Well as a lot of you know, my car was in bad shape a few months ago. I got it shipped up to Buffalo and Viper fixed her all up. The car runs great now, cant complain at all.

Only problem thats still there is the cut off or brick wall at around 4k rpm under full throttle. When that happens the car leans out. Alex and I have been thinking what it could be, we've ranged it down to a few things: 1. needs to be tuned 2. transmission 3. if knock sensor is present, engine detects knock and cuts off the fuel.

However, when manually shifting the autotragic, under full throttle it works okay..leans out but thats most likely because Im probably hitting 7psi (dont know exactly because my boost gauge is f'ed up).

So we are leaning towards the tranny being the problem. Maybe the automatic cant handle the boost? The tranny isnt bad..ive had this problem ever since I got the turbo.

Any ideas?

An auto to manual swap is looking good right now.. cool.gif

 

swift,

just a couple of questions here before we blame the autotragic...

- what fuel management are you using right now?
- stock injectors or larger ones?
- upgraded fuel pump?
- do you have a wideband o2? if yes, can you confirm that there is a lean point before it "hits the wall"?

1. If you have a fuel management system, you'll need to tune it.
2. I don't think it's the tranny
3. The ecu doesn't do fuel cut off when it detects a ping, it will only retard the timing back quite a bit

 

Where have YOU been?

This has been a problem for everyone that has boosted their car. It's the stock ECU cutting the fuel. The only way around it is to go completely around the ECU and supply the fuel yourself. There are several options for doing that.

Let me give you an example on how bad the problem is. I have 42lb injectors. I've bumped my fuel pressure 10psi higher on idle, then set the SAFC from different points of 0 to even +50%. The car will STILL lean out.

Stock ECU = dogshit.

 

isn't Airborne supplying new ECU's? haltech? damn swift that's going to cost you some sweat. anyways keep looking up, you're almost there.

 

JonGTR...I dont knoq where Ive been lol. I dont think Ive ever read that this happens. I guess my head was too far up in the clouds at one point..

Jay..I have a wideband o2 so I definitely can confirm it leans out. Only fuel management I have on there for now is the 190 fuel pump. Planning to put the aem fpr in this week and possibly install the injector spacer kit.

Idk what to really do..if I put in the smt6 and tune it will it help stop it or does a new ecu sound like a much better plan in the long run?

 

wow... all you have was the fuel pump? this was the dsm one you had for a bit? if it is... it is not quite a 190lph fuel pump... but will flow way more that stock.

with just that mod, of course you WILL be running lean... although your fuel flow is better because of a larger flowing pump, the stock injectors are so very limited on what they can do; especially without any fuel management like a device that will "trick" the maf signal (safc or smt-6, etc) or even a fmu to increase the fuel pressure in order for the injectors to push more fuel.

right, now i suggest not boosting while you drive until you get the proper stuff in place.

as far as the aem fpr... if you are using just a 190lph or even the dsm fuel pump, you won't need it. those pumps don't create enough flow to overrun the stock fpr.

stick with the smt-6 and the secondary injector setup, maybe even coupled with a device that kicks the ecu's behind into open loop on the your command, through the smt-6. i have been running that setup for quite a bit now and yes, it works very very well for me.

 

Well I dont know if the car not being tuned is the main problem.

Alex has pretty much the same setup as me, not tuned either, except he has a 5 speed tranny and his car is fine. No lean conditions like mine ever (of course he may get lean conditions but you know what im saying)..he can go to redline if he wants on full boost. So it also doesnt make sense that it can be my ecu unless mine is f'ed up..because alex's is the same, only difference is his tranny..

Not being a pest but those two things dont really add up right now..

 

doesn't he have an fmu; to raise the fuel pressure as the boost increases?

oh btw, with the setup you actually have on your car right now, your max boost should not be more than 4 psi... and anything more will make your car so lean that it will feel like you are "hitting a wall"... i've been there!!!

 

Actually one time Ive boosted 6psi lol right now like I said before its unsure how much Im boosting cause my gauge is off. I know itd help a lot. When Im on cruise, doing about 66 mph (exact i know lol) my afr was around 15.4 to 16.1..might not matter since i wasnt boosting but might help.

No Alex doesnt have the fmu hooked up..gave him problems because he didnt have the fuel pump installed etc.

Do we have knock sensors in the RD?

 

yes, we do have a knock sensor for our cars... as i have told you.. when the ecu detects a knock or a ping, it will retard the timing which in turn will make you lose power

afr that you have mentioned when cruising is not really relevant because you are still in the close loop mode and there is no boost

as for the boost guage, you might wanna invest in a new one that works and is accurate... this is one of the important components of being boosted, but for estimating what is the actual boost you running at the moment; i can't recall your setup but,

- if you have an external wastegate, what is the rating of the spring? if you have an internal wastegate what is the psi rating/setting of the wastegate actuator?
- do you have the vacuum/boost line hooked up directly to the wastegate or do you have a boost controller inline?