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Help tuner says mechanical problems and engine builder says nothing is wrong
Ugh how to start this well I will post my tunes, dyno sheet and data logs for one. So the car seems to be breaking up at the higher rpm range. I have the Brutespeed forced induction cam, Siemens Deka 60# injecttors, return style fuel system with a boost referenced fpr and other mods in the sig. The tuner (after about 4-5 times taken to him) says that it was the same problem since day one when he started tuning it. What changed overtime was the return fuel system, Moser 9", transbrake but the same issue happening at high rpm. I was told that it could be one of two things and 1 being spark blow out and 2 being valve float. I have .650 lift springs in the heads with them and the motor being assembled at ERL. I was running TR6s and switched to BR7s and the same issue. The problem only shows up on the dyno graph when it is getting tuned btw. The other problems that I have is when cranking at times it will act like it wants to die then pick up and run and others it will die and start up just fine. While normal driving, it will feel sluggish from starts or hesitate to go when stepping in it and also feels like it wants to stall when slowing down. I can't think of anything else to put at the moment but if anymore information is needed I am willing to get it out there. I just want to get this issue solved because it has been on going for about 7-8 years now. Thanks for any input.
I don't know that I'd go so far as to say it's all in the tune, but there is some weirdness in the tune:
* The VE table is a mess. The lines are criss-crossing and jumping all over the place instead of smooth transitions.
* THe dynamic airflow is set up for MAF only, but the tune is SD. Could be causing it to fight itself.
* Transient Fuel min fuel milligrams needs to drop to 0.010. That's kind of tuning 101 for larger injectors.
* Injector flow rate data is effed. Typically is not the same value in every field. Also, 60 lb injectors flow closer to 75 at LS pressures, not 60.
Now, one observation on the mechanical side:
* Your map readings at WOT under 3500 rpm are low. Maybe that's normal for a turbo, maybe not, but all of mine at low RPM show near atmospheric pressure at WOT. Might be worth looking for an intake blockage.
* I cannot see in the logs if there is any valve float, but it does seem like power is peaking early. Have a dyno graph to post?
* Edit - if you suspect valve float, your sig does not mention pushrods. If you are running stock pushrods, get some 11/32 from manton
Yes I have pushrods as I had to go with different ones because I was running a 2002 ZO6 cam that got chewed up. I will check to see if there is a blockage also thanks for a starting point. *edit* I thought the dyno graph was downloaded with all the rest of the stuff. dyno that is rough at the top and not sure if it matches any of the logs
Last edited by The Fugitive; 10-03-2018 at 10:43 PM.
Reason: forgot to attach the dyno graph
Yes your tune is very rough and needs help but it's not causing that dyno graph that's for sure, that's valve float or a spark issue guaranteed. The driveability issues are in the tune however.
You can try unhooking the charge pipe to determine whether or not its valve float.
Spark blow-out N/A is very unlikely, so if it does it still, its likely valve float.
I'd recommend a smaller cam either way. Tuning for a large cam N/A is typically harder than tuning boost with a smaller cam. Combining them will test your tuners abilities.
Yes your tune is very rough and needs help but it's not causing that dyno graph that's for sure, that's valve float or a spark issue guaranteed. The driveability issues are in the tune however.
That was the graph before the spark plug change. He didn't give me anything for after it was changed just said the issue was there. As far as the logs show the RPMs never falls off and a steady line to redline or until he gets off of the gas. Wouldn't valve float cause a dip in RPMs?
You can try unhooking the charge pipe to determine whether or not its valve float.
Spark blow-out N/A is very unlikely, so if it does it still, its likely valve float.
I'd recommend a smaller cam either way. Tuning for a large cam N/A is typically harder than tuning boost with a smaller cam. Combining them will test your tuners abilities.
So would it be best to have him fix the issues above with the tune and then try it out or just do the charge pipe first?
That was the graph before the spark plug change. He didn't give me anything for after it was changed just said the issue was there. As far as the logs show the RPMs never falls off and a steady line to redline or until he gets off of the gas. Wouldn't valve float cause a dip in RPMs?
No.
Originally Posted by The Fugitive
So would it be best to have him fix the issues above with the tune and then try it out or just do the charge pipe first?
Do NOT disconnect the charge pipe and try to make a pull unless you want to potentially hurt the turbo in the process.
Do NOT disconnect the charge pipe and try to make a pull unless you want to potentially hurt the turbo in the process.
What else is a sign of valve float? I thought once it floats it won't recover? Also the guy at the tuning school on youtube said it would show in the rpms
what coils are u using? What are u gapping your plugs at? what gas? verified fuel pressure etc.
Using the truck coils, the plugs are gapped at 25, the highest gas off the street I can get is 91 and fuel pressure is 58 when the vacuum is off the fpr. I have 2 walbro 255 in tank. Fast fuel rails -8 feed and using the stock feel as a return. Meth hasn't really been tuned in but is set to come on at 10psi and full at 15psi.
10-03-2018, 02:27 PM
Help tuner says mechanical problems and engine builder says nothing is wrong 
