SR20det: Good Comp, leak and tune - no power

[Corbic]

So for the longest time my SR has run like shit. It drinks fuel, pops and gurgles at idle, won't stay running while cold and has shit throttle response.

It also feels woefully underpowered. My setup is actually a friends old set up. DOC manifold, 550cc and a t60 Turbonetics in place of his 30R. His car also had BC cams and spun 235 17R tires in first, second and 3rd.

I can't break first.

The car has been tuned serval times. Advancing and retarding the timing does nothing. Fueling is spot on.

3k mile plugs
http://i1237.photobucket.com/albums/ff467/AFZombie/48DFC321-3B6C-4CC2-8BE6-4DE5C1675A21_zpsmaciz85q.jpg (http://s1237.photobucket.com/user/AFZombie/media/48DFC321-3B6C-4CC2-8BE6-4DE5C1675A21_zpsmaciz85q.jpg.html)

I get massive blow by and some leakage out the oil cap.

Compression tests on two separate Gage's when warm was 155psi. The second gage need to have the engine cranked longer to get there.

Leak down test was 4-6%. We did it 5 times with 3 different methods.


All the symptoms indicate low compression. There is no boost leaks or vacuum leaks. The turbo was brand new and is still in great shape. Oil is clean. Coolant is clean. The car does not appear to burn oil.


WHAT THE FUCK!



http://i1237.photobucket.com/albums/ff467/AFZombie/E10254D2-728B-4A22-A4CA-D05CCC07A265_zpsudqlur7o.jpg (http://s1237.photobucket.com/user/AFZombie/media/E10254D2-728B-4A22-A4CA-D05CCC07A265_zpsudqlur7o.jpg.html)

[Loufig]

your blow by set up is wrong

[jr_ss]

Have you pulled codes? Tested any of the sensors to see if they are within spec? I'd start there and work your way up or down the list. It could be your knock sensor putting the car into limp mode.

[e1_griego]

Are the AFRs rich? What are you tuning with?

[Corbic]

Have you pulled codes? Tested any of the sensors to see if they are within spec? I'd start there and work your way up or down the list. It could be your knock sensor putting the car into limp mode.


Knock sensor disabled.
O2 works perfectly

[Corbic]

Are the AFRs rich? What are you tuning with?


AFR 11.6 at full boost, 21psi

Moates daughter board, and we synced trigger offset (set timing with timing light)

[e1_griego]

Replaced the CTS?

[ThirtyTwo]

All sensors are verified to be reading correctly via consult datalogging.

[Corbic]

Next theory is the timing chain could be stretched and letting the intake run a few degrees retarded.

[Corbic]

Replaced the CTS?


Was 2 years ago. S14 sensor.

[e1_griego]

Well if it's verified reading correct, then carry on. I've found that sensor causes more problems than any other.

[ultimateirving]

What's up with that picture ? Is that how your pcv system is running currently? And can you describe your symptoms with more detail. Is it bogging Popping bucking slow to rev sluggish?? As much description as possible

[Corbic]

What's up with that picture ? Is that how your pcv system is running currently? And can you describe your symptoms with more detail. Is it bogging Popping bucking slow to rev sluggish?? As much description as possible


That's the engine pulled apart....seeing it's missing the fan and has a compression testing rod down the spark plug tube.

The PVC system vents that wrapped tube straight down in front and straight back into the block on the rear.

The other side (injectors) is blocked off.


Originally the car would die upon hard acceleration then lift. Drive fast, go into neutral, RPMs drop.....to zero.

Das Tunzer recoded the fuel cut, which also eliminated the warm up cycle - so the engine won't stay running without holding the throttle till warm.


As far as idle. It hunts from 500-900 but stays around 700-800 most of the time. It's more or less rhythmic. Yes, we've fucked with the throttle body and IACV.

It pops. Soft puffy random pops at idle.

Off boost it's a dog. Boost won't come on gradually either. It's 930 Porsche shit.

Boooooooog 3,500rmp Boost! 5,600 rpm nooothing!

7-15psi pulls good but 15-21psi adds nothing. The car has no low end and no high end. It also won't break tire traction even dropping the clutch, it just bogs

Driving slow (parking lot) the car wants to just die. Lifting off throttle when in boost basically feels like you slammed on the brakes.

[e1_griego]

Did it ever run correctly? Before you put the big turbo on?

[ThirtyTwo]

not really. Was a slow ass pig on the stock turbo too. Re-tuning stock setup for more boost netted no gains and idle was shit then as well

[jr_ss]

Corbic, what are vac numbers like at idle? Are we talking 15-17 or 18-20? Assuming stock cams and internals? MAF voltage readings? Check your MAF ground and plug/wires for cracked and or frayed wires. Wiggle it while the car is running and see if it changes things. My Nissan pickup would go from running great at idle, to dumping fuel and wanting to die at idle when that plug/harness was touched.

[OBEEWON]

What cams are they? If they are the 272's that is your problem.

[ThirtyTwo]

The "Originally the car would die upon hard acceleration then lift. Drive fast, go into neutral, RPMs drop.....to zero" issue was due to the big turbo spinning after you would rev up and let off. This would cause the maf to continue reading air and make it run rich for a second which would make the engine die out. This is a common issue with draw through MAF big turbo setups.

I wrote some custom code to limit the MAF when at 0% TPS which fixed the issue but caused issues during warmup because it needs more fuel during warm-up. But I can fix this no problem, I just need to adjust the limit value.

[ThirtyTwo]

MAF is good and is logging the correct voltages, brand new harness.


Cams are stock

[Corbic]

What cams are they? If they are the 272's that is your problem.


Stock cams

[maverickmotorsports]

Few things I'd check.

Leaking injectors, you might be tuning around the problem if that is the case
Running out of injectors up top? With E85 + 550cc and 21psi it might be the case.
Clogged PCV valve?

[Corbic]

Corbic, what are vac numbers like at idle? Are we talking 15-17 or 18-20? Assuming stock cams and internals? MAF voltage readings? Check your MAF ground and plug/wires for cracked and or frayed wires. Wiggle it while the car is running and see if it changes things. My Nissan pickup would go from running great at idle, to dumping fuel and wanting to die at idle when that plug/harness was touched.


Z32 MAF

Wiring Specialties harness.

Stock S13 Redtop (gen 1)

[ultimateirving]

You said you verified sensors via consult and datalog. I assumed the tps voltage was linear and had no dead spots. Also why are you venting the crankcase? The front of the T need to go to the suction pipe after the maf

[ultimateirving]

Few things I'd check.

Leaking injectors, you might be tuning around the problem if that is the case
Running out of injectors up top? With E85 + 550cc and 21psi it might be the case.
Clogged PCV valve?

I don't think he's running e85
And 550 cc is definitely too small for 20 psi on e85.

[Corbic]

I don't think he's running e85

And 550 cc is definitely too small for 20 psi on e85.


We tried E85 at 15psi but fuel economy was in the single digits an advancing the timing did nothing.

So we went 93 and maxed out psi with safe afr. It was up to 24 psi but 21-24 made not difference other than maxing the injectors.

[ThirtyTwo]

Venting crankcase to the ground because he doesn't have a catch can. It's not going to cause any issues, the pcv valve side is blocked off so it doesn't pull in un-metered air.

Injectors are 750cc, it was tuned on pump gas as well as e85 but at a lower boost on e85 because injector duty cycle was getting too high at higher boost.

[maverickmotorsports]

I'd start with the basics.

Load a stock rom and adjust for 550cc, Z32maf rescale, and then scale the master fuel trim for E85(~30% extra IIRC).

Start the car and see how it idles. Then adjust the master until you get a good afr. If you're adjusting it a bunch then you probably have a problem elsewhere and should look at the mechanical before continuing to tune the problem away.

Also, venting the valve cover like that won't cause the problem. It's not ideal but it won't make a difference.

[ultimateirving]

Venting crankcase to the ground because he doesn't have a catch can. It's not going to cause any issues, the pcv valve side is blocked off so it doesn't pull in un-metered air.

Injectors are 750cc, it was tuned on pump gas as well as e85 but at a lower boost on e85 because injector duty cycle was getting too high at higher boost.

Yea I can see the 750s getting maxed pretty quick with the ethanol.

I had issues from plugging pcv in the past. Not to this extreme but it's not something I would leave plugged

[ThirtyTwo]

What issues did you have? Only the vacuum tube between the intake manifold and the pcv valve is plugged, this is required when venting the crankcase to atmosphere or else the engine will pull in un-metered air and idle like shit.


The tune settings are very similar to another SR build that I tuned that made over 400whp and most of this car's setup is from that car.

[ultimateirving]

Some wierd whining noise coming from the head near the turbo. After rerouting my pcv lines it was corrected. I been running e85 on a rom tune for a few years now. Gas mileage is consistently 17mpg on 850cc injectors.

Going back to what you said about single digit gas mileage something is definitely not right if your wasting that much fuel.

[Corbic]

So my buddy got his hands on a fancy cam indexer rig.

Sure as shit - intake cam is 2.5-3 degrees advanced and the exhaust cam is 30 degrees retarded of TDC.


They visuals on the cam gears look right (stud placement in proximity to each other).

[Def]

That'll do it. Do you have the proper number of links between the cams? Doesn't sound like it.

[Corbic]

That'll do it. Do you have the proper number of links between the cams? Doesn't sound like it.


That's the damning thing. While we did recheck it, when we examined it the last time the cam gears appeared to be set correctly.

Might be something wrong with the cam itself.

What should RHD exhaust be at. 5 degrees?

[Def]

This should help:

http://www.frsport.com/Installing-Tomei-Poncams-on-S13-SR20DET_t_35.html