CHEROKEE XJ WITH AW4 TURBO PROBLEMS

[Jposses]

hello:

i build a xj turbo automatic with AW4...
the engine works well...the AW4 work extremelly good¡¡

but in hte mid range and mid boost the engine apear to keep lean and produce injection cut...i low the gas pedal and the engine start to work good...at hich revs there is no problem...

The Xj is 2000 and the ECU is a normal OBDII OEM without any mod...

Somebody know something about?

 

[stroked88]

search for brysons write up on his turbo set up. did a really nice job
http://www.naxja.org/forum/showthread.php?t=1031285 here ya go

 

[Jposses]

thanks...incredible thread

 

[Boostwerks.com]

Thanks man. But yeah, you definetly need some form of engine management. How are you retarding the timing? Do you have access to a wideband O2 to see what air/fuel ratios your getting? You'll need at least a 12:1 AFR in boost to be safe, and .75 of a degree of timing pulled for every pound of boost.

 

[Jposses]

Thanks man. But yeah, you definetly need some form of engine management. How are you retarding the timing? Do you have access to a wideband O2 to see what air/fuel ratios your getting? You'll need at least a 12:1 AFR in boost to be safe, and .75 of a degree of timing pulled for every pound of boost.

the AFR under boost is 10.5 i runnig 27lbs fuel injectors and a vortech 12.1 FPR....now know is not the best way to adjust AFR but as you say is safe...my xj have a GT35 Turbo and is setted via WG to 7PSI of Boostt...now i cant not retard the timming...the ECU do everything and also as title the thread produce some injection cut under mid range RPM and mid BOOSt...i mean...when the engine are pulling 3.000RPM and i slow press the gas pedal the engine cut the ingection o just the mix is so lean that the combustion is not enough and also the wideband goes to 16 and more....i know that is the problem but how i fix that...i try a Apexi...its a nightmare....i know a lot of friends using Megasquirt (megashit) and evry single in some moment broke his engine because mega problems....

now when i pull WOT the engine are stronger..no fuel cut and also very responsive aceleration....

the aem F/ic is really impresive but i dont know how it works and what is the main features¡¡¡

give me a hand Bryson...also your work is extremelly good¡¡¡¡¡¡¡¡

sorry for my basic english but iam from chile south america¡¡¡

 

[Boostwerks.com]

Your going lean under part throttle because the ECU is still under closed loop and trying to target a 14.7:1 AFR using the narrow band sensor. This is where the AEM FIC really shines. It can adjust the Narrow bands input into the ECU so the ECU will think it's gone lean, and allow you to enrichen the low load/closed loop portion of the fuel map. This is honestly the ONLY way to keep the factory ECU and prevent going lean under low load.

You also really need something to retard the timing. I highly reccomend the AEM FIC, but the MSD BTM will work as well (eventhough the BTM is almost as expensive as an entire FIC setup and all the BTM does is retard the timing). Your running fairly low boost on a low compression motor, so preignition is probubly not all that noticeable, but I can assure you that the damage will add up over time if nothing is done.

Megasquirt is great when done correctly, but for 99% of people out there it's just too complicated, and will result in more problems than it solves.

I'm more than happy to help out where I can. Again, I love my AEM setup and would even be able to send you a base map that should allow you to get to the point of fine tuning. It's also A LOT easier to wire in than a megasquirt!

 

[Jposses]

Bryson...i really apreciate your help..

i have some questions??

if i go for AEM FIC i need to change the fuel inyectors?? i have 27LBS fuel inyectors???

also if i install the aem i need to eliminate the FMU??

now i really want to install the aem... i need to learn somethings and also i need some help about the installation?? so give me a hand with this¡¡¡

what is the best aem model to my 2000 xj?

 

[Jposses]

Bryson...i really apreciate your help..

i have some questions??

if i go for AEM FIC i need to change the fuel inyectors?? i have 27LBS fuel inyectors???

also if i install the aem i need to eliminate the FMU??

now i really want to install the aem... i need to learn somethings and also i need some help about the installation?? so give me a hand with this¡¡¡

what is the best aem model to my 2000 xj?

Bryson The aFR are goin over 17....normally the AFR work on 10.2 - 10.6 wich is normal....i thnik in 3 posible problems....firts the FMU not work properly...second the adittional fuel pump is mad and the last is a problem with the fuel injection and if is this the problem coul you help me??? the aem is a excellent way but i dont know if work good if present some troubles....please give me a hand...