Jump to content
SAU Community

Recommended Posts

Hi SAU, I need your help / suggestions...

Took my car to my tuner today to get my ignition timing advanced a few degrees, (road tune only) we found that my R34GTT leans out gradually after 5000rpms, sometimes around 4500 onwards, no matter how much fuel my tuner is adding, it still does this.. I have also noticed previously that it dosen't have any top end (its constant and smooth but not 'weld-me-to-my-seat'). That was with our previous tune. We then loaded the stock R34 maps and started from scratch and it still does this even with the stock maps.

As a matter of fact, we backed off and will be taking it to the dyno next week to check if the fuel pump, fuel reg is playing up? Now the pump is a new Walbro GS3442 that was installed and re-wired not more than a couple of months ago, it has a factory sock which has a bit of play where it meets the pump. The car has the usual FMIC, exhaust, 12psi (which holds constant from 2800 onwards), cold airbox, Nistune. So I will be driving in low rpms for now hehe..

Someone please throw in your suggestions as to what could be the cause of this?? ECU retarding timing in high rpms?? We detected no knock thank god, never did, even with previous tunes.. Fuel pump?? I hope not, its the newest item on my car, and it gave me a lot of noticeable power gain after the install, more than anything else.. Fuel reg?? what what.. :(

Could it be my AFM is dirty? - its the stock one.. BTW just wanted to add that before the Nistune and fuel pump, my car was hesitating and had the flat spot at this SAME 5000rpm band - something like 4700-5700rpm - a flat spot zone, Nistune has fixed that, the flat spots gone, acceleration is smooth but theres just no power in this zone - ie I dont feel the turbo pushing me hard in my seat..stock turbo 12psi... before I could feel it, from 6000-7000rpm it felt the strongest then.. And now this leaning out from 5000rpm onwards..

Having a read here:

http://www.evoxforums.com/forums/archive/index.php/t-35897.html

one guy says:

"Don't rule out a bad sensor for your AFR guage. The last two I had fail both started reading lean by almost 3 full points. Funny thing is, they would read okay in closed loop, just not when you got on it."

another says:

"Try ur fp relay first. I seen another post with a guy using blue fpr, same problem, switched to syock, problem solved"

and the answer is:

"found the culprit it is a missing fuel freaking pump relay in my fuse box in the engine bay ! i took the horn relay and put it in the fuel pump relay and my afr was PIG RICH.

really weird and i dunno why evo x over here does not have a fuel pump relay.

been busy @ work but will load up a map and see what happens from there on.

but nevertheless i will double check all hoses again but afaik everything's tight and will do another full boost leak test.

will keep everyone posted soon."

How good to have internet and good people!.. But I still havent found my answer yet.. duh

Connect a fuel pressure and flow guage and monitor pressure and flow while its playing up.

Will save you a fuel pump if theres plenty of pressure and flow.

Also monitor response of the fuel reg - could have a hole in it and not increasing rail pressure with boost.

If he knows what hes doing, your tuner should know to do all these things without you having to find out for yourself on the internet.

One is a dampner Ron.

Need to get it on the dyno with the fuel flow/pressure tester as discussed with u. Its extremely unsafe to do this on the road.

I need to check ur install on the fuel pump. Last time this issue went after filling the tank full.

Have even loaded the fully stock factory map and the issue is still there

Ur car had the same or similar issue with ur old tuner and old fuel pump.

Wiill get it sorted for u. Just harder because u cant leave the car with me

Have heard pple sayin to check the afm, but if that was dirty, we would get less clean air into engine per unit of fuel which means its running rich, but its not, its the opp ie, running lean, dont understand this one

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • As far as I can tell I have everything properly set in the Haltech software for engine size, injector data, all sensors seem to be reporting proper numbers.  If I change any injector details it doesnt run right.    Changing the base map is having the biggest change in response, im not sure how people are saying it doesnt really matter.  I'm guessing under normal conditions the ECU is able to self adjust and keep everything smooth.   Right now my best performance is happening by lowering the base map just enough to where the ECU us doing short term cut of about 45% to reach the target Lambda of 14.7.  That way when I start putting load on it still has high enough fuel map to not be so lean.  After 2500 rpm I raised the base map to what would be really rich at no load, but still helps with the lean spots on load.  I figure I don't have much reason to be above 2500rpm with no load.  When watching other videos it seems their target is reached much faster than mine.  Mine takes forever to adjust and reach the target. My next few days will be spent making sure timing is good, it was running fine before doing the ECU and DBW swap, but want to verify.  I'll also probably swap in the new injectors I bought as well as a walbro 255 pump.  
    • It would be different if the sealant hadn't started to peel up with gaps in the glue about ~6cm and bigger in some areas. I would much prefer not having to do the work take them off the car . However, the filler the owner put in the roof rack mount cavities has shrunk and begun to crack on the rail delete panels. I cant trust that to hold off moisture ingress especially where I live. Not only that but I have faded paint on as well as on either side of these panels, so they would need to come off to give the roofline a proper respray. My goal is to get in there and put a healthy amount of epoxy instead of panel filler/bog and potentially skin with carbon fiber. I have 2 spare rolls from an old motorcycle fairing project from a few years back and I think it'd be a nice touch on a black stag.  I've seen some threads where people replace their roof rack delete with a welded in sheet metal part. But has anyone re-worked the roof rails themselves? It seems like there is a lot of volume there to add in some threads and maybe a keyway for a quick(er) release roof rack system. Not afraid to mill something out if I have to. It would be cool to have a cross bar only setup. That way I can keep the sleek roofline that would accept a couple bolts to gain back that extra utility  3D print some snazzy covers to hide the threaded section to be thorough and keep things covered when not using the rack. 
    • Probably not. A workshop grade scantool is my go to for proper Consult interrogation. Any workshop grade tool should do it. Just go to a workshop.
    • In my head it does make sense to be a fuel problem since that is what I touched when cleaning the system. When I was testing with the fuel pressure gauge, the pressure was constantly 2.5 bar with the FPR vacuum removed. When stalling, the pressure was going up to 3.0 bar (which is how it should be on ignition).
    • ECUtalk pages don't mention they support the ABS computer (consult port has more than one CAN), so you might just need a different scan tool. But, I would expect ABS is a different light to the brake warning/handbrake light, do you see an ABS light come on for a few seconds when you turn the key from ACC to IGN? But since you said: I'd have a look at the ABS sensors in the rear hubs to make sure they are not damaged, disconnected etc.
×
×
  • Create New...