Hey guys, Yesterday i was driving and when i put it to full throttle in any gear, it feels like there is a rev limit at 4500-5000 rpm, and i cant go past it. I had this happen before, so i replaced all the cheap vacuum lines that came with the kit, and it fixed it for a while. And now its happening again?
Some thoughts were the auxilary pump but is there a way to check if it is working?
And i dont have easy access to a dyno so quick fixes would be really helpful. I dont know if its the vacuum lines again? and i havent played with the R4 software at all since i got it tuned a while ago either.
Any ideas?

 

If you can find a dyno check AUX pump pressure with gauge. At 3000 rpm's should show 55 psi. At WOT, should climb to 100 psi and hold. If this was a "new" install I would say check the positive and negative wires on the AUX pump. They might be reversed. In your case, one might be loose.

 

I was thinking about replacing all my vacuum lines again, except this time with high grade fuel lines. Maybe that will solve the problem....In the mean time, anyone have any more ideas??

 

I would think it would have to do with the fuel pump also . Check wires for power and ground .Is your installer near by ? Call and take it back to them...they will have a good idea where to start looking for the problem

 

Yeah my installer is near by, and you are talking to him...lol...i will check my fuel pump wires when i change my vacuum lines today...if this works, ill keep you guys posted...

 

well then you got a good idea what to check....lol.....good luck...hope you find the problem

 

well, i replaced all the vacuum lines and checked the aux pump wires. Everything looks good, but i still have the same problem...the only thing i can think of now is that my R4 software got erased or something???

 

Do you have the R4 software and your original customer file?

--Steve

 

Speaking of r4 software, does anyone have the stock/original 2003 g35 software file?

 

Can you hook up to the ECU with a laptop ? If so...you can hook up to it and read the ECU , and see if any thing has changed . On the fuel map...in the upper left...it has 2 boxes...put your curser on them....one says ....write to ECU and the other says ...read ECU...click on the Read ECU and it will pull it off the ECU .....good luck...Bill

 

Does it only "feel' like you can't rev higher than 4500-5000 or will the motor actually rev higher than that? Will it rev higher than that at idle? Have you checked the Aux. fuel pump fuse? I don't see any gauges listed in your mods. I would suggest a wideband at least and for this problem a fuel pressure gauge.

 

Gauges, Gauges, Gauges! Get yourself a fuel pressure gauge, they're not that expensive and it will save you loads of wondering and headaches. I had a fuel pressure and boost combo, then opted to add a wideband and move the fuel pressure gauge to the engine compartment. You should only need the pressure gauge if you have a problem. Get a gauge and know what your engine is doing.

 

Good observation! It appears to be a Vortech SC fuel pump issue. Doesn't appear to be coming on. If it is wired correctly, the fuze might be the problem.

 

ok, i found the problem. the vacuum line that runs out from the R4 box sits under the battery cover guard, and when the hood closes, it pinches the vacuum line together which restricted the flow. I routed it a different way and now the car runs fine!
As for gauges, tomorrow i am going to get the HKS C.A.M.P system and wire it into my dvd screen. This will read boost, EGT, and a few other stats...Ill post pics of the HKS soon....