Car is finally on the dyno, but ran into issues in higher boost. Need input

After two years, I finally got my car back together and running pretty well. Took the car into FSR to have them put in the ProEFI 128 ecu and give it a tune. It sounds like the 91 octane tune went fine staying conservative and getting to 19psi where I told them to stop and switch to e85. The car put down 300whp at waste gate 7.5psi and 390whp at 12.5psi on e85 (70% ethanol content was what the sensor measured).

Mods.
-Pro EFI 128 w/ ethanol sensor and dual wideband setup
-Billet DR-650 Turbos w/Forge wastegates and green springs
-Ported heads(no idea who ported) and high rev kit
-Adjustable cam gears - Zero'd with degree wheel
-HKS DLI
- MSD Spark plug wires
-Walbro e85 pump - Hotwired
-FIC 1100CC injectors
-8AN fuel and return lines
-Fuel lab FPR
-Generic intake w/ maf deleted
-Greddy type-s bov
-RPS Max 6-puck clutch
-Bellhousing brace
-3sx downpipe
-Maximal Performance High flow cat
-Maximal Performance solid motor mounts.

Here are the issues that was emailed to me:


-The IAC motor seems very slow to respond. Maye it is just dirty or maybe it is on its way out. It has been working less and less well over the last few days.
- I suspected an issue with this after initial startup. Cleaned and it seemed to go away. Looks like it needs to be replaced now

-The rear bank is requiring about 5-7% more fuel, and the differential gets bigger as boost is going up which is why we don't want to push it more.
- Before getting on the dyno, they were trying to locate the source of an exhaust leak in the rear manifold. Could not be isolated. I gave the go ahead for tuning.

-Boost comes on nicely early but falls off drastically without tons of extra wastegate duty cycle. These cars all do that... but this one does it excessively and requires a lot of wastegate percentage as rpm gets past 4000 to keep any boost on the motor; this is indicative of a breathing issue, usually on the exhaust side.

-IAT's are getting to about 200* and the proefi is pulling timing to try to save the motor. E85 helps to cool things down a lot and IAT's will be high with small turbos but not this high. There could be a boost leak only under high boost that we are not seeing with all that stock piping in there

-The y-pipe keeps blowing off anything above 18psi
- Ebay Y-pipe :( Never had issues when running my 13g's. Will upgrade now.

-At high RPM, the dyno shows something is holding up. At low boost we can pull clean to 7k, but with boost on the motor the air fuel starts to get erratic and you can also see on the dyno graph that something isn't holing up. The most likely causes would be excessive backpressure or something in the valvetrain. Below 5krpm it does not seem to be an issue, even with lots of boost such as 25psi


Any thoughts on what could be causing these issues? Car is still on stock bottom end, intercoolers, and catback exhaust. I have not received the dyno charts yet, but will post them up when they arrive. Thinking about replacing all the rubber intercooler lines with silicone lines or moving to an FMIC. I do have a test pipe that I can throw on next time to see if it helps with the back pressure as well.

Andrew

I would put better intercooler there. Who set your timing? If the car is at FSR then they should be able to locate the issues. Also it's a good idea to find out who ported the heads. Make sure the heads are ported equally or atleast pretty close. If the timing is set right it might be your rear head flow a bit better than the front ones. You don't want to have one head flow better than the other. This is the reason why I went with IPS CNC heads because I know both heads and each ports are flowing equally. What o2 housing are you using? Are you using factory ungutted o2 also? I would also check to see if both turbo wastgates are opening equally. If your rear turbo's wasgate open more or sooner than front that could cause issue and act like exhaust leak and running leaner on the back and your boost drop.

Quote:

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Originally Posted by mehrshadvr4

I would put better intercooler there. Who set your timing? If the car is at FSR then they should be able to locate the issues. Also it's a good idea to find out who ported the heads. Make sure the heads are ported equally or atleast pretty close. If the timing is set right it might be your rear head flow a bit better than the front ones. You don't want to have one head flow better than the other. This is the reason why I went with IPS CNC heads because I know both heads and each ports are flowing equally. What o2 housing are you using? Are you using factory ungutted o2 also? I would also check to see if both turbo wastgates are opening equally. If your rear turbo's wasgate open more or sooner than front that could cause issue and act like exhaust leak and running leaner on the back and your boost drop.

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If it was wastegate tension the afr would equalize at target boost and the boost would overshoot and undershoot on the log.

I might recommend you smoke test the exhaust and the charge piping to your target boost pressure. Make sure you turn the engine over by hand to a closed intake valve position for positive pressure and vice versa for the exhaust side. Also make sure you test when the engine is warm. There might be a slew of things to fix regarding couplers, clamps and intake seals. If you find no leaks then pull the injectors and see if they're clogged.

Disable the IAC on the EFI and see if you can lock it out. Log it locked and then unlock it and log it. Compare the voltage vs duty vs rpm vs idle correction. Also compare with your interpolating tables and look at timing with idle. Timing plays a big part in smoothing idle. You don't want a big overshoot like +/- 10° based on IAC and MAP in your idle controls.

I'm suspecting you are trying to diagnose, isolate, and correct these issues to avoid shop time expense? These are things FSR can give you answers for...?

Yes the car is still at FSR, but it has been there for a good amount of time and I would like to take it home to give a good washing. I really don't have a problem with them doing the work, but they do seem pretty busy. It seems like I need to reverify some things on my part though. I have the oval pressure tester and whenever I started to go above 17psi or around there, the adapter would start to lose its seal. This should also be a good time to test the drivability out on the street and report any issues when taking the car back. I did the timing myself and zeroed the cams with a degree wheel. I checked multiple times over a few days while the engine was on the stand.

The heads were purchased on the forums used a few years ago and the owner is no longer on the boards. If I remember right, he ended up taking a sledghammer or something to his car. When I returned from my deployment, I finally got to take a look at the heads. They were in shitty packaging and got scratched up on the mounting surface. I had a shop take apart the heads and do repair. They found sand and some other crap in the galleys. After the repair was done, everything checked out to be good. Very dissappointed though lol.

I am also thinking that since black friday is coming up I can find some good deals on things, but the last thing I really want to do is throw more parts at it. He has mentioned since the start of the tuning that there is a lot of backpressure in the exhaust. I have the stock precats, but both have been gutted. I do have the Maximal performance high flow cat though. I may bring my test pipe up when I bring the car up to do a comparison.

Hopefully I will be able to get some of the dyno graphs today to post.

Just got off the phone with Ian. He said the problem only exists with high boost and high rpm. low boost and high rpm it is fine. High boost low and mid rpm is great and makes a lot of torque. He is thinking either possibly a weak valve spring or lifter possibly. Something mechanical. Any thoughts? Other than that the car runs great on 91 octane and e85 at lower boost.

Attached some quick snapshots of some of the dynos

Yeah get rid of the cat and see how the car reacts.

As already mentioned. Throw on a test pipe and see what happens. Also sounds like you are on stock side mount intercoolers. If you haven't removed and cleaned inside thoroughly they are probably full of oil from blown 9bs at some point in their life. Cheap CXracing FMIC would be a good upgrade though.

FIX YOUR LEAKS. Pre turbo exhaust leaks can kill your spool and power. Intake leaks kill your turbos efficiency. Nothing wrong with an eBay y pipe. Just make sure your coupler is the right size and your clamps can be tightened down good. Order a new silicone reducer if you need to.

Ninjaperformance has IAC in Black Friday sale for $50. Buy one :D

Hairspray will help with keeping couplers on.

^this!