, so i am thinking a dramatic loss in power. When I first boosted my car i detonated out of the blue, dont know why, maybe bad gas. But either way the car lost alot of power, enough to where it would go from pining you to the seat to driving like you are on a sunday cruise.

My point is this. If you are detonating, thats a huge issue and more then likely related to your problem. And you should not detonate at all if you are using meth.

I have pulled fuel up to an afr of 12.5 with 100% meth and never detonated. If you use meth and water mix and still detonate then there is a issue you may want to fix

Have you cleaned your maf, dirty maf is a common cause for detonation.

maxgtr2000

iTrader: (29)

I would log afr and timing to see what's going on. If you feel knocking you should back off. I have to alter my tune when the weather is warm around here either through the airflow map since I have slightly pulled fuel. But in the morning the car runs fine in the cooler air no problem. The ks is probably detecting knock so double check your timing.

Mad-MAX_SE

iTrader: (2)

I've had a similar sensation when my car hits "fat" spots and lean spots in the fuel curve. What's the AFR when you hit the "walls" at?

Kevlo911

iTrader: (36)

It doesn't do it all the time. When it doesn't my AFR is in the 10's/11's. No lean spots.

When it does happen, I am not lookin at the gauge. I will try to replicate it and log it. and it STOPS accelerating when it happens and i let off pretty quick.

Kevlo911

iTrader: (36)

So I did some googling and I have concluded that I likely have spark plug blow out as some of you suggested. I was gonna remove the plugs today but ended up mowing the lawn. Maybe I will do it tomorrow.

Kevlo911

iTrader: (36)

So it was likely spark plug blow out

Old plugs were not gapped right.

New plugs are gapped at .033 now. I can't go for a drive today so I will go tomorrow.

Flava_24/7

iTrader: (46)

Hopefully that solved your problems.

OC_Nooby

iTrader: (11)

Better finding it when driving on the road then at the track....That cost me some time

Mad-MAX_SE

iTrader: (2)

When I was experiencing spark blow out, I noticed a distinct change in tone of the exhaust and massive loss of power. My plugs were ~20k mile old iridium's gapped at .038, but it seemed, in my case, that I was getting spark blowout across the board. The electrodes seemed to be eroded (though I honestly can't remembner what they looked like when I installed them. I swapped to new copper plugs gapped at .036 and haven't had any issues at all since then with spark (they have a fairly huge electrode by comparison to the more precious metal electrodes available).

Considering your other thread, I would say you shouldn't have any issues anymore by normalizing the voltage.

Flava_24/7

iTrader: (46)

My exhaust tone changed as well.

Kevlo911

iTrader: (36)

updated with weird shift log

Nealoc187

iTrader: (23)

you say it happens in boost and not in boost, doesn't sound like spark blowout to me. i never experienced spark blowout when not boosting.


with regard to the lag after shifting:
where is your maf at? not just before/after turbo but how much distance between it, your turbo, and your throttle body? and where is your boost sensor located and where is it getting it's reference?

Kevlo911

iTrader: (36)

A) yea i'm still not set on that yet. I will continue to log and see if I can replicate it.

B) RMT setup, I have an Injen midpipe so the maf is is there. So there is a big distance from the maf and the turbo. The greddy boost sensor reads from the vac tube on the 00vi, it is those metal tubes(ones for pvc and the other is a vac source)

Nealoc187

iTrader: (23)

Is the lag after a shift something like in this video? I think it has to do with the difference in the amount of air that is actually entering the engine (passing through the throttle plate) and the amount of air that your ECU and emanage THINK is entering the engine at that time, given that they are metering air from a different spot (combination of your MAF sensor and the adjustments the MAP sensor are making). There is a little bit of a lag between when the rush of pressurized air from your turbo flows past your maf and MAP, and when it actually starts entering the cylinders and creating the cylinder pressures that your ECU is expecting. In that little bit of time difference, the ECU is pulling timing because it thinks more air is in the cylinders than there really is, it adds more fuel because of the same reason, etc. The result is a bit of time when your car is under-timed and overfueled, until that mass of air your turbo is flowing actually starts entering the engine.





All that being said, it was fairly rare for my car to stumble like that, but it happened on occasion. Of all the videos I have of my car, that vid is the only one in which it has that hesitation. I remember it happening only once in a while. Perhaps there is more that is going on when our cars do that. Does your car do it all the time?

Kevlo911

iTrader: (36)

Yeah, is that your 3-4 shift? It is pretty similar to that. Hesitates/Stumbles and then picks up and goes

Nealoc187

iTrader: (23)

yes but I edited my post, mine did this pretty rarely. of all the vids I have of the car going through the gears, this is the only one in which that hesitation shows up, and it wasn't so common that I thought of it as a "problem" that I needed to "figure out". Only occurred once in a while.

Kevlo911

iTrader: (36)

yea, it didn't used to do it. It doesn't last long as you can see in the eu log so prob not that big of a deal.

t6378tp

iTrader: (69)

So do you think if he either moved the boost source closer to the maf or put the maf right on the tb it would help