Low power on fresh engine, please help
#1
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Hello! I am having a very mysterious issue on my car, I recently put a built engine into my car and have gone through the break in process. after tuning the car and increasing boost the car is making significantly less power than it should be making. I have been diagnosing everything i can think of for the past several days. Any help would be much appreciated! The car made 188whp and 196wtq on virtual dyno @14psi where the stock motor made 250whp. Along with a graph that peaks at 5400rpm and torque falls off immediately on either side of 5400rpm. Here is the setup, and some things I have tried:
The engine had a break-in consisting of:
15 minutes 2k-2.5k rpm
change oil and filter
50 miles, light-moderate load, lots of vacuum
change oil and filter
150 miles, light moderate load, lots of vacuum pulls
change oil and filter to synthetic Castrol Edge 5w-40
The engine is a bp-4w (99')
head needed to be shaved so real compression is close to 9.3:1, otherwise completely stock, cams, valves, etc..
supertech pistons 9:1 compression
manley rods
wiesco xx rings
acl main bearings
king rod bearing
arp head studs
dw200 fuel pump
630cc ka-injection injectors
using NA style cam sensor as reference sensor
48mm inducer ebay 50 trim t3 that was capable of 250whp on the stock motor
Running vics intake manifold with vics currently unplugged
Here are things I've checked so far:
Checked compression while engine was warm, all cylinders tested at 180psi exactly, using a known good otc gauge
checked base timing several times while megasquirt was on fixed advance at 10 degrees, and yes I turned it back to use table afterwards, even changed rpm while checking to ensure there wasn't spark latency
Tried two different cam sensors
I originally thought that the mechanical timing must have been off for this amount of power to be lost, and the chart to look that way. I checked for a slipping harmonic balancer, used a screwdriver to see cylinder one go to tdc, the intake cam gear had the "i" facing up, the exhaust cam had the "e" facing straight up, 19 teeth between the gears. the timing mark on the harmonic balancer was lining up properly where it should be. I even made sure the cam gears were on correctly
I even increased timing in boost by up to 5 degrees which didn't change as much as it should have
The afr all look good at 11.2-11.5 at 16-17 psi, the duty cycle is at 75%
I even increased the boost to 21psi and the car still wasn't making much power at all
I made sure the throttle opens completely
Checked for any boost leaks
no vacuum leaks in the intake system
The MAT is max around 15 Celsius and the ecu is confirmed not pulling any timing, the clt sensor is working properly
That concludes everything I have checked and looked over, This issue is beyond me at this point I have no clue what would cause this behavior. I think the only people who have a chance are possibly @Braineack @18psi I'm sure other knowable people, any help would bee much appreciated and Attached are two data logs at WOT one at 13psi and one at 20psi
The engine had a break-in consisting of:
15 minutes 2k-2.5k rpm
change oil and filter
50 miles, light-moderate load, lots of vacuum
change oil and filter
150 miles, light moderate load, lots of vacuum pulls
change oil and filter to synthetic Castrol Edge 5w-40
The engine is a bp-4w (99')
head needed to be shaved so real compression is close to 9.3:1, otherwise completely stock, cams, valves, etc..
supertech pistons 9:1 compression
manley rods
wiesco xx rings
acl main bearings
king rod bearing
arp head studs
dw200 fuel pump
630cc ka-injection injectors
using NA style cam sensor as reference sensor
48mm inducer ebay 50 trim t3 that was capable of 250whp on the stock motor
Running vics intake manifold with vics currently unplugged
Here are things I've checked so far:
Checked compression while engine was warm, all cylinders tested at 180psi exactly, using a known good otc gauge
checked base timing several times while megasquirt was on fixed advance at 10 degrees, and yes I turned it back to use table afterwards, even changed rpm while checking to ensure there wasn't spark latency
Tried two different cam sensors
I originally thought that the mechanical timing must have been off for this amount of power to be lost, and the chart to look that way. I checked for a slipping harmonic balancer, used a screwdriver to see cylinder one go to tdc, the intake cam gear had the "i" facing up, the exhaust cam had the "e" facing straight up, 19 teeth between the gears. the timing mark on the harmonic balancer was lining up properly where it should be. I even made sure the cam gears were on correctly
I even increased timing in boost by up to 5 degrees which didn't change as much as it should have
The afr all look good at 11.2-11.5 at 16-17 psi, the duty cycle is at 75%
I even increased the boost to 21psi and the car still wasn't making much power at all
I made sure the throttle opens completely
Checked for any boost leaks
no vacuum leaks in the intake system
The MAT is max around 15 Celsius and the ecu is confirmed not pulling any timing, the clt sensor is working properly
That concludes everything I have checked and looked over, This issue is beyond me at this point I have no clue what would cause this behavior. I think the only people who have a chance are possibly @Braineack @18psi I'm sure other knowable people, any help would bee much appreciated and Attached are two data logs at WOT one at 13psi and one at 20psi
#4
Cpt. Slow
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AFRs in my opinion do NOT look good, you hit 175kpa at 4700rpm (ebay turbo FTW), and your AFR is 12.2. You creep to 185kpa (ebay FTW again!), when you finally target 11s, 11.9 to be exact. But your actual is closer to 12.0-12.4. I'd add 6% fuel minimum to that row.
Your 2nd datalog looks much better, although you've increased boost from 12psi to 19psi, and you've only decreased advance by ~1 degree. I usually target at least a degree less of advance per psi. So if you're at 15 degrees at 12psi, I'd expect 11 at 19psi, not 14.
Your break in was fairly short, and I don't like the "15 minutes 2k-2.5k rpm", not sure where you heard this information, but it's bad. You have ~30 seconds to check for leaks after startup, then you should be driving with with high throttle or no throttle for 50 miles, and stay on break in oil for 500-1000, not 200.
Quite frankly, if you're making the boost you should be, your spark is where it should be, your afr is where it should be, then the only remaining factor is a rag in the exhaust or a poorly functioning engine. Try performing a leak down test, IF your break in wasn't successful, I'd expect decent compression numbers but poor leak down results.
Did the VICs runners change at all? Are they still attached? I wouldn't expect 50hp difference, but if they were in the high RPM position previously, and are now stuck in the low RPM position, that may explain some of the difference.
Your 2nd datalog looks much better, although you've increased boost from 12psi to 19psi, and you've only decreased advance by ~1 degree. I usually target at least a degree less of advance per psi. So if you're at 15 degrees at 12psi, I'd expect 11 at 19psi, not 14.
Your break in was fairly short, and I don't like the "15 minutes 2k-2.5k rpm", not sure where you heard this information, but it's bad. You have ~30 seconds to check for leaks after startup, then you should be driving with with high throttle or no throttle for 50 miles, and stay on break in oil for 500-1000, not 200.
Quite frankly, if you're making the boost you should be, your spark is where it should be, your afr is where it should be, then the only remaining factor is a rag in the exhaust or a poorly functioning engine. Try performing a leak down test, IF your break in wasn't successful, I'd expect decent compression numbers but poor leak down results.
Did the VICs runners change at all? Are they still attached? I wouldn't expect 50hp difference, but if they were in the high RPM position previously, and are now stuck in the low RPM position, that may explain some of the difference.
#5
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AFRs in my opinion do NOT look good, you hit 175kpa at 4700rpm (ebay turbo FTW), and your AFR is 12.2. You creep to 185kpa (ebay FTW again!), when you finally target 11s, 11.9 to be exact. But your actual is closer to 12.0-12.4. I'd add 6% fuel minimum to that row.
Your 2nd datalog looks much better, although you've increased boost from 12psi to 19psi, and you've only decreased advance by ~1 degree. I usually target at least a degree less of advance per psi. So if you're at 15 degrees at 12psi, I'd expect 11 at 19psi, not 14.
Your break in was fairly short, and I don't like the "15 minutes 2k-2.5k rpm", not sure where you heard this information, but it's bad. You have ~30 seconds to check for leaks after startup, then you should be driving with with high throttle or no throttle for 50 miles, and stay on break in oil for 500-1000, not 200.
Quite frankly, if you're making the boost you should be, your spark is where it should be, your afr is where it should be, then the only remaining factor is a rag in the exhaust or a poorly functioning engine. Try performing a leak down test, IF your break in wasn't successful, I'd expect decent compression numbers but poor leak down results.
Did the VICs runners change at all? Are they still attached? I wouldn't expect 50hp difference, but if they were in the high RPM position previously, and are now stuck in the low RPM position, that may explain some of the difference.
Your 2nd datalog looks much better, although you've increased boost from 12psi to 19psi, and you've only decreased advance by ~1 degree. I usually target at least a degree less of advance per psi. So if you're at 15 degrees at 12psi, I'd expect 11 at 19psi, not 14.
Your break in was fairly short, and I don't like the "15 minutes 2k-2.5k rpm", not sure where you heard this information, but it's bad. You have ~30 seconds to check for leaks after startup, then you should be driving with with high throttle or no throttle for 50 miles, and stay on break in oil for 500-1000, not 200.
Quite frankly, if you're making the boost you should be, your spark is where it should be, your afr is where it should be, then the only remaining factor is a rag in the exhaust or a poorly functioning engine. Try performing a leak down test, IF your break in wasn't successful, I'd expect decent compression numbers but poor leak down results.
Did the VICs runners change at all? Are they still attached? I wouldn't expect 50hp difference, but if they were in the high RPM position previously, and are now stuck in the low RPM position, that may explain some of the difference.
That afr is perfectly good and will make power the actual afr number can be a wide range and make no difference in power. Yes eBay turbo isn't the best but it made power no issues at all on the stock engine and it gets the job done.
In the map I have timing decreasing to around 11 degrees at 19psi, I am curious how it ended up at 14 from what you're saying. Maybe that's part of the issue?
I've looked into breaking in engines quite a bit every source says run the engine at around 2k rpm the first start until it's fully warm and then flush the oil and change filter. And I've seen all sources say accelerate at light to moderate throttle up to 3-4k rpm and let it decel down back to around 2k and that's what I did. I believe the engine is fully broken in and healthy with perfect compression across the board. The cylinder head is fully rebuilt by a very trustworthy machine shop
I don't have access to a leak down test currently and I'm confident the engine is healthy.
The vics runners are instant completely just unplugged solenoid but I will hook them up to see but I doubt it's that major of a power difference
#8
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OP needs a reality slap.
You join a forum to ask questions from folks who might have more experience than you.
When you actually hook a "big dog" like Curly (who feeds his family by working on nothing but Miatas and has for years) and he takes the time to look through your stuff and come up with his suggestions then types this information specifically for you...
For FREE, he's not making ANY money off of you.
What do you do?
You argue with him....
Had I taken the time to read your logs I probably would have come up with TOO LEAN and maybe TOO MUCH TIMING...
I didn't, I'm a busy shop owner as is Curly and just didn't care enough to take the time.
Dude, this is the recipe for disaster. You will soon be re-doing your engine build.
You have ZERO excess fuel safety net, anything happens under boost and your toast...
You should have said "Thank you SIR for your time and I will look into that shortly" even if you didn't agree with him.
You should have left him a pos-cat.
He is one of the good sources on this forum and I'm guessing he won't help you anymore.
I've been doing this **** for 40+ years, I am extremely competent, and I WOULD not call a motor good without a proper leak down test.
Don't have the tools, Purchase them, you will use them for years on everything...
They are not that expensive.
Lots of people have different ways of breaking in an engine. How you did it doesn't matter that much.
I believe 75% of the "break in" happens in the first 30 seconds it runs...
At idle...
After that try to NEVER keep it at the same RPM for any length of time. No long trips at one speed...
Up and down the range without being savage.
Staying below 75% throttle for the first 10 miles and then sending it...
Non detergent break in oil changed at the 10 mile point (and looked at under magnification for glitter) and then again at the 1000 mile point.
Curly, I just checked, the OP is 18 years old...
Do you ever get the feeling that you are wasting your time when you get a response like that?
I do...
You join a forum to ask questions from folks who might have more experience than you.
When you actually hook a "big dog" like Curly (who feeds his family by working on nothing but Miatas and has for years) and he takes the time to look through your stuff and come up with his suggestions then types this information specifically for you...
For FREE, he's not making ANY money off of you.
What do you do?
You argue with him....
Had I taken the time to read your logs I probably would have come up with TOO LEAN and maybe TOO MUCH TIMING...
I didn't, I'm a busy shop owner as is Curly and just didn't care enough to take the time.
Dude, this is the recipe for disaster. You will soon be re-doing your engine build.
You have ZERO excess fuel safety net, anything happens under boost and your toast...
You should have said "Thank you SIR for your time and I will look into that shortly" even if you didn't agree with him.
You should have left him a pos-cat.
He is one of the good sources on this forum and I'm guessing he won't help you anymore.
I've been doing this **** for 40+ years, I am extremely competent, and I WOULD not call a motor good without a proper leak down test.
Don't have the tools, Purchase them, you will use them for years on everything...
They are not that expensive.
Lots of people have different ways of breaking in an engine. How you did it doesn't matter that much.
I believe 75% of the "break in" happens in the first 30 seconds it runs...
At idle...
After that try to NEVER keep it at the same RPM for any length of time. No long trips at one speed...
Up and down the range without being savage.
Staying below 75% throttle for the first 10 miles and then sending it...
Non detergent break in oil changed at the 10 mile point (and looked at under magnification for glitter) and then again at the 1000 mile point.
Curly, I just checked, the OP is 18 years old...
Do you ever get the feeling that you are wasting your time when you get a response like that?
I do...
#9
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
OP needs a reality slap.
You join a forum to ask questions from folks who might have more experience than you.
When you actually hook a "big dog" like Curly (who feeds his family by working on nothing but Miatas and has for years) and he takes the time to look through your stuff and come up with his suggestions then types this information specifically for you...
For FREE, he's not making ANY money off of you.
What do you do?
You argue with him....
Had I taken the time to read your logs I probably would have come up with TOO LEAN and maybe TOO MUCH TIMING...
I didn't, I'm a busy shop owner as is Curly and just didn't care enough to take the time.
Dude, this is the recipe for disaster. You will soon be re-doing your engine build.
You have ZERO excess fuel safety net, anything happens under boost and your toast...
You should have said "Thank you SIR for your time and I will look into that shortly" even if you didn't agree with him.
You should have left him a pos-cat.
He is one of the good sources on this forum and I'm guessing he won't help you anymore.
I've been doing this **** for 40+ years, I am extremely competent, and I WOULD not call a motor good without a proper leak down test.
Don't have the tools, Purchase them, you will use them for years on everything...
They are not that expensive.
Lots of people have different ways of breaking in an engine. How you did it doesn't matter that much.
I believe 75% of the "break in" happens in the first 30 seconds it runs...
At idle...
After that try to NEVER keep it at the same RPM for any length of time. No long trips at one speed...
Up and down the range without being savage.
Staying below 75% throttle for the first 10 miles and then sending it...
Non detergent break in oil changed at the 10 mile point (and looked at under magnification for glitter) and then again at the 1000 mile point.
Curly, I just checked, the OP is 18 years old...
Do you ever get the feeling that you are wasting your time when you get a response like that?
I do...
You join a forum to ask questions from folks who might have more experience than you.
When you actually hook a "big dog" like Curly (who feeds his family by working on nothing but Miatas and has for years) and he takes the time to look through your stuff and come up with his suggestions then types this information specifically for you...
For FREE, he's not making ANY money off of you.
What do you do?
You argue with him....
Had I taken the time to read your logs I probably would have come up with TOO LEAN and maybe TOO MUCH TIMING...
I didn't, I'm a busy shop owner as is Curly and just didn't care enough to take the time.
Dude, this is the recipe for disaster. You will soon be re-doing your engine build.
You have ZERO excess fuel safety net, anything happens under boost and your toast...
You should have said "Thank you SIR for your time and I will look into that shortly" even if you didn't agree with him.
You should have left him a pos-cat.
He is one of the good sources on this forum and I'm guessing he won't help you anymore.
I've been doing this **** for 40+ years, I am extremely competent, and I WOULD not call a motor good without a proper leak down test.
Don't have the tools, Purchase them, you will use them for years on everything...
They are not that expensive.
Lots of people have different ways of breaking in an engine. How you did it doesn't matter that much.
I believe 75% of the "break in" happens in the first 30 seconds it runs...
At idle...
After that try to NEVER keep it at the same RPM for any length of time. No long trips at one speed...
Up and down the range without being savage.
Staying below 75% throttle for the first 10 miles and then sending it...
Non detergent break in oil changed at the 10 mile point (and looked at under magnification for glitter) and then again at the 1000 mile point.
Curly, I just checked, the OP is 18 years old...
Do you ever get the feeling that you are wasting your time when you get a response like that?
I do...
#10
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
It is possible for a turbo to make high boost with low flow.
How this is achieved is a significant restriction somewhere in the intake PAST the point your took your reading and before the intake valves.
The later super crappy VSCS (?) manifold could do this with the "cold run" butterflys closed...
Not an issue on your set up...
Suggested test for you...
Leak down (hot- this takes skill, much learning is in your near future)
Exhaust back pressure in down pipe (tests your exhaust).
Pressure tests from intake track.
At turbo discharge.
At entrance to throttle body before blade.
From inside plenum.
Those will show your losses throughout the system.
Some losses are expected...
How this is achieved is a significant restriction somewhere in the intake PAST the point your took your reading and before the intake valves.
The later super crappy VSCS (?) manifold could do this with the "cold run" butterflys closed...
Not an issue on your set up...
Suggested test for you...
Leak down (hot- this takes skill, much learning is in your near future)
Exhaust back pressure in down pipe (tests your exhaust).
Pressure tests from intake track.
At turbo discharge.
At entrance to throttle body before blade.
From inside plenum.
Those will show your losses throughout the system.
Some losses are expected...
#12
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
It is possible for a turbo to make high boost with low flow.
How this is achieved is a significant restriction somewhere in the intake PAST the point your took your reading and before the intake valves.
The later super crappy VSCS (?) manifold could do this with the "cold run" butterflys closed...
Not an issue on your set up...
Suggested test for you...
Leak down (hot- this takes skill, much learning is in your near future)
Exhaust back pressure in down pipe (tests your exhaust).
Pressure tests from intake track.
At turbo discharge.
At entrance to throttle body before blade.
From inside plenum.
Those will show your losses throughout the system.
Some losses are expected...
How this is achieved is a significant restriction somewhere in the intake PAST the point your took your reading and before the intake valves.
The later super crappy VSCS (?) manifold could do this with the "cold run" butterflys closed...
Not an issue on your set up...
Suggested test for you...
Leak down (hot- this takes skill, much learning is in your near future)
Exhaust back pressure in down pipe (tests your exhaust).
Pressure tests from intake track.
At turbo discharge.
At entrance to throttle body before blade.
From inside plenum.
Those will show your losses throughout the system.
Some losses are expected...
#15
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
You don't know how to do a leak down and most of the threads regarding this leave important steps out.
I don't really have the time but I guess it's time to make the leak down thread I have been wanting to do for some time now...
Time seems to speed up the older I get...
I don't really have the time but I guess it's time to make the leak down thread I have been wanting to do for some time now...
Time seems to speed up the older I get...
#16
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Very interesting observation I made on the way back home from napa (who didn't have a leak down tester so I'll have to buy one online) while driving I noticed the car seem to have power like it used to and felt great, but only part throttle. If I was roughly 60-70% throttle the boost that was there ~10psi felt great and like it should feel. So I'm thinking what if the VICS butterfly's are open out of boost which makes the engine less efficient and then close up In boost which then makes the turbo less efficient, possibly pushing the turbo further out of it's efficiency range at higher boost. If I was full throttle and higher boost it made less power, maybe cause like you said the restriction inside the manifold ie after the manifold pressure reading and boost gauge reading was creating a higher pressure than actually in the engine. Please lmk what you think of this theory and if it sounds plausible
#17
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I posted a long thread regarding leak down testing.
Check it out.
You shouldn't be hammering it till you diagnose your problem.
After you spend $$$ on another engine you will be more careful.
You must learn patience...
How well something is learned is directly proportional to how much money, blood, or "face" is lost during the learning process...
Check it out.
You shouldn't be hammering it till you diagnose your problem.
After you spend $$$ on another engine you will be more careful.
You must learn patience...
How well something is learned is directly proportional to how much money, blood, or "face" is lost during the learning process...
#18
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I posted a long thread regarding leak down testing.
Check it out.
You shouldn't be hammering it till you diagnose your problem.
After you spend $$$ on another engine you will be more careful.
You must learn patience...
How well something is learned is directly proportional to how much money, blood, or "face" is lost during the learning process...
Check it out.
You shouldn't be hammering it till you diagnose your problem.
After you spend $$$ on another engine you will be more careful.
You must learn patience...
How well something is learned is directly proportional to how much money, blood, or "face" is lost during the learning process...
#19
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Get rid of the VICS manifold and throw on a flat top, VICS crossover is IIRC 5250rpm stock which is right when you are nosediving for power. I wouldnt think if the butterflies are closed that you would lose that much power, and honestly at 19psi even before 5000rpm you should be making WAY over 200ftb the BP will peak tq on stock cams around 5000-5500 with a turbo thats not flow limited. When you set your cam gears the E on the intake side should be at 4 o'clock the the I on the exhaust cam should face 8 o'clock. You dont time the engine with them facing 12 o'clock. I bet your cam timing is off. double check the timing, and line up the marks to the back plate that is attached behind the cam gears.
#20
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Get rid of the VICS manifold and throw on a flat top, VICS crossover is IIRC 5250rpm stock which is right when you are nosediving for power. I wouldnt think if the butterflies are closed that you would lose that much power, and honestly at 19psi even before 5000rpm you should be making WAY over 200ftb the BP will peak tq on stock cams around 5000-5500 with a turbo thats not flow limited. When you set your cam gears the E on the intake side should be at 4 o'clock the the I on the exhaust cam should face 8 o'clock. You dont time the engine with them facing 12 o'clock. I bet your cam timing is off. double check the timing, and line up the marks to the back plate that is attached behind the cam gears.
I am going to wire up the vics butterfly's to megasquirt tomorrow and I believe my turbo may be damaged. I order parts to build a new manifold and I will buy a new turbo soon, probably Gtx gen 2 2871r.
I can check the timing again but I am very confident my cam timing is exactly right on where it should be